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The Belt and Road Initiative proposed by China has significantly increased trade in countries along the Belt and Road (B&R). Since most of these countries are developing and emerging economies, the pressure to reduce carbon emissions poses a leading challenge for them. Carbon productivity has become a key indicator for assessing the degree of low-carbon development, as it can link economic development with CO2 emission reduction. However, few studies have investigated how international trade affects carbon productivity. Based on panel data from 43 countries along the B&R during 2001–2019, this paper uses a system GMM model to explore the impact of international trade on carbon productivity. Then, we divide the 43 countries in the sample into two groups according to their income levels to compare the different effects of international trade on carbon productivity. The results show that, first, the carbon productivity of the examined B&R countries has an overall increasing trend, and there is a significant heterogeneity of carbon productivity among countries with different income levels. Second, the effects of international trade, export, and import on carbon productivity are all significantly positive, and export's effect is higher than import. In the high-income group, carbon productivity is more likely to be improved by trade than in the middle (low)-income group. Third, economic development level, urbanization, and energy productivity are positively associated with carbon productivity, while CO2 per capita and government size inhibit carbon productivity improvement. Insight into the impact of international trade on carbon productivity provides theoretical support for B&R countries to better leverage foreign trade activities to achieve a green economy. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal inoculation can promote plant growth, but specific research on the difference in the symbiosis effect of arbuscular mycorrhizal fungi and plant combination is not yet in-depth. Therefore, this study selected Medicago sativa L., Bromus inermis Leyss, and Festuca arundinacea Schreb., which were commonly used for restoring degraded land in China to inoculate with three AMF separately, to explore the effects of different AMF inoculation on the growth performance and nutrient absorption of different plants and to provide a scientific basis for the research and development of the combination of mycorrhiza and plants. We set up four treatments with inoculation Entrophospora etunicata (EE), Funneliformis mosseae (FM), Rhizophagus intraradices (RI), and non-inoculation. The main research findings are as follows: the three AMF formed a good symbiotic relationship with the three grassland plants, with RI and FM having more significant inoculation effects on plant height, biomass, and tiller number. Compared with C, the aboveground biomass of Medicago sativa L., Bromus inermis Leyss, and Festuca arundinacea Schreb. inoculated with AMF increased by 101.30–174.29%, 51.67–74.14%, and 110.67–174.67%. AMF inoculation enhanced the plant uptake of N, P, and K, and plant P and K contents were significantly correlated with plant biomass. PLS-PM analyses of three plants all showed that AMF inoculation increased plant nutrient uptake and then increased aboveground biomass and underground biomass by increasing plant height and root tillering. This study showed that RI was a more suitable AMF for combination with grassland degradation restoration grass species and proposed the potential mechanism of AMF–plant symbiosis to increase yield. [ABSTRACT FROM AUTHOR]

As global ecological degradation intensifies, the long-term impacts of afforestation on productivity and soil fertility in barren lands have become critical in improving global ecological security and productivity. Through meta-analysis, this study integrates data from 109 barren land afforestation sites across China, aiming to comprehensively analyze the effects on plant productivity and soil fertility while identifying the key environmental drivers of these changes. We found that afforestation consistently enhances plant productivity across 60 years. However, soil fertility and moisture initially surged significantly after afforestation but gradually declined after the first decade, indicating the limited long-term benefits. Climatic factors, namely precipitation and humidity index, are crucial in enhancing plant productivity, while geographic factors, specifically lower elevations and gentler slopes, are associated with greater increases in soil fertility. Elevation and slope are two key factors that influence soil moisture after afforestation. These findings highlight the need for ongoing soil management and ecological maintenance in afforestation projects to sustain the soil fertility benefits. Our study provides a robust scientific foundation for afforestation strategies aimed at barren land restoration and offers valuable insights for policy formulation in barren land afforestation. [ABSTRACT FROM AUTHOR]

Hemisphere photos are now widely applied to provide information about solar radiation dynamics, canopy structure and their contribution to biophysical processes, plant productivity and ecosystem properties. The present study aims to improve the original 'edge detection' method for binary classification between sky and canopy, which works not well for closed canopies. We supposed such inaccuracy probably is due to the influence of sky pixels on their neighbor canopy pixels. Here, we introduced a new term 'neighbor distance', defined as the distance between pixels participated in the calculation of contrast at the edges between classified canopy and sky, into the 'edge detection' method. We showed that choosing a suitable neighbor distance for a photo with a specific gap fraction can significantly improve the accuracy of the original 'edge detection' method. We developed an ND-IS (Neighbor Distance-Iteration Selection) method that can automatically determine the threshold values of hemisphere photos with high accuracy and reproductivity. It combines the modified 'edge detection' method and an iterative selection method, with the aid of an empirical power function for the relationship between neighbor distance and manually verified gap fraction. This procedure worked well throughout a broad range of gap fractions (0.019–0.945) with different canopy compositions and structures, in five forest biomes along a broad gradient of latitude and longitude across Eastern China. Our results highlight the necessity of integrating neighbor distance into the original 'edge detection' algorithm. The advantages and limitations of the method, and the application of the method in the field were also discussed. [ABSTRACT FROM AUTHOR]

The shoot apical meristem culture has been used widely to produce virus-free plantlets which have the advantages of strong disease resistance, high yield, and prosperous growth potential. However, this virus-free plant will be naturally reinfected in the field. The physiological and metabolic responses in the reinfected plant are still unknown. The flower of chrysanthemum 'Hangju' is a traditional medicine which is unique to China. In this study, we found that the virus-free 'Hangju' (VFH) was reinfected with chrysanthemum virus B/R in the field. However, the reinfected VFH (RVFH) exhibited an increased yield and medicinal components compared with virus-infected 'Hangju' (VIH). Comparative analysis of transcriptomes was performed to explore the molecular response mechanisms of the RVFH to CVB infection. A total of 6223 differentially expressed genes (DEGs) were identified in the RVFH vs. the VIH. KEGG enrichment and physiological analyses indicated that treatment with the virus-free technology significantly mitigated the plants' lipid and galactose metabolic stress responses in the RVFH. Furthermore, GO enrichment showed that plant viral diseases affected salicylic acid (SA)-related processes in the RVFH. Specifically, we found that phenylalanine ammonia-lyase (PAL) genes played a major role in defense-related SA biosynthesis in 'Hangju'. These findings provided new insights into the molecular mechanisms underlying plant virus–host interactions and have implications for developing strategies to improve plant resistance against viruses. [ABSTRACT FROM AUTHOR]

Nature reserves play an important role in the protection of biological habitats and the maintenance of biodiversity, but the performance and mechanisms of desert steppe nature reserves in improving plant community productivity, biodiversity and soil nutrient content are still largely unknown. To investigate the conservation effects of desert steppe nature reserve management on plant productivity and biodiversity, we compared the plant biomass, diversity and soil nutrient content inside and outside the West Ordos National Nature Reserve through sample survey, biomass determination, diversity index calculation and soil nutrient content determination. We found the following: (1) The aboveground biomass and belowground biomass of plant communities in the nature reserve were significantly larger than those outside the reserve; and the aboveground biomass of plant communities in shrub–steppe was significantly larger than that of herb grassland in both the nature reserve and the outside of the reserve. (2) The Margalef richness index, Shannon–Wiener index and Simpson index were significantly greater in the reserve than outside the nature reserve. In the desert steppe, the establishment of the nature reserve increased the α-diversity of the plant community. (3) The soil organic carbon (SOC) and soil total nitrogen (STN) were greater in the nature reserve than outside the reserve, and for the 10–20 cm and 20–40 cm soil layers, the SOC and STN were significantly greater in the core protected zone of the reserve than outside the reserve. The reserve significantly increased the nutrient content of the deeper soil layers. (4) The aboveground biomass of the plant community had a significant positive linear relationship with the species richness index, the Shannon index, and the Simpson index. There was a positive correlation between the diversity of the plant community and the soil nutrients. In summary, the nature reserve improved local plant productivity, biodiversity and the soil nutrient content, and the soil nutrient content in deeper soil layers may be the driving factor for the increase in productivity and biodiversity, which deepens our understanding of the conservation effectiveness of the nature reserve and its mechanisms. [ABSTRACT FROM AUTHOR]

Seasonal grazing is a common alternative to the rest‐rotation grazing management regime. Although that research has been extensive on the impacts of grazing on soil organic carbon (SOC) and nitrogen (N) sequestration, there is limited understanding of the regulatory mechanisms of plant productivity and species on SOC and N sequestration under seasonal grazing. To address this problem, the response of plant properties was quantified in five different seasonal grazing regimes (no grazing control, continuous grazing, early summer and late summer grazing, mid summer and early autumn grazing, late summer and mid autumn grazing) in a semi‐arid grassland of North China between 2012 and 2018. The results indicated that early summer and late summer grazing had little damage to the plant communities but reduced the SOC and N sequestration in the 10–20 cm layer, while mid summer and early autumn grazing maintained a relatively high plant productivity but resulted in the losses of SOC and N sequestration in the 0–20 cm layer. The late summer and mid autumn grazing regime enhanced SOC and N sequestration in the 0–20 cm layer by producing higher yields of Stipa krylovii and root biomass. The improved biomass of S. krylovii and roots is an indicator of soil quality evolution in the context of grazing management. It is therefore proposed that the late summer and mid autumn grazing regime, including a two‐month rest period, is likely to be a beneficial strategy to conserve both plant communities and soil nutrients for sustainable management of the studied grassland. [ABSTRACT FROM AUTHOR]

Terrestrial ecosystems can exhibit various behaviors in response to climate change and human activities. Nonlinear and abrupt shifts in ecosystems are particularly important as they indicate substantial modifications in ecosystem structure and function, posing a threat to the provision of ecosystem services. Here we distinguish between linear, curvilinear, and abrupt shifts in ecosystem productivity from 2000 to 2020 in China's Loess Plateau. We utilize spatial Random Forest models to analyze the driving factors behind these change patterns. Our findings indicate that 84.1% of the ecosystems experienced a positive change in plant productivity, while a small proportion (2.5%) exhibited a negative change. Abrupt shifts are prevalent in both positive and negative changes in ecosystem productivity, with negative changes often manifesting as abrupt shifts (79.3%). Negative changes in plant productivity, particularly the negative abrupt shifts, are primarily associated with human activities characterized by increased nighttime light and urbanization. Land conversion to forest is linked to a curvilinear trajectory in plant productivity, characterized by nonlinear changes with acceleration. Higher water availability and a wetter environment are more likely to promote positive changes in plant productivity. Moderate warming trends contribute to abrupt positive changes in plant productivity, while high warming trends are associated with increased negative abrupt and curvilinear changes. We highlight the importance of accounting for diverse change behaviors in ecosystems for the development of targeted conservation and restoration measures. Plain Language Summary: Terrestrial vegetation provides numerous benefits to humans, including soil conservation, carbon sequestration, and regulation of water flows. Understanding how vegetation responds to climate change and human activities is crucial for developing targeted conservation and restoration measures. In China's Loess Plateau, we distinguish three types of change trajectories in ecosystem productivity from 2000 to 2020: linear, curvilinear, and abrupt shifts. We find that 84.1% of the ecosystems experienced positive changes in plant productivity, and only a small portion (2.5%) experienced negative changes. Interestingly, abrupt shifts occurred in both positive and negative changes in plant productivity. Human activities, land use conversions, and climatic factors collectively shape the diverse change trajectories in ecosystem productivity. These findings underscore the importance of considering different change behaviors in vegetation ecosystems when designing conservation and restoration strategies. Key Points: Most areas of China's Loess Plateau (84.1%) experienced positive changes in plant productivityAbrupt shifts were common in positive and negative plant productivity changesHuman activities, land use conversions, and climate collectively shape the diverse trajectories in plant productivity [ABSTRACT FROM AUTHOR]

Background: Vegetation phenology can characterize ecosystem functions and plays a key role in the dynamics of plant productivity. Here we investigated the changes in growing season metrics (start of growing season, SOS; end of growing season, EOS; length of growing season, LOS) and their relationships with net primary productivity (NPP) in forestland and grassland in China during 1981–2016. Results: SOS advanced, EOS delayed, LOS prolonged and NPP increased significantly in 23.7%, 21.0%, 40.5% and 19.9% of the study areas, with an average rate of 3.9 days decade−1, 3.3 days·decade−1, 6.7 days·decade−1 and 10.7 gC m−2·decade−1, respectively. The changes in growing season metrics were obvious in Northwest China (NWC) and North China (NC), but the least in Northeast China (NEC). NPP was negatively correlated with SOS and positively correlated with EOS and LOS in 22.0%, 16.3% and 22.8% of the study areas, respectively, and the correlation between NPP and growing season metrics was strong in NWC, NC and Southwest China (SWC), but weak in NEC and South China (SC). Conclusion: The advanced SOS, delayed EOS and prolonged LOS all contribute to the increased NPP in forestland and grassland in China, especially in NWC, NC and SWC. This study also highlights the need to further study the response of NPP to growing season changes in different regions and under the influence of multiple factors. [ABSTRACT FROM AUTHOR]

Large herbivores can exert pronounced top-down effects on plant communities in grassland ecosystems. Previous studies highlighted the importance of the composition and traits of living plants in regulating the impact of herbivores on plant community. However, there has been little consideration of whether and how plant litter, a ubiquitous "after-life" plant component, affects the outcome of herbivore grazing on grasslands. Here, we conducted a large-scale field experiment in temperate grasslands of northeastern China to investigate how standing plant litter influenced top-down effects of large herbivores (sheep; Ovis aries) on plant species richness, evenness, community composition, and productivity. We found that, in the presence of standing litter, sheep grazing significantly reduced living biomass of forbs by 56%, but have no effects on biomass of the dominant grass, Leymus chinensis. However, in the absence of standing litter, sheep shifted their diet preference from forbs to the grass L. chinensis, leading to a 36% decrease in the biomass of L. chinensis and a 21% decrease in total biomass. Such changes in foraging pressure on plant species led to competitive release that in turn significantly altered plant community composition and increased species evenness. Synthesis and applications. Our results demonstrate that standing litter can alter foraging behaviors of large herbivores and modifying the outcome of their top-down effects on plant community properties in grasslands. These cryptic but perhaps ubiquitous interactions between litter and herbivores may help us better understand the organization and dynamics of plant communities in the grazed grasslands, with important implications for developing effective management and conservation plans. [ABSTRACT FROM AUTHOR]

The quantification of plant diversity–productivity relationships is essential for accurate productivity assessments. Global change drivers are altering resource availability and biodiversity. However, the extent to which multiple attributes of diversity (species, functions) buffer community productivity in response to the resource availability changes and the potential driver mechanisms of the diversity‐productivity relationship still needs to be the consensus. We investigated the ephemeral plant diversity–productivity relationships of different attributes along a precipitation gradient in the Gurbantunggut Desert, China. To evaluate the potential mechanisms by which diversity and functional composition affect aboveground productivity (niche complementarity and selection effect). Our results showed that (1) the variance of species richness (SR), Rao's quadratic entropy (RaoQ), community‐weighted mean of height (CWMH), and community‐weighted mean of leaf phosphorus concentration (CWMP) was larger among sites (variation between different sites) than subplots (variation between different subplots). Among subplots, the variance of community‐weighted mean of specific leaf area (CWMSLA), community‐weighted mean of leaf carbon concentration (CWMC), and community‐weighted mean of leaf nitrogen concentration (CWMN) was larger than the sites. (2) SR, RaoQ, CWMC, CWMN, CWMH, pH, and mean annual precipitation (MAP) collectively influenced the accumulation of aboveground biomass (AGB). (3) Species diversity and MAP have strongly affected AGB and accounted for 50% and 42%. The study confirms that SR is the optimal predictor of biomass in ephemeral plants. Complementation effects may be the primary mechanism explaining the relationship between biodiversity and productivity in the Gurbantunggut Desert, and thus the effect of plant diversity cannot be downplayed. [ABSTRACT FROM AUTHOR]

Introduction: In achieving food security and sustainable agricultural development, improving and maintaining soil health is considered as a key driving factor. The improvement based on different forms of nitrogen fertilization has aroused great public interest in improving and restoring monocropping obstacles for specific soil problems. Methods: For this, a short-term cucumber cropping field experiment was conducted in the subtropical region of China under four fertilization treatments: ammonium (AN), nitrate (NN), ammonium with dicyandiamide (AN +DCD), nitrate with dicyandiamide (NN+DCD). In this study, we measured the effects of nitrogen forms addition on plant productivity and soil health in a monocropping system over seven seasons. Results: To systematically evaluate soil health, a wide range of soil environmental factors were measured and incorporated into the soil health index (SHI) by entropy method. Compared with ammonium treatment (SHIAN = 0.059, SHIAN +DCD = 0.081), the positive effect of nitrate was mainly reflected in improving soil health (SHINN = 0.097, SHINN+DCD = 0.094), which was positively correlated with the increase in plant productivity of cucumber after seven seasons of monocropping. The most critical factor affecting SHI is soil ammonium nitrogen content, which was negatively correlated with plant productivity. Discussion: Nitrate promotes soil health and plant productivity by optimizing soil environmental factors. The study thus emphasized the necessity of nitrate input for the sustenance of soil-crop ecosystems, with the consequent possibility of application of the results in planning monoculture obstacle prevention and management measures. [ABSTRACT FROM AUTHOR]

In a locale-scale mountainous forest, changes in slope aspect can cause microclimate heterogeneity, which can impact both soil environment and plant community, and influence the soil microbial communities as well. However, the relationship between the aboveground plant community and belowground soil microbial communities and the change in slope aspect is not well understood. A case study was carried out in a subalpine coniferous forest in western China to investigate the above- and belowground relationship of three slope aspects, the north-facing slope, the flat site and the south-facing slope. The plant community attributes were evaluated by the community survey, considering species diversity and the plant total basal area of trees and shrubs to represent the plant productivity. Soil bacteria were determined based on 16S rRNA gene and soil fungi on a nuclear ribosomal internal transcribed spacer (ITS) using high-throughput Illumina sequencing. The results showed that slope aspects significantly affect the aboveground plant productivity and diversity, and the community composition and structure of both aboveground plants and soil bacteria and soil fungi. Soil bacteria and soil fungi correlated differently with aboveground plant community changes in the slope aspects in terms of diversity and community composition and structure. A structural equation model (SEM) revealed that slope aspects caused by aboveground plant productivity changes correlated significantly with the soil fungal community composition and structure, while the soil bacterial community was rather weakly correlated with the plant community, and its changes in community composition and structure were mainly affected by the soil properties and soil fungal community. Further studies considering plant functional traits, soil microbial functional groups, and seasonal changes may reveal a deeper correlation between the aboveground plants and belowground soil microbials at the local scale in subalpine coniferous forests. [ABSTRACT FROM AUTHOR]

Purpose: Research on makers and innovation has been equivocal regarding whether maker innovation is driven by internal motivation or external incentives. The motivation view favors the intrinsic motives of makers, whereas the incentive view supports external economic incentives. The authors combine both views to explore how innovation tournaments promote the product innovation outcomes of different creative and entrepreneurial makers, using economic incentives (money) or social incentives (love). Design/methodology/approach: The authors interviewed 42 makers and collected a panel dataset of 29,823 makers from the largest digital maker community in China using a Python crawling program. The authors analyzed the data using multiple methods, including cluster analysis, discriminant analysis, factor analysis and negative binomial regression. Findings: Compared with entrepreneurial makers, the product productivity of creative makers is inferior, but their product popularity is greater. The social incentive of innovation tournaments promotes the product productivity and popularity of creative makers compared with that of entrepreneurial makers, but the economic incentive is contradictory. In addition, social and economic incentives interact to generate inconsistent influences. Originality/value: The study identifies creative and entrepreneurial makers and contributes to user innovation and innovation tournaments by integrating motivation and incentive views. [ABSTRACT FROM AUTHOR]

Aims: Changes in global precipitation regimes are caused by an increase in the frequency of extremely wet and dry years inter-annually and extreme rainfall intensity intra-annually. However, the interactive effects of these precipitation variabilities remain relatively unclear. Methods: To better understand the responses of semi-arid ecosystems to precipitation changes, a manipulative field experiment was conducted with multilevel annual precipitation amounts and precipitation allocation, at a temporal scale, within desert shrubland in the Mu Us Desert in northern China. Results: With fewer, yet larger, precipitation events, the annual net primary production (ANPP) was found to increase in dry years. The annual precipitation amount and precipitation intervals affected the community ANPP. However, precipitation intervals only affected the ANPP in the context of low precipitation amounts. Extending the intervals between precipitation events significantly increased the ANPP of shrubs and weeds however decreased that of grasses. The nursery effect of shrubs on the herbs and competition between the grass and weeds can interfere with the response of the community ANPP to precipitation. Conclusions: With a global shift toward precipitation regimes dominated by lower frequency and higher intensity, an increase in productivity in this desert shrubland ecosystem is expected, with shrubs largely dominating the community composition. This study advances the current understanding of how community productivity is shaped by the interaction between inter-annual precipitation amount and intra-annual precipitation distribution. Meanwhile, plant–plant interactions between different functional species also have essential roles in community productivity stabilization within the context of precipitation change. [ABSTRACT FROM AUTHOR]

Climate change is an important issue that affects both global warming and precipitation, and the main cause is increased N2O emissions. Temperature and moisture are key factors in grassland ecosystem's response to climate change, and they can affect N2O fluxes. To clarify the impacts of warming and precipitation changes on N2O fluxes, an experiment was conducted in a semiarid steppe in Inner Mongolia, China over a nine‐year period (2011–2019). Plant productivity and soil nutrient dynamics were examined concurrently from 2017 to 2019, and N2O fluxes were monitored in response to different treatment conditions: control (C), warming (W), precipitation addition (P), and warming and precipitation addition (WP). The results showed that N2O emissions in the growing season were higher than those in the nongrowing season. Warming and precipitation addition had no significant effect on N2O fluxes compared with ambient conditions. Compared with P treatment, warming increased N2O flux in nongrowing season and decreased it in growing season. N2O flux was positively correlated with soil temperature and moisture (p < 0.05). Warming had a significant positive effect on soil NH4+‐N, whereas additional precipitation had a large positive effect on soil total nitrogen and soil nitrate nitrogen. With the WP treatment, soil microbial biomass nitrogen (MBN) and soil microbial biomass carbon (MBC) increased by 53.8% and 41.9%, respectively. The decrease in N2O emissions during the growing season in the W treatment compared with the P treatment may be largely attributed to the greater dominance of Leymus chinensis. The results highlight that changes in species dominance play an important role in regulating N2O emissions, and that the N2O fluxes in the nongrowing season account for a large proportion of the changes in N2O fluxes. Therefore, The warming effects on N2O emissions during nongrowing seasons should be further investigated. [ABSTRACT FROM AUTHOR]

Changes in net ecosystem productivity (NEP) in terrestrial ecosystems in response to climate warming and land cover changes have been of great concern. In this study, we applied the normalized difference vegetation index (NDVI), average temperature, and sunshine hours to drive the C-FIX model and to simulate the regional NEP in China from 2000 to 2019. We also analyzed the spatial patterns and the spatiotemporal variation characteristics of the NEP of terrestrial ecosystems and discussed their main influencing factors. The results showed that (1) the annual average NEP of terrestrial ecosystems in China from 2000 to 2019 was 1.08 PgC, exhibiting a highly significant increasing trend with a rate of change of 0.83 PgC/10 y. The terrestrial ecosystems in China remained as carbon sinks from 2000 to 2019, and the carbon sink capacity increased significantly. The NEP of the terrestrial ecosystem increased by 65% during 2015-2019 compared to 2000-2004 (2) There was spatial differences in the NEP distribution of the terrestrial ecosystems in China from 2000-2019. Taking the line along the Daxinganling-Yin Mountains-Helan Mountains-Transverse Range as the boundary, the NEP was significantly higher in the eastern part than in the western part. Among them, the NEP was positive (carbon sink) in northeastern, central, and southern China, and negative (carbon source) in parts of northwestern China and the Tibet Autonomous Region. The spatial variation of NEP in terrestrial ecosystems increased from 2000 to 2009. The areas with a significant increase accounted for 45.85% and were mainly located in the central and southwestern regions. (3) The simulation results revealed that vegetation changes and CO2 concentration changes both contributed to the increase in the NEP in China, contributing 85.96% and 36.84%, respectively. The vegetation changes were the main factor causing the increase in the NEP. The main contribution of this study is to further quantify the NEP of terrestrial ecosystems in China and identify the influencing factors that caused these changes. [ABSTRACT FROM AUTHOR]

Quantifying and predicting variation in gross primary productivity (GPP) is important for accurate assessment of the ecosystem carbon budget under global change. Scaling traits to community scales for predicting ecosystem functions (i.e., GPP) remain challenging, while it is promising and well appreciated with the rapid development of trait-based ecology. In this study, we aim to integrate multiple plant traits with the recently developed trait-based productivity (TBP) theory, verify it via Bayesian structural equation modeling (SEM) and complementary independent effect analysis. We further distinguish the relative importance of different traits in explaining the variation in GPP. We apply the TBP theory based on plant community traits to a multi-trait dataset containing more than 13,000 measurements of approximately 2,500 species in Chinese forest and grassland systems. Remarkably, our SEM accurately predicts variation in annual and monthly GPP across China (R2 values of 0.87 and 0.73, respectively). Plant community traits play a key role. This study shows that integrating multiple plant functional traits into the TBP theory strengthens the quantification of ecosystem primary productivity variability and further advances understanding of the trait-productivity relationship. Our findings facilitate integration of the growing plant trait data into future ecological models. Integration of plant functional traits into trait-based productivity theory helps quantify primary productivity in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Soil microbial communities are essential for regulating the dynamics of plant productivity. However, how soil microbes mediate temporal stability of plant productivity at large scales across various soil fertility conditions remains unclear. Here, we combined a regional survey of 51 sites in the temperate grasslands of northern China with a global grassland survey of 120 sites to assess the potential roles of soil microbial diversity in regulating ecosystem stability. The temporal stability of plant productivity was quantified as the ratio of the mean normalized difference vegetation index to its standard deviation. Soil fungal diversity, but not bacterial diversity, was positively associated with ecosystem stability, and particular fungal functional groups determined ecosystem stability under contrasting conditions of soil fertility. The richness of soil fungal saprobes was positively correlated with ecosystem stability under high-fertility conditions, while a positive relationship was observed with the richness of mycorrhizal fungi under low-fertility conditions. These relationships were maintained after accounting for plant diversity and environmental factors. Our findings highlight the essential role of fungal diversity in maintaining stable grassland productivity, and suggest that future studies incorporating fungal functional groups into biodiversity–stability relationships will advance our understanding of their linkages under different fertility conditions. [ABSTRACT FROM AUTHOR]

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Background: Shifts in forest phenological events serve as strong indicators of climate change. However, the sensitivity of phenology events to climate change in relation to forest origins has received limited attention. Moreover, it is unknown whether forest phenology changes with the proximity to forest edge. Methods: This study examined the green-up dates, dormancy dates, time-integrated NDVI (LiNDVI, a measure of vegetation productivity in growing season), and their sensitivities to climatic factors along the gradients of distance (i.e. proximity) to forest edge (0-2 km) in China's natural forests (NF) and planted forests (PF). For the analysis, field-surveyed data were integrated with Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI from 2000 to 2022. Results: Our results reveal that PF had earlier green-up dates, later dormancy dates, and higher LiNDVI than NF. However, green-up sensitivities to temperature were higher at the edges of NF, whereas no such pattern was observed in PF. Conversely, the sensitivity of dormancy dates remains relatively stable from the inner to the edge of both NF and PF, except for a quadratic change in dormancy date sensitivity to precipitation found in NF. Additionally, we found that the green-up sensitivity to temperature increased with decreasing proximity to edge in NF evergreen forests, while it showed the opposite trend in PF evergreen forests. Furthermore, we observed that the precipitation impact on green-up dates shifts from postponing to advancing from the inner to the edge of NF, whereas precipitation dominantly postpones PF's green-up dates regardless of the proximity to edge. The LiNDVI exhibits higher sensitivity to precipitation at the edge areas, a phenomenon observed in NF but not in PF. Conclusions: These results suggest that the responses of forests to climate change vary with the distance to the edge. With increasing edge forests, which results from fragmentation caused by global changes, we anticipate that desynchronized phenological events along the distance to the edge could alter biogeochemical cycles and reshape ecosystem services such as energy flows, pollination duration, and the tourism industry. Therefore, we advocate for further investigations of edge effects to improve ecosystem modelling, enhance forest stability, and promote sustainable tourism. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) are crucial nutrients for regulating plant growth. The classic growth rate hypothesis (GRH) proposes that fast‐growing organisms have lower N:P ratios, and it is promising to predict net primary productivity (NPP) using the leaf N:P ratio at the community level (N:PCom). However, whether leaf N:P ratio can predict NPP in natural ecosystems on a large scale remains nebulous. Here, we systematically calculated leaf N:PCom (community biomass‐weighted mean and species arithmetic mean) using the consistently measured data of 2192 plant species‐site combinations and productivity (biomass‐based aboveground NPP and flux‐based NPP) in 66 natural ecosystems in China. Unexpectedly, leaf N:PCom hardly predicted productivity in natural ecosystems due to their weak correlation, although significantly negative or positive relationships across different ecosystems were observed. The ambiguous relationship between leaf N:P and species dominance reflected a luxury consumption of N and P in turnover and structure in natural communities, unlike what GRH suggests. Climate, soil, and leaf nutrients (rather than N:P) influenced productivity, which highlighted the importance of external environment and nutrient constrains. Our findings pose a major challenge for leaf N:PCom as a direct parameter in productivity models and further question the direct application of classic hypotheses in short‐term experiments or model species to long‐term and complex natural ecosystems. [ABSTRACT FROM AUTHOR]

Forest ecosystems play an important role in the global carbon cycle. Clarifying the large-scale dynamics of net primary productivity (NPP) and its correlation with climatic factors is essential for national forest ecology and management. Hence, this study aimed to explore the effects of major climatic factors on the Carnegie–Ames–Stanford Approach (CASA) model-estimated NPP of the entire forest and all its corresponding vegetation types in China from 1982 to 2015. The spatiotemporal patterns of interannual variability of forest NPP were illustrated using linear regression and geographic information system (GIS) spatial analysis. The correlations between forest NPP and climatic factors were evaluated using partial correlation analysis and sliding correlation analysis. We found that over thirty years, the average annual NPP of the forests was 887 × 1012 g C/a, and the average annual NPP per unit area was 650.73 g C/m2/a. The interannual NPP of the entire forest and all its corresponding vegetation types significantly increased (p < 0.01). The increase in the NPP of evergreen broad-leaved forests was markedly substantial among forest types. From the spatial perspective, the NPP of the entire forest vegetation gradually increased from northwest to southeast. Over the years, the proportions of the entire forest and all its corresponding vegetation types with a considerable increase in NPP were higher than those with a significant decrease, indicating, generally, improvements in forest NPP. We also found climatic factors variably affected the NPP of forests over time considering that the rise in temperature and solar radiation improved the interannual forest NPP, and the decline in precipitation diminished the forest NPP. Such varying strength of the relationship between the interannual forest NPP and climatic factors also varied across many forest types. Understanding the spatiotemporal pattern of forest NPP and its varying responses to climatic change will improve our knowledge to manage forest ecosystems and maintain their sustainability under a changing environment. [ABSTRACT FROM AUTHOR]

Soil restoration is a crucial approach to improving plant productivity in orchards with soil degradation, yield reduction, and fruit quality declination in China. A self-invented root-zone ecological restoration practice (RERP) with soil conditioner, or organic fertilizer, was employed in a degraded peach orchard in Beijing in 2020 to investigate the consequent impacts on soil bacterial composition and functionality at soil depths of 0–20 cm and 20–40 cm. Bacterial diversity was sensitive to RERP, especially in subsurface soil. RERP with soil conditioner significantly increased bacterial diversity, and affected abundances of certain genera, such as a significantly increased amount of Bacillus in surface soil and Blastococcus, Microvirga, Nocardioides, and Sphingomonas in subsurface soil. It also significantly affected abundances of bacterial functions related to metabolism in subsurface soil, particularly those with low abundance such as decreased transcription abundance and increased amino acid metabolism abundance. Soil bacterial functions were observably affected by bacterial diversity and composition, particularly in the deep soil layer. RERP affected bacterial functionality via responses of soil bacteria and bacteria-mediated alterations to the changed soil property. Correlation analysis between soil properties, bacterial taxonomy, and bacterial functions revealed that RERP affected bacterial functionality by altering the soil microenvironment with ample nutrients and water supply in root zone. Consequently, shifted bacterial functionality could have a potential in orchard ecosystem services in view of fruit yield and quality. Taken together, RERP had notably positive impacts on soil bacterial diversity and functions, and a prospect of increased plant productivity in the degrade orchard ecosystem. [ABSTRACT FROM AUTHOR]

Increased atmospheric nitrogen (N) deposition could create an imbalance between N and phosphorus (P), which may substantially impact ecosystem functioning. Changes in autumnal phenology (i.e. leaf senescence) and associated leaf nutrient resorption may profoundly impact plant fitness and productivity. However, we know little about how and to what extent nutrient addition affects leaf senescence in tree species, or how changes in senescence may influence resorption. We thus investigated the impacts of N and P addition on leaf senescence and leaf N resorption in 2-year-old larch (Larix principisrupprechtii) seedlings in northern China. Results showed that nutrient addition (i.e. N, P or N + P addition) significantly delayed autumnal leaf senescence, and decreased leaf N resorption efficiency (NRE) and proficiency (NRP), particularly in the N and N + P treatments. Improved leaf N concentrations were correlated with delayed leaf senescence, as indicated by the positive relationship between mature leaf N concentrations and the timing of leaf senescence. Following nutrient addition, larch seedlings shifted toward delayed onset, but more rapid, leaf senescence. Additionally, we observed an initial negative correlation between the timing of leaf senescence and NRE and NRP, followed by a positive correlation, indicating delayed and less efficient remobilization during the early stages of senescence, followed by accelerated resorption in the later stages. However, the latter effect was potentially impaired by the increased risk of early autumn frost damage, thus failed to fully compensate for the negative effects observed during the early stages of senescence. Improved soil P availability increased leaf N resorption and thus weakened the negative impact of delayed leaf senescence on leaf N resorption, so P addition had no significant impact on leaf N resorption. Overall, our findings clarify the relationship between nutrient addition–resorption and the linkage with leaf senescence, and would have important implications for plant nutrient conservation strategy and nutrient cycling. [ABSTRACT FROM AUTHOR]

The purpose of this contribution is to compute the popular Malmquist productivity index while adding a component representing plant capacity utilisation. In particular, this is—to the best of our knowledge—the first empirical application estimating both input- and output-oriented Malmquist productivity indices in conjunction with the corresponding input- and output-oriented plant capacity utilisation measures. Our empirical application focuses on a provincial data set of tourism activities in China over the period 2008–2016. The results contain the output- and input-oriented Malmquist productivity indices, some Spearman rank correlations between both, a t-test whether these indices differ from unity, and some bootstrapping analysis. [ABSTRACT FROM AUTHOR]

Grassland is the dominant vegetation type in the Loess Plateau, and grassland productivity and processes are limited by nitrogen (N) and phosphorus (P). Studies have shown that productivity would change following fertilization in the grassland. The response of productivity to fertilization mainly depends on the dominant species traits. Trait-based methods provide a useful tool for explaining the variations in grassland productivity following fertilization. However, the relative contribution of plant functional traits to grassland productivity under N and P addition in the Loess Plateau is not clear. We measured aboveground biomass (AGB) and leaf N content (LN), leaf P content (LP), leaf N/P ratio (LN/P), specific leaf area (SLA), leaf tissue density (LTD), leaf dry matter content (LDMC), and maximum plant height (Hmax) to study how these plant functional traits regulate the relative biomass of different species and grassland productivity following fertilization. Our results showed, that under different nutrient addition levels, the linkages between plant functional traits and the relative biomass of different species were different. Community AGB was positively related to community−weighted mean LN (CWM_LN), CWM_LN/P, CWM_SLA, and CWM_Hmax, but negatively related to CWM_LTD and CWM_LDMC. Dominant species traits largely determined grassland productivity, in line with the mass ratio hypothesis. These findings further highlight the close linkages between community-level functional traits and grassland productivity. Our study contributes to the mechanisms underlying biodiversity–ecosystem function relationships and has significance for guiding semiarid grassland management. [ABSTRACT FROM AUTHOR]

Grassland is the primary land use in China, which has experienced extensive degradation in recent decades due to overexploitation. Here, we conducted field experiments to quantify the degraded grassland's recovery rate in Northeast Inner Mongolia in response to restoration measures, including fallow + enclosure (FE) and mowing + enclosure (ME) in comparison to livestock grazing (LG), since 2005. Plant community properties were surveyed and aboveground biomass (AGB) sampled in summer 2013. Our results showed that the regional dominant species Leymus chinensis retained its dominance under FE, whereas a range of forb species gained dominance under LG. Vegetative cover was maximal under FE and minimal under LG. The least amount of vegetation development and AGB were observed under LG. However, plant diversity showed an opposite pattern, with maximal diversity under LG and minimal under FE. Statistical analysis revealed that AGB was negatively associated with plant diversity for all treatments except ME. For ME, a positive AGB-diversity relationship was characterized, suggesting that mowing intensity was a controlling factor for the AGB-diversity relationship. Overall, these results demonstrated that enclosure plus mowing represented an effective conservation measure that provided fair support to forage production and a progressive pathway to a more resilient grassland system. [ABSTRACT FROM AUTHOR]

Water availability is the main factor affecting the forage productivity of artificial grasslands, particularly in semi-arid regions. Generally, intercropping of gramineous grass and leguminous grass can achieve high productivity. However, how different water availability levels affect the productivity of intercropping system remains unclear. Here, we conducted a 3-year (2015-2017) study by manipulating the water conditions (CK equivalent to the annual precipitation, C50% treatment equivalent to 50% increase over the average precipitation, and -50% treatment equivalent to 50% decrease over the average precipitation) to explore the responses of plant traits, nitrogen use efficiency, and biomass of the monoculture of Medicago sativa (a leguminous grass, M.s), monoculture of Elymus nutans (a gramineous grass, E.n), and intercropping of M.s and E.n in a semi-arid region in Inner Mongolia, China. The results showed that the biomass obtained by intercropping of M.s and E.n decreased by 24.4% in -50% treatment compared to the CK treatment, while that of the monoculture of M.s decreased by 34.4% under the -50% treatment compared to the CK treatment. However, there was no significant difference in the biomass between intercropping artificial grassland and monoculture M. sativa under +50% treatment. Compared to monoculture, M.s can obtain more nitrogen by biological nitrogen fixation and decrease the proportion of nitrogen absorbed from soils under intercropping in the same water conditions. Under the intercropping system, the proportions of nitrogen absorbed from soils by M.s were 87.4%, 85.1, and 76.9% in -50%, CK, and C50% treatments, respectively. Under monoculture, these proportions were 91.9, 89.3, and 82.3% in -50%, CK, and C50% treatments, respectively. Plant trait, but not soil nitrogen content, was the main regulator for the productivity responses to water level changes. Our results highlight that intercropping can achieve higher productivity in both dry and wet conditions. Therefore, considering the fluctuating rainfall events in the future, it might be useful to alter the proportions of intercropped forage species in an artificial grassland to obtain optimal productivity by reducing the limitations of nitrogen availability. However, the economic viability of intercropping M. sativa and E. nutans should be evaluated in the future. [ABSTRACT FROM AUTHOR]

Aims: The general effects of grazing by large herbivores on plant species composition and productivity are well known. Meanwhile, how different livestock species affect community structure is not fully understood. In northern China, livestock species composition is changing rapidly and hence, it is imperative to understand the resulting effects on grassland productivity and composition. Location: Xilingol, Inner Mongolia, China. Methods: We studied how grazing by three major livestock species affects typical steppe dominated by Leymus chinensis, Stipa grandis, Cleistogenes squarrosa and Carex korshinskyi, in a 4‐year field experiment using a random block‐design with four treatments (sheep, goat, cattle, no grazing), under summer grazing at moderate intensity. We calculated above‐ground net primary productivity (ANPP) and a selectivity index (SI) based on biomass to quantify livestock forage preferences. Result: We found that (i) sheep preferred Leymus chinensis and mixed subordinate species, cattle preferred Stipa grandis, and goat preferred Carex korshinskyi and Cleistogenes squarrosa. (ii) Consistent with these preferences, sheep increased the relative biomass of Stipa grandis, but reduced that of Carex korshinskyi; cattle reduced the relative biomass of Stipa grandis and Carex korshinskyi but increased that of mixed subordinate species; and goats reduced the relative biomass of Cleistogenes squarrosa and Carex korshinskyi but increased that of mixed subordinate species. (iii) Overall, grazing significantly increased ANPP, mainly due to an increase in ANPP of Leymus chinensis and subordinate species, at the cost of Stipa grandis. Conclusions: Summer grazing by different livestock species at moderate intensity can increase ANPP, while livestock forage preferences can drive divergent changes in species composition. Our results also imply that livestock composition can be used as a mean to manage vegetation dynamics. [ABSTRACT FROM AUTHOR]

Globally, higher inputs of acid deposition and anthropogenic reactive nitrogen cause lower pH in soils, that is, soil acidification, which may broadly influence both above‐ and below‐ground biota and their habitats. However, we know little about the consequences of soil acidification for a wide range of ecosystem functions and services (i.e. ecosystem multifunctionality).Here, we examined the impacts of short‐term soil acidification on 19 ecosystem functions relevant to ecosystem primary productivity and the cycling and/or storage of soil carbon (C), nitrogen (N) and phosphorus (P) using a 2‐year acid addition field experiment in a semi‐arid grassland on the Loess Plateau, China. We further assessed the potential pathways through which plant diversity and soil processes drive ecosystem multifunctionality (hereafter, EMF, EMF‐productivity, EMF‐C, EMF‐N, EMF‐P).We found that soil acidification suppressed 15 of the 19 individual ecosystem functions. By accounting for other biotic and abiotic confounding variables, we found that soil pH remains to be the dominant one explaining the variation in EMF, EMF‐C and EMF‐N. The underlying mechanisms of soil pH driving multifunctionality varied substantially among the groups of multifunctionality. Specifically, plant‐related variables (i.e. species richness and abundance) exhibited stronger mediating effects on EMF‐productivity and EMF‐C than did soil properties (i.e. soil K+, Ca2+, Mg2+ and Na+ ions) and microbial‐related variables (i.e. microbial biomass C and N).Our findings provide empirical evidence that short‐term soil acidification could have greater negative effects on ecosystem multifunctionality than expected in the arid and semi‐arid areas where alkaline soils are commonly seen. This study also indicates that more attention should be paid to the biological mechanisms mediating multifunctional ecosystems under a global change scenario in the future. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Understanding the constraints on light‐use efficiency (LUE) induced by high evaporative water demand (vapour–pressure deficit; VPD) and soil water stress (soil moisture content; SMC) is crucial for understanding and simulating vegetation productivity, particularly in the arid and semi‐arid regions. However, the relative impacts of VPD and SMC on LUE are unclear, as we lack a mechanistic understanding of impacts and their interactions. In this study, we quantified the relative roles of VPD and SMC in limiting LUE and analysed the interactions among VPD, SMC and LUE using data from CO2 and water flux stations and weather stations along a climatic gradient in the Heihe River Basin, China. We found a threshold of VPD constraint on LUE; above the threshold, LUE decreased at only 3.6% to 23.1% of the rate below the threshold. As SMC decreased, however, the VPD threshold increased, and the reduction of LUE caused by VPD decreased significantly, which is more than half of that in moister regions. Therefore, both VPD and SMC played essential roles in LUE limitation caused by water stress. A threshold also existed for heat flux and the correlation between SMC and LUE; the strength of the correlation first decreased and then increased with increasing VPD. Our results clarified the relative impacts of VPD and SMC on LUE, and can improve simulation and prediction of plant productivity. [ABSTRACT FROM AUTHOR]

With increasing numbers and types of nature reserves (NRs), objective evaluation and comparison of the effects of different nature NRs on conservation efforts are of great importance for protecting species diversity, ensuring reasonable national economic input, and adjusting government management schemes. Developing a method for the combined assessment of flagship or umbrella species and ecosystem quality will improve the evaluation of NRs. However, it is also important to establish a new framework for rapid evaluation of ecosystem quality, supported by the advantages of scientific, economic, and regular principles. Here, we proposed a new framework that incorporates the novel concept of ideal references into evaluation systems, which will facilitate the comparison of results from different periods and regions. Furthermore, from the perspective of making the framework as objective, rapid, and economical as possible, we recommended some key ecological indicators, such as net primary productivity, soil organic matter, plant diversity, for use in the new evaluation framework. The new framework, referred to as "ideal reference and key indicators" (IRKI), can sufficiently meet the requirements for the rapid evaluation of ecosystem quality both regionally and nationally. Furthermore, IRKI can identify the restoration potential and restoration periods of NRs, thus facilitating the rational distribution of resources and enhancing the protective effect. There are many types of NRs in China, and it is necessary to partially alter the assessment methods or parameters for different types of NRs. Overall, IRKI provides a simple, clear, and comparable framework that will strongly enhance the conservation of protected areas (PAs) and facilitate the standardization of management practices. [ABSTRACT FROM AUTHOR]

Accurate and timely appraisal of plant nitrogen (N) demand is imperative to regulate the canopy structure and corn production. The strength and time of plant N deficit can be quantified by critical N concentration. The study was aimed to analyze nitrogen nutrition index (NNI), nitrogen deficit content (NDC), plant nitrogen productivity (PNP), and a fraction of intercepted photosynthetic active radiation (FIPAR) across different N treatments and to develop NNI-NDC, NNI-PNP, NNI-FIPAR, NDC-PNP, and NDC-FIPAR relationships from V6 to V12 stages of corn to quantify the suitable PNP and FIPAR values under the optimal plant N condition. Four multi-N rates (0, 75, 90, 150, 180, 225, 270, and 300 kg N ha−1) field experiments were conducted with two cultivars of corn in Henan province of China. Results indicated that N fertilization affected yield, plant biomass, plant N content, and leaf area index. The values of NNI and NDC were from 0.54 to 1.28 kg ha−1 and from −28.13 to 21.99 kg ha−1 under the different treatments of N rate, respectively. The NDC and NNI showed significantly negative relationships from V6 to V12 stages. The values of PNP and FIPAR increased gradually with the crop growth process. The PNP values gradually declined while the FIPAR values of every leaf layer increased with the increase of N supply. The NDC-PNP and NNI-FIPAR relationships were significantly positive; however, the relationships between NNI-PNP and NDC-FIPAR were significantly negative during the vegetative period of corn. The coefficient of determination (R 2) based on NNI was better than that on NDC. The FIPAR values were ~0.35, 0.67, and 0.76% at the upper, middle, and bottom of leaf layers, respectively, and PNP values were ~39, 44, and 51 kg kg−1 at V6, V9, and V12 stages, respectively, when NNI and NDC values were equal to 1 and 0 kg ha−1, respectively. This study described the quantitative information about the effect of a plant's internal N deficit on plant N productivity and canopy light intercept. The projected results would assist in predicting the appropriate plant growth status during key N top-dressing stages of corn, which can optimize N application and improve N use efficiency. [ABSTRACT FROM AUTHOR]

Background and Aims: Declaring the drought-resistance of plant communities in grassland and the underlying mechanisms is crucial under climatic change scenario. Here we aimed to quantify aboveground & belowground net primary productivity (ANPP & BNPP) and their allocation in response to extreme droughts, and to uncover any underlying factors of drought resistance. Methods: We experimentally reduced growing season rainfall by 66% for four years in two grassland sites (Sandy and Loamy site respectively), and measured ANPP and BNPP yearly and evaluated the relatedness of drought-induced changes for them to plant traits (Plant height, δ13C, SLA and LNC) and community composition. Results: Experimental drought decreased species richness, ANPP of forbs and the total at both sites, but decreased ANPP of grasses only at the Sandy site. Experimental drought has non-significant effect on total BNPP at both sites, but increased 10–20 cm BNPP and decreased 0–10 cm BNPP. BNPP ratio was kept unchanged at the Loamy site but increased at the Sandy site. Moreover, the communities at the Loamy site showed lower δ13C, SLA and LNC, but greater height. Conclusions: Our study demonstrates that extreme drought can impact community productivity and structure, and highlights the importance of plant traits, community composition and soil properties in modulating the responses and resistance of steppe communities to extreme drought. [ABSTRACT FROM AUTHOR]

Plant community productivity is a major expression of grassland ecosystem services and functions. In the background of intensified atmospheric nitrogen deposition, studies on the productivity of semiarid sandy grassland with fragile ecological environments have mainly focused on the short-term effects of nitrogen addition, and most of them had concentrated on the aboveground, with relatively few studies on the belowground. In this study, we conducted long-term (from 2014 to 2022) experiment of nitrogen addition (10 g N m−2 year−1) and litter manipulation (litter removal(C1), litter doubling(C2) on sandy grassland in northern China, and measured plant community composition and productivity in 2022 to provide a scientific basis for plant restoration and management of semiarid sandy grasslands. The results were found: (1) Nitrogen addition significantly increased plant community height, coverage, aboveground biomass and total biomass, while litter removal significantly reduced plant coverage by 32.61% (P < 0.01) and significantly decreased the aboveground biomass of grasses by 40.24% (P < 0.05). (2) Nitrogen addition and aboveground litter had no significant effect on belowground biomass at different soil depths and belowground biomass. (3) Grasses were the main contributors to the productivity of plant communities in semiarid sandy grasslands. The belowground biomass was mainly concentrated in the 0–10 cm soil depth, and its proportion was 54% ∼ 78%. (4) The structural equation model showed that nutrient addition indirectly affected the total biomass through a significantly positive effect on soil nitrate nitrogen, dissolved organic carbon and community height. Litter manipulation indirectly affected the total biomass through a significantly negative effect on nitrate nitrogen. Overall, in sandy grassland, long-time litter removal can reduce the aboveground productivity of dominant functional group grasses, while appropriate nitrogen addition management can help to improve the productivity of grassland and promote its recovery and sustainability. Our findings highlight the importance of soil environmental characteristics and plant community characteristics in driving the long-term response of sandy grassland ecosystem productivity to climate change. • Nitrogen addition significantly increased the aboveground biomass and total biomass, while litter removal significantly decreased the aboveground biomass of grasses. • Nitrogen addition and aboveground litter had no significant effect on underground biomass at different soil depths and belowground biomass. • Grasses were the main contributors to the productivity of plant communities in semiarid sandy grasslands. • Nitrogen addition could directly affect the total biomass, and indirectly affected the total biomass through significant positive effects on soil nitrate nitrogen, dissolved organic nitrogen and community height. • Litter manipulation indirectly affected the total biomass through significantly negative effect on nitrate nitrogen. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition has been increasing for decades and has profoundly influenced the structure and function of grassland ecosystems in many regions of the world. However, the impact of N deposition on alpine grasslands is less well documented. We conducted a 3-year field experiment to determine the effects of N deposition on plant species richness, composition, and community productivity in an alpine meadow of the Qinghai-Tibetan Plateau of China. We found that 3 years of N deposition had a profound effect on these plant community parameters. Increasing N rates increased the dominance of graminoids and reduced the presence of non-graminoids. Species richness was inversely associated with aboveground biomass. The shift in plant species and functional group composition was largely responsible for the increase in productivity associated with N deposition. Climatic factors also interacted with N addition to influence productivity. Our findings suggest that short-term N deposition could increase the productivity of alpine meadows through shifts in composition toward a graminoid-dominated community. Longer-term studies are needed to determine if shifts in composition and increased productivity will be maintained. Future work must also evaluate whether decreasing plant diversity will impair the long-term stability and function of sensitive alpine grasslands. [ABSTRACT FROM AUTHOR]

This article empirically examines the role of radical targets for grain yields in triggering China's Great Famine (1959–61), one of the largest man-made catastrophes in human history. Beginning in 1958, the Chinese central government assigned different targets for grain yields in most counties, based on their geographic location. All targets seemed unrealistically high. Using novel county-level data, combined with a spatial regression discontinuity strategy, we find evidence that these radical grain targets prompted excessive procurement and subsequent famine. Our estimates show that a one-standard deviation increase in grain yield targets led to an 18‰ higher death rate in 1960. This article sheds new light on the consequences of target-setting in an authoritarian regime without considering local contexts. (JEL O21, N45, P26). [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) availability often limits plant productivity. Classical theories suggest that total P content declines at the temporal scale of pedogenesis, and ecosystems develop toward the efficient use of scarce P during succession. However, the trajectory of ecosystem P within shorter time scales of succession remains unclear. We analyzed changes to P pools at the early (I), middle (II), and late (III) stages of growth of plantation forests (PFs) and the successional stages of natural forests (NFs) at 1969 sites in China. We found significantly lower P contents at later growth stages compared to earlier ones in the PF (p <.05), but higher contents at late successional stages than in earlier stages in the NF (p <.05). Our results indicate that increasing P demand of natural vegetation during succession, may raise, retain, and accumulate P from deeper soil layers. In contrast, ecosystem P in PF was depleted by the more rapidly increasing demand outpacing the development of a P‐efficient system. We advocate for more studies to illuminate the mechanisms for determining the divergent changes, which would improve forest management and avoid the vast degradation of PF ecosystems suffering from the ongoing depletion of P. [ABSTRACT FROM AUTHOR]

How climate warming interacts with atmospheric nitrogen (N) deposition to affect carbon (C) release from soils remains largely elusive, posing a major challenge in projecting climate change‒terrestrial C feedback.As part of a 5‐year (2006–2010) field manipulative experiment, this study was designed to examine the effects of 24‐hr continuous warming and N addition on soil respiration and explore the underlying mechanisms in a semi‐arid grassland on the Mongolian Plateau, China.Across the 5 years and all plots, soil respiration was not changed under the continuous warming, but was decreased by 3.7% under the N addition. The suppression of soil respiration by N addition in the third year and later could be mainly due to the reductions in the forb‐to‐grass biomass ratios. Moreover, there were interactive effects between continuous warming and N addition on soil respiration. Continuous warming increased soil respiration by 5.8% in the ambient N plots, but reduced it by 6.3% in the enriched N plots. Soil respiration was unaffected by N addition in the ambient temperature plots yet decreased by 9.4% in the elevated temperature plots. Changes of soil moisture and the proportion of legume biomass in the community might be primarily responsible for the non‐additive effects of continuous warming and N addition on soil respiration.This study provides empirical evidence for the positive climate warming‒soil C feedback in the ambient N condition. However, N deposition reverses the positive warming‒soil C feedback into a negative feedback, leading to decreased C loss from soils under a warming climate. Incorporating our findings into C‐cycling models could reduce the uncertainties of model projections for land C sink and global C cycling under multifactorial global change scenarios. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Relationships between biodiversity and multiple ecosystem functions (that is, ecosystem multifunctionality) are context-dependent. Both plant and soil microbial diversity have been reported to regulate ecosystem multifunctionality, but how their relative importance varies along environmental gradients remains poorly understood. Here, we relate plant and microbial diversity to soil multifunctionality across 130 dryland sites along a 4,000 km aridity gradient in northern China. Our results show a strong positive association between plant species richness and soil multifunctionality in less arid regions, whereas microbial diversity, in particular of fungi, is positively associated with multifunctionality in more arid regions. This shift in the relationships between plant or microbial diversity and soil multifunctionality occur at an aridity level of ∼0.8, the boundary between semiarid and arid climates, which is predicted to advance geographically ∼28% by the end of the current century. Our study highlights that biodiversity loss of plants and soil microorganisms may have especially strong consequences under low and high aridity conditions, respectively, which calls for climate-specific biodiversity conservation strategies to mitigate the effects of aridification. Biodiversity-ecosystem functioning relationships may vary with climate. Here, the authors study relationships of plant and soil microbial diversity with soil nutrient multifunctionality in 130 dryland sites in China, finding a shift towards greater importance of soil microbial diversity in arid conditions. [ABSTRACT FROM AUTHOR]

Fertilizer addition can improve soil nutrients in degraded grasslands, change plant community composition, and promote community productivity. An experiment was established in 2014 near Hulunbuir Grassland Ecosystem National Field Observation Station at Hulunbuir in Inner Mongolia, China, using L14 (34) orthogonal test with 14 treatments totally, to compare the change of plant community productivity and plant diversity during three years of fertilization. We monitored the dynamic responses of aboveground biomass, plant species composition, species richness, Shannon diversity, Pielou’s evenness after nitrogen (N), phosphorus (P), and potassium (K) addition once a year from 2014 to 2016. Compared to the control treatment of no additional fertilizer, we found that, (1) The fertilization combination of N (274 kg ha-1), P (350 kg ha-1), and K (57 kg ha-1) had a greater effect on biomass after the third year of fertilizer addition; (2) Gramineae accounted for a major portion of biomass in 2016, whereas the proportion of other species declined or disappeared; and (3) the longer the fertilization treatments went on, the lower Shannon diversity and Pielou’s evenness turned out to be. All these responses are strongly interrelated in a cascade of changes. The interrelationships between fertilizers and different plant communities attribute the change not only to climate shift but also to time. [ABSTRACT FROM AUTHOR]

Future climate may profoundly impact the functioning of terrestrial ecosystems. However, we do not know well how the functioning of different types of grassland ecosystems is associated with variation in temperature and precipitation. Here, we used long‐term field measurements to examine how climatic changes between the 1980s and the 2010s (i.e., growing season temperature, precipitation, habitat moisture index, solar radiation, and sunshine duration) have affected aboveground net primary productivity (ANPP) for all major grassland types in northern China. We found that ANPP consistently declined over the 30‐year period across all types of grassland, on average by about 6.1%. Warming, associated with increased solar radiation and, hence, soil temperature, was the primary factor driving the decrease of ANPP. We further show that ANPP was more sensitive to climate change in alpine and lowland grasslands than in temperate grasslands. Together, our findings indicate that climate warming consistently reduces plant productivity of different types of grassland ecosystems, and emphasize the importance of soil temperature in driving the decline in grassland productivity under climate change. Plain Language Summary: Future climate may profoundly impact the functioning of terrestrial ecosystems. However, we do not know well how the functioning of different types of grassland ecosystems is associated with variation in temperature and precipitation. Here, we used long‐term field measurements to examine how climatic changes between the 1980s and the 2010s (i.e., growing season temperature, precipitation, habitat moisture index, solar radiation, and sunshine duration) have affected aboveground net primary productivity (ANPP) for all major grassland types in northern China. We found that ANPP consistently declined over the 30‐year period across all types of grassland, on average by about 6.1%. Warming, associated with increased solar radiation and, hence, soil temperature, was the primary factor driving the decrease of ANPP. We further show that ANPP was more sensitive to climate change in alpine and lowland grasslands than in temperate grasslands. Together, our findings indicate that climate warming consistently reduces plant productivity of different types of grassland ecosystems, and emphasize the importance of soil temperature in driving the decline in grassland productivity under climate change. Key Points: There is a universal decrease in aboveground net primary productivity (ANPP) over 30 years across different grassland types, and the magnitude of ANPP decline differed between typesThe air temperature and soil temperature rather than precipitation were the primary drivers of ANPP decline to climate changeThe increased air temperature and soil temperature from increased total solar radiation were the main drivers for ANPP decline [ABSTRACT FROM AUTHOR]

Aims: Water and nitrogen availability are primary determinants of woody communities in dryland ecosystems and are strongly affected by global change. However, the mechanisms by which resource availability and plant demographic responses regulate woody-herb composition are unclear. Methods: We investigated plant productivity, shrub demography, and resource availability in a 5-year field experiment involving three levels of precipitation (ambient, + 20% precipitation, + 40% precipitation) and two levels of nitrogen addition (0, 60 kg N ha− 1 yr− 1) in a desert shrubland of northern China. Results: Increased precipitation had similar positive effects on shrub and herbaceous productivity and, thus, did not alter the community composition. However, nitrogen enrichment dramatically increased herbaceous productivity but tended to decrease shrub productivity. Five years after the experimental manipulation, increased precipitation and nitrogen enrichment significantly altered shrub demography. Increased precipitation decreased the number and cover of small shrubs but increased those of large shrubs. Nitrogen enrichment largely decreased the number and cover of small shrubs, whereas large shrubs showed a higher resistance. Structural equation modeling revealed that nitrogen-enhanced herbaceous competition for water and light potentially reduced shrub growth, especially the growth of small shrubs. Conclusions: Our results suggest that large shrubs can coexist with herbs, whereas small shrubs tend to be competitively excluded from the system under enhanced precipitation and nitrogen deposition. Nitrogen enrichment may lead to continued declines in shrub recruitment and growth, and a conversion to grassland. Our findings highlight the competitive and demographic mechanisms underlying the responses of woody communities to global change. [ABSTRACT FROM AUTHOR]

Although empirical studies show that invasive Spartina alterniflora Loisel. (S. alterniflora) has reduced soil bulk density (BD), the mechanisms that underpin this response are still unclear. To explore this pattern, we used a space‐for‐time substitution approach and collected soil samples from the eastern coast of China, where S. alterniflora ecosystems were established a short period of time after initial invasion. We used structural equation modelling to test the hypothesis that S. alterniflora invasion has an indirect influence on BD through the interacting effects of soil and plant variables, including plant productivity, soil organic carbon (SOC), total nitrogen (TN), pH, salinity, sand, and clay content. These variables, which are associated with S. alterniflora invasion, were assumed to represent multiple physicochemical and biological processes. The model showed that these processes explain 82% of the BD variation in response to S. alterniflora invasion. We observed that SOC had the most direct influence on BD, followed by salinity and soil sand content. We also found that S. alterniflora invasion had an important direct influence on the measured variables. Although plant productivity was not directly related to BD, it was indirectly associated with the impacts of plant productivity on salinity. Our results highlight the occurrence of BD variability within an interacting system of soil and plants wherein S. alterniflora invasion leads to a decrease in BD. This work also highlights that identifying the mechanisms driving BD variability in response to S. alterniflora invasion would help to improve our understanding of soil development in S. alterniflora marshes. [ABSTRACT FROM AUTHOR]

The large-scale relationship between gross primary productivity (GPP) and plant species richness (PSR) remains a fundamental topic in macro-ecology. Although there have been numerous studies of the connection between GPP and PSR, this relationship (linear or unimodal) is still debatable at geographical scales. Using geographically weighted regression and ordinary least squares, GPP and PSR data from protected areas in China were used to explore the complex relationship between GPP and PSR across different taxonomic groups (i.e. vascular plants, ferns, seed plants, gymnosperms, and angiosperms). Results showed that GPP was significantly related to PSR for all taxonomic groups at geographical scales (p < 0.001). Such relationships varied among taxonomic groups. The explanatory power of GPP was highest for PSR in seed plants (58.5%; p < 0.001). Further, the study found that the GPP–PSR relationships across different taxonomic groups at geographical scales were best described by a cubic regression, differing from the linear or unimodal relationships described thus far. Specifically, negative relationships were found between GPP and PSR at extremely low levels of GPP and GPP–PSR relationships were unimodal at relatively high GPP levels. This analysis provides new evidence regarding the relationship between GPP and PSR based on different taxonomic groups and develops the mechanisms and models of GPP linking to PSR at broad scales. [ABSTRACT FROM AUTHOR]

Soil quality has been defined as the capacity to sustain biological productivity and maintain environmental quality. Mowing and fertilization may affect ecosystem function through numerous soil properties, especially in semiarid grasslands where plant growth is limited by nutrient availability. However, the effects of grassland management on the trade‐off between soil quality and plant community structure is still unclear. Understanding the effect of land use type on soil quality is essential to adopt proper grassland management practices for a specific region. Principal component analysis was used to calculate a soil quality index (SQI) with 18 variables under the following treatments: control, mowing, nitrogen addition, and mowing plus nitrogen addition in August 2017 in a typical steppe of North China. This study showed that nitrogen addition significantly increased SQI by 0.82, field water capacity by 3.77%, soil capillary porosity by 3.30%, and soil available nitrogen content by 13.85 mg kg−1, but reduced soil aggregate proportion by 3.07%, microbial biomass nitrogen content by 7.74 mg kg−1, arbuscular mycorrhizal fungi by 0.02 μmol g−1, the ratio of fungus to bacteria by 0.16, and the ratio of Gram‐positive bacteria to Gram‐negative bacteria by 0.13 across the mowing and unmowing treatments. Nitrogen addition could improve productivity by increasing the soil quality but reduce plant diversity of the grassland ecosystems. Mowing did not affect SQI and aboveground biomass. The results suggested that fertilization as grassland management improved soil quality and productivity, whereas mowing was a sustainable way to maintain plant diversity in this semiarid grassland. [ABSTRACT FROM AUTHOR]

Understanding the relationships among multiple ecosystem services could improve the landscape capacity to provide benefits to human society. However, the underlying mechanisms shaping ecosystem services relationships are still unclear although some studies have been conducted to explore how natural and socioeconomic factors influence the relationships among ecosystem services. In this study, the karst landscape in southwestern China, a vulnerable system with intensive human activities, was focused on, aiming to explore relationships between ecosystem services and associated social and ecological factors. The results showed that the distribution of eight individual ecosystem services were spatially heterogeneous and clustered based on the characteristics of the karst landscape. The relationships between provisioning services and regulating services, such as grain production and net primary productivity, as well as water yield and soil retention, were quite different between high karst coverage regions and low karst coverage regions. Among five ecosystem service bundles identified, ecosystem services in the urban development bundle were mainly determined by socioeconomic factors, while in the other four bundles of multifunction, grain production, habitat conservation, and carbon sequestration, ecosystem services were dominated by ecological factors. However, socioeconomic factors (i.e. population density and night-time light intensity) appeared to explain the overall ecosystem service delivery more than karst terrain. This study provided insights for sustainable ecosystem management in a vulnerable karst region through exploring social-ecological factors of the relationships among ecosystem services. [ABSTRACT FROM AUTHOR]

Plant litter decomposition is a crucial ecosystem process that regulates nutrient cycling, soil fertility, and plant productivity and is strongly influenced by increased nitrogen (N) deposition. However, the effects of exogenous N input on litter decomposition are still poorly understood, especially in temperate shrublands, which hinders predictions of soil C and nutrient dynamics under the context of global change. Temperate shrub ecosystems are usually N-limited and particularly sensitive to changes in exogenous N input. To investigate the responses of Vitex negundo and Spiraea trilobata litter decomposition to N addition, we conducted a field experiment in Vitex - and Spiraea -dominated shrublands located on Mt. Dongling in Beijing, North China. Four N treatment levels were applied: control (N0; no N addition), low N (N1; 20 kg⋅N⋅ha–1⋅year–1), moderate N (N2; 50 kg⋅N⋅ha–1⋅year–1), and high N (N3; 100 kg⋅N⋅ha–1⋅year–1). The litter decomposition in V. negundo was faster than that in S. trilobata , which may be due to the differences in their nutrient content and C/N ratio. N addition increased the amount of remaining N in the two litter types but had no effect on the remaining mass, C, or P. Nitrogen treatment did not affect the litter decomposition rates (k) of either litter type; i.e., N addition had no effect on litter decomposition in temperate shrublands. The neutral effect of N addition on litter decomposition may be primarily explained by the low temperatures and P limitation at the site as well as the opposing effects of the exogenous inorganic N, whereby exogenous N inhibits lignin degradation but promotes the decomposition of readily decomposed litter components. These results suggest that short-term N deposition may have a significant impact on N cycling but not C or P cycling in such shrub ecosystems. [ABSTRACT FROM AUTHOR]

Bulb rot causes a great loss of rare perennial medicinal Fritillaria przewalskii Maxim., which is exacerbated with growth year and seriously constrains the plant productivity, but the pathogens responsible for the disease were still unknown. In this paper, we attempted to explore the potential pathogens leading to bulb rotting and their occurrence patterns in artificial domesticated F. przewalskii. Fungus strains were isolated from the bulb rot spot of the 3‐ to 5‐year‐old diseased F. przewalskii plants by tissue separation, further assayed for pathogenicity according to Koch's law and finally identified by both morphological and molecular methods. Seven pathogenic strains (F1‐F7) were detected in 5‐year‐old rot bulbs, six (F1‐F6) in 4‐year‐old rot bulbs and four (F1, F2, F5, F6) in 3‐year‐old rot bulbs. All of the strains were able to infect bulbs by stabbing and some exhibited varying levels of aggressiveness. Relative to the non‐stabbing controls, the bulbs stab‐inoculated with F5, F2, F7, F4, F1, F6, and F3 showed 76.65%, 75.15%, 71.44%, 40.37%, 39.09%, 36.87%, and 34.93% rot after 8 days, respectively. Phylogenetic analysis revealed that these seven strains were clustered into Bionectria ochroleuca (F1, F3, F4), Fusarium oxysporum (F2, F7), Fusarium tricinctum (F5), and Clonostachys rosea (F6). The two species of Fusarium had the strongest pathogenicity, followed by Bionectria ochroleuca and Clonostachys rosea. Although leading to low bulb rot incidence by stab inoculation, F1 showed the highest isolation rate (48.9%) among all strains. Thus, the edible and medicinal bulbs of F. przewalskii are susceptible to synergetic contamination by these seven pathogens at some point after their third year of growth, which has contributed to the species endangered status, with the two strains of Fusarium being the predominant pathogens. To our knowledge, this is the first report on the seven strains of four fungal species causing F. przewalskii bulb rot in China. [ABSTRACT FROM AUTHOR]