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The initial concentration of litter nutrient not only affects the following decomposition process but also determines the quantities of nutrients returned to the soil. The aim of this study is to assess the global patterns and driving factors of three macronutrients, namely potassium (K), calcium (Ca) and magnesium (Mg), in freshly fallen litter.By synthesizing 5861 data points extracted from 584 publications, we quantitatively evaluated the concentrations of litter K, Ca and Mg in different litter types, life forms, taxonomic divisions and mycorrhizal associations. Also, using the machine learning method, we predicted their global patterns in forests, grasslands and shrublands.We found that (1) mean K, Ca and Mg concentrations ranged from 2.63 to 6.23, 1.05 to 11.50 and 0.20 to 2.74 g/kg, respectively, across different litter types; (2) the initial nutrients of the litter were significantly affected by plant functional types (e.g. life form, taxonomic division and mycorrhizal association), climate (e.g. isothermality, mean diurnal range, annual evapotranspiration and precipitation seasonality) and soil properties (e.g. pH, exchangeable Ca concentration and water content), with a higher litter K concentration of herbaceous plants, higher K, Ca and Mg concentrations from angiosperms and higher K and Mg concentrations from plants associated with arbuscular mycorrhiza (AM) fungi; and (3) the predicted leaf litter K, Ca and Mg concentrations were lower in high‐latitude regions compared with those in low‐ and/or mid‐latitude regions.Our study provides a globally comprehensive analysis on the patterns and driving factors of three important macronutrients in freshly fallen litter, contributing to a better understanding of their role in the decomposition process of litter, as well as the associated biogeochemical cycles under the future climate change scenario. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Forest microclimates can contrast substantially from the macroclimate outside forests. These microclimates regulate understory biodiversity and ecosystem functions. Studies have quantified the global patterns and driving factors of forest understory temperature offsets, but data from China were almost missing, making the global assessment incomplete. To fill this knowledge gap, we quantitatively synthesized 494 paired observations from China extracted from 91 publications to quantify mean (Tmean), maximum (Tmax) and minimum temperature offsets (Tmin). Results showed that (1) forest canopies significantly buffered understory Tmean and Tmax against macroclimatic temperature, with average offsets of 1.0 and 1.5°C, respectively, while understory Tmin offsets were not significantly different from zero; (2) forest type (broadleaved, mixed, vs. coniferous) and forest location (rural vs. urban) did not affect Tmean, Tmax or Tmin offsets, but climate zone and season showed significant impacts; and (3) macroclimatic temperature, wind speed, tree height and canopy density also impacted temperature offsets, although their effects varied among Tmean, Tmax and Tmin. Our results complement the global assessment of forest buffering capacity, and reiterate the necessity for incorporating microclimatic variability into future bioclimatic modelling of species demography and distributions. [ABSTRACT FROM AUTHOR]

Mining causes severe damage to soil ecosystems. Vegetation restoration in abandoned mine areas is an inevitable requirement for sustainable development. Soil microbes, as the most active component of soil organic matter, play a crucial role in the transformation of carbon, nitrogen, phosphorus, and other elements. They are often used as indicators to assess the extent of vegetation restoration in ecologically fragile areas. However, the impacts of vegetation restoration on soil microbial community structure in mining areas at the global scale remains largely un-known. Based on 310 paired observations from 44 papers, we employed the meta-analysis approach to examine the influence of vegetation restoration on soil microbial abundance and biomass in mining area. The results indicated that vegetation restoration significantly promotes soil microbial biomass in mining areas. In comparison to bare soil, vegetation restoration leads to a significant 95.1% increase in soil microbial biomass carbon and a 87.8% increase in soil microbial biomass nitrogen. The abundance of soil bacteria, fungi, and actinomycetes are significantly increased by 1005.4%, 472.4%, and 177.7%, respectively. Among various vegetation restoration types, the exclusive planting of trees exhibits the most pronounced promotion effect on soil microbial biomass and population, which results in a significant increase of 540.3% in soil fungi and 104.5% in actinomycetes, along with a respective enhancement of 110.3% and 106.4% in microbial biomass carbon and nitrogen. Model selection results revealed that soil saturated water content and vegetation restoration history contribute most significantly to the abundance of soil bacteria and fungi. Soil available nitrogen has the most significant impact on the abundance of actinomycetes and microbial biomass carbon, while soil available phosphorus emerges as a crucial factor affecting microbial biomass nitrogen. This research could contribute to understanding the relationship between vegetation restoration and the structure of soil microbial communities in mining areas, and providing scientific support for determining appropriate vegetation restoration types in mining areas. [ABSTRACT FROM AUTHOR]

Litter decomposition is a key ecological process that determines carbon (C) and nutrient cycling in terrestrial ecosystems. The initial concentrations of C and nutrients in litter play a critical role in this process, yet the global patterns of litter initial concentrations of C, nitrogen (N) and phosphorus (P) are poorly understood.We employed machine learning with a global database to quantitatively assess the global patterns and drivers of leaf litter initial C, N and P concentrations, as well as their returning amounts (i.e. amounts returned to soils).The medians of litter C, N and P concentrations were 46.7, 1.1, and 0.1%, respectively, and the medians of litter C, N and P returning amounts were 1.436, 0.038 and 0.004 Mg ha−1 year−1, respectively. Soil and climate emerged as the key predictors of leaf litter C, N and P concentrations. Predicted global maps showed that leaf litter N and P concentrations decreased with latitude, while C concentration exhibited an opposite pattern. Additionally, the returning amounts of leaf litter C, N and P all declined from the equator to the poles in both hemispheres.Synthesis: Our results provide a quantitative assessment of the global concentrations and returning amounts of leaf litter C, N and P, which showed new light on the role of leaf litter in global C and nutrients cycling. [ABSTRACT FROM AUTHOR]

Global climate change has led to more frequent and severe droughts, which can negatively affect instream invertebrate communities, but we lack a perspective on the global patterns and drivers of such drought effects. Here, using meta-analysis, we synthesized 997 paired observations extracted from 94 peer-reviewed publications to assess how drought affects the biomass, density, taxonomic richness, and diversity (Shannon–Wiener, Simpson, and Pielou indices) of instream invertebrates at a global scale. We found that (i) drought significantly decreased instream invertebrate density and taxonomic richness by an average of 4.9 and 5.0%, respectively, had marginal negative effects on Shannon–Wiener index, but did not affect biomass, Simpson index or Pielou index; (ii) the effects of drought on instream invertebrate biomass, density, and diversity were not affected by taxonomic level, indicating the robustness of our results; and (iii) stream water physiochemical characteristics such as water flow velocity, pH, conductivity, discharge, total nitrogen concentration, and chlorophyll-a concentration were important moderator variables of drought effects on instream invertebrate communities. Overall, our results clearly showed the global patterns and driving factors of drought effects on instream invertebrate biomass, density, richness, and diversity, which helps scientists better understand the responses of instream invertebrate communities under ongoing global climate change. [ABSTRACT FROM AUTHOR]

Human activities have been responsible for substantial land use changes, including the conversion of different ecosystems to tree plantations (thereafter plantations). Despite that these land use changes can have significant effects on hydrological processes in soils, a global perspective on how land use changes may impact soil water holding characteristics is still lacking. Here we performed a meta-analysis with 11078 paired observations collected from 330 peer-reviewed publications to assess how the conversion of croplands, deserts, grasslands, primary forests, secondary forests, shrublands, and bare lands to plantations might affect soil water content (WC), water holding capacity (WHC), saturated water content (SWC), and capillary holding water (CHW). We found that converting croplands to plantations significantly increased WHC and CHW by 14.4% and 30.1%, respectively. Converting deserts into plantations increased CHW by 25.3%, while converting grasslands to plantations increased WHC by 12.7%. The conversion of bare lands to plantations increased soil SWC and CHW by 37.7% and 41.5%, respectively. In contrast, cropland and grassland conversion to plantations decreased soil WC by 17.8% and 15.6%, respectively. The conversion of primary forests, secondary forests, and shrublands to plantations did not affect soil WC, WHC, SWC, or CHW. Finally, the effects of land use change on soil water holding characteristics were regulated by multiple moderator variables, with climate, geographical location, and tree species functional types being the most important. Overall, our quantitative analyses clearly showed how ecosystem conversion affected soil water holding characteristics at the global scale, which will help us to better understand and predict soil hydrological processes following land use changes under future global change. • Converting croplands and grasslands to plantations decreased soil water content by 17.8% and 15.6%, respectively. • Converting primary and secondary forests and shrublands to plantations did not affect soil water. • Climate, geographical location, and vegetation characteristics were the essential driving factors. [ABSTRACT FROM AUTHOR]

Plant litter is not only the major component of terrestrial ecosystem net productivity, the decomposition of which is also an important process for the returns of elements, including sodium (Na) and aluminum (Al), which can be beneficial or toxic for plant growth. However, to date, the global characteristics and driving factors of Na and Al concentrations in freshly fallen litter still remain elusive. Here, we evaluated the concentrations and drivers of litter Na and Al with 491 observations extracted from 116 publications across the globe. Results showed that (1) the average concentrations of Na in leaf, branch, root, stem, bark, and reproductive tissue (flowers and fruits) litter were 0.989, 0.891, 1.820, 0.500, 1.390, and 0.500 g/kg, respectively, and the concentrations of Al in leaf, branch, and root were 0.424, 0.200 and 1.540 g/kg, respectively. (2) mycorrhizal association significantly affected litter Na and Al concentration. The highest concentration of Na was found in litter from trees associated with both arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (ECM), followed by litter from trees with AM and ECM. Lifeform, taxonomic, and leaf form had significant impacts on the concentration of Na and Al in plant litter of different tissues. (3) leaf litter Na concentration was mainly driven by mycorrhizal association, leaf form and soil phosphorus concentration, while leaf litter Al concentration was mainly controlled by mycorrhizal association, leaf form, and precipitation in the wettest month. Overall, our study clearly assessed the global patterns and influencing factors of litter Na and Al concentrations, which may help us to better understand their roles in the associated biogeochemical cycles in forest ecosystem., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Wu, Wu, Yue, Yuan, Yuan and Peng.)

Background: Grassland plays an important role in the ecosystem, but overgrazing harms the grassland system in many places. Grazing prohibition is an effective method to restore grassland ecosystems, and it plays a great role in realizing the sustainable development of grassland systems. Therefore, it is necessary to carry out research on the influence of regional grazing prohibition on the physical and chemical properties of different grassland systems., Methods: In Potatso National Park, Southwest China, we selected experimental plots in the artificial grazing meadow area to study the effects of grazing prohibition on plant and soil indexes in subalpine meadows and swamp meadows. We investigated the biomass and species diversity of grazing prohibition treatment and grazing treatment plots and sampled and tested the soil index. The variation percentage was used to remove the original heterogeneity and yearly variation, allowing us to compare differences in plant index and soil index values between grazing prohibition and grazing treatments., Results: Grazing prohibition increased the aboveground biomass, total biomass, total meadow coverage, average height, richness index, Shannon diversity index and evenness index and reduced the belowground biomass and root/shoot ratio in the subalpine meadow and swamp meadow. Additionally, grazing prohibition reduced the pH and soil bulk density and increased the soil total carbon, soil organic carbon, soil total nitrogen, soil hydrolyzable nitrogen, soil total phosphorus and soil available phosphorus in the subalpine meadow and swamp meadow. Nonmetric multidimensional scaling (NMDS) analysis showed that both plant indexes and soil indexes were significantly different between grazing and grazing prohibition treatments and between meadow types. Short-term grazing prohibition had a great impact on improving the fertility of meadow soil in the study area. We suggest that long-term and extensive research should be carried out to promote the restoration and sustainable development of regional grassland systems., Competing Interests: The authors declare there are no competing interests., (©2021 Zhu et al.)

Background: Soil respiration ( R S ) plays an important role in the concentration of atmospheric CO 2 and thus in global climate patterns. Due to the feedback between R S and climate, it is important to investigate R S responses to climate warming., Methods: A soil warming experiment was conducted to explore R S responses and temperature sensitivity ( Q 10 ) to climate warming in subtropical forests in Southwestern China, and infrared radiators were used to simulate climate warming., Results: Warming treatment increased the soil temperature and R S value by 1.4 °C and 7.3%, respectively, and decreased the soil water level by 4.2% (%/%). Both one- and two-factor regressions showed that warming increased the Q 10 values by 89.1% and 67.4%, respectively. The effects of water on Q 10 show a parabolic relationship to the soil water sensitivity coefficient. Both R S and Q 10 show no acclimation to climate warming, suggesting that global warming will accelerate soil carbon release., Competing Interests: The authors declare there are no competing interests., (©2019 Yuan et al.)