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Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change, while the capacity of trees to cope with drought recovery through physiological and biochemical adjustment remains unclear. We aimed to examine the coupling of physiology and biochemistry in trees during drought and the following recovery. Methods Potted seedlings of Cinnamomum camphora were grown under well watered conditions prior to the experimental drought stress, which was initiated by withholding water. Seedlings were rewatered following attainment of two drought severities: mild drought (stomatal closure) and moderate drought (ψxylem = −1.5 MPa). We measured leaf-level water potential, gas exchange (photosynthesis and stomatal conductance), abscisic acid (ABA), proline and non-structural carbohydrates (NSCs) concentrations in seedlings of C. camphora during drought and a 4-day recovery. Important Findings We found that drought severity largely determined physiological and biochemical responses and affected the rate of recovery. Stomatal closure occurred at the mild drought stress, accompanied with ABA accumulation in leaves and decline in water potential, while leaf proline accumulation and variable NSC were evident at the moderate drought stress. More severe drought stress led to delayed recovery of gas exchange, but it did not have significant effect on water potential recovery. The relationships of water potential and gas exchange differed during drought stress and post-drought recovery. There was tight coupling between water potential and gas exchange during drought, but not during rewatering due to high ABA accumulation in leaves, thereby delaying recovery of stomatal conductance. Our results demonstrate that ABA could be an important factor in delaying the recovery of stomatal conductance following rewatering and after water potential recovery of C. camphora. Furthermore, greater drought severity had significant impacts on the rate of recovery of tree physiology and biochemistry.

Tree age (AGE) and stocking degree (P) strongly influence tree shape, but their effects have been neglected in most tree profile equations. In addition, data used to build traditional tree profile equations usually do not meet the statistical requirements of independence and identical distribution of observations. The main objectives were to present a method to improve taper equations with measurements easily collected in tree inventories (age, stocking degree) and also improve the statistical accuracy of those equations by selecting parameters with a more rigorous way than that is traditionally being done. We evaluated the effects of incorporating age and stocking degree as regressors in tree profile equations selected among 30 candidate foundation equations and parameterized with data from 1,858 Larix gmelinii (Rupr.) trees growing in the northern China. We used nonlinear mixed-effects models to minimize statistical problems present when building traditional tree profile equations: lack of independence and identical distribution of observations, random effects related to individual trees. Equations incorporating age and stocking degree significantly improved their accuracy. When the equation parameters were estimated with mixed- effects models containing exponential variance functions and accounting for non-independence of observations from the same tree, diameters at any height along the tree bole were more accurately estimated. We demonstrate a new methodology to build more accurate tree profile equations that could support better economic valorization of timber and improve calculations of carbon flows in forests, not only for natural L. gmelinii forest but for other species growing in dense natural stands around the globe. This study was funded by the National Key R&D Program of China (2017YFC0504003-2), National Natural Science Foundations of Inner Mongolia Autonomous Region (2015BS0303) and Excellent Young Scientist Foundation of Inner Mongolia Agricultural University of China (No. 2014XYQ-6).

Large amounts of nitrogen (N) are loaded in tropical and subtropical regions due to anthropogenic activities. However, the long-term effect of this deposition on soil biodiversity and its ecological functions remains poorly understood. In this study, we established a 10-year-long field experiment examining the effect of simulated N deposition on soil bacterial diversity and litter decomposition processes in a subtropical Chinese fir forest. The N levels were 0 (control), 6, 12, and 24 g m−2 yr−1. Soil bacterial diversity was measured by high throughput sequencing analysis, while litter decomposition was investigated by a microcosm experiment with a reciprocal soil and litter design. Our long-term experimental results demonstrated that N addition significantly changed soil pH, NH4+-N, available P and soil moisture; reduced soil bacterial diversity; and changed soil microbial community composition at the phyla and class levels. Meanwhile, the rate of litter decomposition decreased in treatments with high doses of N addition. The decreased soil pH and changes in understory plants were significantly correlated with the altered soil microbial diversity and community composition according to the structure equation model analysis. Our results showed that changes in soil microbial community composition (but not soil microbial diversity) mainly contributed to the decline in litter decomposition in higher doses of N addition. Our findings conclude that global change phenomena such as N deposition would depress both above- and below-ground biodiversity and would strongly affect ecosystem functions and processes in subtropical forests.

Fine roots play a prominent role in plants’ acquisition of nutrients and water from the soil, and their amounts and dynamics determine trees’ growth and adaptation to environmental stress. However, the relationship between fine tree roots (including absorptive roots and fine transport roots) and forest biomass or fine understory vegetation roots (understory roots) remains poorly understood, which was the main objective of this study. We selected 20 plots in Chinese fir (Cunninghamia lanceolata) plantation forests of the similar ages (23 years old on average) in different areas with various levels of forest biomass in subtropical China to assess the above-mentioned relationship. Forest biomass was used as a proxy for soil condition. We found that all fine root biomass of trees and understory vegetation were significantly and negatively correlated with forest biomass. To our surprise, both total Chinese fir fine root biomass (absorptive roots and fine transport roots) and fine transport root biomass showed significant and positive correlations with understory root biomass. These results clearly demonstrate that fine tree root biomass is significantly promoted and increased due to competition from understory vegetation where forest biomass is low.

Long-term nitrogen (N) fertilization has been shown to profoundly affect the soil microorganisms and strongly result in several imbalances in element concentrations. The objective of this study was to examine links among the soil microorganisms, enzyme activities, and soil carbon (C), N, and phosphorus (P) stoichiometry in a subtropical Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantation after continuous N fertilization for 13 years. This study was performed in 25-year-old fir plantation along a fertilization gradient (0, 60, 120, and 240 kg N ha−1 yr.−1), designated as N0, N1, N2, and N3, respectively. Soil microbial properties, including the microbial community composition, as revealed by phospholipid fatty acids (PLFAs), and soil enzyme activities (i.e., sucrase, urease and catalase) were measured, and soil elemental stoichiometry was calculated based on soil C, N, and P concentrations. A redundancy analysis (RDA) was conducted to determine the relationship between soil C:N:P stoichiometry and soil microbial properties. Compared with the control (N0), N fertilization decreased the total PLFAs (−12.20%), bacteria (−14.33%), fungi (−12.97%), and actinomycetes (−17.11%) on average. Sucrase, urease and catalase activities were enhanced by low and middle levels of N (N1 and N2), but not with high level of N (N3). Long-term N fertilization decreased soil pH, C to N ratio (C/N), and C to P ratio (C/P), while increased soil C, N and N to P ratio (N/P). The RDA identified the first two axes of soil stoichiometry variation that explained 20.4% of the variation at the soil depth of 0–20 cm, 28.6% at 20–40 cm and 49.9% at 40–60 cm in PLFAs biomarkers and enzymes, respectively. Significant correlations between soil stoichiometry (soil N/P and C/P ratio) and soil microbial properties were found in this study. These observations suggested that long-term N fertilization influenced soil microbial community composition and enzyme activities by changing the soil C/P and N/P ratios. Future studies are needed to consider the coupling relationships between soil microbial community composition, enzyme activities and elemental stoichiometry in different ecosystems under future climatic change.

A systematic approach helps to illuminate the complex forest-water nexus

Background Water-use efficiency (WUE) represents the coupling of forest carbon and water. Little is known about the responses of WUE to thinning at multiple spatial scales. The objective of this research was to use field measurements to understand short-term effects of two thinning treatments (T1: 4500 stems ha−1; and T2: 1100 stems ha−1) and the control (NT: 27,000 stems ha−1) on WUE at the three spatial scales (leaf level: the ratio of leaf photosynthesis to leaf transpiration; tree-level: tree growth to tree transpiration; and stand level: net primary production (NPP) to stand transpiration) and intrinsic WUEi (the ratio of leaf photosynthesis to stomatal conductance at leaf-level; and NPP to canopy conductance at stand-level) in a 16-year old natural lodgepole pine forest. Leaf-level measurements were conducted in 2017, while tree- and stand-level measurements were conducted in both 2016 (the normal precipitation year) and 2017 (the drought year). Results The thinning treatments did not significantly affect the tree- and stand-level WUE in the normal year of 2016. However, the thinning significantly affected WUE in the drought year of 2017: T2 exhibited significantly higher tree-level WUE (0.49 mm2 kg−1) than NT (0.08 mm2 kg−1), and compared to NT, the stand-level WUE values in the thinned stands (T1 and T2) were significantly higher, with means of 0.31, 0.56 and 0.70 kg m−3, respectively. However, the leaf-level and stand-level WUEi in the thinned stands in the drought year were significantly lower than those in the unthinned stands. No significant differences in the leaf-level WUE were found among the treatments in 2017. In addition, the thinning did not significantly change the WUE-VPD relationships at any studied spatial scale. Conclusions The thinning treatments did not cause significant changes in all studied WUE metrics in a normal year. However, their effects were significantly promoted under the drought conditions probably due to the decrease in soil water availability, demonstrating that thinning can improve WUE and consequently support forests to cope with the drought effects. The inconsistent results on the effects of the thinning on forest carbon and water coupling at the spatial scales and the lack of the consistent WUE metrics constraint across-scale comparison and transferring of WUE.

Species diversity plays an essential role in enhancing ecosystem functions (EF) in both natural and plantation forests. However, we do not fully understand whether species diversity could maintain the sustainability of EFs in multiple-rotation plantations. Here, we hypothesized that tree species mixtures could mitigate declines in EFs along successive rotations, but could not maintain ecosystem multifunctionality. To test our hypothesis, we examined the effects of species diversity on four EFs, i.e., aboveground biomass (AGB), soil available nitrogen (SAN) and phosphorus (SAP), and soil organic matter (SOM), based on pure model simulation in plantations of subtropical China. The model fusion framework was set up by the integration of the process-based FORECAST and Multivariate Diversity-Interactions models. In the simulation, four local typical plantation tree species (two conifers, one evergreen broadleaf, and one deciduous N-fixing broadleaf) were selected and combined to form four monoculture and 11 mixture stands, and for each stand, the simulation was made for four 25-year rotations. The results showed that all the four EFs declined with the progress of rotations in both monoculture and mixtures, and the declining range was larger in monoculture than in mixtures in each rotation. Particularly, SAP significantly decreased while AGB, SAN, and SOM increased with diversity evenness from 0 (monoculture) to 1 (four species being equal abundant in the mixture). Overall, SAP and AGB displayed higher sensitivity to the disturbance of successive rotations compared with SAN and SOM. These results suggest that mixing species could not maintain EFs along with successive rotations because it could not alleviate SAP deficiencies in the soils resulted from the disturbances of silvicultural measures.

Since December 2019 to May 2020, coronavirus disease 2019 (COVID-19) has infected over 6 million people worldwide. Due to its sudden and rapid outbreak, effective treatment for COVID-19 is scarce. Based on national clinical trials of novel treatments, China, Italy, Germany, and other countries and organizations have published multiple guidelines for COVID-19 and advised many medicines, such as chloroquine and tocilizumab. In this paper, we summarize the pharmacotherapy for COVID-19 according to those guidelines, highlight updates of the pharmacotherapy guidelines, and review the efficacy and safety of the indicated anti-COVID-19 drugs.

Background Forest disturbance induced changes in the coupling of forest carbon and water have important implications for ecosystem functioning and sustainable forest management. However, this is rarely investigated at the large watershed scale with cumulative forest disturbance. We used a combination of techniques including modeling, statistical analysis, and machine learning to investigate the effects of cumulative forest disturbance on water use efficiency (WUE, a proxy for carbon and water coupling) in the 19,200 km2 Chilcotin watershed situated in the central interior of British Columbia, Canada. Harvesting, wildfire, and a severe Mountain Pine Beetle (MPB) infestation have gradually cumulated over the 45-year study period, and the watershed reached a cumulative equivalent clear-cut area of 10% in 1999 and then 40% in 2016. Results Surprisingly, with the dramatic forest disturbance increase from 2000 to 2016 which was mainly due to MPB, watershed-level carbon stocks and sequestration showed an insignificant reduction. This resilience was mainly due to landscape-level carbon dynamics that saw a balance between a variety of disturbance rates and types, an accumulation of older stand types, and fast growing young regenerated forests. Watershed-level carbon sequestration capacity was sustained, measured by Net Primary Production (NPP). A concurrent significant decrease in annual evapotranspiration (ET), led to a 19% increase in WUE (defined as the ratio of NPP to ET), which is contrary to common findings after disturbance at the forest stand-level. During this period of high disturbance, ET was the dominant driver of the WUE increase. Conclusions We conclude that disturbance-driven forest dynamics and the appropriate scale must be considered when investigating carbon and water relationship. In contrast to the stand-level trade-off relationship between carbon and water, forested watersheds may be managed to maintain timber, carbon and water resources across large landscapes.

BackgroundWater-use efficiency (WUE) represents the coupling of forest carbon and water. Little is known about the responses of WUE to thinning at multiple spatial scales. The objective of this research was to use field measurements to understand short-term effects of two thinning treatments (T1: 4,500 stems ha-1; and T2: 1,100 stems ha-1) and the control (C: 27,000 stems ha-1) on WUE (the ratio of leaf photosynthesis to leaf transpiration, or tree growth to tree transpiration, or net stand above-ground biomass (AGB) accumulation to stand transpiration) and the intrinsic WUE (WUEi, the ratio of leaf photosynthesis to stomatal conductance or the net stand AGB accumulation to canopy conductance) in a 16-year old natural lodgepole pine forest. Leaf-level measurements were conducted in 2017, while tree- and stand-level measurements were conducted in both 2016 (the normal year) and 2017 (the drought year).ResultsThere was no significant effect of thinning on the tree- and stand-level WUE in 2016, while in 2017, only T2 exhibited significantly higher tree-level WUE (0.63 mm2 kg-1) than the C (0.06 mm2 kg-1), and the stand-level WUE values were significantly higher in the thinned stands, with the means of 0.34, 0.61 and 0.7 kg m-3 for the control, T1 and T2, respectively. Stand-level WUEi was, however, significantly higher in the unthinned stands than in the thinned stands. In contrast, the leaf-level WUE values were not significantly different from each other, while the leaf-level WUEi was statistically higher in C than in the thinned stands. Thinning changed the WUE-VPD relationships at tree and stand levels, but not at the leaf level.Conclusions The effects of thinning on forest carbon and water coupling differed with the spatial scales and the metrics (WUE or WUEi) of water use efficiency. Lacking consistent reponses of WUE metrics to thinning treatments across the spatial scales suggests that caution must be exercised when transferring and modeling WUE from one spatial scale to others. Both tree-level and stand-level WUE values in the more heavily thinning stands were significantly promoted under the drough condition, demonstrating that thinning can improve WUE and consequently support forests to cope with the drought effects.

International audience; Key messageThe 19-year monitoring study revealed continuously positive and dynamic responses of tree growth to logging residue loadings. However, the lack of changes in soil nutrients suggested that increased growth might result from enhanced nutrient cycling with no net accumulation in the soil.ContextUnderstanding how logging residue loadings affect soil nutrients and forest growth is critical for designing management strategies for sustaining long-term productivity in forest ecosystems.AimsWe aimed to examine the relationships among logging residue loadings, soil nutrients, and tree growth over a long-term field experiment in lodgepole pine (Pinus contorta Doug. ex Loud.) forests.MethodsWe established a field experiment in 1996 to examine the responses of lodgepole pine growth and soil nutrients to four residue loading treatments in the central interior of British Columbia, Canada. The four treatments were removal of all residues on the forest floor (N, 0 mg ha−1), residues loading similar to whole-tree harvesting (W, 35–45 mg ha−1), residues loading similar to stem-only harvesting (S, 60–70 mg ha−1), and residues loading similar to that found in disease- or insect-killed forests (D, 100–120 mg ha−1).ResultsLogging residue loadings had significantly positive and dynamic effects on diameter and height growths. The logging residue loadings did not significantly change soil nutrients in mineral soil pools in the long run, and there was no difference in tree growth between the treatments S and W over the study period.ConclusionLogging residue loadings significantly improved tree growth. The lack of response of soil nutrients leads to the hypothesis that nutrient fluxes from logging residues might play a more important role in tree growth in lodgepole pine forests. Our results can have important implications for bio-energy production and designing of nature-based practices for sustainable forest productivity.

BackgroundWe proposed a new method to evaluate the height of the posterior articular surface in displaced intra-articular calcaneal fractures (DIACFs) by drawing two lines on the lateral radiograph of hindfoot: one line was drawn from the apex of the posterior facet to the apex of the posterior tuberosity (the apex line), and the other line was drawn from the apex of the anterior process to the posterior process (the anterior posterior process line). The aim of this study was to analyze the relationship between these two lines in normal calcanei and their changes in DIACFs.MethodsLateral radiographs of normal calcanei and DIACFs between January 2018 and February 2020 were collected. We draw two lines on the lateral radiograph, one line was the apex line and the other line was the anterior posterior process line. The value of the angle formed by these two lines was recorded, if these two lines were parallel to each other, the angle was recorded as 0°. if these two lines formed an angle anteriorly this was recorded as positive, and if these two lines formed an angle behind the calcaneum this was recorded as negative.ResultsIn 135 normal calcanei lateral radiographs, the minimum angle was − 8°, and the maximum angle was 6°, with an average angle of -1 ± 3°. In 145 DIACFs, the minimum angle was 6°; the maximum angle was 37°, and the average angle was 17°±6°. The difference between normal calcanei and DIACFs was statistically significant (P༜.001).ConclusionThe relationship between the apex line and the anterior posterior process line on lateral radiograph can evaluate the height of the calcaneal posterior facet simply and accurately. The two lines are approximately parallel or angulated backward in the normal calcanei, in DIACFs, these two lines angulated forward.Level of Evidence: Level III-retrospective comparative study.

Aboveground biomass (AGB) estimates at the plot level plays a major part in connecting accurate single-tree AGB measurements to relatively difficult regional-scale AGB estimates. However, complex and spatially heterogeneous landscapes, where multiple environmental covariates (such as longitude, latitude, and forest structure) affect the spatial distribution of AGB, make upscaling of plot-level models more challenging. To address this challenge, this study proposes an approach that combines machine learning with spatial statistics to construct a more accurate plot-level AGB model. The study was conducted in a Eucalyptus plantation in Nanjing, China. We developed, evaluated, and compared the accuracy and performance of three different machine learning models [support vector machine (SVM), random forest (RF), and the radial basis function artificial neural network (RBF-ANN)], one spatial statistics model (P-BSHADE), and three combinations thereof (SVM & P-BSHADE, RF & P-BSHADE, RBF-ANN & P-BSHADE) for forest AGB estimates based on AGB data from 30 sample plots and their corresponding environmental covariates. The results show that the performance indices RMSE, nRMSE, MAE, and MRE of all combined models are substantially smaller than those of any individual models, with the RF & P-BSHADE combined method giving the smallest value. These results demonstrate clearly that combined models, especially the RF & P-BSHADE model, can improve the accuracy of plot-level AGB models and reduce uncertainty on plot-level AGB estimates or even on large-forested-landscape AGB estimates. These research results are important because they reduce the uncertainty in estimates of the regional carbon balance.

This chapter reviews how global change affects forest-water interactions and water availability to ecosystems and people and synthesises current understanding of the implications of present and anticipated changes to forests and tree cover for local and global hydrology. Forest cover has declined in the past half-century, despite an increase in plantation forestry. Natural and human disturbances affect forest components (e.g. canopy and leaf area, litter and soil surface, rooting depth, and soil porosity) that in turn affect hydrological processes (e.g. interception, evapotranspiration, infiltration, soil moisture storage, and percolation). Many of these changes result from several influential natural disturbance processes including insects and pathogens, wildfire, ice storms, and windthrow, and human disturbances including establishment and harvest of forests, plantations, agroforestry areas, and urban/peri-urban forests. However, each disturbance process affects different components of the forest, producing distinctive hydrologic effects. Climate change will directly alter forest hydrological processes, and social and economic factors will directly alter forest management, via intensive plantations, deforestation, forest degradation, selective logging, loss of riparian forest, and loss of urban trees, and changes in disturbance regimes. Despite extensive knowledge of forest hydrology, forest changes and their effects on hydrology are poorly documented in many areas of the world, and novel combinations of processes and contexts may produce surprising outcomes. Thus, there is a clear need for more geographically extensive and long-term place-based studies of forest and water. In summary, future climate and social changes will alter forests and water, requiring continued research and collaboration with forest managers and forest owners both for improved resilience to such changes, and to better realize multiple benefits.

Estimating timber volume and carbon stock in forests is fundamental for silviculture and for accurate estimation of national and global carbon budgets. Taper models are important tools for predicting diameter at any height along a tree bole. Mean annual temperature (MAT) and mean annual precipitation (MAP) influence tree growth, but their precise effects on stem shape are still poorly understood and climatic factors are seldom included in taper models. To evaluate the effect of climate on tree stems, we incorporated MAT and MAP as covariates in the Kozak (2004) model to improve model performance in goodness-of-fit. The Kozak (2004) model with the incorporation of MAT and MAP was refitted using nonlinear mixed-effects (NLME) modeling techniques to account for within-sample tree heteroscedasticity and autocorrelation structure in residuals from data measured at different points along the same individual tree stem of Larix gmelinii (Rupr.). Results showed that the predictive accuracy of the Kozak (2004) model was improved by incorporating MAT and MAP as covariates. The Kozak (2004) model incorporating both MAT and MAP had the highest prediction accuracy for stem diameter, closely followed by the model incorporating only MAT and then the model incorporating only MAP. MAT effect on tree stem shape was stronger than that of MAP. The NLME Kozak (2004) model incorporating MAT and MAP with exponential variance function and first-order continuous autoregressive correlation structure (CAR(1) model) removed the heteroscedasticity and autocorrelation in the residuals, had the best prediction performance. Therefore, such refined model is recommended for planning and management of natural L. gmelinii forests. In conclusion, incorporating the effect of climate variables in stem taper equations could significantly improve timber volume and biomass estimations, particularly in harsh environments, such as natural boreal forests. This study was funded by the Transformation Project of Science and Technology Result of Inner Mongolia Autonomous Region (CGZH2018058) and Excellent Young Scientist Foundation of Inner Mongolia Agricultural University of China (No. 2014XYQ-6).

The handling of sewage sludge (SS) and urban plant litter (UPL) has become an important concern. Immobilizing heavy metals (HMs) is regarded as a necessary process for recycling SS in agriculture and forestry. Here, HM removal and HM phytotoxicity in SS during vermicomposting with different additive UPLs was investigated. The results show that vermicomposting with additive UPL significantly reduced the content of HMs, and increased organic carbon content and the proportion of macroaggregates in SS. This process also significantly immobilized HMs by mainly transforming extractable and reducible HMs into residual products. The litters of Dracontomelon duperreanum and Bauhinia purpurea increased oxidizable HMs in SS and the accumulation capacity of HMs of earthworms during vermicomposting. The Cd content in vermicomposts with the B. purpurea litter addition was decreased by 31% relative to the initial SS. Maize in vermicomposts with UPL additions, especially with B. purpurea litter, exhibited significan5tly higher seed germination rates, seedling biomass, root activity, and a lower accumulation of HMs than in SS compost without UPL additions. These results suggest that vermicomposting with additive UPL can alleviate the phytotoxicity of HMs in SS and provides a new method for simultaneously recycling SS and UPL.

Aim: To develop a population pharmacokinetic (PK) model of tacrolimus in Chinese Han renal transplant population and establish the influence of different covariates (especially different CYP3A5/3A4/POR genotype) on PK properties. Materials & methods: Trough tacrolimus concentrations, clinical characteristics and CYP3A5/CYP3A4/POR genotypes were collected from 141 adult renal transplant recipients after transplantation. The population PK analysis was carried out using the nonlinear mixed-effect modeling software NONMEM version 3.4.2. Results: Tacrolimus PK profiles exhibited high interpatient variability. A two compartment model with first-order input and elimination described the tacrolimus PK profiles in the studied population. Among the genotypes, only CYP3A5 genotype was confirmed to have clinical significance. Conclusion: Our final model confirmed that CYP3A5*3 plays a more significant role in tacrolimus PK and could affect the blood concentrations and CL/F (clearance rate/bioavailbility). This model is expected to help to improve individualized tacrolimus dosing.

In the headwater catchments of the Hun River, Northeast China, secondary forests (SF) have been replaced by plantations since the 1960s. Concern has been growing over this loss and the decline in water quality caused by the plantations. To test the effects of plantations on water quality, we selected two separate catchments covered by SF and Pinus koraiensis plantations (KP) to monitor physical and chemical properties of various hydrological variables including throughfall, stemflow, through-litterfall and runoff (flowing out of outlets of the catchments). The physical properties of water declined after water flowed through the two catchments as compared with rainwater. The pH of runoff in both catchments also dramatically decreased. The concentrations of Cl−, NO3− and NH4+ in the runoff from the two catchments were similar (concentrations of Cl− and NH4+ in both catchments were similar to those in rainwater). Total P concentration in runoff of the SF catchment was higher than that of the KP catchment (P concentrations in both catchments were also higher than in rainwater) because P concentrations in litter and soil of the SF catchment were higher than those in the KP catchment. In summary, the rainwater became acidic in both catchments, but the responses of most water quality variables were similar in the two catchments, suggesting that appropriate ratios of KP in SF are feasible for secondary forest recovery and for preserving water quality (KP did not cause a decline in quality) in the headstream regions in Northeast of China.

The long-term stressful utilization of forests and grasslands has led to ecosystem degradation and C loss. Since the late 1970s China has launched six key national ecological restoration projects to protect its environment and restore degraded ecosystems. Here, we conducted a large-scale field investigation and a literature survey of biomass and soil C in China's forest, shrubland, and grassland ecosystems across the regions where the six projects were implemented (∼16% of the country's land area). We investigated the changes in the C stocks of these ecosystems to evaluate the contributions of the projects to the country's C sink between 2001 and 2010. Over this decade, we estimated that the total annual C sink in the project region was 132 Tg C per y (1 Tg = 1012 g), over half of which (74 Tg C per y, 56%) was attributed to the implementation of the projects. Our results demonstrate that these restoration projects have substantially contributed to CO2 mitigation in China.

The modified quadratic discriminant function (MQDF) is an effective classifier for handwritten Chinese character recognition (HCCR). However, it suffers from high memory requirement for the storage of its parameters, which makes it impractical to be embedded in memory limited hand-held devices. In this paper, we explore the applicability of sparse coding to build compact MQDF classifiers. To be specific, we use sparse coding to compact the parameters of MQDF. Two methods of sparse coding, viz., the maximum likelihood-based method and the K-SVD method, are adopted to build two compact MQDF classifiers, namely, MQDF-ML classifier and MQDF-KSVD classifier. Furthermore, we learn multiple dictionaries rather than single dictionary for sparse coding, because the multiple dictionary learning is capable of not only greatly reducing the computational complexity, but also alleviating the degradation of recognition accuracy, compared to the single dictionary learning. Experiments and comparison with the existing method have demonstrated the effectiveness of our proposed method for the issue of unconstrained handwritten Chinese character recognition.

Estimating the aboveground biomass (AGB) at the plot level plays a major role in connecting accurate single-tree AGB measurements to relatively difficult regional AGB estimates. However, AGB estimates at the plot level suffer from many uncertainties. The goal of this study is to determine whether combining machine learning with spatial statistics reduces the uncertainty of plot-level AGB estimates. To illustrate this issue, this study evaluates and compares the performance of different models for estimating plot-level forest AGB. These models include three different machine learning models [support vector machine (SVM), random forest (RF), and a radial basis function artificial neural network (RBF-ANN)], one spatial statistic model (P-BSHADE), and three combinations thereof (SVM & P-BSHADE, RF & P-BSHADE, and RBF-ANN & P-BSHADE). The results show that the root mean square error, mean absolute error, and mean relative error of all combined models are substantially smaller than those of any individual model, with the RF & P-BSHADE combined method generating the smallest values. These results indicate that a combined approach using machine learning with spatial statistics, especially the RF & P-BSHADE model, improves the accuracy of plot-level AGB models. These research results contribute to the development of accurate large-forested-landscape AGB maps.

Fetal growth restriction (FGR) is a well-known risk factor for cognitive dysfunction, especially for learning and memory abilities. However, knowledge about prevention and treatment methods of learning and memory abilities of fetal are limit. Here, Morris water maze and passive avoidance tests showed zinc supplementation could protect the impairment of the learning and memory abilities caused by FGR. As accumulating evidence suggested that insufficiency of placental trophoblast cell invasion was closely related to FGR fetal neurodevelopmental dysplasia, we further explored the relationship between zinc supplementation during pregnancy and placental trophoblast. Microarray identified 346 differently expressed genes in placental tissues with and without zinc supplementation, and GO and KEGG analyses showed these differently expressed genes were highly enriched in cell invasion and migration and STAT3 pathway. Protein-protein interaction(PPI) analysis found that STAT3 interacted with matrix metalloproteinase-2/9 (MMP-2/9). In vivo, western blot results authenticated that the expression levels of phospho-STAT3, STAT3, MMP-2 and MMP-9 were up-regulated in placental tissues after zinc treatment. To validate whether zinc could promotes trophoblast cell invasion and migration via enhancing STAT3-MMP-2/9 activity. In vitro, Transwell assay was performed, and we observed that abilities of invasion and migration were obviously increased in zinc treated trophoblast cells. And phospho-STAT3, STAT3, MMP-2 and MMP-9 expression levels were correspondingly increased in zinc treated trophoblast cells, which were dose-dependent. Moreover, gain–of-function and loss-of-function of STAT3 confirmed that zinc promotes cell invasion and migration via regulating STAT3 mediated up-regulation of MMP-2/9 activity. We propose that activation of MMP-2/9 mediated by STAT3 may contribute to invasion and migration of trophoblast cells, which improved neurodevelopmental impairment of FGR rats probably via contributing to placental development. Our findings are the first to show a possible mechanism of reversing neurodevelopmental impairment of FGR rats by zinc supplementation, holding promise for the development of novel therapeutic modalities for learning and memory abilities impairment caused by FGR.

Stem CO 2 efflux ( E s ) plays a critical role in forest carbon budgets and net ecosystem CO 2 exchanges, but there is still a significant knowledge gap on E s and its controlling factors in subtropical forests where forest productivity and transpiration are both very high. In this study, E s and the possible controlling factors such as stem temperature ( T s ), sap velocity ( v s ), and other climatic variables were simultaneously measured in a Pinus elliottii plantation of Subtropical China from January 2014 to July 2015. Temporal dynamics of E s followed similar trends as T s at a 1-cm depth with bell-shaped curves. The monthly E s values were significantly higher during the fast-growing season (April to October) than in the slow-growing season (November to next March). However, temperature sensitivity ( Q 10 , the relative increase of E s with a 10 °C rise in temperature) fluctuated throughout the entire year without a clear pattern. Significant and exponential relationships were found between E s and T s , with correlation factors higher during the slow-growing season than in the fast-growing season. Additionally, the coefficients of determination of E s to stem temperature were highly divergent with respect to tree size during the fast-growing season but not in the slow-growing season. The residuals (Δ E s ), calculated as the difference between the modeled fluxes ( E p ) based on night-time data at zero sap flow and the measured fluxes ( E m ) during the daytime when sap flow occurred, became more prominent during the fast-growing season. Thus, significant and positive correlations were observed between the ratio of Δ E s to E p and v s during the fast-growing season ( r 2 = 0.59, p v s , sap flows could potentially reduce the measured CO 2 efflux to up to 25% of those predicted values on temperature alone during the daytime. Our results clearly demonstrated that temperature was not sufficient to quantify E s , and thus, the effect of sap flow on E s must be integrated into any models simulating stem respiration and carbon budgets in forest ecosystems.

Despite extensive studies on hydrological responses to forest cover change in small watersheds, the hydrological responses to forest change and associated mechanisms across multiple spatial scales have not been fully understood. This review thus examined about 312 watersheds worldwide to provide a generalized framework to evaluate hydrological responses to forest cover change and to identify the contribution of spatial scale, climate, forest type and hydrological regime in determining the intensity of forest change related hydrological responses in small (

Alpine glaciers and perennial snow fields are important hydrologic elements in many mountain environments providing runoff during the late summer and during periods of drought. Because relatively long records of glacier mass-balance data are absent from many glacierized catchments, it remains unclear to what extent shrinking perennial snow and glaciers have affected runoff trends from these watersheds. Here we employ a hydrograph separation technique that uses a double mass curve in an attempt to isolate changes in runoff due to glacier retreat and disappearance of perennial snow. The method is tested using hydrometric data from 20 glacierized and 16 non-glacierized catchments in the Columbia Basin of Canada. The resulting estimates on cryosphere storage contribution to streamflow were well correlated to other regional estimates based on measurements as well as empirical and mechanistic models. Annual cryosphere runoff changed from +19 to -55% during the period 1975-2012, with an average decline of 26%. For August runoff, these changes ranged from +17 to -66%, with an average decrease of 24%. Reduction of cryosphere contributions to annual and late summer flows are expected to continue in coming decades as glaciers and the perennial snow patches shrink. Our method to isolate changes in late summer cryospheric storage contributions can be used as a first order estimate on changes in glacier contributions to flow and may help researchers and water managers target watersheds for further analysis.

Understanding hydrological responses to reforestation is an important subject in watershed management, particularly in large forested watersheds ( > 1000 km2). In this study, we selected two large forested watersheds (Pingjiang and Xiangshui) located in the upper reach of the Poyang Lake watershed, southeastern China (with an area of 3261.4 and 1458 km2, respectively), along with long-term data on climate and hydrology (1954–2006) to assess the effects of large-scale reforestation on streamflow. Both watersheds have similar climate and experienced comparable and dramatic forest changes during the past decades, but with different watershed properties (e.g., the topography is much steeper in Xiangshui than in Pingjiang), which provides us with a unique opportunity to compare the differences in hydrological recovery in two contrasted watersheds. Streamflow at different percentiles (e.g., 5, 10, 50 and 95 %) were compared using a combination of statistical analysis with a year-wise method for each watershed. The results showed that forest recovery had no significant effects on median flows (Q50%) in both watersheds. However, reforestation significantly reduced high flows in Pingjiang, but had limited influence in Xiangshui. Similarly, reforestation had significant and positive effects on low flows (Q95%) in Pingjiang, while it did not significantly change low flows in Xiangshui. Thus, hydrological recovery is limited and slower in the steeper Xiangshui watershed, highlighting that watershed properties are also important for determining hydrological responses to reforestation. This finding has important implications for designing reforestation and watershed management strategies in the context of hydrological recovery.

Riverscapes are coupled social-ecological systems (SESs), in which the differences between the scales and functioning of interacting social and ecological components ( &ldquo, mismatch&rdquo, ) impose challenges for global arid basin sustainability. Here, we defined riverscape SESs as networks of connected ecological and social components (nodes) to disentangle the structure and effects of SESs in Heihe River Basin (HRB) in arid regions of northwest China. Results showed the ecological network in HRB has low network density and high vertex strength. Heihe River Basin Bureau, as an emerging bridging organization, changed the SES structure and increased the matching degree of SES from 0.33 to 0.53, which has caused an obvious improvement in the downstream ecology. However, the characteristics of the ecological network demonstrated that cross-boundary management actions restricted to only the river would exacerbate local environmental pressures, such as the continued decline of groundwater in midstream regions and the potential appropriation of water for ecology by the expanding farmland in the downstream region. Our study demonstrated that network analysis could be one promising direction to untangle the complex SES and understand the relationship between SES structure and outcomes. We suggest comanaging the cross-boundary river and lands to further match the SES for basin sustainability.

High-precision prediction of large-scale forest aboveground biomass (AGB) is important but challenging on account of the uncertainty involved in the prediction process from various sources, especially the uncertainty due to non-representative sample units. Usually caused by inadequate sampling, non-representative sample units are common and can lead to geographic clusters of localities. But they cannot fully capture complex and spatially heterogeneous patterns, in which multiple environmental covariates (such as longitude, latitude, and forest structures) affect the spatial distribution of AGB. To address this challenge, we propose herein a low-cost approach that combines machine learning with spatial statistics to construct a regional AGB map from non-representative sample units. The experimental results demonstrate that the combined methods can improve the accuracy of AGB mapping in regions where only non-representative sample units are available. This work provides a useful reference for AGB remote-sensing mapping and ecological modelling in various regions of the world.

Enriched planting of native tree species in monoculture plantation forests is a commonly recommended forest practice. However, its effect on various ecological processes is generally lacking. Here, we carried out an experiment in a 16-year-old Eucalyptus plantation in South China to assess the effects of enriched planting of native tree species on surface water, soil erosion and nutrient losses. Two treatments were conducted in 2008: (1) enriched planting of native broadleaved tree species with uniform thinning of 60% of Eucalyptus trees (TEP); and (2) enriched planting of native broadleaved tree species without thinning (NEP). The original Eucalyptus plantation stands was used as the control (CK). Runoff plots (total n = 9, 3 for each treatment or CK) were established in 2009, and surface water flow, sediment, nitrogen (N) and phosphorus (P) losses were monitored from major rainfall events in 2010–2012. Results showed that enriched planting in Eucalyptus plantation significantly reduced surface water flow and soil erosion. Compared with CK, TEP and NEP reduced annual surface water flow by 29–43% and 11–16%, and reduced annual soil erosion by 38–54% and 20–33% throughout the study period, respectively. TEP and NEP had significantly lower annual mean concentrations of N and P in surface water. Compared with CK, TEP reduced annual N and P losses through surface water by 42–60% and 44–64%, respectively, while NEP reduced them by 25–28% and 24–34%, respectively. N and P losses were significantly related to surface water flow. Between the two treatments, TEP was better for retaining water and soil, and for preventing nutrient loss. These results clearly demonstrated that the enriched planting of native tree species effectively retained surface water and nutrients.

Fruit tree planting is a common practice for alleviating poverty and restoring degraded environment in developing countries. Yet, its environmental effects are rarely assessed. The Jiujushui watershed (261.4 km2), located in the subtropical Jiangxi Province of China, was selected to assess responses of several flow regime components on both reforestation and fruit tree planting. Three periods of forest changes, including a reference (1961 to 1985), reforestation (1986 to 2000) and fruit tree planting (2001 to 2016) were identified for assessment. Results suggest that the reforestation significantly decreased the average magnitude of high flow by 8.78%, and shortened high flow duration by 2.2 days compared with the reference. In contrast, fruit tree planting significantly increased the average magnitude of high flow by 27.43%. For low flows, reforestation significantly increased the average magnitude by 46.38%, and shortened low flow duration by 8.8 days, while the fruit tree planting had no significant impact on any flow regime components of low flows. We conclude that reforestation had positive impacts on high and low flows, while to our surprise, fruit tree planting had negative effects on high flows, suggesting that large areas of fruit tree planting may potentially become an important driver for some negative hydrological effects in our study area.

Forests in tropical and sub-tropical countries face severe pressures due to a combination of poverty and environment degradation. To be effective, measures to protect these forests must therefore consider both economic and ecological dimensions synergistically. The purpose of this paper was to synthesize our long-term work (1994–2015) on a Ginkgo (Ginkgo biloba L.) agroforestry system and demonstrate its potential for achieving both goals, and discuss its wider application in tropical and sub-tropical countries. The performance of various ecological, economic, and social indicators was compared among five Ginkgo agroforestry systems. Two additional indicators, Harmony Degree (HD) and Development Degree (DD), were also used to show the integrated performance of these indicators. Ginkgo-Wheat-Peanut (G+W+P) and Ginkgo-Rapeseed-Peanut (G+R+P) are the best systems when compared to pure and mixed Ginkgo plantations, or pure agricultural crops. Results demonstrate that it is possible to achieve both economic development and environmental protection through implementation of sustainable agroforestry systems in sub-tropical regions.

Forest change and climatic variability are two major drivers for influencing change in watershed hydrology in forest–dominated watersheds. Quantifying their relative contributions is important to fully understand their individual effects. This review paper summarizes the progress on quantifying the relative contributions of forest or land cover change and climatic variability to hydrology in large watersheds using available case studies. It compared pros and cons of various research methods, identified research challenges and proposed future research priorities. Our synthesis shows that the relative hydrological effects of forest changes and climatic variability are largely dependent on their own change magnitudes and watershed characteristics. In some severely disturbed watersheds, impacts of forest changes or land use changes can be as important as those from climatic variability. This paper provides a brief review on eight selected research methods for this type of research. Because each method or technique has its own strengths and weaknesses, combining two or more methods is a more robust approach than using any single method alone. Future research priorities include conducting more case studies, refining research methods, and considering mechanism-based research using landscape ecology and geochemistry approaches.