NobleBlocks

State Key Laboratory of Vegetation and Environmental Change

facilityBeijing, China

Research output, citation impact, and the most-cited recent papers from State Key Laboratory of Vegetation and Environmental Change. Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
136
Citations
8.5K
h-index
52
i10-index
111
Also known as
State Key Lab of Vegetation and Environmental ChangeState Key Laboratory of Vegetation and Environmental Change植被与环境变化国家重点实验室

Top-cited papers from State Key Laboratory of Vegetation and Environmental Change

Plant responses to drought and rewatering
Zhenzhu Xu, Guangsheng Zhou, Hideyuki Shimizu
2010· Plant Signaling & Behavior646doi:10.4161/psb.5.6.11398

Plants would be more vulnerable to water stress and thereafter rewatering or a cycled water environmental change, which occur more frequently under climatic change conditions in terms of the prediction scenarios. Effects of water stress on plants alone have been well-documented in many reports. However, the combined responses to drought and rewatering and its mechanism are relatively scant. As we known, plant growth, photosynthesis and stomatal aperture may be limited under water deficit, which would be regulated by physical and chemical signals. Under severe drought, while peroxidation may be provoked, the relevant antioxidant metabolism would be involved to annihilate the damage of reactive oxygen species. As rewatering, the recoveries of plant growth and photosynthesis would appear immediately through growing new plant parts, re-opening the stomata, and decreasing peroxidation; the recovery extents (reversely: pre-drought limitation) due to rewatering strongly depend on pre-drought intensity, duration and species. Understanding how plants response to episodic drought and watering pulse and the underlying mechanism is remarkably helpful to implement vegetation management practices in climatic changing.

The effects of salinity and osmotic stress on barley germination rate: sodium as an osmotic regulator
Hongxiang Zhang, Louis Irving, Craig McGill, C. Matthew +2 more
2010· Annals of Botany218doi:10.1093/aob/mcq204

BACKGROUND AND AIMS: Seed germination is negatively affected by salinity, which is thought to be due to both osmotic and ion-toxicity effects. We hypothesize that salt is absorbed by seeds, allowing them to generate additional osmotic potential, and to germinate in conditions under which they would otherwise not be able to germinate. METHODS: Seeds of barley, Hordeum vulgare, were germinated in the presence of either pure water or one of five iso-osmotic solutions of polyethylene-glycol (PEG) or NaCl at 5, 12, 20 or 27 °C. Germination time courses were recorded and germination indices were calculated. Dry mass, water content and sodium concentration of germinating and non-germinating seeds in the NaCl treatments at 12 °C were measured. Fifty supplemental seeds were used to evaluate the changes in seed properties with time. KEY RESULTS: Seeds incubated in saline conditions were able to germinate at lower osmotic potentials than those incubated in iso-osmotic PEG solutions and generally germinated faster. A positive correlation existed between external salinity and seed salt content in the saline-incubated seeds. Water content and sodium concentration increased with time for seeds incubated in NaCl. At higher temperatures, germination percentage and dry mass decreased whereas germination index and sodium concentration increased. CONCLUSIONS: The results suggest that barley seeds can take up sodium, allowing them to generate additional osmotic potential, absorb more water and germinate more rapidly in environments of lower water potential. This may have ecological implications, allowing halophytic species and varieties to out-compete glycophytes in saline soils.

Are plant growth and photosynthesis limited by pre-drought following rewatering in grass?
Zhenzhu Xu, Guangsheng Zhou, Hideyuki Shimizu
2009· Journal of Experimental Botany199doi:10.1093/jxb/erp216

Although the relationship between grassland productivity and soil water status has been extensively researched, the responses of plant growth and photosynthetic physiological processes to long-term drought and rewatering are not fully understood. Here, the perennial grass (Leymus chinensis), predominantly distributed in the Euro-Asia steppe, was used as an experimental plant for an irrigation manipulation experiment involving five soil moisture levels [75-80, 60-75, 50-60, 35-50, and 25-35% of soil relative water content (SRWC), i.e. the ratio between present soil moisture and field capacity] to examine the effects of soil drought and rewatering on plant biomass, relative growth rate (RGR), and photosynthetic potential. The recovery of plant biomass following rewatering was lower for the plants that had experienced previous drought compared with the controls; the extent of recovery was proportional to the intensity of soil drought. However, the plant RGR, leaf photosynthesis, and light use potential were markedly stimulated by the previous drought, depending on drought intensity, whereas stomatal conductance (g(s)) achieved only partial recovery. The results indicated that g(s) may be responsible for regulating actual photosynthetic efficiency. It is assumed that the new plant growth and photosynthetic potential enhanced by pre-drought following rewatering may try to overcompensate the great loss of the plant's net primary production due to the pre-drought effect. The present results highlight the episodic effects of drought on grass growth and photosynthesis. This study will assist in understanding how degraded ecosystems can potentially cope with climate change.

A comprehensive benchmarking system for evaluating global vegetation models
Douglas I. Kelley, I. Colin Prentice, Sandy P. Harrison, Han Wang +3 more
2013· Biogeosciences176doi:10.5194/bg-10-3313-2013

Abstract. We present a benchmark system for global vegetation models. This system provides a quantitative evaluation of multiple simulated vegetation properties, including primary production; seasonal net ecosystem production; vegetation cover; composition and height; fire regime; and runoff. The benchmarks are derived from remotely sensed gridded datasets and site-based observations. The datasets allow comparisons of annual average conditions and seasonal and inter-annual variability, and they allow the impact of spatial and temporal biases in means and variability to be assessed separately. Specifically designed metrics quantify model performance for each process, and are compared to scores based on the temporal or spatial mean value of the observations and a "random" model produced by bootstrap resampling of the observations. The benchmark system is applied to three models: a simple light-use efficiency and water-balance model (the Simple Diagnostic Biosphere Model: SDBM), the Lund-Potsdam-Jena (LPJ) and Land Processes and eXchanges (LPX) dynamic global vegetation models (DGVMs). In general, the SDBM performs better than either of the DGVMs. It reproduces independent measurements of net primary production (NPP) but underestimates the amplitude of the observed CO2 seasonal cycle. The two DGVMs show little difference for most benchmarks (including the inter-annual variability in the growth rate and seasonal cycle of atmospheric CO2), but LPX represents burnt fraction demonstrably more accurately. Benchmarking also identified several weaknesses common to both DGVMs. The benchmarking system provides a quantitative approach for evaluating how adequately processes are represented in a model, identifying errors and biases, tracking improvements in performance through model development, and discriminating among models. Adoption of such a system would do much to improve confidence in terrestrial model predictions of climate change impacts and feedbacks.

A Comparison of Terrestrial Arthropod Sampling Methods
Yi Zou, Feng Jinchao, Xue Dayuan, Sang Weiguo +1 more
2012· Journal of Resources and Ecology120doi:10.5814/j.issn.1674-764x.2012.02.010

Terrestrial arthropods are extremely important ecosystem components. The choice of best approaches to collect the wide range of terrestrial arthropods has been a topic of long-lasting debates. This article provides a brief overview of common sampling methods for terrestrial arthropod assemblages. We divide sampling methods into three main categories: passive sampling methods without any “activity density” bias, passive sampling methods with an “activity density” bias, and active sampling methods with inherent “activity density” and often further species-dependent biases, discussing their individual advantages and shortcomings as basis for biodiversity studies and pest control management. The selection of the optimal sampling methods depends strongly on the purpose of individual studies and the ecology and behavior of the arthropod groups targeted. A combination of different suitable methods is highly recommended in many cases.

The China Plant Trait Database: toward a comprehensive regional compilation of functional traits for land plants
Han Wang, Sandy P. Harrison, I. Colin Prentice, Yanzheng Yang +4 more
2017· Ecology118doi:10.1002/ecy.2091

Plant functional traits provide information about adaptations to climate and environmental conditions, and can be used to explore the existence of alternative plant strategies within ecosystems. Trait data are also increasingly being used to provide parameter estimates for vegetation models. Here we present a new database of plant functional traits from China. Most global climate and vegetation types can be found in China, and thus the database is relevant for global modeling. The China Plant Trait Database contains information on morphometric, physical, chemical, and photosynthetic traits from 122 sites spanning the range from boreal to tropical, and from deserts and steppes through woodlands and forests, including montane vegetation. Data collection at each site was based either on sampling the dominant species or on a stratified sampling of each ecosystem layer. The database contains information on 1,215 unique species, though many species have been sampled at multiple sites. The original field identifications have been taxonomically standardized to the Flora of China. Similarly, derived photosynthetic traits, such as electron-transport and carboxylation capacities, were calculated using a standardized method. To facilitate trait-environment analyses, the database also contains detailed climate and vegetation information for each site. The data set is released under a Creative Commons BY license. When using the data set, we kindly request that you cite this article, recognizing the hard work that went into collecting the data and the authors' willingness to make it publicly available.

Responses of leaf traits to climatic gradients: adaptive variation versus compositional shifts
Tingting Meng, Han Wang, Sandy P. Harrison, I. Colin Prentice +2 more
2015· Biogeosciences91doi:10.5194/bg-12-5339-2015

Abstract. Dynamic global vegetation models (DGVMs) typically rely on plant functional types (PFTs), which are assigned distinct environmental tolerances and replace one another progressively along environmental gradients. Fixed values of traits are assigned to each PFT; modelled trait variation along gradients is thus driven by PFT replacement. But empirical studies have revealed "universal" scaling relationships (quantitative trait variations with climate that are similar within and between species, PFTs and communities); and continuous, adaptive trait variation has been proposed to replace PFTs as the basis for next-generation DGVMs. Here we analyse quantitative leaf-trait variation on long temperature and moisture gradients in China with a view to understanding the relative importance of PFT replacement vs. continuous adaptive variation within PFTs. Leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC) and nitrogen content of dry matter were measured on all species at 80 sites ranging from temperate to tropical climates and from dense forests to deserts. Chlorophyll fluorescence traits and carbon, phosphorus and potassium contents were measured at 47 sites. Generalized linear models were used to relate log-transformed trait values to growing-season temperature and moisture indices, with or without PFT identity as a predictor, and to test for differences in trait responses among PFTs. Continuous trait variation was found to be ubiquitous. Responses to moisture availability were generally similar within and between PFTs, but biophysical traits (LA, SLA and LDMC) of forbs and grasses responded differently from woody plants. SLA and LDMC responses to temperature were dominated by the prevalence of evergreen PFTs with thick, dense leaves at the warm end of the gradient. Nutrient (N, P and K) responses to climate gradients were generally similar within all PFTs. Area-based nutrients generally declined with moisture; Narea and Karea declined with temperature, but Parea increased with temperature. Although the adaptive nature of many of these trait-climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits. Finally, models should take account of the diversity of trait values that is found in all sites and PFTs, representing the "pool" of variation that is locally available for the natural adaptation of ecosystem function to environmental change.

Mapping high-resolution forest aboveground biomass of China using multisource remote sensing data
Qiuli Yang, Chunyue Niu, Xiaoqiang Liu, Yuhao Feng +4 more
2023· GIScience & Remote Sensing85doi:10.1080/15481603.2023.2203303

Forest aboveground biomass (AGB) estimation is crucial for carbon cycle studies and climate change mitigation actions. However, because of limitations in timely and reliable forestry surveys and high-resolution remote sensing data, producing a fine resolution and spatial continuous forest AGB map of China is challenging. Here, we combined 4789 ground-truth AGB measurements and multisource remote sensing data such as a recently released forest canopy-height product, optical spectral indexes, topographic data, climatological data, and soil properties to train a random forest regression model for forest AGB estimation of China at 30-m resolution. The accuracy of the estimated AGB can yield R2 = 0.67 and RMSE = 70.71 Mg/ha. The nationwide estimates show that the average forest AGB and total forest carbon storage were 97.57 ± 23.85 Mg/ha and 11.06 Pg C for the year 2019, respectively. The value of AGB uncertainty ranges from 0.68 Mg/ha to 37.80 Mg/ha, and the average AGB uncertainty was 4.32 ± 1.75 Mg/ha. The forest AGB estimates of China in this study correspond reasonably well with the AGB estimates derived from the forestry and grassland statistical yearbook at the provincial level (R2 = 0.61, RMSE = 30.15 Mg/ha). In addition, we found that previous AGB products generally underestimate the forest AGB compared with our estimated AGB at the pixel-level and ground-truth AGB measurements. The high-resolution forest AGB map provides an important alternative data source for forest carbon cycle studies and can be used as a baseline map for forest management and conservation practices.

Glutamate Receptor Homolog3.4 is Involved in Regulation of Seed Germination Under Salt Stress in Arabidopsis
Yao Cheng, Xiuxiu Zhang, Tianyang Sun, Qiuying Tian +1 more
2018· Plant and Cell Physiology80doi:10.1093/pcp/pcy034

Seed germination is sensitive to salt stress. ABA and Ca2+ are involved in the regulation of seed germination under salt stress. Ca2+ influx mediated by glutamate receptors (GLRs) plays important roles in many physiological processes in plants. Here, we investigated the correlation of GLRs, Ca2+ and ABA during seed germination in response to salt stress by using Arabidopsis thaliana wild-type and T-DNA insertion knockout mutants of glutamate receptor homolog3.4. We demonstrated that atglr3.4-1 and atglr3.4-2 mutants were more sensitive to NaCl during seed germination and post-germination growth than wild-type plants. Treatments of wild-type seedlings with NaCl evoked a marked elevation in cytosolic Ca2+ activity ([Ca2+]cyt), and the elevation was inhibited by antagonists of GLRs, while the NaCl-induced elevation in [Ca2+]cyt was impaired in atglr3.4-1 and atglr3.4-2 mutants. Moreover, the mutants exhibited a lower expression of SOS3, SOS2 and SOS1, and greater accumulation of Na+ than wild-type seeds in the presence of NaCl. Mutation of AtGLR3.4 rendered the mutants more sensitive to ABA, while overexpression of AtGLR3.4 made the transgenic lines more tolerant to ABA in terms of seed germination. However, there was no difference in ABA content between atglr3.4 mutants and wild-type seeds, accompanied by lower expression of ABI3 and ABI4 in atglr3.4 mutants when challenged with NaCl. These results demonstrate that AtGLR3.4-mediated Ca2+ influx may be involved in the regulation of seed germination under salt stress by modulating Na+ accumulation through the SOS pathway.

Pharmaceuticals and personal care products (PPCPs) in urban and suburban rivers of Beijing, China: occurrence, source apportionment and potential ecological risk
Guohua Dai, Bin Wang, Chaochen Fu, Rui Dong +4 more
2016· Environmental Science Processes & Impacts68doi:10.1039/c6em00018e

This study analyzed 15 pharmaceuticals and personal care products (PPCPs) in two rivers with different urbanization levels in the surrounding watershed (urban and suburb) in Beijing, China. Along the rivers, effluent samples from wastewater treatment plants (WWTPs) and wastewater samples from direct discharge outlets were also collected to reveal their possible contribution to the occurrence of PPCPs in these two rivers. Among the 15 PPCPs, 14 compounds were detected with caffeine (maximum 11,900 ng L(-1)) being the dominant compound. The total concentration of the detected PPCPs in direct discharge outlets (median 4706 ng L(-1)) was much higher than that in river waters (2780 ng L(-1)) and WWTP effluents (1971 ng L(-1)). The suburban-influenced Liangshui River had significantly higher PPCP concentrations compared to the urban-influenced Qing River due to more input of untreated wastewater from direct discharge outlets. Source apportionment showed that approximately 55% of the total PPCPs were contributed by untreated wastewater in the suburban-influenced river. Finally, ecological risk assessment has been regarded as a necessary part of general research. According to the environmental risk assessment results, caffeine, trimethoprim and metoprolol were found to be the most critical compounds, due to their high risk quotient values. The results of the present study can provide useful information for future PPCP pollution control and sustainable water management in Beijing, China.

Responses of plant biomass, photosynthesis and lipid peroxidation to warming and precipitation change in two dominant species (<i>Stipa grandis</i> and <i>Leymus chinensis</i>) from North China Grasslands
Xiliang Song, Yuhui Wang, Xiaomin Lv
2016· Ecology and Evolution66doi:10.1002/ece3.1982

Influential factors of global change affect plant carbon uptake and biomass simultaneously. Although the effects from warming and precipitation change have been extensive studied separately, the responses of plant biomass, photosynthesis, and lipid peroxidation to the interaction of these factors are still not fully understood. In this study, we examined the physiological responses of two dominant plant species from grasslands of northern China with different functional traits to combinations of five simulated warming patterns and five simulated precipitation patterns in environment-controlled chambers. Our results showed that the biomass, net CO 2 assimilation rate (P n), maximal efficiency of photosystem II photochemistry (F v/F m), and chlorophyll content (Chl) of Stipa grandis and Leymus chinensis were enhanced by moderate warming and plus precipitation, but they declined drastically with high temperature and drought. High temperature and drought also led to significant malondialdehyde (MDA) accumulation, which had a negative correlation with leaf biomass. The lower level of lipid peroxidation in leaves of S. grandis suggests that this species is better protected from oxidative damage under heat stress, drought stress and their interactive conditions than L. chinensis. Using the subordinate function values method, we found S. grandis to be more sensitive to climate change than L. chinensis and the gross biomass and root biomass of S. grandis and the leaf biomass of L. chinensis were most sensitive to climate change. Furthermore, the P n of both S. grandis and L. chinensis had a significant linear relationship with F v/F m and Chl, indicating that carbon assimilation may be caused by nonstomatal limitations.

Net primary productivity and its partitioning in response to precipitation gradient in an alpine meadow
Fangyue Zhang, Quan Quan, Bing Song, Jian Sun +3 more
2017· Scientific Reports63doi:10.1038/s41598-017-15580-6

The dynamics of net primary productivity (NPP) and its partitioning to the aboveground versus belowground are of fundamental importance to understand carbon cycling and its feedback to climate change. However, the responses of NPP and its partitioning to precipitation gradient are poorly understood. We conducted a manipulative field experiment with six precipitation treatments (1/12 P, 1/4 P, 1/2 P, 3/4 P, P, and 5/4 P, P is annual precipitation) in an alpine meadow to examine aboveground and belowground NPP (ANPP and BNPP) in response to precipitation gradient in 2015 and 2016. We found that changes in precipitation had no significant impact on ANPP or belowground biomass in 2015. Compared with control, only the extremely drought treatment (1/12 P) significantly reduced ANPP by 37.68% and increased BNPP at the depth of 20-40 cm by 80.59% in 2016. Across the gradient, ANPP showed a nonlinear response to precipitation amount in 2016. Neither BNPP nor NPP had significant relationship with precipitation changes. The variance in ANPP were mostly due to forbs production, which was ultimately caused by altering soil water content and soil inorganic nitrogen concentration. The nonlinear precipitation-ANPP relationship indicates that future precipitation changes especially extreme drought will dramatically decrease ANPP and push this ecosystem beyond threshold.

Forest type affects the coupled relationships of soil C and N mineralization in the temperate forests of northern China
Quan Quan, Changhui Wang, Nianpeng He, Zhen Zhang +4 more
2014· Scientific Reports61doi:10.1038/srep06584

Decomposition of soil organic matter (SOM) is sensitive to vegetation and climate change. Here, we investigated the influence of changes in forest types on the mineralization of soil carbon (C) and nitrogen (N), and their temperature sensitivity (Q10) and coupling relationships by using a laboratory soil incubation experiments. We sampled soils from four forest types, namely, a primary Quercus liaotungensis forest (QL), Larix principis-rupprechtii plantation (LP), Pinus tabulaeformis plantation (PT), and secondary shrub forest (SS) in temperate northern China. The results showed that soil C and N mineralization differed significantly among forest types. Soil C and N mineralization were closely coupled in all plots, and C:N ratios of mineralized SOM ranged from 2.54 to 4.12. Forest type significantly influenced the Q10 values of soil C and N mineralization. The activation energy (Ea) of soil C and N mineralization was negatively related to the SOM quality index in all forest types. The reverse relationships suggested that the carbon quality-temperature (CQT) hypothesis was simultaneously applicable to soil C and N mineralization. Our findings show that the coupled relationships of soil C and N mineralization can be affected by vegetation change.

Spatial Risk Assessment of Alien Invasive Plants in China
Fan Bai, Ryan A. Chisholm, Weiguo Sang, Ming Dong
2013· Environmental Science & Technology55doi:10.1021/es400382c

The large-scale distribution patterns of alien invasive plants (AIP) can provide key information and a theoretical basis for management strategies, including the prevention of invasions, the control and eradication of established AIPs, and the identification of areas at high risk of invasion. This study aims to quantify distribution patterns of AIP in China, to develop approaches that measure the social, economic, and ecological impacts, and to identify areas that are at higher risk of plant invasion. Based on published literature, there were 384 AIPs in China, representing 233 genera from 66 families. Climatic factors were among the primary factors determining AIPs' overall distribution patterns. The majority of AIPs were tropically distributed in China, meaning that they were mainly restricted to southern China. Temperate-distributed AIPs, those distributed only or predominantly in northern China, were fewer but had higher average rates of spread than tropically distributed AIPs. Average ecological and economic impact per AIP was negatively correlated with AIP richness, meaning that areas with relatively few AIPs nevertheless have some of the most detrimental ones. Our comparative evaluation showed that the risk of invasion differed among regions of China, with high-risk areas in southern China (Yunnan, Guangxi, and Guangdong) and central coastal areas of eastern China (Shandong, Hebei, and Jiangsu). In the context of climate change, areas around latitudes of 33° N, including Hebei, Shandong, Henan, and Jiangsu, should be given more attention for the control and prevention of plant invasions. Predictions of high-risk areas for future invasions differed depending on the scale of aggregation and the evaluation index, indicating that invasive risk assessments should be based on multiple factors.

“Medieval Warm Period” on the northern slope of central Tianshan Mountains, Xinjiang, NW China
Yun Zhang, Zhao Chen Kong, Yan Shun, Zhen Yang +1 more
2009· Geophysical Research Letters53doi:10.1029/2009gl037375

“Medieval Warm Period” is used to describe a past climate epochs in Europe and neighboring regions from the ninth to the fourteenth centuries. In order to discuss the palaeoclimate changes during the MWP on the northern slope of central Tianshan Mountains in Xinjiang Autonomous Region, northwestern China, three Holocene sediment profiles in Daxigou region, Caotan Lake and Sichang Lake located in different elevations and vegetation zones were chosen for further discussion. A multi‐proxy reconstruction of the climate change in these three profiles using pollen, phytolith records, and the data of loss of ignition (LOI), grain size, and susceptibility showed that the climate was humid during the period corresponded in time with the MWP (from the middle of the Tang Dynasty to the middle of Yuan Dynasty). Complemented by tree‐ring record, other pollen records, data of plant seeds and historical documents; we conclude that during the MWP the climate was humid on the north slopes of Tianshan Mountains in Xinjiang.

The carbon sequestration potential of China's grasslands
Jian Song, Shiqiang Wan, Shushi Peng, Shilong Piao +4 more
2018· Ecosphere52doi:10.1002/ecs2.2452

Abstract With the consequences of anthropogenic activities such as overgrazing and cropland expansion, grasslands in China suffer severe degradation since the 1980s. The national grassland restoration policy enacted at the beginning of the 21th century has the potential to increase plant growth and productivity and hence regional carbon (C) sequestration. Here, we assessed plant and soil organic C ( SOC ) stocks for both degraded and restored/non‐degraded plots at 802 sites in Northern and Northwest China using pairwise field sampling and quantified the C sequestration potential ( CSP ) of China's grasslands. A geostatistical model was performed to upscale the field measurements to national scale. Averaged across the 802 paired grassland sites, the mean plant biomass C and SOC density in the top 1 m depth were 0.44 ± 0.17 and 8.82 ± 1.78 kg C/m 2 , respectively. Compared to the degraded grasslands, the restored grasslands had an average of 0.11 ± 0.17 (29.2%) and 1.02 ± 1.28 kg C/m 2 (12.3%) greater plant biomass C and SOC density, respectively. The geostatistical model produced a total CSP of 17.3 ± 2.3 Pg C in China's grasslands, with 94% in soils. If the CSP estimated in this study could be achieved, the current grassland SOC stock would increase by 61%, offsetting 11 yr (2000–2010) of national fossil CO 2 emissions.

Nitrogen enrichment and grazing accelerate vegetation restoration in degraded grassland patches
Quan Quan, Nianpeng He, Zhen Zhang, Zhang Yunhai +1 more
2014· Ecological Engineering33doi:10.1016/j.ecoleng.2014.11.053

A rapid increase in grazing intensity since the 1980s has caused large areas of the Inner Mongolian grasslands to become degraded. Increasing atmospheric nitrogen (N) deposition might exert an important influence on vegetation restoration in these degraded grasslands by increasing available N and relieving N limitations on productivity. However, no previous studies have tested the assumption that increasing N deposition promotes vegetation restoration in degraded grasslands. By conducting a 4-year field restoration experiment with four N addition treatments (0, 5, 10, and 20 g Nm (2) year (1)) and two grazing treatments (grazed and ungrazed), we investigated the effects of N enrichment and grazing on the restoration of patches in which vegetation had been degraded. N addition significantly accelerated the restoration of vegetation-degraded grassland patches regarding both plant cover and diversity. Moderate grazing also promoted the restoration of degraded-vegetation patches in term of both plant diversity and species similarity. Importantly, the positive effects of N addition on the restoration of degraded patches may be augmented by grazing. This study demonstrate that low levels of N enrichment (or increasing atmospheric N deposition) positively impact vegetation restoration in degraded grassland patches, particularly under moderate grazing practices. Our findings provide new insights into the management of severely degraded grasslands through the regulation of N inputs and grazing practices. (C) 2014 Elsevier B.V. All rights reserved.

Global Validation of a Process-Based Model on Vegetation Gross Primary Production Using Eddy Covariance Observations
Dan Liu, Wenwen Cai, Jiangzhou Xia, Wenjie Dong +4 more
2014· PLoS ONE31doi:10.1371/journal.pone.0110407

Gross Primary Production (GPP) is the largest flux in the global carbon cycle. However, large uncertainties in current global estimations persist. In this study, we examined the performance of a process-based model (Integrated BIosphere Simulator, IBIS) at 62 eddy covariance sites around the world. Our results indicated that the IBIS model explained 60% of the observed variation in daily GPP at all validation sites. Comparison with a satellite-based vegetation model (Eddy Covariance-Light Use Efficiency, EC-LUE) revealed that the IBIS simulations yielded comparable GPP results as the EC-LUE model. Global mean GPP estimated by the IBIS model was 107.50±1.37 Pg C year(-1) (mean value ± standard deviation) across the vegetated area for the period 2000-2006, consistent with the results of the EC-LUE model (109.39±1.48 Pg C year(-1)). To evaluate the uncertainty introduced by the parameter Vcmax, which represents the maximum photosynthetic capacity, we inversed Vcmax using Markov Chain-Monte Carlo (MCMC) procedures. Using the inversed Vcmax values, the simulated global GPP increased by 16.5 Pg C year(-1), indicating that IBIS model is sensitive to Vcmax, and large uncertainty exists in model parameterization.

Enhancement of Carbon Sequestration in Soil in the Temperature Grasslands of Northern China by Addition of Nitrogen and Phosphorus
Nianpeng He, Qiang Yu, Ruomeng Wang, Yunhai Zhang +2 more
2013· PLoS ONE31doi:10.1371/journal.pone.0077241

Increased nitrogen (N) deposition is common worldwide. Questions of where, how, and if reactive N-input influences soil carbon (C) sequestration in terrestrial ecosystems are of great concern. To explore the potential for soil C sequestration in steppe region under N and phosphorus (P) addition, we conducted a field experiment between 2006 and 2012 in the temperate grasslands of northern China. The experiment examined 6 levels of N (0-56 g N m(-2) yr(-1)), 6 levels of P (0-12.4 g P m(-2) yr(-1)), and a control scenario. Our results showed that addition of both N and P enhanced soil total C storage in grasslands due to significant increases of C input from litter and roots. Compared with control plots, soil organic carbon (SOC) in the 0-100 cm soil layer varied quadratically, from 156.8 to 1352.9 g C m(-2) with N addition gradient (R(2) = 0.99, P < 0.001); and logarithmically, from 293.6 to 788.6 g C m(-2) with P addition gradient (R(2) = 0.56, P = 0.087). Soil inorganic carbon (SIC) decreased quadratically with N addition. The net C sequestration on grassland (including plant, roots, SIC, and SOC) increased linearly from -128.6 to 729.0 g C m(-2) under N addition (R(2) = 0.72, P = 0.023); and increased logarithmically, from 248.5 to 698 g C m(-2)under P addition (R(2) = 0.82, P = 0.014). Our study implies that N addition has complex effects on soil carbon dynamics, and future studies of soil C sequestration on grasslands should include evaluations of both SOC and SIC under various scenarios.

Responses of physiological parameters, grain yield, and grain quality to foliar application of potassium nitrate in two contrasting winter wheat cultivars under salinity stress
Yanhai Zheng, Xianbin Xu, Matthew Simmons, Chao Zhang +2 more
2010· Journal of Plant Nutrition and Soil Science27doi:10.1002/jpln.200900313

Abstract An experiment was conducted to test whether foliar application of KNO 3 on wheat in the heading stage could reduce salinity‐induced injuries, produce high grain yield, and improve grain quality. Salt‐resistant DK961 and salt‐sensitive JN17 wheat cultivars under 0 or 100 mM–NaCl conditions were foliarly watered with distilled water or a 10 mM–KNO 3 solution. The four treatments included: T 1 (CK 1 ), 0 mM NaCl + distilled water; T 2 , 0 mM NaCl + 10 mM KNO 3 ; T 3 (CK 2 ), 100 mM NaCl + distilled water; T 4 , 100 mM NaCl + 10 mM KNO 3 . The results indicate that there were no differences ( p &gt; 0.05) in plant growth, grain yield, and grain quality between T 2 and T 1 in both cultivars, but these response variables were significantly lower in T 3 than in T 1 . K + : Na + ratio, chlorophyll content, photosynthetic capacity, grain yield, flour yield, water absorbance, ash content, dough‐development time and dough‐stability time were significantly higher in T 4 than in T 3 , while protein concentration, wet‐gluten concentration, and antioxidant enzyme activities were lower. Although foliar application of KNO 3 on JN17 enhanced plant growth, grain yield, and grain quality, these parameters were still lower in T 4 than in T 1 . Our findings suggest that cultivating the salt‐resistant wheat cultivar combined with foliar application of KNO 3 at heading stage may alleviate salinity injuries and produce higher grain yield and better grain quality under saline conditions.