The Experts below are selected from a list of 11463 Experts worldwide ranked by ideXlab platform
Jinsheng He - One of the best experts on this subject based on the ideXlab platform.
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neutral effect of nitrogen addition and negative effect of phosphorus addition on topsoil extracellular enzymatic activities in an alpine Grassland Ecosystem
Applied Soil Ecology, 2016Co-Authors: Xin Jing, Huakun Zhou, Xiaoxia Yang, Jinsheng HeAbstract:Abstract Soil nitrogen (N) and phosphorus (P) are common limiting nutrients affecting plant primary productivity in alpine Ecosystems due to the low decomposition rate, though anthropogenic activities have greatly increased their inputs into Ecosystems. Little is known regarding the effects of increasing N and P availabilities on the functioning of belowground microbial communities. To determine how soil microorganisms respond to N and P addition, we measured plant primary productivity, soil microbial biomass, soil mineral N availability, soil respiration, and the activities of soil extracellular enzymes after two years of N- and P-addition in an alpine Grassland Ecosystem on the Tibetan Plateau. We observed no significant effect of N addition on plant biomass, soil microbial biomass, soil respiration, or the activities of soil extracellular enzymes. In contrast, P addition increased plant biomass but suppressed the activities of most labile-C-cycling enzymes at 0–10 cm of soil depth, although the effects on soil microbial biomass and soil respiration were minor. Moreover, there was no interaction between N and P addition on these variables. Overall, N addition does not appear to exert a significant effect on plant primary productivity and microbial activity, whereas P addition increases plant primary productivity and tends to suppress topsoil microbial activity after two years of nutrient application.
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no temperature acclimation of soil extracellular enzymes to experimental warming in an alpine Grassland Ecosystem on the tibetan plateau
Biogeochemistry, 2014Co-Authors: Xin Jing, Shi Ping WANG, Jinsheng He, Yonghui Wang, Haegeun Chung, Zhaorong Mi, Hui ZengAbstract:Alpine Grassland soils store large amounts of soil organic carbon (SOC) and are susceptible to rising air temperature. Soil extracellular enzymes catalyze the rate-limiting step in SOC decomposition and their catalysis, production and degradation rates are regulated by temperature. Therefore, the responses of these enzymes to warming could have a profound impact on carbon cycling in the alpine Grassland Ecosystems. This study was conducted to measure the responses of soil extracellular enzyme activity and temperature sensitivity (Q10) to experimental warming in samples from an alpine Grassland Ecosystem on the Tibetan Plateau. A free air-temperature enhancement system was set up in May 2006. We measured soil microbial biomass, nutrient availability and the activity of five extracellular enzymes in 2009 and 2010. The Q10 of each enzyme was calculated using a simple first-order exponential equation. We found that warming had no significant effects on soil microbial biomass C, the labile C or N content, or nutrient availability. Significant differences in the activity of most extracellular enzymes among sampling dates were found, with typically higher enzyme activity during the warm period of the year. The effects of warming on the activity of the five extracellular enzymes at 20 °C were not significant. Enzyme activity in vitro strongly increased with temperature up to 27 °C or over 30 °C (optimum temperature; Topt). Seasonal variations in the Q10 were found, but the effects of warming on Q10 were not significant. We conclude that soil extracellular enzymes adapted to seasonal temperature variations, but did not acclimate to the field experimental warming.
Peter Manning - One of the best experts on this subject based on the ideXlab platform.
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impacts of 120 years of fertilizer addition on a temperate Grassland Ecosystem
PLOS ONE, 2017Co-Authors: Peter Manning, J Kidd, Janet Simkin, Simon Peacock, E A StockdaleAbstract:The widespread application of fertilizers has greatly influenced many processes and properties of agroEcosystems, and agricultural fertilization is expected to increase even further in the future. To date, most research on fertilizer impacts has used short-term studies, which may be unrepresentative of long-term responses, thus hindering our capacity to predict long-term impacts. Here, we examined the effects of long-term fertilizer addition on key Ecosystem properties in a long-term Grassland experiment (Palace Leas Hay Meadow) in which farmyard manure (FYM) and inorganic fertilizer treatments have been applied consistently for 120 years in order to characterize the experimental site more fully and compare Ecosystem responses with those observed at other long-term and short-term experiments. FYM inputs increased soil organic carbon (SOC) stocks, hay yield, nutrient availability and acted as a buffer against soil acidification (>pH 5). In contrast, N-containing inorganic fertilizers strongly acidified the soil (
Grassland experiments) in that fertilization effects on plant and soil properties appeared to be driven by differences in both nutrient input and changes to soil pH. We also established that the direction of long-term fertilization effects tended to be comparable with short-term experiments, but that their magnitude differed considerably, particularly where ammonium sulphate-induced acidification had occurred. We therefore conclude that short-term studies are unlikely to possess the required timeframe to accurately predict long-term responses, thus necessitating the use of long-term study sites. Such experiments should be strategically established in regions where future fertilizer use is expected to increase rapidly. -
locally rare species influence Grassland Ecosystem multifunctionality
Philosophical Transactions of the Royal Society B, 2016Co-Authors: Santiago Soliveres, Peter Manning, Daniel Prati, Martin M Gossner, Hartmut Arndt, Vanessa Baumgartner, Julia Binkenstein, Klaus Birkhofer, Stefan BlaserAbstract:Species diversity promotes the delivery of multiple Ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity–multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 Ecosystem functions on 150 Grasslands across a land-use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community-level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species-specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for Ecosystem multifunctionality and help guiding future conservation priorities.
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plant functional group composition modifies the effects of precipitation change on Grassland Ecosystem function
PLOS ONE, 2013Co-Authors: Peter Manning, David G P Allen, Alex Hurst, Georg Everwand, Martin Rimmler, Sally A PowerAbstract:Temperate Grassland Ecosystems face a future of precipitation change, which can alter community composition and Ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of Ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional Grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials) and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in Grasslandscontaining a range of perennial and annual species, and that maintaining the presence of key functional groups should be a crucial consideration in future Grassland management.
Douglas A Frank - One of the best experts on this subject based on the ideXlab platform.
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drought effects on above and belowground production of a grazed temperate Grassland Ecosystem
Oecologia, 2007Co-Authors: Douglas A FrankAbstract:The effect of climatic variation on terrestrial aboveground productivity (ANPP) has been well studied. However, little is known about how variable climate, including drought, may influence belowground productivity (BNPP), which constitutes most of the annual primary production of Grasslands. The objectives of this study were to (1) examine how a 3-year period of declining moisture, which began as climatically wet to average across Yellowstone National Park (YNP) and ended in drought, affected ANPP and BNPP in Grasslands of YNP and (2) how herds of grazing ungulates, which were shown previously to stimulate Grassland shoot and root growth in YNP, may have interacted with climatic conditions to influence Grassland production. ANPP and 0–20 cm BNPP, representing the bulk of the root dynamics, were measured in grazed and ungrazed (fenced) Grassland at nine sites ranging widely in elevation, soil conditions and plant production during the 3-year study. Results revealed that 0–20 cm BNPP was strongly influenced by drought (P = 0.0005) and declined from 1999 to 2001 among ungrazed and grazed Grasslands by 39 and 49%, respectively. The greater reduction in 0–20 cm BNPP among grazed Grasslands was due, in part, to a decline (P = 0.07) in the stimulatory effect of grazing, i.e., the ratio g BNPP stimulated: g shoot consumed. In contrast, ANPP was unaffected by drought in either type of Grassland. Thus, the effect of this drought in YNP was a large reduction in BNPP, which was a function of (1) a direct negative influence of increased moisture stress on root growth and (2) a weak interaction between drought and herbivory that led to a decline in the positive feedback from grazers to BNPP. These findings highlight the need to better understand factors that control root growth and to study the effects of climatic variation on Grasslands within an Ecosystem framework to include potentially important climate–consumer interactions.
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herbivore influence on soil microbial biomass and nitrogen mineralization in a northern Grassland Ecosystem yellowstone national park
Oecologia, 1998Co-Authors: Benjamin F Tracy, Douglas A FrankAbstract:Microorganisms are largely responsible for soil nutrient cycling and energy flow in terrestrial Ecosystems. Although soil microorganisms are affected by topography and grazing, little is known about how these two variables may interact to influence microbial processes. Even less is known about how these variables influence microorganisms in systems that contain large populations of free-roaming ungulates. In this study, we compared microbial biomass size and activity, as measured by in situ net N mineralization, inside and outside 35- to 40-year exclosures across a topographic gradient in northern Yellowstone National Park. The objective was to determine the relative effect of topography and large grazers on microbial biomass and nitrogen mineralization. Microbial C and N varied by almost an order of magnitude across sites. Topographic depressions that contained high plant biomass and fine-textured soils supported the greatest microbial biomass. We found that plant biomass accurately predicted microbial biomass across our sites suggesting that carbon inputs from plants constrained microbial biomass. Chronic grazing neither depleted soil C nor reduced microbial biomass. We hypothesize that microbial populations in grazed Grasslands are sustained mainly by inputs of labile C from dung deposition and increased root turnover or root exudation beneath grazed plants. Mineral N fluxes were affected more by grazing than topography. Net N mineralization rates were highest in grazed Grassland and increased from dry, unproductive to mesic, highly productive communities. Overall, our results indicate that topography mainly influences microbial biomass size, while mineral N fluxes (microbial activity) are affected more by grazing in this Grassland Ecosystem.
Yongjian Ding - One of the best experts on this subject based on the ideXlab platform.
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Frozen soil change and adaptation of animal husbandry: A case of the source regions of Yangtze and Yellow Rivers
Environmental Science and Policy, 2011Co-Authors: Yiping Fang, Dahe Qin, Yongjian DingAbstract:This paper discusses the spatial and temporal change of different frozen soil types from 1980s to 2000s, and the impacts of frozen soil change on rangeland productivity and sustainable livelihood in the source regions of Yangtze and Yellow Rivers employed numerical model and GIS technology. Authors use the analytical framework of adaptation of animal husbandry according to national, regional, community and household scales, and release three key instruments of cryospheric change adaptation, including adaptive capacity of the policies, adaptive capacity of the people, and adaptive capacity of the Grassland Ecosystem. Analysis result shows that there is clearly a need, to develop institutional processes that support policy analysis to draw on existing information, that facilitate multidisciplinary research on topics of policy relevance, and that link the accumulation of credible cryosphere scientific evidence with policy making. Finally, Authors suggest that further support to mainstream climatic and cryospheric change concerns in adaptation policies and strategies of animal husbandry must include a focus on: (1) Formulating ecological compensation policy and mechanism for Grassland Ecosystem maintenance; (2) Strengthening vocational training, long-term essential-qualities-oriented education to improve indigenous people's professional skills and abilities; (3) Strengthening development of livestock replacement industries to broaden employment channels of indigenous people; (4) Strengthening the consciousness of Ecosystem maintenance, improvement the social civilization level for indigenous people; (5) Continuous implementation the Ecological Protection and Restoration Program in the Three-River Source Region in national scale. © 2011.
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Changes in stress within Grassland Ecosystems in the three counties of the source regions of the Yangtze and Yellow Rivers
Journal of Arid Land, 2010Co-Authors: Yiping Fang, Yongjian DingAbstract:Based on a database of more than 40 years of second production process and energy flow records for Maduo, Qumalai and Yushu counties, a dynamic model of the stress within Grassland Ecosystems was established using a nonlinear regression method for this source regions of the Yangtze and Yellow Rivers. The results show that dynamic curves of stress within Grassland Ecosystems in the three counties were in the shape of an inverted "U" during the period 1965-2007. It also revealed that the variation in actual amount of livestock inventories reflected the general trends of the stress within the Grassland Ecosystems in the source regions, although there were many other factors for the increase or reduction in Grassland Ecosystem stress.
Wei Song - One of the best experts on this subject based on the ideXlab platform.
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Grassland Ecosystem responses to climate change and human activities within the three river headwaters region of china
Scientific Reports, 2018Co-Authors: Wei Song, Xiangzheng Deng, Xinliang XuAbstract:The Three-River Headwaters region (TRHR) of China is an important part of the Qinghai-Tibetan Plateau. Although the TRHR is rich in Grassland resources, the Ecosystem of this area is extremely fragile. Natural and artificial interference have been key to the development of Grassland Ecosystem spatiotemporal heterogeneity, although the intensity and mode of their influence on ecological processes varies depending on scale; analyses in this area are therefore also scale-dependent. We use multi-scale nested data to analyze the mechanisms underlying the influence of climate change and human activities on Grassland net primary productivity (NPP) by applying a multi-level modeling approach. The results of this study show that: (1) The annual Grassland NPP of the TRHR has risen in a wavelike pattern over time, increasing by 39.88% overall; (2) Differences of 54.9% and 41.1% in temporal Grassland NPP can be attributed to variations between these watersheds as well as county characteristics, and; (3) Although the ‘warm and moist’ climate trend seen over the course of this study has proved beneficial in enhancing Grassland NPP, the rate of increase has tended to be faster in relatively dry and warm regions. Economic development and population growth have both exerted negative impacts on Grassland NPP.
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what is the main cause of Grassland degradation a case study of Grassland Ecosystem service in the middle south inner mongolia
Catena, 2017Co-Authors: Zhihui Li, Xiangzheng Deng, Zhan Wang, Wei Song, Jiancheng ChenAbstract:Abstract In this study, we analyze the changes of indicators of Ecosystem services and functions, in order to understand the main cause of Grassland degradation due to climatic variation or land use changes in the middle-south Inner Mongolia. The soil nutrient and the water supply of supporting service got recovery during 1988–2008. The loss of net primary production declined, and the quality of the retained unconverted Grassland (RUG) even increasingly degraded from 2000 to 2008. Analytical results show that environmental degradation on the land-use-changed-area is lower than that on the RUG from 2000 to 2008. It illustrates that climatic variation has more negative impacts on Grassland Ecosystem service, and which is significantly higher than the so-called “overgrazing” induced Grassland degradation. Moreover, it cannot be excluded that those species died out on the RUG due to natural selection or competitive evolution in an evolutionary process under the deteriorative weather condition rather than overgrazing. The positive impacts of human activities such as conservation programs and wildlife protection laws also benefit to regional Grassland Ecosystem obviously in the study area, so that can delay the environmental degradation even if each planet has its life cycle. It indicates that an integrated regional planning involving the considerations of climatic conditions, geographical characteristics, socioeconomic factors, and ecological functions and biodiversity can benefit to regional Grassland conservation based on monitoring and management via scientific methods.
