Nitrogen deposition changes the distribution of key plant species in the meadow steppe in Hulunbeier, China

2018 ◽  
Vol 40 (2) ◽  
pp. 129 ◽  
Author(s):  
Wang Xuan ◽  
Wang Xin Ting ◽  
Liang Cun Zhu ◽  
Niu Yong Mei
Keyword(s):  
Spatial Distribution ◽  
Plant Species ◽  
Niche Overlap ◽  
N Deposition ◽  
Nutrient Addition ◽  
Leymus Chinensis ◽  
Point Pattern ◽  
Ecological Change ◽  
Meadow Steppe ◽  
The Impact

Improved understanding of how nutrient levels affect the distribution of plants can provide important insights into the potential impacts of increasing global nitrogen (N) deposition. We used point pattern analyses to examine the impact of nutrient addition on heterogeneity in the spatial distribution of the three main plant species of the meadow steppe community of Hulunbeier, Inner Mongolia: Leymus chinensis (Trin.) Tzvel (aka Aneurotepidimu chinense), a rhizamotous grass; Stipa baicalensis Rasher, a bunch grass; and Artemisia tanacetifolia Linn, a rhizamotous forb. The six treatments tested added nitrogen N in three different concentrations, N with phosphorus (P), P alone and a Control. Although the three plant species were randomly distributed at the start of the experiment in 2011, the spatial distribution of some species in some treatments had changed at the end of 3 years of nutrient addition. There was a significant increase in aggregation of L. chinensis at fine scales of analysis from application of N and P in tandem. However, S. baicalensis and A. tanacetifolia distributions remained random under all treatments. Positive associations of L. chinensis with S. baicalensis and with A. tanacetifolia were apparent at the lowest concentration of added N, 2.5 g N m–2 year–1, which represented an approximate doubling of global N deposition. These associations, which represent clustering among individuals of these species were also apparent where only P was applied. Negative associations, representing dispersion, were prevalent with higher N concentrations. The results indicate that increases in global N deposition up to about double current levels may have a positive influence on meadow steppe communities by increasing the niche overlap of different species. However, increases beyond that level may trigger substantial ecological change through increased competition for other, more limited, environmental resources, and disassociation between plants of the different dominant species. Our findings suggest that studies of the spatial patterning of plant communities can contribute to understanding the potential impacts of climate change.

scholarly journals Species Differences in Nitrogen Acquisition in Humid Subtropical Forest Inferred From 15N Natural Abundance and Its Response to Tracer Addition

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 991 ◽  
Author(s):  
Geshere Abdisa Gurmesa ◽  
Xiankai Lu ◽  
Per Gundersen ◽  
Qinggong Mao ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Plant Species ◽  
N Uptake ◽  
N Deposition ◽  
Subtropical Forest ◽  
Species Variation ◽  
N Addition ◽  
Subtropical Forests ◽  
The Impact ◽  
N Acquisition ◽  
Leaf N

Differences in nitrogen (N) acquisition patterns between plant species are often reflected in the natural 15N isotope ratios (δ15N) of the plant tissues, however, such differences are poorly understood for co-occurring plants in tropical and subtropical forests. To evaluate species variation in N acquisition traits, we measured leaf N concentration (%N) and δ15N in tree and understory plant species under ambient N deposition (control) and after a decade of N addition at 50 kg N ha−1 yr−1 (N-plots) in an old-growth subtropical forest in southern China. We also measured changes in leaf δ15N after one-year of 15N addition in both the control and N-plots. The results show consistent significant species variation in leaf %N in both control and N-plots, but decadal N addition did not significantly affect leaf %N. Leaf δ15N values were also significantly different among the plant species both in tree and understory layers, and both in control and N-plots, suggesting differences in N acquisition strategies such as variation in N sources and dominant forms of N uptake and dependence on mycorrhizal associations among the co-occurring plant species. Significant differences between the plant species (in both control and N-plots) in changes in leaf δ15N after 15N addition were observed only in the understory plants, indicating difference in access (or use) of deposited N among the plants. Decadal N addition had species-dependent effects on leaf δ15N, suggesting the N acquisition patterns of these plant species are differently affected by N deposition. These results suggest that co-occurring plants in N-rich and subtropical forests vary in their N acquisition traits; these differences need to be accounted for when evaluating the impact of N deposition on N cycling in these ecosystems.

scholarly journals Influence of Selected Environmental Parameters on Rove Beetle (Coleoptera: Staphylinidae) Communities in Central European Floodplain Forests

2021 ◽  
Author(s):  
Slavomír Stašiov ◽  
Juraj Litavský ◽  
Oto Majzlan ◽  
Marek Svitok ◽  
Peter Fedor
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Ecological Change ◽  
Floodplain Forests ◽  
Pitfall Trapping ◽  
Dynamic Activity ◽  
Rove Beetle ◽  
The Impact ◽  
Vegetation Layer ◽  
Number Of Plant Species

Abstract Wetlands and especially floodplain forests belong to the most endangered ecosystems in Europe, characterized by complex dynamics of flood and dry periods and providing specific irreplaceable habitats for many organisms, including bioindicators. Many rove beetle species, for instance, are well-known detectors in monitoring ecological change, however, their use in environmental assessment requires to expand the insufficient knowledge on ecological environmental particularities of their assemblages. Therefore, we compared the rove beetle communities in eight habitats of floodplain forests from 2015 to 2016. Staphylinids were sampled by pitfall trapping. We compared the rove beetle taxocoenoses in the floodplain forests and their ecotones alongside three rivers (Danube, Tisa and Begej). We evaluated the impact of plant diversity and cover of vegetation layers, area, circumference and age of forest stands, distance to the forest edge, thickness of the litter layer, physical and chemical properties of soil and leaf litter (conductivity, pH, P, N, H, C) and anthropogenic impact on structure of rove beetle communities. We recorded significant interactions between total dynamic activity of rove beetles and number of plant species in shrub vegetation layer. Species richness was significantly positively correlated with number of plant species in shrub vegetation layer and soil pH, and negatively with relative H content of soil. We did not find any significant correlation between Shannon diversity, but evenness was negatively linked with species richness of plant communities in shrub layer.

Does nitrogen deposition lead to a weaker or stronger carbon sink in nutrient-poor peatlands?

2020 ◽  
Author(s):  
Tuula Larmola ◽  
Jani Antila ◽  
Liisa Maanavilja ◽  
Sari Juutinen ◽  
Jill L. Bubier ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Vascular Plant ◽  
N Deposition ◽  
Plant Litter ◽  
Nutrient Addition ◽  
N Addition ◽  
Plant Abundance ◽  
Gross Photosynthesis ◽  
The Impact

<p>Atmospheric nitrogen (N) deposition is increasing owing to fossil fuel burning and agriculture. In nutrient limited peatland ecosystems, the excess of reactive N has been found to increase vascular plant growth, but decrease Sphagnum growth. Higher vascular plant abundance and higher nutrient content alter decomposability of plant litter. These changes are likely to affect net imbalance of production and decomposition and thus carbon (C) accumulation in peatlands, which store about a third of global soil C. We studied whether the vegetation feedbacks of N deposition lead to stronger or weaker C sink in nutrient-poor peatlands. We investigated vegetation and ecosystem CO<sub>2 </sub>exchange at two of the longest-running nutrient addition experiments on peatlands, Mer Bleue Bog, Canada and Degerö Stormyr poor fen, Sweden that have been fertilized with NH<sub>4</sub>NO<sub>3</sub> (2-15 times ambient annual wet deposition) for 12-23 years. Gross photosynthesis, ecosystem respiration and net CO<sub>2</sub> exchange were measured weekly during June-August using chambers. To examine vegetation changes with increasing N influx, we determined the peak growing season aboveground biomass and coverage of vascular plants using the point intercept method. After 12-23 years of nutrient addition, the two sites revealed contrasting patterns: At Mer Bleue the highest nutrient additions were associated with up to 3-fold net CO<sub>2</sub> uptake potential than in the control, whereas N addition treatments at Degerö Stormyr showed close to zero net CO<sub>2</sub> uptake potential, only 0.3 fold compared to the control. The stronger C sink potential at Mer Bleue was mainly due to up to 50% increase in the gross photosynthesis and a diminished C sink potential at Degerö Stormyr due to down to 40 % lower gross photosynthesis. Ecosystem respiration showed similar trends at both peatlands: the rates were unaltered or increased to a lesser extent under N load. At both sites, the vegetation structure had changed remarkably. Most of the N addition treatments showed an increase of up to 90% in total vascular aboveground plant abundance and a concomitant loss of Sphagnum. At Mer Bleue along with the decrease in Sphagnum cover, the plots under highest N additions had become wetter, counterbalancing the impact of dry summer conditions in the study year whereas at Degerö Stormyr long term treatments did not alter wetness of the site. Thus, the contrasting C sink responses to long term N load may be explained by the type of vegetation and the water table depth. Shrubs were strong competitors at the dry Mer Bleue Bog while sedges had gained in abundance under N load at the wetter Degerö Stormyr. Our bog-fen comparison emphasizes the value of the long-term experiments in examining the ecosystem response of peatlands to N deposition, possible nonlinear responses and whether the key feedback mechanisms to ecosystem C sink potential differ in two main types of peatlands.</p>

Modelling Agricultural Controls for Flooding and Soil Erosion

2018 ◽  
pp. 776-796
Author(s):  
Roger Moussa ◽  
Bruno Cheviron
Keyword(s):  
Spatial Distribution ◽  
Model Structure ◽  
Land Uses ◽  
Research Challenges ◽  
Water And Sediment ◽  
Flow Processes ◽  
Cultivation Practices ◽  
Modelling Strategies ◽  
The Impact ◽  
Significant Factors

Floods are the highest-impact natural disasters. In agricultural basins, anthropogenic features are significant factors in controlling flood and erosion. A hydrological-hydraulic-erosion diagnosis is necessary in order to choose the most relevant action zones and to make recommendations for alternative land uses and cultivation practices in order to control and reduce floods and erosion. This chapter first aims to provide an overview of the flow processes represented in the various possible choices of model structure and refinement. It then focuses on the impact of the spatial distribution and temporal variation of hydrological soil properties in farmed basins, representing their effects on the modelled water and sediment flows. Research challenges and leads are then tackled, trying to identify the conditions in which sufficient adequacy exists between site data and modelling strategies.

scholarly journals Measuring spatial allocative efficiency in basketball

2020 ◽  
Vol 16 (4) ◽  
pp. 271-289
Author(s):  
Nathan Sandholtz ◽  
Jacob Mortensen ◽  
Luke Bornn
Keyword(s):  
Spatial Distribution ◽  
Hierarchical Model ◽  
Opportunity Cost ◽  
Allocative Efficiency ◽  
Bayesian Hierarchical Model ◽  
National Basketball Association ◽  
Spatial Context ◽  
Bayesian Hierarchical ◽  
The Impact

AbstractEvery shot in basketball has an opportunity cost; one player’s shot eliminates all potential opportunities from their teammates for that play. For this reason, player-shot efficiency should ultimately be considered relative to the lineup. This aspect of efficiency—the optimal way to allocate shots within a lineup—is the focus of our paper. Allocative efficiency should be considered in a spatial context since the distribution of shot attempts within a lineup is highly dependent on court location. We propose a new metric for spatial allocative efficiency by comparing a player’s field goal percentage (FG%) to their field goal attempt (FGA) rate in context of both their four teammates on the court and the spatial distribution of their shots. Leveraging publicly available data provided by the National Basketball Association (NBA), we estimate player FG% at every location in the offensive half court using a Bayesian hierarchical model. Then, by ordering a lineup’s estimated FG%s and pairing these rankings with the lineup’s empirical FGA rate rankings, we detect areas where the lineup exhibits inefficient shot allocation. Lastly, we analyze the impact that sub-optimal shot allocation has on a team’s overall offensive potential, demonstrating that inefficient shot allocation correlates with reduced scoring.

A Pandemic of Violence? The Impact of COVID-19 on Conflict

2020 ◽  
Vol 26 (3) ◽  
Author(s):  
Sara M.T. Polo
Keyword(s):  
Spatial Distribution ◽  
Real Time ◽  
Case Studies ◽  
Armed Conflict ◽  
Event Data ◽  
Social Unrest ◽  
Johns Hopkins University ◽  
The World ◽  
Political Advantage ◽  
The Impact

AbstractThis article examines the impact and repercussions of the COVID-19 pandemic on patterns of armed conflict around the world. It argues that there are two main ways in which the pandemic is likely to fuel, rather than mitigate, conflict and engender further violence in conflict-prone countries: (1) the exacerbating effect of COVID-19 on the underlying root causes of conflict and (2) the exploitation of the crisis by governments and non-state actors who have used the coronavirus to gain political advantage and territorial control. The article uses data collected in real-time by the Armed Conflict Location & Event Data Project (ACLED) and the Johns Hopkins University to illustrate the unfolding and spatial distribution of conflict events before and during the pandemic and combine this with three brief case studies of Afghanistan, Nigeria, and Libya. Descriptive evidence shows how levels of violence have remained unabated or even escalated during the first five months of the pandemic and how COVID-19-related social unrest has spread beyond conflict-affected countries.

scholarly journals Spatial distribution patterns of soil total phosphorus influenced by climatic factors in China’s forest ecosystems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Zhu ◽  
Anchi Wu ◽  
Guoyi Zhou
Keyword(s):  
Spatial Distribution ◽  
Forest Ecosystems ◽  
Climatic Factors ◽  
Critical Role ◽  
Effect Of Temperature ◽  
P Concentration ◽  
Single Effect ◽  
The Impact ◽  
P Distribution ◽  
Total P

AbstractPhosphorus (P) is an important element in terrestrial ecosystems and plays a critical role in soil quality and ecosystem productivity. Soil total P distributions have undergone large spatial changes as a result of centuries of climate change. It is necessary to study the characteristics of the horizontal and vertical distributions of soil total P and its influencing factors. In particular, the influence of climatic factors on the spatial distribution of soil total P in China’s forest ecosystems remain relatively unknown. Here, we conducted an intensive field investigation in different forest ecosystems in China to assess the effect of climatic factors on soil total P concentration and distribution. The results showed that soil total P concentration significantly decreased with increasing soil depth. The spatial distribution of soil total P increased with increasing latitude and elevation gradient but decreased with increasing longitude gradient. Random forest models and linear regression analyses showed that the explanation rate of bioclimatic factors and their relationship with soil total P concentration gradually decreased with increasing soil depths. Variance partitioning analysis demonstrated that the most important factor affecting soil total P distribution was the combined effect of temperature and precipitation factor, and the single effect of temperature factors had a higher explanation rate compare with the single effect of precipitation factors. This work provides a new farmework for the geographic distribution pattern of soil total P and the impact of climate variability on P distribution in forest ecosystems.

scholarly journals Spatial Dependence Evaluation of Agricultural Technical Efficiency—Based on the Stochastic Frontier and Spatial Econometric Model

2021 ◽  
Vol 13 (5) ◽  
pp. 2708
Author(s):  
Ziqi Yin ◽  
Jianzhai Wu
Keyword(s):  
Spatial Distribution ◽  
Technical Efficiency ◽  
Spatial Dependence ◽  
Stochastic Frontier ◽  
Hebei Province ◽  
Agricultural Technology ◽  
Agricultural Product ◽  
Spatial Econometric ◽  
Frontier Analysis ◽  
The Impact

In recent years, through the implementation of a series of policies, such as the delimitation of major grain producing areas and the construction of advantageous and characteristic agricultural product areas, the spatial distribution of agriculture in China has changed significantly; however, research on the impact of such changes on the efficiency of agricultural technology is still lacking. Taking 11 cities in Hebei Province as the research object, this study examines the spatial dependence of regional agricultural technical efficiency using the stochastic frontier analysis and spatial econometric analysis. The results show that the improvement in agricultural technical efficiency is evident in all cities in Hebei Province from 2008 to 2017, but there is scope for further improvement. Industrial agglomeration has statistical significance in improving the efficiency of agricultural technology. Further, there is an obvious spatial correlation and difference in agricultural technical efficiency. Optimizing the spatial distribution of agricultural production, promoting the innovation, development, and application of agricultural technology, and promoting the expansion of regional elements can contribute to improving agricultural technical efficiency.

scholarly journals Coastal Mangrove Response to Marine Erosion: Evaluating the Impacts of Spatial Distribution and Vegetation Growth in Bangkok Bay from 1987 to 2017

2020 ◽  
Vol 12 (2) ◽  
pp. 220 ◽  
Author(s):  
Han Xiao ◽  
Fenzhen Su ◽  
Dongjie Fu ◽  
Qi Wang ◽  
Chong Huang
Keyword(s):  
Spatial Distribution ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Mangrove Ecosystem ◽  
Early Growth ◽  
Growth Stages ◽  
Human Disturbances ◽  
Vegetation Growth ◽  
Two Parameters ◽  
The Impact

Long time-series monitoring of mangroves to marine erosion in the Bay of Bangkok, using Landsat data from 1987 to 2017, shows responses including landward retreat and seaward extension. Quantitative assessment of these responses with respect to spatial distribution and vegetation growth shows differing relationships depending on mangrove growth stage. Using transects perpendicular to the shoreline, we calculated the cross-shore mangrove extent (width) to represent spatial distribution, and the normalized difference vegetation index (NDVI) was used to represent vegetation growth. Correlations were then compared between mangrove seaside changes and the two parameters—mangrove width and NDVI—at yearly and 10-year scales. Both spatial distribution and vegetation growth display positive impacts on mangrove ecosystem stability: At early growth stages, mangrove stability is positively related to spatial distribution, whereas at mature growth the impact of vegetation growth is greater. Thus, we conclude that at early growth stages, planting width and area are more critical for stability, whereas for mature mangroves, management activities should focus on sustaining vegetation health and density. This study provides new rapid insights into monitoring and managing mangroves, based on analyses of parameters from historical satellite-derived information, which succinctly capture the net effect of complex environmental and human disturbances.

“Hollows” in the spatial distribution of earthworms in a meadow steppe

2006 ◽  
Vol 408 (1) ◽  
pp. 229-232
Author(s):  
A. D. Pokarzhevskii ◽  
K. B. Gongalsky ◽  
A. S. Zaitsev ◽  
O. I. Belyakova ◽  
F. A. Savin
Keyword(s):  
Spatial Distribution ◽  
Meadow Steppe
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