Disturbance of the terrestrial ecosystems stability due to global-scale anthropogenic impacts

1988 ◽  
Vol 11 (3) ◽  
pp. 239-246 ◽  
Author(s):  
Yu. A. Izrael ◽  
L. M. Filippova ◽  
G. E. Insarov ◽  
F. N. Semevsky ◽  
S. M. Semenov
Keyword(s):  
Anthropogenic Impacts ◽  
Terrestrial Ecosystems ◽  
Global Scale

scholarly journals Reduced resilience of terrestrial ecosystems locally is not reflected on a global scale

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yuhao Feng ◽  
Haojie Su ◽  
Zhiyao Tang ◽  
Shaopeng Wang ◽  
Xia Zhao ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Vegetation Index ◽  
Global Climate ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Ecological Resilience ◽  
Terrestrial Vegetation ◽  
Ecosystem Resilience

AbstractGlobal climate change likely alters the structure and function of vegetation and the stability of terrestrial ecosystems. It is therefore important to assess the factors controlling ecosystem resilience from local to global scales. Here we assess terrestrial vegetation resilience over the past 35 years using early warning indicators calculated from normalized difference vegetation index data. On a local scale we find that climate change reduced the resilience of ecosystems in 64.5% of the global terrestrial vegetated area. Temperature had a greater influence on vegetation resilience than precipitation, while climate mean state had a greater influence than climate variability. However, there is no evidence for decreased ecological resilience on larger scales. Instead, climate warming increased spatial asynchrony of vegetation which buffered the global-scale impacts on resilience. We suggest that the response of terrestrial ecosystem resilience to global climate change is scale-dependent and influenced by spatial asynchrony on the global scale.

scholarly journals On the potential vegetation feedbacks that enhance phosphorus availability – insights from a process-based model linking geological and ecological timescales

2014 ◽  
Vol 11 (13) ◽  
pp. 3661-3683 ◽  
Author(s):  
C. Buendía ◽  
S. Arens ◽  
T. Hickler ◽  
S. I. Higgins ◽  
P. Porada ◽  
...  
Keyword(s):  
Biomass Production ◽  
Primary Productivity ◽  
Chemical Weathering ◽  
Production Efficiency ◽  
Root Exudation ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
P Uptake ◽  
P Availability ◽  
P Limitation

Abstract. In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycles including chemical weathering at the global scale. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. We find that active P uptake is an essential mechanism for sustaining P availability on long timescales, whereas biotic de-occlusion might serve as a buffer on timescales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modelling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on old soils has a smaller biomass production rate when P becomes limiting. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and ecological timescales under different environmental settings.

The spatio-temporal evolution of groundwater dependent precipitation

2021 ◽  
Author(s):  
Cristina Passet ◽  
Lan Wang-Erlandsson ◽  
Yoshihide Wada ◽  
Agnes Pranindita ◽  
Agatha De Boer
Keyword(s):  
Temporal Evolution ◽  
Groundwater Resources ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Groundwater Abstraction ◽  
Groundwater Availability ◽  
Basin Scale ◽  
The Usa ◽  
Spatio Temporal ◽  
Selection Of

<div><span>A<strong> </strong>substantial portion of groundwater abstracted from aquifers is used for irrigation and evaporated to the atmosphere, potentially contributing towards downwind precipitation. While the fate of evaporation fluxes from land have been analysed, the atmospheric pathways of evaporation originating from groundwater have not yet been globally quantified. This study analysed the geographical distribution, the seasonality and the magnitude of groundwater-dependent precipitation (Pgw) </span><span>at a global scale and for a selection of countries and river basins. The Eulerian moisture tracking WAM-2layers model was used to process meteorological and groundwater abstraction input data from 1980 to 2010.  Results show considerable contributions of groundwater to precipitation downwind of the most heavily irrigated areas, leading to net groundwater losses over these areas. Globally, 40% of the Pgw </span><span>precipitates directly in the oceans, and do not contribute to biomass production in terrestrial ecosystems. Some of the countries with the highest rates of groundwater abstraction (India, the USA, Pakistan and Iran), receive low volumes of Pgw </span><span>and are net losers of groundwater resources. The countries with the highest net gain of groundwater are China, Canada and Russia. At river basin scale, the Indus, Ganges and Mississippi basins are net losers of groundwater to downwind Pgw</span><span>, while the Yangtze, Tarim and Brahmaputra basins receive more Pgw </span><span>than their groundwater withdrawals. The share of precipitation that originates from groundwater varies considerably with seasons, and can be especially high when low local precipitation levels occur in combination with high upwind groundwater abstraction. Furthermore, precipitation dependence on </span><span>groundwater (ρgw)</span><span>, has steadily increased between 1980 to 2010 in all studied areas and globally. Our study suggests that the countries and basins with a high and increasing dependency on ρgw </span><span>to support their precipitation can be vulnerable to groundwater availability upwind.</span></div>

scholarly journals Global signal of top-down control of terrestrial plant communities by herbivores

2018 ◽  
Vol 115 (24) ◽  
pp. 6237-6242 ◽  
Author(s):  
Shihong Jia ◽  
Xugao Wang ◽  
Zuoqiang Yuan ◽  
Fei Lin ◽  
Ji Ye ◽  
...  
Keyword(s):  
Plant Communities ◽  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Basic Site ◽  
Plant Interactions ◽  
Top Down ◽  
Plant Abundance ◽  
Terrestrial Plant ◽  
Positive Effects

The theory of “top-down” ecological regulation predicts that herbivory suppresses plant abundance, biomass, and survival but increases diversity through the disproportionate consumption of dominant species, which inhibits competitive exclusion. To date, these outcomes have been clear in aquatic ecosystems but not on land. We explicate this discrepancy using a meta-analysis of experimental results from 123 native animal exclusions in natural terrestrial ecosystems (623 pairwise comparisons). Consistent with top-down predictions, we found that herbivores significantly reduced plant abundance, biomass, survival, and reproduction (allP< 0.01) and increased species evenness but not richness (P= 0.06 andP= 0.59, respectively). However, when examining patterns in the strength of top-down effects, with few exceptions, we were unable to detect significantly different effect sizes among biomes, based on local site characteristics (climate or productivity) or study characteristics (study duration or exclosure size). The positive effects on diversity were only significant in studies excluding large animals or located in temperate grasslands. The results demonstrate that top-down regulation by herbivores is a pervasive process shaping terrestrial plant communities at the global scale, but its strength is highly site specific and not predicted by basic site conditions. We suggest that including herbivore densities as a covariate in future exclosure studies will facilitate the discovery of unresolved macroecology trends in the strength of herbivore–plant interactions.

A conservation strategy for dugongs: implications of Australian research

1999 ◽  
Author(s):  
Helene Marsh ◽  
Carole Eros ◽  
Peter Corkeron ◽  
Barbara Breen
Keyword(s):  
Life History ◽  
Anthropogenic Impacts ◽  
Significant Proportion ◽  
Global Scale ◽  
Reproductive Rate ◽  
Conservation Strategy ◽  
Slight Reduction ◽  
Large Numbers ◽  
High Investment ◽  
Optimum Management

The dugong (Dugong dugon) is listed as vulnerable to extinction at a global scale. It has a large range that spans some forty countries and includes tropical and subtropical coastal and island waters from east Africa to Vanuatu. A significant proportion of the world’s dugongs is found in northern Australian waters where most modern dugong research has been conducted. Dugongs are long-lived animals with a low reproductive rate, long generation time, and a high investment in each offspring. Population simulations indicate that even with the most optimistic combinations of life-history parameters (e.g. low natural mortality and no human-induced mortality) a dugong population is unlikely to increase by more than 5% per year. Dugongs are vulnerable to anthropogenic impacts because of their life history and their dependence on seagrasses that are restricted to coastal habitats. Even a slight reduction in adult survivorship as a result of habitat loss, disease, hunting or incidental drowning in nets can cause a chronic decline in a dugong population. The optimum management strategy is to identify areas that consistently support large numbers of dugongs and to set these aside as dugong sanctuaries in which dugong mortality is minimized and their habitat protected.

Inferring non-steady-state terrestrial vegetation carbon turnover times from multi-decadal space-borne observations on global scale

2020 ◽  
Author(s):  
Naixin Fan ◽  
Simon Besnard ◽  
Maurizio Santoro ◽  
Oliver Cartus ◽  
Nuno Carvalhais
Keyword(s):  
Climate Change ◽  
Steady State ◽  
Carbon Fixation ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Turnover Time ◽  
Terrestrial Vegetation ◽  
Time Step

&lt;p&gt;The global biomass is determined by the vegetation turnover times (&amp;#964;) and carbon fixation through photosynthesis. Vegetation turnover time is a central parameter that not only partially determines the terrestrial carbon sink but also the response of terrestrial vegetation to the future changes in climate. However, the change of magnitude, spatial patterns and uncertainties in &amp;#964; as well as the sensitivity of these processes to climate change is not well understood due to lack of observations on global scale. In this study, we explore a new dataset of annual above-ground biomass (AGB) change from 1993 to 2018 from spaceborne scatterometer observations. Using the long-term, spatial-explicit global dynamic dataset, we investigated how &amp;#964; change over almost three decades including the uncertainties. Previous estimations of &amp;#964; under steady-state assumption can now be challenged acknowledging that terrestrial ecosystems are, for the most of cases, not in balance. In this study, we explore this new dataset to derive global maps of &amp;#964; in non-steady-state for different periods of time. We used a non-steady-state carbon model in which the change of AGB is a function of Gross Primary Production (GPP) and &amp;#964; (&amp;#916;AGB = &amp;#945;*GPP-AGB/ &amp;#964;). The parameter &amp;#945; represents the percentage of incorporation of carbon from GPP to biomass. By exploring the AGB change in 5 to 10 years of time step, we were able to infer &amp;#964; and &amp;#945; from the observations of AGB and GPP change by solving the linear equation. We show how &amp;#964; changes after potential disturbances in the early 2000s in comparison to the previous decade. We also show the spatial distributions of &amp;#945; from the change of AGB. By accessing the change in biomass, &amp;#964; and &amp;#945; as well as their associated uncertainties, we provide a comprehensive diagnostic on the vegetation dynamics and the potential response of biomass to disturbance and to climate change.&amp;#160; &amp;#160;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;&lt;p&gt;&lt;/p&gt;

scholarly journals Extreme events in gross primary production: a characterization across continents

2014 ◽  
Vol 11 (1) ◽  
pp. 1869-1907 ◽  
Author(s):  
J. Zscheischler ◽  
M. D. Mahecha ◽  
S. Harmeling ◽  
A. Rammig ◽  
E. Tomelleri ◽  
...  
Keyword(s):  
South America ◽  
Primary Production ◽  
Extreme Events ◽  
Gross Primary Production ◽  
Climate Extremes ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Early Summer ◽  
Seasonal Effects ◽  
Data Sets

Abstract. Climate extremes can affect the functioning of terrestrial ecosystems, for instance via a reduction of the photosynthetic capacity or alterations of respiratory processes. Yet the dominant regional and seasonal effects of hydrometeorological extremes are still not well documented. Here we quantify and characterize the role of large spatiotemporal extreme events in gross primary production (GPP) as triggers of continental anomalies. We also investigate seasonal dynamics of extreme impacts on continental GPP anomalies. We find that the 50 largest positive (increase in uptake) and negative extremes (decrease in uptake) on each continent can explain most of the continental variation in GPP, which is in line with previous results obtained at the global scale. We show that negative extremes are larger than positive ones and demonstrate that this asymmetry is particularly strong in South America and Europe. Most extremes in GPP start in early summer. Our analysis indicates that the overall impacts and the spatial extents of GPP extremes are power law distributed with exponents that vary little across continents. Moreover, we show that on all continents and for all data sets the spatial extents play a more important role than durations or maximal GPP anomaly when it comes to the overall impact of GPP extremes. An analysis of possible causes implies that across continents most extremes in GPP can best be explained by water scarcity rather than by extreme temperatures. However, for Europe, South America and Oceania we identify also fire as an important driver. Our findings are consistent with remote sensing products. An independent validation against a literature survey on specific extreme events supports our results to a large extent.

scholarly journals Terrestrial ecosystems of the Antarctic Peninsula and their responses to climate change and anthropogenic impacts

2020 ◽  
pp. 84-97
Author(s):  
R. Bargagli ◽  
Keyword(s):  
Antarctic Peninsula ◽  
Native Species ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Extreme Temperature ◽  
Terrestrial Ecosystems ◽  
Indigenous Species ◽  
Non Indigenous Species ◽  
Food Web Complexity ◽  
The Antarctic

Antarctica and the Southern Ocean are unique natural laboratories where organisms adapted to extreme environmental conditions have evolved in isolation for millions of years. These unique biotic communities on Earth are facing complex climatic and environmental changes. Terrestrial ecosystems in the Antarctic Peninsula Region (APR) have experienced the highest rate of climate warming and, being the most impacted by human activities, are facing the greatest risk of detrimental changes. This review provides an overview of the most recent findings on how biotic communities in terrestrial ecosystems of the Antarctic Peninsula Region (APR) are responding and will likely respond to further environmental changes and direct anthropogenic impacts. Knowledge gained from studies on relatively simple terrestrial ecosystems could be very useful in predicting what may happen in much more complex ecosystems in regions with less extreme temperature changes. The rapid warming of the APR has led to the retreat of glaciers, the loss of snow and permafrost and the increase of ice-free areas, with a consequent enhancement of soil-forming processes, biotic communities, and food web complexity. However, most human activity is concentrated in APR coastal ice-free areas and poses many threats to terrestrial ecosystems such as environmental pollution or disturbances to soilcommunities and wildlife. People who work or visit APR may inadvertently introduce alien organisms and/or spread native species to spatially isolated ice-free areas. The number of introduced non-indigenous species and xenobiotic compounds in the APR is likely to be greater than currently documented, and several biosecurity and monitoring activities are therefore suggested to Antarctic national scientific programs and tourism operators to minimize the risk of irreversible loss of integrity by the unique terrestrial ecosystems of APR.

scholarly journals Spatial patterns of aboveground phytogenic Si stocks in a grass-dominated catchment – Results from UAS based high resolution remote sensing

2021 ◽  
Author(s):  
Marc Wehrhan ◽  
Daniel Puppe ◽  
Danuta Kaczorek ◽  
Michael Sommer
Keyword(s):  
Remote Sensing ◽  
Soil Properties ◽  
Spatial Patterns ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Plant Biomass ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Promising Tool ◽  
Technical Features

Abstract. Various studies have been performed to quantify silicon (Si) stocks in plant biomass and related Si fluxes in terrestrial biogeosystems. Most of these studies were performed at relatively small plots with an intended low heterogeneity in soils and plant canopy composition, and results were extrapolated to larger spatial units up to global scale implicitly assuming similar environmental conditions. However, the emergence of new technical features and increasing knowledge on details in Si cycling leads to a more complex picture at landscape or catchment scales. Dynamic and static soil properties change along the soil continuum and might influence not only the species composition of natural vegetation, but its biomass distribution and related Si stocks. Maximum Likelihood (ML) classification was applied to multispectral imagery captured by an Unmanned Aerial System (UAS) aiming the identification of land cover classes (LCC). Subsequently, the Normalized Difference Vegetation Index (NDVI) and ground-based measurements of biomass were used to quantify aboveground Si stocks in two Si accumulating plants (Calamagrostis epigejos and Phragmites australis) in a heterogeneous catchment and related corresponding spatial patterns of these stocks to soil properties. We found aboveground Si stocks of C. epigejos and P. australis to be surprisingly high (maxima of Si stocks reach values up to 98 g Si m−2), i.e., comparable to or markedly exceeding reported values for the Si storage in aboveground vegetation of various terrestrial ecosystems. We further found spatial patterns of plant aboveground Si stocks to reflect spatial heterogeneities in soil properties. From our results we concluded that (i) aboveground biomass of plants seems to be the main factor of corresponding phytogenic Si stock quantities and (ii) a detection of biomass heterogeneities via UAS-based remote sensing represents a promising tool for the quantification of lifelike phytogenic Si pools at landscape scales.

Processes in Microbial Ecology

2018 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Microbial Ecology ◽  
Homo Sapiens ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Natural Environments ◽  
Biogeochemical Processes ◽  
Ecological Interactions ◽  
Viral Lysis ◽  
Molecular Approaches ◽  
Uncultivated Bacteria

Processes in Microbial Ecology discusses the major processes carried out by viruses, bacteria, fungi, protozoa, and other protists—the microbes—in freshwater, marine, and terrestrial ecosystems. The book shows how advances in genomic and other molecular approaches have uncovered the incredible diversity of microbes in natural environments and unraveled complex biogeochemical processes carried out by uncultivated bacteria, archaea, and fungi. The microbes and biogeochemical processes are affected by ecological interactions, including competition for limiting nutrients, viral lysis, and predation by protists in soils and aquatic habitats. The book links up processes occurring at the micron scale to events happening at the global scale, including the carbon cycle and its connection to climate change issues. The book ends with a chapter devoted to symbiosis and other relationships between microbes and large organisms, which have large impacts not only on biogeochemical cycles, but also on the ecology and evolution of large organisms, including Homo sapiens.

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