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Ecosystem

About: Ecosystem is a research topic. Over the lifetime, 25460 publications have been published within this topic receiving 1291375 citations. The topic is also known as: ecological system & Ecosystem.


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Journal ArticleDOI
TL;DR: It is shown that herbivore species richness can be critical for maintaining the structure and function of coral reefs, because complementary feeding by diverse herbivores produces positive, but indirect, effects on corals, the foundation species for the ecosystem.
Abstract: Consumer effects on prey are well known for cascading through food webs and producing dramatic top-down effects on community structure and ecosystem function. Bottom-up effects of prey (primary producer) biodiversity are also well known. However, the role of consumer diversity in affecting community structure or ecosystem function is not well understood. Here, we show that herbivore species richness can be critical for maintaining the structure and function of coral reefs. In two experiments over 2 years, we constructed large cages enclosing single herbivore species, equal densities of mixed species of herbivores, or excluding herbivores and assessed effects on both seaweeds and corals. When compared with single-herbivore treatments, mixed-herbivore treatments lowered macroalgal abundance by 54–76%, enhanced cover of crustose coralline algae (preferred recruitment sites for corals) by 52–64%, increased coral cover by 22%, and prevented coral mortality. Complementary feeding by herbivorous fishes drove the herbivore richness effects, because macroalgae were unable to effectively deter fishes with different feeding strategies. Maintaining herbivore species richness appears critical for preserving coral reefs, because complementary feeding by diverse herbivores produces positive, but indirect, effects on corals, the foundation species for the ecosystem.

428 citations

Journal ArticleDOI
TL;DR: In this article, a constrained implementation of a new structured TBM, the Ecosystem Demography model version 2 (ED2), which explicitly tracks the dynamics of fine-scale ecosystem structure and function is presented.
Abstract: [1] Insights into how terrestrial ecosystems affect the Earth’s response to changes in climate and rising atmospheric CO2 levels rely heavily on the predictions of terrestrial biosphere models (TBMs). These models contain detailed mechanistic representations of biological processes affecting terrestrial ecosystems; however, their ability to simultaneously predict field-based measurements of terrestrial vegetation dynamics and carbon fluxes has remained largely untested. In this study, we address this issue by developing a constrained implementation of a new structured TBM, the Ecosystem Demography model version 2 (ED2), which explicitly tracks the dynamics of fine-scale ecosystem structure and function. Carbon and water flux measurements from an eddy-flux tower are used in conjunction with forest inventory measurements of tree growth and mortality at Harvard Forest (42.5N, 72.1W) to estimate a number of important but weakly constrained model parameters. Evaluation against a decade of tower flux and forest dynamics measurements shows that the constrained ED2 model yields greatly improved predictions of annual net ecosystem productivity, carbon partitioning, and growth and mortality dynamics of both hardwood and conifer trees. The generality of the model formulation is then evaluated by comparing the model’s predictions against measurements from two other eddy-flux towers and forest inventories of the northeastern United States and Quebec. Despite the markedly different composition throughout this region, the optimized model realistically predicts observed patterns of carbon fluxes and tree growth. These results demonstrate how TBMs parameterized with field-based measurements can provide quantitative insight into the underlying biological processes governing ecosystem composition, structure, and function at larger scales.

428 citations

Journal ArticleDOI
TL;DR: It is recommended that following the reinstatement of low-input management, the measurement of a significant increase in the soil fungal:bacterial biomass ratio, and perhaps total microbial biomass, may be an indicator of successful conversion to a grassland system reliant of self-regulation.
Abstract: There is much interest in the development of agricultural land management strategies aimed at enhancing reliance on ecosystem self-regulation rather than on artificial inputs such as fertilisers and pesticides This study tested the usefulness of measures of soil microbial biomass and fungal:bacterial biomass ratios as indicators of effective conversion from an intensive grassland system, reliant mainly on fertilisers for crop nutrition, to a low-input system reliant mainly on self-regulation through soil biological pathways of nutrient turnover Analysis of soils from a wide range of meadow grassland sites in northern England, along a gradient of long-term management intensity, showed that fungal:bacterial biomass ratios (measured by phospholipid fatty acid analysis; PLFA) were consistently and significantly higher in the unfertilised than the fertilised grasslands There was also some evidence that microbial biomass, measured by chloroform fumigation and total PLFA, was higher in the unfertilised than in the fertilised grasslands It was also found that levels of inorganic nitrogen (N), in particular nitrate-N, were significantly higher in the fertilised than in the unfertilised grasslands However, microbial activity, measured as basal respiration, did not differ between the sites A field manipulation trial was conducted to determine whether the reinstatement of traditional management on an improved mesotrophic grassland, for 6 years, resulted in similar changes in the soil microbial community It was found that neither the cessation of fertiliser applications nor changes in cutting and grazing management significantly affected soil microbial biomass or the fungal:bacterial biomass ratio It is suggested that the lack of effects on the soil microbial community may be related to high residual fertility caused by retention of fertiliser N in the soil On the basis of these results it is recommended that following the reinstatement of low-input management, the measurement of a significant increase in the soil fungal:bacterial biomass ratio, and perhaps total microbial biomass, may be an indicator of successful conversion to a grassland system reliant of self-regulation

428 citations

Journal ArticleDOI
TL;DR: This paper studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of carbon inputs via aboveground net primary production.
Abstract: Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (41000gm � 2 ) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being nonlinear in grasslands to linear in shrublands. Thus, relatively abrupt (o50 years) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental-scale pattern of C inputs and their control by MAP in ways that exceed the direct effects of climate change alone.

428 citations

Journal ArticleDOI
01 Feb 2010-Ecology
TL;DR: Supporting the singular hypothesis for plant diversity, the results suggest that plant species are unique, each contributing to the functioning of the belowground system and reinforce the need for long-term biodiversity experiments to fully appreciate consequences of current biodiversity loss for ecosystem functioning.
Abstract: The global decline in biodiversity has generated concern over the consequences for ecosystem functioning and services. Although ecosystem functions driven by soil microorganisms such as plant productivity, decomposition, and nutrient cycling are of particular importance, interrelationships between plant diversity and soil microorganisms are poorly understood. We analyzed the response of soil microorganisms to variations in plant species richness (1-60) and plant functional group richness (1-4) in an experimental grassland system over a period of six years. Major abiotic and biotic factors were considered for exploring the mechanisms responsible for diversity effects. Further, microbial growth characteristics were assessed following the addition of macronutrients. Effects of plant diversity on soil microorganisms were most pronounced in the most diverse plant communities though differences only became established after a time lag of four years. Differences in microbial growth characteristics indicate successional changes from a disturbed (zymogeneous) to an established (autochthonous) microbial community four years after establishment of the experiment. Supporting the singular hypothesis for plant diversity, the results suggest that plant species are unique, each contributing to the functioning of the belowground system. The results reinforce the need for long-term biodiversity experiments to fully appreciate consequences of current biodiversity loss for ecosystem functioning.

427 citations


Network Information
Related Topics (5)
Biodiversity
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Species richness
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Vegetation
49.2K papers, 1.4M citations
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Climate change
99.2K papers, 3.5M citations
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Biological dispersal
30K papers, 1.2M citations
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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20235,630
202210,638
20212,059
20201,701
20191,681