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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: In this article, the effects of changes in species distributions and dominances on key ecosystem processes and properties are considered, based upon best estimates of the trajectories of key transformations, their magnitude and rates of change.
Abstract: Global environmental change, related to climate change and the deposition of airborne N-containing contaminants, has already resulted in shifts in plant community composition among plant functional types in Arctic and temperate alpine regions. In this paper, we review how key ecosystem processes will be altered by these transformations, the complex biological cascades and feedbacks that might result, and some of the potential broader consequences for the earth system. Firstly, we consider how patterns of growth and allocation, and nutrient uptake, will be altered by the shifts in plant dominance. The ways in which these changes may disproportionately affect the consumer communities, and rates of decomposition, are then discussed. We show that the occurrence of a broad spectrum of plant growth forms in these regions (from cryptogams to deciduous and evergreen dwarf shrubs, graminoids and forbs), together with hypothesized low functional redundancy, will mean that shifts in plant dominance result in a complex series of biotic cascades, couplings and feedbacks which are supplemental to the direct responses of ecosystem components to the primary global change drivers. The nature of these complex interactions is highlighted using the example of the climate-driven increase in shrub cover in low-Arctic tundra, and the contrasting transformations in plant functional composition in mid-latitude alpine systems. Finally, the potential effects of the transformations on ecosystem properties and processes that link with the earth system are reviewed. We conclude that the effects of global change on these ecosystems, and potential climate-change feedbacks, cannot be predicted from simple empirical relationships between processes and driving variables. Rather, the effects of changes in species distributions and dominances on key ecosystem processes and properties must also be considered, based upon best estimates of the trajectories of key transformations, their magnitude and rates of change.

368 citations

Journal ArticleDOI
TL;DR: The strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011 and is mainly observed in temperate and arctic ecosystems.
Abstract: Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.

368 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the long-term effects of increasing atmospheric CO2 concentration on terrestrial higher plants' response to changes in plant C metabolism and the decomposition of soil organic matter and plant litter.
Abstract: Terrestrial higher plants exchange large amounts of CO2 with the atmosphere each year; c. 15% of the atmospheric pool of C is assimilated in terrestrial-plant photosynthesis each year, with an about equal amount returned to the atmosphere as CO2 in plant respiration and the decomposition of soil organic matter and plant litter. Any global change in plant C metabolism can potentially affect atmospheric CO2 content during the course of years to decades. In particular, plant responses to the presently increasing atmospheric CO2 concentration might influence the rate of atmospheric CO2 increase through various biotic feedbacks. Climatic changes caused by increasing atmospheric CO2 concentration may modulate plant and ecosystem responses to CO2 concentration. Climatic changes and increases in pollution associated with increasing atmospheric CO2 concentration may be as significant to plant and ecosystem C balance as CO2 concentration itself. Moreover, human activities such as deforestation and livestock grazing can have impacts on the C balance and structure of individual terrestrial ecosystems that far outweigh effects of increasing CO2 concentration and climatic change. In short-term experiments, which in this case means on the order of 10 years or less, elevated atmospheric CO2 concentration affects terrestrial higher plants in several ways. Elevated CO2 can stimulate photosynthesis, but plants may acclimate and (or) adapt to a change in atmospheric CO2 concentration. Acclimation and adaptation of photosynthesis to increasing CO2 concentration is unlikely to be complete, however. Plant water use efficiency is positively related to CO2 concentration, implying the potential for more plant growth per unit of precipitation or soil moisture with increasing atmospheric CO2 concentration. Plant respiration may be inhibited by elevated CO2 concentration, and although a naive C balance perspective would count this as a benefit to a plant, because respiration is essential for plant growth and health, an inhibition of respiration can be detrimental. The net effect on terrestrial plants of elevated atmospheric CO2 concentration is generally an increase in growth and C accumulation in phytomass. Published estimations, and speculations about, the magnitude of global terrestrial-plant growth responses to increasing atmospheric CO2 concentration range from negligible to fantastic. Well-reasoned analyses point to moderate global plant responses to CO2 concentration. Transfer of C from plants to soils is likely to increase with elevated CO2 concentrations because of greater plant growth, but quantitative effects of those increased inputs to soils on soil C pool sizes are unknown. Whether increases in leaf-level photosynthesis and short-term plant growth stimulations caused by elevated atmospheric CO2 concentration will have, by themselves, significant long-term (tens to hundreds of years) effects on ecosystem C storage and atmospheric CO2 concentration is a matter for speculation, not firm conclusion. Long-term field studies of plant responses to elevated atmospheric CO2 are needed. These will be expensive, difficult, and by definition, results will not be forthcoming for at least decades. Analyses of plants and ecosystems surrounding natural geological CO2 degassing vents may provide the best surrogates for long-term controlled experiments, and therefore the most relevant information pertaining to long-term terrestrial-plant responses to elevated CO2 concentration, but pollutants associated with the vents are a concern in some cases, and quantitative knowledge of the history of atmospheric CO2 concentrations near vents is limited. On the whole, terrestrial higher-plant responses to increasing atmospheric CO2 concentration probably act as negative feedbacks on atmospheric CO2 concentration increases, but they cannot by themselves stop the fossil-fuel-oxidation-driven increase in atmospheric CO2 concentration. And, in the very long-term, atmospheric CO2 concentration is controlled by atmosphere-ocean C equilibrium rather than by terrestrial plant and ecosystem responses to atmospheric CO2 concentration.

368 citations

Journal ArticleDOI
TL;DR: The structure and dynamics of small plantations of pine and mahogany were compared with those of paired secondary forest stands of similar age and growing adjacent to each other under similar edaphic and climatic conditions to challenge the conventional dogma with respect to differences between plantations and native successional ecosystems.
Abstract: The structure and dynamics of small plantations of pine (Pinus caribaea; 4 and 18.5 yr old in 1980) and mahogany (Swietenia macrophylla; 17 and 49 yr old in 1980) were compared with those of paired secondary forest stands of similar age and growing adjacent to each other under similar edaphic and climatic conditions. The study was conducted in the Luquillo Experimental Forest between 1980 and 1984. Comparisons included a variety of demographic, production, and nutrient cycling characteristics of stands. Although the small unmanaged plantations had a lower number of species in understory than paired secondary forests, the understory of the older plantations developed high species richness, including many of native tree species. After 17 yr, native tree species invaded the overstory of plantations. After 50 years the species richness in the understory of a mahogany plantation approached that of its paired secondary forest. Plantation un- derstories had important ecological roles, including high nutrient accumulation. Understory plant tissue, particularly leaf litter, had higher nutrient concentration in pine plantations than in paired secondary forests. Understory biomass in plantations accumulated a higher proportion of the total nutrient inventory in the stand than did the understory in paired secondary forests. Plantations had higher aboveground biomass and net aboveground bio- mass production than paired secondary forests. Higher root densities and biomass were found in secondary forests as were greater depth of root penetration, higher nutrient con- centration in roots, and more microsites where roots grow, than paired plantations. These characteristics may improve the capacity of secondary forests relative to that of paired plantations to rapidly recapture nutrients that become available by mineralization and that could otherwise be lost through hydrological or gaseous pathways. Both forest types accumulated nutrients and mass, but secondary forests recirculated nutrients much faster than the plantations, which tended to store the nutrients. Plantations had higher leaf fall and total litterfall, had litterfall with lower nutrient concentrations, accumulated more nutrients in litter, decomposed more litter on an annual basis, exhibited more variation in the spatial distribution of litter mass, and had more month-to-month variation in litter storage than paired secondary forests. Litter of the secondary forests, on the other hand, had a faster nutrient turnover than plantation litter, though plantations retranslocated more nutrients before leaf fall than did secondary forests. Nutrient retranslocation increased with plantation age. Plantations, particularly pine plantations, produced more litter mass per unit nutrient return than did paired secondary forests. Total nutrient storage in soil gave the best correlation with nutrient use efficiency estimated as element: mass ratios in various compartments. Nutrient use efficiency ranked differently among forest pairs, depending upon which nutrient and ecosystem parameters were being compared. Because of high retranslocation of nutrients, and in spite of greater nutrient "need" to produce higher biomass, plantations had nutrient demands on soil similar to paired secondary forests. Among the ecosystem parameters measured, nutrients in leaf fall correlated best with differences in soil nutrients across stands. Nutrient concentrations in understory species appeared to be a sensitive indicator of whole-stand nutrient use efficiency. Some of the observations of the study could be attributed to intrinsic differences between small un- managed plantations and secondary forests, but many could be explained by species dif- ferences (i.e., timing of leaf fall), age of plantation (i.e., accumulation of biomass or species), or the relative importance of angiosperms and gymnosperms (i.e., nutritional quality of litter). The study challenges the conventional dogma with respect to differences between plantations and native successional ecosystems and underscores the dangers of generalizing about all tropical tree plantations or all natural tropical forests, or even extrapolating from one sector of the ecosystem to another.

368 citations

Book
01 Jan 2000
TL;DR: This chapter discusses the effects of climate change on the evolution and distribution of species, and the results of evolution: convergent and parallel evolution.
Abstract: Chapter 1: Ecology and How to Do It 1.1 Introduction 1.2 Scales, diversity and rigor 1.2.1 Questions of scale 1.2.2 The diversity of ecological evidence 1.2.3 Statistics and scientific rigor 1.3 Ecology in practice 1.3.1 The brown trout in New Zealand - effects on individuals, populations, communities and ecosystems 1.3.2 Successions on old fields in Minnesota - a study in time and space 1.3.3 Hubbard Brook - a long-term commitment of large-scale significance 1.3.4 A model study: Genetically modified crops - bad for biodiversity? Summary Review Questions Chapter 2: The Ecology of Evolution 2.1 Introduction 2.2 Evolution by natural selection 2.3 Evolution within species 2.3.1 Geographical variation within species 2.3.2 Variation within a species with man-made selection pressures 2.3.3 Adaptive peaks and specialized abysses 2.4 The ecology of speciation 2.4.1 What do we mean by a "species"? 2.4.2 Islands and speciation 2.5 The effects of climate change on the evolution and distribution of species 2.6 The effects of continental drift on the ecology of evolution 2.7 Interpreting the results of evolution: convergent and parallel evolution Summary Review Questions Chapter 3: Physical Conditions and the Availability of Resources 3.1 Introduction 3.2 Environmental conditions 3.2.1 What do we mean by "harsh," "benign," and "extreme"? 3.2.2 Effects of conditions 3.2.3 Conditions as stimuli 3.2.4 The effects of conditions on interactions between organisms 3.2.5 Responses by sedentary organisms 3.2.6 Animal responses to environmental temperature 3.2.7 Microorganisms in extreme environments 3.3 Plant resources 3.3.1 Solar radiation 3.3.2 Water 3.3.3 Mineral nutrients 3.3.4 Carbon dioxide 3.4 Animals and their resources 3.4.1 Nutritional needs and provisions 3.4.2 Defense 3.5 The effect of intraspecific competition for resources 3.6 Conditions, resources, and the ecological niche Summary Review Questions Chapter 4: Conditions, Resources and the World's Communities 4.1 Introduction 4.2 Geographical patterns at large and small scales 4.2.1 Large-scale climatic patterns 4.2.2 Small-scale patterns in conditions and resources 4.2.3 Patterns in conditions and resources in aquatic environments 4.3 Temporal patterns in conditions and resources - succession 4.4 The terrestrial biomes 4.4.1 Describing and classifying biomes 4.4.2 Tropical rain forest 4.4.3 Savanna 4.4.4 Temperate grasslands 4.4.5 Desert 4.4.6 Temperate forest 4.4.7 Northern coniferous forest (taiga) grading into tundra 4.5 Aquatic environments 4.5.1 Stream ecology 4.5.2 Lake ecology 4.5.3 The oceans 4.5.4 Coasts 4.5.5 Estuaries Summary Review Questions Chapter 5: Birth, Death and Movement 5.1 Introduction 5.1.1 What is an individual? 5.1.2 Counting individuals, births, and deaths 5.2 Life Cycles 5.2.1 Life cycles and reproduction 5.2.2 Annual life cycles 5.2.3 Longer life cycles 5.3 Monitoring birth and death: life tables and fecundity schedules (Part conents)

368 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