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991.
As society faces the urgent need to mitigate climate change, it is critical to understand how various ecosystems contribute to the climate, and to express these contributions in terms that are meaningful to policymakers, economists, land managers, and other nonscience interest holders. Efforts to mitigate climate change call for quantification of the full greenhouse gas (GHG) effects of land use decisions, yet we lack an appropriate metric of the full GHG implications of maintaining a given ecosystem over a multiple year time frame. Here, we propose the concept of greenhouse gas value (GHGV) of ecosystems, which accounts for potential GHG release upon clearing of stored organic matter, annual GHG flux, and probable GHG exchanges resulting from disturbance. It treats these ecosystem–atmosphere exchanges in a time‐sensitive manner, thereby providing an appropriate framework for computing of the GHG consequences of any land use decision. To illustrate this concept, we provide estimates of the GHGV of various biome types (based on data compiled from the literature), disturbance regimes, and decisions on the treatment of time. We show that natural ecosystems generally have high GHGV's, whereas managed ecosystems generally have lower or negative GHGV's; that GHGV decreases with increasing probability of disturbance, and that decisions on the treatment of time can be important, affecting some ecosystem types more strongly than others. In addition, we show how GHGV may be used to quantify the full GHG effects of land‐use or land‐cover change in a thorough and rigorous manner. Finally, we provide comparisons of GHGV to other major paradigms for valuing the GHG contributions of ecosystems, showing that – for many purposes –GHGV is the most appropriate method of quantifying the GHG services of ecosystems. 相似文献
992.
Conversion to soy on the Amazonian agricultural frontier increases streamflow without affecting stormflow dynamics 总被引:1,自引:0,他引:1
SHELBY J. HAYHOE CHRISTOPHER NEILL STEPHEN PORDER RICHARD MCHORNEY PAUL LEFEBVRE MICHAEL T. COE HELMUT ELSENBEER ALEX V. KRUSCHE 《Global Change Biology》2011,17(5):1821-1833
Large‐scale soy agriculture in the southern Brazilian Amazon now rivals deforestation for pasture as the region's predominant form of land use change. Such landscape‐level change can have substantial consequences for local and regional hydrology, but these effects remain relatively unstudied in this ecologically and economically important region. We examined how the conversion to soy agriculture influences water balances and stormflows using stream discharge (water yields) and the timing of discharge (stream hydrographs) in small (2.5–13.5 km2) forested and soy headwater watersheds in the Upper Xingu Watershed in the state of Mato Grosso, Brazil. We monitored water yield for 1 year in three forested and four soy watersheds. Mean daily water yields were approximately four times higher in soy than forested watersheds, and soy watersheds showed greater seasonal variability in discharge. The contribution of stormflows to annual streamflow in all streams was low (<13% of annual streamflow), and the contribution of stormflow to streamflow did not differ between land uses. If the increases in water yield observed in this study are typical, landscape‐scale conversion to soy substantially alters water‐balance, potentially altering the regional hydrology over large areas of the southern Amazon. 相似文献
993.
Matthew E. Aiello‐Lammens Ma. Librada Chu‐Agor Matteo Convertino Richard A. Fischer Igor Linkov H. Resit Akçakaya 《Global Change Biology》2011,17(12):3644-3654
Sea‐level rise (SLR) is a projected consequence of global climate change that will result in complex changes in coastal ecosystems. These changes will cause transitions among coastal habitat types, which will be compounded by human‐made barriers to the gradual inland migration of these habitat types. The effect of these changes on the future viability of coastal species will depend on the habitat requirements and population dynamics of these species. Thus, realistic assessments of the impact of SLR require linking geomorphological models with habitat and population models. In this study, we implemented a framework that allows this linkage, and demonstrated its feasibility to assess the effect of SLR on the viability of the Snowy Plover population in Florida. The results indicate that SLR will cause a decline in suitable habitat and carrying capacity for this species, and an increase in the risk of its extinction and decline. The model projected that the population size will decline faster than the area of habitat or carrying capacity, demonstrating the necessity of incorporating population dynamics in assessing the impacts of SLR on coastal species. The results were most sensitive to uncertainties in survival rate and fecundity, and suggested that future studies on this species should focus on the average and variability of these demographic rates and their dependence on population density. The effect of SLR on this species’ viability was qualitatively similar with most alternative models that used the extreme values of each uncertain parameter, indicating that the results are robust to uncertainties in the model. 相似文献
994.
Biogeographical patterns of soil molecular microbial biomass as influenced by soil characteristics and management 总被引:3,自引:0,他引:3
S. Dequiedt N. P. A. Saby M. Lelievre C. Jolivet J. Thioulouse B. Toutain D. Arrouays A. Bispo P. Lemanceau L. Ranjard 《Global Ecology and Biogeography》2011,20(4):641-652
Aim The spatial organization of soil microbial communities on large scales and the identification of environmental factors structuring their distribution have been little investigated. The overall objective of this study was to determine the spatial patterning of microbial biomass in soils over a wide extent and to rank the environmental filters most influencing this distribution. Location French territory using the French Soil Quality Monitoring Network. This network covers the entire French territory and soils were sampled at 2150 sites along a systematic grid. Methods The soil DNA extracted from all these soils was expressed in terms of soil molecular microbial biomass and related to other soil and land‐use data over French territory. Results This study provides the first extensive map of microbial biomass and reveals the heterogeneous and spatially structured distribution of this biomass on the scale of France. The main factors driving biomass distribution are the physico‐chemical properties of the soil (texture, pH and total organic carbon) as well as land use. Soils from land used for intensive agriculture, especially monoculture and vineyards, exhibited the smallest biomass pools. Interestingly, factors known to influence the large‐scale distribution of macroorganisms, such as climatic factors, were not identified as important drivers for microbial communities. Main conclusions Microbial abundance is spatially structured and dependent on local filters such as soil characteristics and land use but is relatively independent of global filters such as climatic factors or the presence of natural barriers. Our study confirms that the biogeography of microorganisms differs fundamentally from the biogeography of ‘macroorganisms’ and that soil management can have significant large‐scale effects. 相似文献
995.
Kees Klein Goldewijk Arthur Beusen Gerard van Drecht Martine de Vos 《Global Ecology and Biogeography》2011,20(1):73-86
Aim This paper presents a tool for long‐term global change studies; it is an update of the History Database of the Global Environment (HYDE) with estimates of some of the underlying demographic and agricultural driving factors. Methods Historical population, cropland and pasture statistics are combined with satellite information and specific allocation algorithms (which change over time) to create spatially explicit maps, which are fully consistent on a 5′ longitude/latitude grid resolution, and cover the period 10,000 bc to ad 2000. Results Cropland occupied roughly less than 1% of the global ice‐free land area for a long time until ad 1000, similar to the area used for pasture. In the centuries that followed, the share of global cropland increased to 2% in ad 1700 (c. 3 million km2) and 11% in ad 2000 (15 million km2), while the share of pasture area grew from 2% in ad 1700 to 24% in ad 2000 (34 million km2) These profound land‐use changes have had, and will continue to have, quite considerable consequences for global biogeochemical cycles, and subsequently global climate change. Main conclusions Some researchers suggest that humans have shifted from living in the Holocene (emergence of agriculture) into the Anthropocene (humans capable of changing the Earth's atmosphere) since the start of the Industrial Revolution. But in the light of the sheer size and magnitude of some historical land‐use changes (e.g. as result of the depopulation of Europe due to the Black Death in the 14th century and the aftermath of the colonization of the Americas in the 16th century) we believe that this point might have occurred earlier in time. While there are still many uncertainties and gaps in our knowledge about the importance of land use (change) in the global biogeochemical cycle, we hope that this database can help global (climate) change modellers to close parts of this gap. 相似文献
996.
David D. Zhang Harry F. Lee Cong Wang Baosheng Li Jane Zhang Qing Pei Jingan Chen 《Global Ecology and Biogeography》2011,20(4):520-531
Aim It has long been assumed that deteriorating climate (cooling and warming above the norm) could shrink the carrying capacity of agrarian lands, depriving the human population of sufficient food. Population collapses (i.e. negative population growth) follow. However, this human–ecological relationship has rarely been verified scientifically, and evidence of warming‐caused disaster has never been found. This research sought to explore quantitatively the temporal pattern, spatial pattern and triggers of population collapses in relation to climate change at the global scale over 1100 years. Location Various countries/regions in the Northern Hemisphere (NH) during the pre‐industrial era. Methods We performed time‐series analysis to examine the association between temperature change and country‐wide/region‐wide population collapses in different climatic zones. All of the known population collapse incidents in the NH in the period ce 800–1900 were included in our data analysis. Results Nearly 90% of population collapses in various NH countries/regions occurred during periods of climate deterioration characterized by shrinking carrying capacity of the land. In addition, we found that cooling dampened the human ecosystem and brought about 80% of the collapses in warmer humid, cooler humid and dry zones, while warming adversely affected the ecosystems in dry and tropical humid zones. All of the population collapses and growth declines in periods of warm climate occurred in dry and tropical humid zones. Malthusian checks (famines, wars and epidemics) were the dominant triggers of population collapses, which peaked dramatically when climate deteriorated. Main conclusions Global demographic catastrophes and most population collapse incidents occurred in periods with great climate change, owing to overpopulation caused by diminished carrying capacity of the land and the resultant outbreak of Malthusian checks. Impacts of cooling or warming on land carrying capacity varied geographically, as a result of the diversified ecosystems in different parts of the Earth. The observed climate–population synchrony challenges Malthusian theory and demonstrates that it is not population growth alone but climate‐induced subsistence shortage and population growth working synergistically, that cause large‐scale human population collapses on the long‐term scale. 相似文献
997.
Tropical forests are experiencing large-scale structural changes, the most apparent of which may be the increase in liana (woody vine) abundance and biomass. Lianas permeate most lowland tropical forests, where they can have a huge effect on tree diversity, recruitment, growth and survival, which, in turn, can alter tree community composition, carbon storage and carbon, nutrient and water fluxes. Consequently, increasing liana abundance and biomass have potentially profound ramifications for tropical forest composition and functioning. Currently, eight studies support the pattern of increasing liana abundance and biomass in American tropical and subtropical forests, whereas two studies, both from Africa, do not. The putative mechanisms to explain increasing lianas include increasing evapotranspirative demand, increasing forest disturbance and turnover, changes in land use and fragmentation and elevated atmospheric CO?. Each of these mechanisms probably contributes to the observed patterns of increasing liana abundance and biomass, and the mechanisms are likely to be interrelated and synergistic. To determine whether liana increases are occurring throughout the tropics and to determine the mechanisms responsible for the observed patterns, a widespread network of large-scale, long-term monitoring plots combined with observational and manipulative studies that more directly investigate the putative mechanisms are essential. 相似文献
998.
Katinka X. Ruthrof Michael C. Calver Bernard Dell Giles E. St. J. Hardy 《Ecological Management & Restoration》2011,12(2):154-157
This study tested the efficacy of smokewater to determine the potential germination from soil seed bank in three management sites of the same National Park: a forest site prior to restoration, an ex‐pine plantation site and an ex‐mine site. This will provide further information to land managers so that more accurate planning can occur. Results showed that smokewater significantly increased the germination from the soil seed bank, and significant differences in the level of germination of weed species from the soil seed bank were seen between the three management sites. This use of smokewater may be a useful tool to help predict differences in the soil seed bank compared with predicting soil seed bank based on land‐use history and recent condition. 相似文献
999.
JANA GEVERS TOKE THOMAS HØYE CHRIS JOHN TOPPING MICHAEL GLEMNITZ BORIS SCHRÖDER 《Global Change Biology Bioenergy》2011,3(6):472-482
The public promotion of renewable energies is expected to increase the number of biogas plants and stimulate energy crops cultivation (e.g. maize) in Germany. In order to assess the indirect effects of the resulting land‐use changes on biodiversity, we developed six land‐use scenarios and simulated the responses of six farmland wildlife species with the spatially explicit agent‐based model system ALMaSS. The scenarios differed in composition and spatial configuration of arable crops. We implemented scenarios where maize for energy production replaced 15% and 30% of the area covered by other cash crops. Biogas maize farms were either randomly distributed or located within small or large aggregation clusters. The animal species investigated were skylark (Alauda arvensis), grey partridge (Perdix perdix), European brown hare (Lepus europaeus), field vole (Microtus agrestis), a linyphiid spider (Erigone atra) and a carabid beetle (Bembidion lampros). The changes in crop composition had a negative effect on the population sizes of skylark, partridge and hare and a positive effect on the population sizes of spider and beetle and no effect on the population size of vole. An aggregated cultivation of maize amplified these effects for skylark. Species responses to changes in the crop composition were consistent across three differently structured landscapes. Our work suggests that with the compliance to some recommendations, negative effects of biogas‐related land‐use change on the populations of the six representative farmland species can largely be avoided. 相似文献
1000.
The impact of landscape structure and land management on dispersal of populations of wild
species inhabiting the agricultural landscape was investigated focusing on the field vole
(Microtus agrestis) in three different areas in Denmark using molecular genetic
markers. The main hypotheses were the following: (i) organic farms act as genetic sources
and diversity reservoirs for species living in agricultural areas and (ii) gene flow and
genetic structure in the agricultural landscape are influenced by the degree of landscape
complexity and connectivity. A total of 443 individual voles were sampled within 2
consecutive years from two agricultural areas and one relatively undisturbed grassland
area. As genetic markers, 15 polymorphic microsatellite loci (nuclear markers) and the
central part of the cytochrome-b (mitochondrial sequence) were analysed for all
samples. The results indicate that management (that is, organic or conventional
management) was important for genetic population structure across the landscape, but that
landscape structure was the main factor shaping gene flow and genetic diversity. More
importantly, the presence of organically managed areas did not act as a genetic reservoir
for conventional areas, instead the most important predictor of effective population size
was the amount of unmanaged available habitat (core area). The relatively undisturbed
natural area showed a lower level of genetic structuring and genetic diversity compared
with the two agricultural areas. These findings altogether suggest that political
decisions for supporting wildlife friendly land management should take into account both
management and landscape structure factors. 相似文献