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Katja Irob Niels Blaum Selina Baldauf Leon Kerger Ben Strohbach Angelina Kanduvarisa Dirk Lohmann Britta Tietjen 《Ecology and evolution》2022,12(3)
Changing climatic conditions and unsustainable land use are major threats to savannas worldwide. Historically, many African savannas were used intensively for livestock grazing, which contributed to widespread patterns of bush encroachment across savanna systems. To reverse bush encroachment, it has been proposed to change the cattle‐dominated land use to one dominated by comparatively specialized browsers and usually native herbivores. However, the consequences for ecosystem properties and processes remain largely unclear. We used the ecohydrological, spatially explicit model EcoHyD to assess the impacts of two contrasting, herbivore land‐use strategies on a Namibian savanna: grazer‐ versus browser‐dominated herbivore communities. We varied the densities of grazers and browsers and determined the resulting composition and diversity of the plant community, total vegetation cover, soil moisture, and water use by plants. Our results showed that plant types that are less palatable to herbivores were best adapted to grazing or browsing animals in all simulated densities. Also, plant types that had a competitive advantage under limited water availability were among the dominant ones irrespective of land‐use scenario. Overall, the results were in line with our expectations: under high grazer densities, we found heavy bush encroachment and the loss of the perennial grass matrix. Importantly, regardless of the density of browsers, grass cover and plant functional diversity were significantly higher in browsing scenarios. Browsing herbivores increased grass cover, and the higher total cover in turn improved water uptake by plants overall. We concluded that, in contrast to grazing‐dominated land‐use strategies, land‐use strategies dominated by browsing herbivores, even at high herbivore densities, sustain diverse vegetation communities with high cover of perennial grasses, resulting in lower erosion risk and bolstering ecosystem services. 相似文献
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Freshwater resources are at a premium across the world, including many water‐limited areas across Australia. Ongoing water level decline in some groundwater systems suggests that the rate of loss may have reached unsustainable levels . However, identifying which factors are primarily responsible for the trend (lack of rainfall–recharge, presence of vegetation, and groundwater pumping) remains challenging using groundwater observations alone. We applied satellite‐derived estimates of evapotranspiration (ETa), which, when combined with local rainfall data and field‐based groundwater level observations, established a regional water balance spanning 1,500 km2 and seven groundwater lenses over a 10‐year period (2000 – 2010). Assuming that the extent of the freshwater isohaline represents the recharge area for a lens, the water balance suggests that the median annual groundwater recharge rate varied between 226 ± 92 mm year−1 (Mikkira) and −162 ± 194 mm year−1 (Uley East). Uley South is the most regionally significant lens in the system and recorded a median annual recharge rate of 91 ± 182 mm year−1. Overlaying vegetation highlighted the impact of woodland areas on groundwater recharge, where the trees were accessing groundwater to support ETa, provided the water table was <10 m. Areas of grassland demonstrated the highest median groundwater recharge rates of 151 mm year−1, followed by cropping (133 mm year−1) and pasture (95 mm year−1). Exploring the resilience of the groundwater system to variations in extraction (pumping) and woodland coverage suggests that resource managers must consider both systematic losses in order to maintain groundwater equilibrium. 相似文献
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The Brazilian Cerrado is recognized as one of the most threatened biomes in the world, as the region has experienced a striking change from natural Cerrado vegetation to intense cash crop production. This paper reviews the history of land conversion in the Cerrado and the development of soil properties and water resources under past and ongoing land use. We compared soil and water quality parameters from different land uses considering 80 soil and 18 water studies conducted in different regions across the Cerrado to provide quantitative evidence of soil and water alterations from land use change. Following the conversion of native Cerrado, significant effects on soil pH, bulk density and available P and K for croplands and less‐pronounced effects on pastures were evident. Soil total N did not differ between land uses because most of the sites classified as croplands were nitrogen‐fixing soybeans, which are not artificially fertilized with N. In contrast, water quality studies showed nitrogen enrichment in agricultural catchments, indicating fertilizer impacts and potential susceptibility to eutrophication. Regardless of the land use, P is widely absent because of the high‐fixing capacities of deeply weathered soils and the filtering capacity of riparian vegetation. Pesticides, however, were consistently detected throughout the entire aquatic system. In several case studies, extremely high‐peak concentrations exceeded Brazilian and European Union (EU) water quality limits, which were potentially accompanied by serious health implications. Land use intensification is likely to continue, particularly in regions where less annual rainfall and severe droughts are projected in the northeastern and western Cerrado. Thus, the leaching risk and displacement of agrochemicals are expected to increase, particularly because the current legislation has caused a reduction in riparian vegetation. We conclude that land use intensification is likely to seriously limit the Cerrado's future regarding both agricultural productivity and ecosystem stability. Because only limited data are available, we recommend further field studies to understand the interaction between terrestrial and aquatic systems. This study may serve as a valuable database for integrated modelling to investigate the impact of land use and climate change on soil and water resources and to test and develop mitigation measures for the Cerrado. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Abstract Modification of native ecosystems through land use can affect the biophysical functioning of agroecosystems, with spatial arrangement (configuration) through time often determining the degree to which landscapes experience dysfunctional states. An improved understanding is needed of how spatial and temporal patterns in land use affect ecohydrological dysfunctions, such as how landscapes leak or fail to retain water and soil, at scales relevant to farm management. We develop and apply a Graphical LAndscape Map Survey method, or ‘GLAMS’, for measuring changes in landscape function based upon a 3D graphic of a hypothetical sub-catchment. GLAMS was applied within four Landcare Groups comprised of farmers from the Western Catchments of Southeast Queensland, Australia. The aim was to capture the behaviors of farmers who manage land use under natural variations in precipitation, especially extended dry periods, and with the associated risks from ecohydrologically dysfunctional or ‘leaky’ landscapes. GLAMS provided variable spatial and temporal resolution which allowed quantification of the land use responses for three different property sizes: (1) small, less than 100 ha; (2) medium, 100–500 ha; and (3) large, larger than 500 ha. Responses were quantified using Bayesian Belief Networks to provide probability estimates of the likelihood of a given action, taking place within a particular part of the landscape, considering both climatic and ecohydrological risks. The findings indicated that GLAMS was more intuitive to farmers than traditional question-based surveys, resulting in a low cost technique that is rapid to implement while providing spatially explicit information relevant to farm and catchment management. 相似文献
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Multiple Methods in the Study of Driving Forces of Land Use and Land Cover Change: A Case Study of SE Kajiado District,Kenya 总被引:1,自引:0,他引:1
David J. Campbell David P. Lusch Thomas A. Smucker Edna E. Wangui 《Human ecology: an interdisciplinary journal》2005,33(6):763-794
This landscape-scale study combines analysis of multitemporal satellite imagery spanning 30 years and information from field
studies extending over 25 years to assess the extent and causes of land use and land cover change in the Loitokitok area,
southeast Kajiado District, Kenya. Rain fed and irrigated agriculture, livestock herding, and wildlife and tourism have all
experienced rapid change in their structure, extent, and interactions over the past 30 years in response to a variety of economic,
cultural, political, institutional, and demographic processes. Land use patterns and processes are explored through a complementary
application of interpretation of satellite imagery and case study analysis that explicitly addresses the local–national spatial
scale over a time frame appropriate to the identification of fundamental causal processes. The results illustrate that this
combination provides an effective basis for describing and explaining patterns of land use and land cover change and their
root causes. 相似文献
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Impact of land use and land cover change on groundwater recharge and quality in the southwestern US 总被引:12,自引:0,他引:12
Bridget R. Scanlon Robert C. Reedy David A. Stonestrom† David E. Prudic‡ Kevin F. Dennehy§ 《Global Change Biology》2005,11(10):1577-1593
Humans have exerted large‐scale changes on the terrestrial biosphere, primarily through agriculture; however, the impacts of such changes on the hydrologic cycle are poorly understood. The purpose of this study was to test the hypothesis that the conversion of natural rangeland ecosystems to agricultural ecosystems impacts the subsurface portion of the hydrologic cycle by changing groundwater recharge and flushing salts to underlying aquifers. The hypothesis was examined through point and areal studies investigating the effects of land use/land cover (LU/LC) changes on groundwater recharge and solute transport in the Amargosa Desert (AD) in Nevada and in the High Plains (HP) in Texas, US. Studies use the fact that matric (pore‐water‐pressure) potential and environmental‐tracer profiles in thick unsaturated zones archive past changes in recharging fluxes. Results show that recharge is related to LU/LC as follows: discharge through evapotranspiration (i.e., no recharge; upward fluxes <0.1 mm yr?1) in natural rangeland ecosystems (low matric potentials; high chloride and nitrate concentrations); moderate‐to‐high recharge in irrigated agricultural ecosystems (high matric potentials; low‐to‐moderate chloride and nitrate concentrations) (AD recharge: ~130–640 mm yr?1); and moderate recharge in nonirrigated (dryland) agricultural ecosystems (high matric potentials; low chloride and nitrate concentrations, and increasing groundwater levels) (HP recharge: ~9–32 mm yr?1). Replacement of rangeland with agriculture changed flow directions from upward (discharge) to downward (recharge). Recent replacement of rangeland with irrigated ecosystems was documented through downward displacement of chloride and nitrate fronts. Thick unsaturated zones contain a reservoir of salts that are readily mobilized under increased recharge related to LU/LC changes, potentially degrading groundwater quality. Sustainable land use requires quantitative knowledge of the linkages between ecosystem change, recharge, and groundwater quality. 相似文献
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In the last 100 years or so, desertification, degradation, and woody plant encroachment have altered huge tracts of semiarid rangelands. It is expected that the changes thus brought about significantly affect water balance in these regions; and in fact, at the headwater‐catchment and smaller scales, such effects are reasonably well documented. For larger scales, however, there is surprisingly little documentation of hydrological change. In this paper, we evaluate the extent to which streamflow from large rangeland watersheds in central Texas has changed concurrent with the dramatic shifts in vegetation cover (transition from pristine prairie to degraded grassland to woodland/savanna) that have taken place during the last century. Our study focused on the three watersheds that supply the major tributaries of the Concho River – those of the North Concho (3279 km2), the Middle Concho (5398 km2), and the South Concho (1070 km2). Using data from the period of record (1926–2005), we found that annual streamflow for the North Concho decreased by about 70% between 1960 and 2005. Not only did we find no downtrend in precipitation that might explain this reduced flow, we found no corresponding change in annual streamflow for the other two watersheds (which have more karst parent material). When we analyzed trends in baseflow (contributions from groundwater) and stormflow (runoff events linked to specific precipitation events), however, we found that in spite of large increases in woody plants, baseflow for all the watersheds has remained essentially consistent or has increased slightly since 1960. At the same time, stormflows were of smaller magnitude. Animal numbers have declined precipitously in the latter half of the last century. We suggest that these lower stormflows result from generally higher soil infiltrability due to generally improving range condition. There is no indication that the decline in streamflow is related to diminished groundwater flows caused by extraction of subsurface water by woody plants. 相似文献
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Mediterranean agro-silvo-pastoral systems play a key role in view of the positive contribution that they could offer to a sustainable development of European agriculture. The knowledge of the vegetation dynamics and of the processes and land uses favoring different vegetation types related to the same actual potential natural vegetation (PNV) could represent a sound reference framework for monitoring and managing plant biodiversity in these systems. The aim of the research was to evaluate plant diversity along a gradient of use intensity comparing the actual vegetation versus the PNV. The results of our research showed that in the studied Mediterranean agro-silvo-pastoral system, included in the same environmental unit, human activities enhanced plant biodiversity. Moreover, the case study presented here confirmed the effectiveness of those landscape approaches comparing actual vegetation versus the PNV for plant biodiversity monitoring and reinforced previous studies showing the effect of human activities on plant community diversity at the environmental unit scale in different biogeographical contexts. 相似文献
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Land-use change and water losses: the case of grassland afforestation across a soil textural gradient in central Argentina 总被引:1,自引:0,他引:1
Marcelo D. Nosetto † Esteban G. Jobbágy José M. Paruelo‡ 《Global Change Biology》2005,11(7):1101-1117
Vegetation changes, particularly those involving transitions between tree‐ and grass‐dominated covers, often modify evaporative water losses as a result of plant‐mediated shifts in moisture access and demand. Massive afforestation of native grasslands, particularly important in the Southern Hemisphere, may have strong yet poorly quantified effects on the hydrological cycle. We explored water use patterns in Eucalyptus grandis plantations and the native humid grasslands that they replace in Central Argentina. In order to uncover the interactive effects that land cover type, soil texture and climate variability may have on evaporative water losses and water use efficiency, we estimated daily evapotranspiration (ET) in 117 tree plantations and grasslands plots across a soil textural gradient (clay‐textured Vertisols to sandy‐textured Entisols) using radiometric information from seven Landsat scenes, existing timber productions records, and 13C measurements in tree stems. Tree plantations had cooler surface temperatures (?5°C on average) and evaporated more water (+80% on average) than grasslands at all times and across all sites. Absolute ET differences between grasslands and plantations ranged from ~0.6 to 2 mm day?1 and annual up‐scaling suggested values of ~630 and ~1150 mm yr?1 for each vegetation type, respectively. The temporal variability of ET was significantly lower in plantations compared with grasslands (coefficient of variation 36% vs. 49%). Daily ET increased as the water balance became more positive (accumulated balance for previous 18 days) with a saturation response in grassland vs. a continuous linear increase in plantations, suggesting lower ecophysiological limits to water loss in tree canopies compared with the native vegetation. Plantation ET was more strongly affected by soil texture than grassland ET and peaked in coarse textured sites followed by medium and fine textured sites. Timber productivity as well as 13C concentration in stems peaked in medium textured sites, indicating lower water use efficiency on extreme textures and suggesting that water limitation was not responsible for productivity declines towards finer and coarser soils. Our study highlighted the key role that vegetation type plays on evapotranspiration and, therefore, in the hydrological cycle. Considering that tree plantations may continue their expansion over grasslands, problematic changes in water management and, perhaps, in local climate can develop from the higher evaporative water losses of tree plantations. 相似文献
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土地利用类型与水体水质之间存在显著相关关系,这种相关关系受到土地利用类型及其空间分布的影响.人类活动造成流域中不同汇水单元间土地利用异质性,进而影响和改变了汇水单元水质状况.在自然或半自然区域内,采用多个汇水单元的综合分析能够体现出流域土地利用类型与水质的相关关系.然而,在城市区域中,可能存在由于土地利用特征差异而导致这种相关关系的抵消和降低,致使分析结果与实际存在偏差.为证实这一现象的存在,选取武汉市汉阳地区龙阳湖等4个湖泊流域为研究对象,分别从汇水单元综合分析、以影响水质的主要用地类型作为变量进行聚类分析和以湖泊流域为对象的分析等3个角度,分析汇水单元间的土地利用特征差异对水质的影响,结果显示土地利用异质性影响甚至改变了土地利用类型与水质的相关关系.因此,在研究城市土地利用与水体水质相关性时,需要同时考虑土地利用类型的特征和格局. 相似文献
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密云水库上游流域土地利用与地表径流营养物的关系 总被引:1,自引:0,他引:1
定量刻画土地利用与水体营养物浓度的关系,有助于指导流域土地利用管理,以控制水体富营养化.以往研究较多关注土地利用的数量结构,对其强度、空间分布等刻画相对不足.本研究以密云水库上游流域为例,基于覆盖全流域52个子流域的水质采样,通过遥感解译和空间计算,提取土地利用强度、所处坡度、与河道及监测断面距离以及位置邻接关系等信息,构建土地利用与总氮、总磷和化学需氧量浓度的多元线性回归方程.结果表明: 土地利用与总氮、总磷和化学需氧量浓度回归方程的决定系数由未纳入任何信息的0.294、0.471和0.223分别增加到0.532、0.685和0.489,显著提高了模型的解释能力.在厘定每一空间位置土地利用对监测断面营养物浓度贡献率的基础上,比较与河道不同迁移路径距离下土地利用对营养物浓度的平均累积贡献率及面积累计百分比,确定了距离河道1 km范围内的河岸带为水体富营养化的关键控制范围.最后提出了优化农田施肥管理、加强牲畜粪便处理、建设林地过滤带和河岸缓冲带等水质污染控制和调控的措施建议. 相似文献
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YANG Wen-yu KANG Xin LUAN Xia-li CHEN Bin ZHENG A-bao HOU Chang-ying LIU Mao-song XU Chi 《生态学杂志》2017,36(9):2658
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A means of deriving a disturbance index reflecting forest use history is demonstrated here to establish a disturbance gradient and enable comparison of different forest areas within and across individual forests. Detailed reference is made to Kakamega Forest in western Kenya for which a long‐term time series has been established, although the study is spread to four further forests in Kenya and Uganda. A wide variety of sources are drawn upon for spatially resolved data that are integrated in a geographic information system. Three indices are derived: for commercial disturbance, local disturbance, and forest cover change. Results show a wide range of disturbance values (from low to heavy) for the research sites within Kakamega Forest, while results for Budongo and Mabira Forest sites show low and moderate levels, respectively. Correlations of low disturbance levels with nature or national reserves appear to be marked, while a correlation of disturbance with differing management authority is also suggested with Kenya Wildlife Service achieving the lowest disturbance levels. Results from the index are reviewed against other means of estimating disturbance with the conclusion that disturbance evaluations should be both spatially resolved and long‐term in nature. 相似文献
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J. M. Waddington P. J. Morris N. Kettridge G. Granath D. K. Thompson P. A. Moore 《Ecohydrology》2015,8(1):113-127
Northern peatlands provide important global and regional ecosystem services (carbon storage, water storage, and biodiversity). However, these ecosystems face increases in the severity, areal extent and frequency of climate‐mediated (e.g. wildfire and drought) and land‐use change (e.g. drainage, flooding and mining) disturbances that are placing the future security of these critical ecosystem services in doubt. Here, we provide the first detailed synthesis of autogenic hydrological feedbacks that operate within northern peatlands to regulate their response to changes in seasonal water deficit and varying disturbances. We review, synthesize and critique the current process‐based understanding and qualitatively assess the relative strengths of these feedbacks for different peatland types within different climate regions. We suggest that understanding the role of hydrological feedbacks in regulating changes in precipitation and temperature are essential for understanding the resistance, resilience and vulnerability of northern peatlands to a changing climate. Finally, we propose that these hydrological feedbacks also represent the foundation of developing an ecohydrological understanding of coupled hydrological, biogeochemical and ecological feedbacks. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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裸沙表面的蒸发虽然是一个物理问题,但对于沙地植被演替的初始阶段非常重要。目前存在的地表蒸发的机理性模型大多是瞬时或者短时期的 ,而年尺度以上的蒸发量与降水和蒸发驱动下的土壤水分系统的状态变化及其对蒸发过程的反馈密切相关。一些估算毛乌素年蒸发量的实验结 果之间分歧很大且缺乏准确的机理性解释。该文利用生态系统模型中的土壤水分运动和蒸发模块计算了毛乌素裸沙丘从日到年际尺度的实际蒸 发量,发展了一个以单次降雨量和降雨频率为驱动因素的降雨-蒸发模型对年蒸发量进行简单的估算,并研究了年蒸发量对降雨格局的响应。结 果表明毛乌素裸沙丘的多年平均蒸发量为166 mm,占多年平均降雨量的56%。虽然研究区1959~1992年降雨总量无显著变化趋势,但是裸沙丘斑 块的实际蒸发量呈现较明显的增加趋势(1.30 mm&;#8226;a-1)。小降雨事件对蒸发量贡献的显著增加(0.69 mm&;#8226;a-1)是导致实际蒸发量增大的重 要原因。大强度降雨事件的频度和雨量对降雨总量的贡献要远高于对蒸发总量的贡献,小于12 mm的降雨事件在年际比较稳定,很大程度上保证 了年蒸发量100 mm左右的基数值。这些因素使得年蒸发量的变异程度小于年降雨量的变异程度。由于降雨格局的年际变化会对蒸发量产生直接 的影响,降雨-蒸发模型可以相对有效地预测年度蒸发量,而用年降雨量预测年蒸发量误差较大。 相似文献
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Effects of anthropogenic activities on habitats and species communities and populations are complex and vary across species depending on their ecological traits. Movement ecology may provide important insights into species’ responses to habitat structures and quality. We investigated how movement behavior across a human‐modified landscape depends on species identity and species traits, with particular focus on habitat specialization, feeding guilds, and dispersal behavior. We tracked 34 individuals of nine Afrotropical bird species during three years in an anthropogenic riparian landscape of East Africa. We investigated whether species’ functional traits predicted their habitat use and movement behavior better than species’ identities. Our results indicate that habitat specialists mainly occur in dense riparian thickets, while habitat generalists do occur in agricultural land. Home‐ranges of omnivorous habitat generalists are larger than of frugivorous and insectivorous generalists and omnivorous and insectivorous specialists. Movement speed was highest in settlement areas for all species, with activity peaks during morning and afternoon for habitat specialists. Our results reveal that functional traits and species identity provide complementary insights into responses of organisms to habitat structures and habitat quality. 相似文献
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Markus Bonsch Florian Humpenöder Alexander Popp Benjamin Bodirsky Jan Philipp Dietrich Susanne Rolinski Anne Biewald Hermann Lotze‐Campen Isabelle Weindl Dieter Gerten Miodrag Stevanovic 《Global Change Biology Bioenergy》2016,8(1):11-24
Bioenergy is expected to play an important role in the future energy mix as it can substitute fossil fuels and contribute to climate change mitigation. However, large‐scale bioenergy cultivation may put substantial pressure on land and water resources. While irrigated bioenergy production can reduce the pressure on land due to higher yields, associated irrigation water requirements may lead to degradation of freshwater ecosystems and to conflicts with other potential users. In this article, we investigate the trade‐offs between land and water requirements of large‐scale bioenergy production. To this end, we adopt an exogenous demand trajectory for bioenergy from dedicated energy crops, targeted at limiting greenhouse gas emissions in the energy sector to 1100 Gt carbon dioxide equivalent until 2095. We then use the spatially explicit global land‐ and water‐use allocation model MAgPIE to project the implications of this bioenergy target for global land and water resources. We find that producing 300 EJ yr?1 of bioenergy in 2095 from dedicated bioenergy crops is likely to double agricultural water withdrawals if no explicit water protection policies are implemented. Since current human water withdrawals are dominated by agriculture and already lead to ecosystem degradation and biodiversity loss, such a doubling will pose a severe threat to freshwater ecosystems. If irrigated bioenergy production is prohibited to prevent negative impacts of bioenergy cultivation on water resources, bioenergy land requirements for meeting a 300 EJ yr?1 bioenergy target increase substantially (+ 41%) – mainly at the expense of pasture areas and tropical forests. Thus, avoiding negative environmental impacts of large‐scale bioenergy production will require policies that balance associated water and land requirements. 相似文献
19.
《植物生态学报》2014,38(5):425
2008年和2009年(均为枯水年), 在半干旱区内蒙古太仆寺旗农田-草地生态系统国家野外站开展观测实验, 通过观测蒸散发(波文比系统)、土壤水分(烘干称重法)、降水量, 以及植被土壤特征调查, 基于水量平衡理论, 对比研究了3块天然草地、3块不同退耕时间草地共6个样地的水分收支, 旨在定量地评估退耕草地的水分收支, 为采取科学措施促进退耕草地尽快向天然草地过渡提供依据。结果表明: 1)随着退耕时间增加, 植被盖度逐渐增加, 但是群落中科、属、种的数量趋于减少, 且优势种从一年生的中旱生草本植物逐渐转变成多年生的旱生草本植物; 2)植被蒸腾是草原植被主要的耗水途径, 随着退耕时间增加, 退耕草地的蒸散发量呈增加趋势, 其最大值在4.5-5.8 mm·d-1之间; 3)退耕草地土壤含水量平均值为0.09 m3·m-3, 其水分剧烈变化主要发生在距地 表60 cm内, 且随退耕时间增加土壤含水量减少, 而天然草地土壤含水量平均值为0.06 m3·m-3, 其水分剧烈变化发生在距地 表20 cm内; 4)随退耕时间增加, 退耕草地与天然草地的土壤水分与蒸散发在数值上差距逐渐缩小; 5)退耕草地水分收支基本平衡, 但在极枯年份(降水量174 mm)的生长季, 降水不能满足蒸散发需求, 呈现水分亏损。退耕草地逐步向天然草地过渡, 但是退耕草地的土壤水分在逐渐减少, 呈现“生境干旱化现象”。今后应加强对草地的封育与监测, 促进植物群落向水分利用效率更高、更适应半干旱环境的方向演替。 相似文献
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Afshin Pourmokhtarian Charles T. Driscoll John L. Campbell Katharine Hayhoe Anne M. K. Stoner Mary Beth Adams Douglas Burns Ivan Fernandez Myron J. Mitchell James B. Shanley 《Global Change Biology》2017,23(2):840-856
A cross‐site analysis was conducted on seven diverse, forested watersheds in the northeastern United States to evaluate hydrological responses (evapotranspiration, soil moisture, seasonal and annual streamflow, and water stress) to projections of future climate. We used output from four atmosphere–ocean general circulation models (AOGCMs; CCSM4, HadGEM2‐CC, MIROC5, and MRI‐CGCM3) included in Phase 5 of the Coupled Model Intercomparison Project, coupled with two Representative Concentration Pathways (RCP 8.5 and 4.5). The coarse resolution AOGCMs outputs were statistically downscaled using an asynchronous regional regression model to provide finer resolution future climate projections as inputs to the deterministic dynamic ecosystem model PnET‐BGC. Simulation results indicated that projected warmer temperatures and longer growing seasons in the northeastern United States are anticipated to increase evapotranspiration across all sites, although invoking CO2 effects on vegetation (growth enhancement and increases in water use efficiency (WUE)) diminish this response. The model showed enhanced evapotranspiration resulted in drier growing season conditions across all sites and all scenarios in the future. Spruce‐fir conifer forests have a lower optimum temperature for photosynthesis, making them more susceptible to temperature stress than more tolerant hardwood species, potentially giving hardwoods a competitive advantage in the future. However, some hardwood forests are projected to experience seasonal water stress, despite anticipated increases in precipitation, due to the higher temperatures, earlier loss of snow packs, longer growing seasons, and associated water deficits. Considering future CO2 effects on WUE in the model alleviated water stress across all sites. Modeled streamflow responses were highly variable, with some sites showing significant increases in annual water yield, while others showed decreases. This variability in streamflow responses poses a challenge to water resource management in the northeastern United States. Our analyses suggest that dominant vegetation type and soil type are important attributes in determining future hydrological responses to climate change. 相似文献