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501.
通过采集不同地貌部位(塬面、塬坡和沟坡)各土地利用(农地、草地、灌木地和林地)坡面土壤和根系样品,采用综合土壤可蚀性指数(CSEI)评价了植被恢复对土壤可蚀性的影响。结果表明:(1)不同地貌部位的CSEI差异显著,沟坡CSEI较塬坡和塬面分别增加8.1%和77.7%。(2)塬面草地、灌木地和林地的CSEI较农地分别降低21.1%、29.2%和28.8%;而塬坡和沟坡林地CSEI均低于其他土地利用。(3)CSEI与粘粒含量、砂粒含量、毛管孔隙度、根重密度、根平均直径、根长密度及根表面积密度均呈极显著负相关,而与粉粒含量和土壤容重呈显著正相关关系;粉粒含量、土壤容重和根重密度是影响CSEI的关键因素,其中粉粒含量对CSEI的直接影响最大,而根重密度通过直接或间接作用对CSEI产生负相关影响。建议在塬面上以灌木作为植被恢复模式的首选,而在塬坡和沟坡上选择以乔木为优势群落的恢复模式对水土流失的控制更为有效。  相似文献   
502.
为探究新疆地区植被活动与昼夜增温之间的复杂关系,本文利用2000~2015年归一化植被指数(NDVI)及气象数据,定量研究了新疆北疆、南疆及伊犁地区生长季日间最高气温(Tmax)、夜间最低气温(Tmin)变化趋势及植被对非对称性累积昼夜增温的时滞响应,通过二阶偏相关分析了Tmax、Tmin对新疆地区植被的影响.结果表明:北疆、南疆及伊犁地区昼夜增温均呈非对称性,昼夜增温空间异质性显著,北疆地区Tmin增温速率为Tmax增温速率的1.67倍,南疆地区Tmin增温速率为Tmax增温速率的1.59倍,伊犁地区Tmin增温速率为Tmax增温速率的2.67倍,伊犁地区昼夜温差缩小趋势显著.植被对非对称性昼夜累积增温时滞性呈现明显的空间差异,Tmax、Tmin对新疆地区植被平均滞后时间为(0.97±0.93)个月和(0.91±0.95)个月.南疆、北疆及伊犁地区针叶林、阔叶林及草甸草原植被受日间增温的影响,荒漠草原、典型草原受夜间增温影响显著,夜间增温影响范围更广.  相似文献   
503.
This research aims to map Brazilian companies that have business models aligned with the concept of the circular economy. Data were collected for this study through use of a survey and additional research based on the survey results. Within these businesses’ models, an emphasis on the second use of materials as well as the marketing of the product as a service has been highlighted.  相似文献   
504.
Globally, anthropogenic land-cover change has been dramatic over the last few centuries and is frequently invoked as a major cause of wildlife population declines. Baseline data currently used to assess population trends, however, began well after major changes to the landscape. In the United States and Canada, breeding bird population trends are assessed by the North American Breeding Bird Survey, which began in the 1960s. Estimates of distribution and abundance prior to major habitat alteration would add historical perspective to contemporary trends and allow for historically based conservation targets. We used a hindcasting framework to estimate change in distribution and abundance of 7 bird species in the Willamette Valley, Oregon (United States). After reconciling classification schemes of current and 1850s reconstructed land cover, we used multiscale species distribution models and hierarchical distance sampling models to predict spatially explicit densities in the modern and historical landscapes. We estimated that since the 1850s, White-breasted Nuthatch (Sitta carolinensis) and Western Meadowlark (Sturnella neglecta) populations, 2 species sensitive to fragmentation of oak woodlands and grasslands, declined by 93% and 97%, respectively. Five other species we estimated nearly stable or increasing populations, despite steep regional declines since the 1960s. Based on these estimates, we developed historically based conservation targets for amount of habitat, population, and density for each species. Hindcasted reconstructions provide historical perspective for assessing contemporary trends and allow for historically based conservation targets that can inform current management.  相似文献   
505.
Biodiversity offset schemes are globally popular policy tools for balancing the competing demands of conservation and development. Trading currencies for losses and gains in biodiversity value at development and credit sites are usually based on several vegetation attributes combined to yield a simple score (multimetric), but the score is rarely validated prior to implementation. Inaccurate biodiversity trading currencies are likely to accelerate global biodiversity loss through unrepresentative trades of losses and gains. We tested a model vegetation multimetric (i.e., vegetation structural and compositional attributes) typical of offset trading currencies to determine whether it represented measurable components of compositional and functional biodiversity. Study sites were located in remnant patches of a critically endangered ecological community in western Sydney, Australia, an area representative of global conflicts between conservation and expanding urban development. We sampled ant fauna composition with pitfall traps and enumerated removal by ants of native plant seeds from artificial seed containers (seed depots). Ants are an excellent model taxon because they are strongly associated with habitat complexity, respond rapidly to environmental change, and are functionally important at many trophic levels. The vegetation multimetric did not predict differences in ant community composition or seed removal, despite underlying assumptions that biodiversity trading currencies used in offset schemes represent all components of a site's biodiversity value. This suggests that vegetation multimetrics are inadequate surrogates for total biodiversity value. These findings highlight the urgent need to refine existing offsetting multimetrics to ensure they meet underlying assumptions of surrogacy. Despite the best intentions, offset schemes will never achieve their goal of no net loss of biodiversity values if trades are based on metrics unrepresentative of total biodiversity.  相似文献   
506.
Vegetation is sparsely distributed over Antarctica's ice‐free ground, and distinct plant communities are present in each of the continent's 15 recently identified Antarctic Conservation Biogeographic Regions (ACBRs). With rapidly increasing human activity in Antarctica, terrestrial plant communities are at risk of damage or destruction by trampling, overland transport, and infrastructure construction and from the impacts of anthropogenically introduced species, as well as uncontrollable pressures such as fur seal (Arctocephalus gazella) activity and climate change. Under the Protocol on Environmental Protection to the Antarctic Treaty, the conservation of plant communities can be enacted and facilitated through the designation of Antarctic Specially Protected Areas (ASPAs). We examined the distribution within the 15 ACBRs of the 33 ASPAs whose explicit purpose includes protecting macroscopic terrestrial flora. We completed the first survey using normalized difference vegetation index (NDVI) satellite remote sensing to provide baseline data on the extent of vegetation cover in all ASPAs designated for plant protection in Antarctica. Large omissions in the protection of Antarctic botanical diversity were found. There was no protection of plant communities in 6 ACBRs, and in another 6, <0.4% of the ACBR area was included in an ASPA that protected vegetation. Protected vegetation cover within the 33 ASPAs totaled 16.1 km2 for the entire Antarctic continent; over half was within a single protected area. Over 96% of the protected vegetation was contained in 2 ACBRs, which together contributed only 7.8% of the continent's ice‐free ground. We conclude that Antarctic botanical diversity is clearly inadequately protected and call for systematic designation of ASPAs protecting plant communities by the Antarctic Treaty Consultative Parties, the members of the governing body of the continent.  相似文献   
507.
朱溪流域植被覆盖的时空变化及地形分异特征   总被引:1,自引:0,他引:1  
分析2003~2011年朱溪流域植被覆盖的时空分布状况及其变化的地形响应特征,为该地区进一步治理水土流失和生态恢复工程提供决策支持。基于RS和GIS技术,采用像元二分法模型计算植被覆盖度,通过植被重心模型、地形响应指数表征其植被覆盖的时空变化规律。(1)朱溪流域植被覆盖度整体呈上升趋势,Ⅳ、Ⅴ类的植被覆盖面积比率已达到区域的62.28%;格局动态上,Ⅰ、Ⅱ类重心向东北方向移动,Ⅲ、Ⅳ、Ⅴ类重心向西南方向移动,表现为流域植被中、西部改善,东部零散退化的空间格局;(2)在海拔0~300m、坡度小于5°和大于35°区域各等级植被覆盖面积变化最显著,治理措施有效到位,而海拔450~500m处I类植被覆盖面积增加,应引起相关注意。8年间该流域植被覆盖有明显改善,各等级植被覆盖变化在不同地形条件下差异明显。  相似文献   
508.
ABSTRACT

This paper follows the evolution of the discourse of agricultural productivity, from its inception in colonial land-use mapping to current land-use changes, using a case study of the expansion of an oil palm company onto the territory of an indigenous community in the Peruvian Amazon that caused large-scale deforestation. Drawing on analytical tools of political ecology and insights from historical geographythis paper shows how current soil and land classification, forest usufruct rules, and forest designations under the 2011 Forest and Wildlife law stem from a colonial discourse of agricultural productivity. This discourse excludes other forms of land-use, such as indigenous forest management, and the identities and relationships bound up in those. This research contributes to an understanding of how the processes that seek to quantify and determine land-use change are historically embedded in western ideas of agricultural productivity.  相似文献   
509.
Emission of metals in the urbanenvironment is a growing concern throughout theworld. In order to identify metal emissionssources in the Stockholm metropolitan region, amethod for detailed mapping of roof coatings andother urban land covers has been developedconducted. High accuracy area calculation ofcopper roof coatings based on scanned aerialphotography was used. The geometric resolution ofthe digital photographs was 0.4 metre. Imagelayers with identified copper roof objects weremerged with a digital elevation model of 1 metregeometric resolution. The slope gradient for eachroof was calculated in order to account for slopein the calculation of roof areas. In total,622,590 m2 of copper roofs were accounted,of which 176,845 m2 and 447,745 m2represent new and patinated copper respectively.The number of copper roofs larger than 1,000m2 was 142. Applying corrosion and runoffrates on these figures, a yearly Cu flux ofapproximately 1,200 kg in Stockholm may bederived from copper coated building.  相似文献   
510.
Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.  相似文献   
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