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991.
Protected areas (PAs) are at the forefront of conservation efforts, and yet despite considerable progress towards the global target of having 17% of the world''s land area within protected areas by 2020, biodiversity continues to decline. The discrepancy between increasing PA coverage and negative biodiversity trends has resulted in renewed efforts to enhance PA effectiveness. The global conservation community has conducted thousands of assessments of protected area management effectiveness (PAME), and interest in the use of these data to help measure the conservation impact of PA management interventions is high. Here, we summarize the status of PAME assessment, review the published evidence for a link between PAME assessment results and the conservation impacts of PAs, and discuss the limitations and future use of PAME data in measuring the impact of PA management interventions on conservation outcomes. We conclude that PAME data, while designed as a tool for local adaptive management, may also help to provide insights into the impact of PA management interventions from the local-to-global scale. However, the subjective and ordinal characteristics of the data present significant limitations for their application in rigorous scientific impact evaluations, a problem that should be recognized and mitigated where possible.  相似文献   
992.
The rising prominence of more rigorous approaches to measuring conservation outcomes has included greater adoption of impact evaluation by conservation non-governmental organizations (CNGOs). Within the scientific literature, however, little consideration has been given to the unique and specific roles of CNGOs in advancing impact evaluation. We explore these issues in the context of one CNGO—Conservation International (CI)—and its experiences producing, using and funding impact evaluations over the past decade. We examine the contributions of impact evaluation to CI''s mission at three different stages of CI''s strategy: innovation, demonstration and amplification. Furthermore, we review incentives and barriers encountered by CI in its 10+ years'' experience in impact evaluation. More coordinated and strategic use of impact evaluation by CNGOs would facilitate learning and promote accountability across the conservation community.  相似文献   
993.
赵晓静  张胜利  马国栋 《生态学报》2015,35(24):8155-8164
将森林抚育间伐与森林水化学效应结合起来进行研究,探讨小强度间伐对森林水质的影响。基于固定样地的研究方法,在秦岭火地塘林区选择天然锐齿栎林,设置抚育间伐强度分别为5%、10%、15%和20%的样地和对照样地,定期采集大气降雨、林内雨和枯透水样品,测定其水化学物质浓度,采用对比分析的方法,研究间伐强度对锐齿栎林内雨和枯透水化学效应的影响。结果表明:间伐样地林内雨和枯透水的pH值均低于对照样地,呈弱酸性,在5%的间伐强度下,森林冠层和枯落物层对大气降雨pH值的调升作用较显著,随着间伐强度的增加,调升幅度逐渐减小;大气降雨对森林冠层和枯落物层中的SO_4~(2-)、NO_3~-和PO_4~(3-)均具有淋溶作用,尤其是对照样地林内雨和枯透水中SO_4~(2-)的浓度增幅最显著,NO_3~-次之,PO_4~(3-)最不显著。间伐样地,雨水对林冠层和枯落物层SO_4~(2-)、NO_3~-和PO_4~(3-)的淋溶作用均低于对照样地,20%的间伐强度最有利于净化雨水中的SO_4~(2-),其在林内雨和枯透水中的含量较对照样地降幅最大,间伐强度为5%时,林内雨中NO_3~-、NH_4~+和PO_4~(3-)的含量最低,三者较对照样地的含量分别降低了56.3%、46%和9.2%而枯透水中三者的降幅分别为64.6%、45%和60.8%;在10%的间伐强度下,大气降雨对林冠层和枯落物层中K~+、Ca~(2+)、Mg~(2+)的淋溶作用最强,3种离子中以Ca~(2+)和Mg~(2+)的含量增幅最为显著。林内雨中Ca~(2+)和Mg~(2+)的含量分别较对照样地增加了89.9%和120%,枯透水中二者较对照样地分别增加了72.4%和40%,K~+的增幅相对不明显;大气降雨中的Pb~(2+)、Zn~(2+)和Cd~(2+)经过森林冠层和枯落物层的阻减,其在林内雨和枯透水中的含量随着间伐强度的增加呈先增大后减小的趋势,当间伐强度达到20%时,三者含量明显降低。总体上,20%的间伐强度最有利于森林冠层及枯落物层对重金属Pb~(2+)、Zn~(2+)和Cd~(2+)的截留净化。  相似文献   
994.
尺度约束是地表复杂系统的基本规律,环评尺度约束常隐存于主观经验或零存于环评导则中,环评尺度约束较少被明确关注。讨论了环境影响尺度约束、环评尺度约束和环评技术框架尺度约束。研究发现,环境影响的尺度约束性内在原因在于环境影响主体、客体和影响内容存在等级结构;环评受空间、时间和分析三类尺度约束,空间尺度约束体现于空间范围和空间信息分辨率对环评影响,时间尺度约束体现于环评的时长和时频,分析尺度约束表现为环评技术方法和环境影响主观认知水平对评价的影响,三类尺度约束同时贯穿于环评过程,任何环评都可以在三类尺度空间中定位;环评技术框架的关键环节都受空间、时间和分析尺度约束,且以环境影响主体的空间、时间尺度为核心,具有一定弹性,一般空间或时间范围先放大再缩小、分辨率由粗到细。  相似文献   
995.
996.
The present study addresses the topic of recycling materials from construction and demolition (C&D) wastes by proposing an environmental comparison between two recycling schemes for gravel wastes. The first scheme is the baseline process, and leads to direct most of the gravel to road construction. The second scheme relies on an innovative technology for the processing of gravel, based on electrical fragmentation, which leads to a clear separation between the aggregate contained in the gravel and the cement paste. The purity of the obtained materials opens new recycling outlets—as part of high‐quality structural concrete for the aggregate and as a substitute to natural minerals in clinker kilns for the cement paste. This shift towards more‐specific outlets for the materials found in reclaimed gravel carries significant modifications in the overall handling of C&D wastes and in the supply of natural and non‐natural materials for road construction and concrete formulation. The environmental implications of these modifications are evaluated according to a life cycle assessment methodology, which specifically addresses the influence of the distances and modalities of transportation of wastes to the crushing processes, as well as of natural and recycled aggregate to construction and demolition sites. The results point out significant environmental gains for the alternative recycling scheme, in all the considered impact categories and whatever the implemented scenarios. These gains are modulated by the various transport distances of the heavy materials heeded in the global system.  相似文献   
997.
Dietary behavioral choices have a strong effect on the environmental impact associated with the food system. Here, we consider the greenhouse gas (GHG) emissions associated with production of food that is lost at the retail and consumer level, as well as the potential effects on GHG emissions of a shift to dietary recommendations. Calculations are based on the U.S. Department of Agriculture's (USDA) food availability data set and literature meta‐analysis of emission factors for various food types. Food losses contribute 1.4 kilograms (kg) carbon dioxide equivalents (CO2‐eq) capita?1day?1 (28%) to the overall carbon footprint of the average U.S. diet; in total, this is equivalent to the emissions of 33 million average passenger vehicles annually. Whereas beef accounts for only 4% of the retail food supply by weight, it represents 36% of the diet‐related GHG emissions. An iso‐caloric shift from the current average U.S. diet to USDA dietary recommendations could result in a 12% increase in diet‐related GHG emissions, whereas a shift that includes a decrease in caloric intake, based on the needs of the population (assuming moderate activity), results in a small (1%) decrease in diet‐related GHG emissions. These findings emphasize the need to consider environmental costs of food production in formulating recommended food patterns.  相似文献   
998.
By altering fluxes of heat, momentum, and moisture exchanges between the land surface and atmosphere, forestry and other land‐use activities affect climate. Although long recognized scientifically as being important, these so‐called biogeophysical forcings are rarely included in climate policies for forestry and other land management projects due to the many challenges associated with their quantification. Here, we review the scientific literature in the fields of atmospheric science and terrestrial ecology in light of three main objectives: (i) to elucidate the challenges associated with quantifying biogeophysical climate forcings connected to land use and land management, with a focus on the forestry sector; (ii) to identify and describe scientific approaches and/or metrics facilitating the quantification and interpretation of direct biogeophysical climate forcings; and (iii) to identify and recommend research priorities that can help overcome the challenges of their attribution to specific land‐use activities, bridging the knowledge gap between the climate modeling, forest ecology, and resource management communities. We find that ignoring surface biogeophysics may mislead climate mitigation policies, yet existing metrics are unlikely to be sufficient. Successful metrics ought to (i) include both radiative and nonradiative climate forcings; (ii) reconcile disparities between biogeophysical and biogeochemical forcings, and (iii) acknowledge trade‐offs between global and local climate benefits. We call for more coordinated research among terrestrial ecologists, resource managers, and coupled climate modelers to harmonize datasets, refine analytical techniques, and corroborate and validate metrics that are more amenable to analyses at the scale of an individual site or region.  相似文献   
999.
1000.
The major impact of the livestock sector on the environment may be reduced by feeding agricultural co-products to animals. Since the last decade, co-products from biodiesel production, such as rapeseed meal (RSM), became increasingly available in Europe. Consequently, an increase in RSM content in livestock diets was observed at the expense of soybean meal (SBM) content. Cultivation of SBM is associated with high environmental impacts, especially when emissions related to land use change (LUC) are included. This study aims to assess the environmental impact of replacing SBM with RSM in finishing pig diets. As RSM has a lower nutritional value, we assessed the environmental impact of replacing SBM with RSM using scenarios that differed in handling changes in nutritional level. Scenario 1 (S1) was the basic scenario containing SBM. In scenario 2 (S2), RSM replaced SBM based on CP content, resulting in reduced energy and amino acid content, and hence an increased feed intake to realize the same growth rate. The diet of scenario 3 (S3) was identical to S2; however, we assumed that pigs were not able to increase their feed intake, leading to reduced growth performance. In scenario 4 (S4), the energy and amino acid content were increased to the same level of S1. Pig performances were simulated using a growth model. We analyzed the environmental impact of each scenario using life-cycle assessment, including processes of feed production, manure management, piglet production, enteric fermentation and housing. Results show that, expressed as per kg of BW, replacing SBM with RSM in finishing pig diets marginally decreased global warming potential (GWP) and energy use (EU) but decreased land use (LU) up to 12%. Between scenarios, S3 had the maximum potential to reduce the environmental impact, due to a lower impact per kg of feed and an increased body protein-to-lipid ratio of the pigs, resulting in a better feed conversion ratio. Optimization of the body protein-to-lipid ratio, therefore, might result in a reduced environmental impact of pig production. Furthermore, the impact of replacing SBM with RSM changed only marginally when emissions related to direct (up to 2.9%) and indirect LUC (up to 2.5%) were included. When we evaluated environmental impacts of feed production only, which implies excluding other processes along the chain as is generally found in the literature, GWP decreased up to 10%, including LUC, EU up to 5% and LU up to 16%.  相似文献   
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