BIOGEOCHEMICAL EFFECTS OF GLOBAL CHANGE ON U.S. NATIONAL PARKS1

ABSTRACT: Federal parks and other public lands have unique mandates and rules regulating their use and conservation. Because of variation in their response to local, regional, and global‐scale disturbance, development of mitigation strategies requires substantial research in the context of long‐term inventory and monitoring. In 1982, the National Park Service began long‐term, watershed‐level studies in a series of national parks. The objective was to provide a more comprehensive database against which the effects of global change and other issues could be quantified. A subset of five sites in North Carolina, Texas, Washington, Michigan, and Alaska, is examined here. During the last 50 years, temperatures have declined at the southern sites and increased at the northern sites with the greatest increase in Alaska. Only the most southern site has shown an increase in precipitation amount. The net effect of these trends, especially for the most northern and southern sites, would likely be an increase in the growing season and especially the time soil processes could continue without moisture or temperature limitations. During the last 18 years, there were few trends in atmospheric ion inputs. The most evident was the decline in SO₄² deposition. There were no significant relationships between ion input and stream water output. This finding suggests other factors as modification of precipitation or canopy throughfall by soil processes, hydrologic flow path, and snowmelt rates are major processes regulating stream water chemical outputs.     

生态位理论的发展及其在农业生产中的应用

生态位理论近年来在理论生态学和应用生态学的发展中起到了重要的作用。本文回顾了生态位理论的发展概况,介绍了在生态位理论发展历程中作出巨大贡献的三位生态学家,格林尼尔的“空间生态位”,埃尔顿的“功能生态位”,哈奇森的“多维超体积生态位”概念。用系统论的观点总结了如何正确理解生态位概念及其理论,并就如何应用生态位理论来指导农业生产实践提出了切实可行的多种途径,如高效合理利用现存的生态位,开拓潜在生态位,定向改变基础生态位等,也为生态位理论更好地指导农业生产实践提供了新思路。     

长江经济带生态系统服务权衡与协同及其驱动因素

生态系统服务及其变化是多种因素驱动的复杂过程,了解生态系统服务之间的权衡与协同作用及其驱动因素,对于实现生态系统服务有效管理和人类福祉至关重要.以长江经济带为研究区域,分析了2000~2020年产水、土壤保持、碳固定和粮食供给这4项生态系统服务的时空变化特征,运用相关性分析和地理加权回归识别和量化了生态系统服务间的权衡与协同关系,在此基础上应用偏最小二乘结构方程模型探究自然与人类活动对生态系统服务的影响,再通过地理探测器分析生态系统服务关系变化的驱动机制.结果表明:①近20年来,碳固定服务年均值由946.14 t·km^-2增至1 202.73 t·km^-2,粮食供给均值则由32.73万元·km^-2增至127.22万元·km^-2;产水和土壤保持服务增加幅度较小.②整体上,碳固定与土壤保持、粮食供给与产水为协同关系,其他生态系统服务之间为权衡关系;生态系统服务间的关系在不同地区存在一定的差异.③地形和气候是生态系统服务及多对生态系统服务权衡与协同关系的重要驱动因素,其中结构方程模型结果表明,气候对产水为正向影响（S = 0.73）,地形对粮食供给为负向影响（S = -0.57）;地理探测器结果揭示,影响碳固定与产水在空间上关系的主要驱动因子为海拔（q = 0.38）和降水（q = 0.19）.研究结果可为长江经济带生态系统服务可持续管理和实现该区域生态环境保护与社会经济的协同发展提供科学参考.     

森林生态系统生态资产核算的模式与方法

全球变化背景下.植被对CO2的减排作用得到了广泛关注.森林生态系统具有诸多功能,不同功能的货币化基准难以统一,是进行总体生态资产价值定量核算的制约要素.在资源、环境与生态经济原理指导下,分析相关方法评估生态系统生态资产的可行性,选择量化评估参数,并通过多种模式与方法进行估算乌鲁木齐城市2004年森林生态系统的生态资产.森林生态系统涵养水源类、生物多样性维持类、净化空气类、保护土壤类以及大气调节类生态资产分别为0.224 8×108元、10.608 8x108元、0.630 8×108元、0.2592×108元及12.9653×108元,乌鲁木齐市森林生态总资产为24.6889×108元.各类生态资产具有一定的时空差异性.城市森林生态系统生态资产估算模式及方法的研究具有重要的理论价值与现实意义.     

基于过程的河北平原农田生态系统稳定性评价

论文旨在探讨河北平原区农田生态系统稳定性的概念及内涵,构建稳定性评价指标体系并进行定量评价实证研究。首先,在总结生态系统领域有关稳定性研究相关成果的基础上,结合农田生态系统稳定性的特点,给出了农田生态系统稳定性的概念,并分析了其稳定性内涵。然后,以县域为研究单元构建了一个包括产量形成、投入产出、土壤生态等主导过程及生态环境效应4个方面22个具体指标的评价指标体系。最后,构建了区域农田生态系统稳定性评价的数学模型;并以雄县为例,运用所建模型进行评价,发现1995~2005年该区农田生态系统稳定性水平变化较大且呈阶段性发展,1995~1999年呈直线式逐年下降,2000~2005年呈波浪式发展,且投入产出过程对该区农田生态系统稳定性影响最大。     

Human Impacts on Regional Avian Diversity and Abundance

Abstract: Patterns of association between humans and biodiversity typically show positive, negative, or negative quadratic relationships and can be described by 3 hypotheses: biologically rich areas that support high human population densities co‐occur with areas of high biodiversity (productivity); biodiversity decreases monotonically with increasing human activities (ecosystem stress); and biodiversity peaks at intermediate levels of human influence (intermediate disturbance). To test these hypotheses, we compared anthropogenic land cover and housing units, as indices of human influence, with bird species richness and abundance across the Midwestern United States. We modeled richness of native birds with 12 candidate models of land cover and housing to evaluate the empirical evidence. To assess which species were responsible for observed variation in richness, we repeated our model‐selection analysis with relative abundance of each native species as the response and then asked whether natural‐history traits were associated with positive, negative, or mixed responses. Native avian richness was highest where anthropogenic land cover was lowest and housing units were intermediate based on model‐averaged predictions among a confidence set of candidate models. Eighty‐three of 132 species showed some pattern of association with our measures of human influence. Of these species approximately 40% were negatively associated, approximately 6% were positively associated, and approximately 7% showed evidence of an intermediate relationship with human influence measures. Natural‐history traits were not closely related to the direction of the relationship between abundance and human influence. Nevertheless, pooling species that exhibited any relationship with human influence and comparing them with unrelated species indicated they were significantly smaller, nested closer to the ground, had shorter incubation and fledging times, and tended to be altricial. Our results support the ecosystem‐stress hypothesis for the majority of individual species and for overall species diversity when focusing on anthropogenic land cover. Nevertheless, the great variability in housing units across the land‐cover gradient indicates that an intermediate‐disturbance relationship is also supported. Our findings suggest preemptive conservation action should be taken, whereby areas with little anthropogenic land cover are given conservation priority. Nevertheless, conservation action should not be limited to pristine landscapes because our results showed that native avian richness and the relative abundance of many species peaked at intermediate housing densities and levels of anthropogenic land cover.     

Managing Invasive Aquatic Plants in a Changing System: Strategic Consideration of Ecosystem Services

Abstract:  Climate change is projected to increase stress for many coastal plant communities. Along large portions of the North American coast, habitat degradation from anthropogenic changes to the environment already threaten the community structure of tidal marshes and submerged aquatic grass beds. The potential loss of ecological services historically provided by these communities has been a long-standing rationale for aggressive control of invading plants such as Phragmites australis and Hydrilla verticillata . Increasing evidence of ecological services provided by invasive species such as P. australis and H. verticillata suggest that, in the face of increasing stress, it may be prudent to take a more pragmatic approach regarding the effect of these species on coastal ecosystems. The notable resilience of these species to control efforts and their competitive success and comparative vigor in stressed systems and capacity to provide at least some beneficial services combine to suggest some invasive species may have a useful role in managed coastal ecosystems.     

生态系统对酸沉降敏感性评价方法与进展

评述水体、土壤和整个生态系统对酸沉降敏感性评价的各种方法,这些方法用系统 的不同物理化学性质表征它们缓冲酸输入的能力。     

人工复合生态系统对太湖局部水域水质的净化作用

根据不同生态类型水生高等植物的净化能力及其微生境特点,设计建造了由漂浮、浮叶、沉水植物及其根际微生物等组成的人工复合生态系统（artificialcomplexecosystem;AcE）,并在太湖五里湖中桥湖湾内以动态模拟试验,从群落水平研究了多种水生植物镶嵌组合的人工复合生态系统对富营养化湖水的净化能力。结果表明,富营养化湖水经该系统净化后,藻类生物量（以Chla计）下降58％,氨氮下降66％,总氮下降60％,总磷下降72％,可溶性磷酸盐下降80％,水质得到明显改善。与以该湖湾湖水为水源的水厂出水相比,人工复合生态系统出水的氨氮比水厂出水的氨氮平均低45％,总氮低37％,可见经人工复合生态系统处理的湖水部分指标优于同源的自来水。     

上海城市内河生态系统服务的条件价值评估

条件价值评估法(CVM)是估算生态系统服务最主要的技术方法之一。浦东张家浜的综合整治为全国河道整治的样板工程,笔者采用CVM引出张家浜沿线居民对改善张家浜生态系统的平均支付意愿(528 8元 a),初步估算出张家浜综合整治后的生态系统服务价值约为3 014～5 262亿元 a。讨论了导致支付意愿产生偏差的各方面原因,研究了张家浜沿线居民对张家浜整治项目的支付意愿和被调查者收入、年龄、受教育程度等因素的关系。最后提出了CVM研究结果的可靠性和国内在CVM研究中亟待解决的问题。