Presence–Absence versus Abundance Data for Monitoring Threatened Species

Abstract:  Effective detection of population trend is crucial for managing threatened species. Little theory exists, however, to assist managers in choosing the most cost-effective monitoring techniques for diagnosing trend. We present a framework for determining the optimal monitoring strategy by simulating a manager collecting data on a declining species, the Chestnut-rumped Hylacola ( Hylacola pyrrhopygia parkeri ), to determine whether the species should be listed under the IUCN (World Conservation Union) Red List. We compared the efficiencies of two strategies for detecting trend, abundance, and presence–absence surveys, under financial constraints. One might expect the abundance surveys to be superior under all circumstances because more information is collected at each site. Nevertheless, the presence–absence data can be collected at more sites because the surveyor is not obliged to spend a fixed amount of time at each site. The optimal strategy for monitoring was very dependent on the budget available. Under some circumstances, presence–absence surveys outperformed abundance surveys for diagnosing the IUCN Red List categories cost-effectively. Abundance surveys were best if the species was expected to be recorded more than 16 times/year; otherwise, presence–absence surveys were best. The relationship between the strategies we investigated is likely to be relevant for many comparisons of presence–absence or abundance data. Managers of any cryptic or low-density species who hope to maximize their success of estimating trend should find an application for our results.     

建设用地扩张与碳排放效应的库兹涅茨曲线假说及验证

论文基于无锡市1996—2008年的土地利用和能源消耗数据,分析了无锡市13 a间建设用地扩张及碳排放特征,并构建了建设用地比例与碳排放强度之间的库兹涅茨曲线模型,对无锡市建设用地扩张与碳排放效应之间的相关关系进行了实证研究,尝试验证库兹涅茨曲线在建设用地扩张与碳排放强度之间的存在性。结果表明:①建设用地总量在1996—2008年间迅速增长,绝对增长量44 032.97 hm²,且除了农村居民点逐渐下降以外,其余地类均呈逐年增长态势,无锡市1996—2008年间的碳排放基本上也呈现逐年增长趋势,绝对增长量1 936.38×10⁴ t;②建设用地总量与碳排放强度之间呈倒U型曲线关系,即随着建设用地扩张至拐点后,碳排放强度则逐渐下降,且拐点位于建设用地比例1.91%附近,但是目前仅仅刚开始出现拐点的迹象,表明目前无锡市建设用地扩张还未完全达到集约及精明增长的标准,建设用地扩张对碳排放而言仍然具有较强的推动作用,但是可以预见,随着产业结构调整和能源技术的提高,碳排放强度会逐渐进入下降的阶段;③城市用地与碳排放强度之间为三次曲线关系,建制镇用地、农村居民点用地与碳排放强度之间分别为正相关和负相关线性关系,其他建设用地与碳排放强度之间则存在一种不明显的库兹涅茨曲线关系。建设用地地类组成的不同会导致不同形态的库兹涅茨曲线,由于城市用地和建制镇用地对碳排放具有明显的驱动作用,其比例的提高亦会促使库兹涅茨曲线更加陡峭,并延缓库兹涅茨曲线拐点的到来。     

生态足迹的实证分析--中国经济增长中的生态制约

本文通过中国生态足迹的实证分析，讨论了生态系统资源供给方面对经济增长的制约，资源生态足迹是生态足迹的主要部分，反映了经济系统的资源消费，计算发现，1961-1999年中国资源生态足迹持续增长，从1961年的3.3亿hm^2年递增到1999年的16.8亿hm^2年平均增长率为4.4%，资源生态足迹的增长支持了同期的经济增长，但是，实证比较发展资源生态承载力大大低于资源生态足迹，这些实证结果表晨；一方面，中国经济持续增长造成了资源消费持续增加，而另一方面，中国生态系统资源供给能力有限，不能支持当前的资源消费及其增长，由于自然资源是经济系统进行生产的特质基础，其供给不足必然成为经济增长的制约因素。     

基于生态足迹模型中国可持续发展动态分析

在介绍生态足迹模型的基本概念、计算方法和研究进展的基础上。对中国历年的生态足迹进行了实证研究。结果表明：从1981-2001年，中国人均生态承载力比较稳定。人均生态足迹从1981年到1996年逐步上升，1997年开始小幅度下降。本文对中国生态足迹时间序列的研究分析表明若要改变长期的不可持续发展状态，就要降低人口数量。改变资源消费模式和消费结构。     

环境经济学在中国的最新进展与展望

本文从环境经济学领域的研究角度出发，介绍了环境经济学在中国最新的研究进展，并对环境经济学在中国未来的一段时间内的发展研究做了展望，随着中国全面建设小康社会和公众环境质量需求的提高，环境经济学所关注的内容会更加全面并逐步深化，环境经济学在中国环境管理中的作用也日益显著。     

Introduction: Natural Capital, Poverty and Development

Can development occur without running down natural resources in an unsustainable way? The concept of natural capital offers a way for those with divergent views (ecologists and economists for example) to discuss this difficult question. Four aspects are examined in detail. First, the role of institutions in facilitating sustainable development is discussed, with examples from forestry. Then examples from (eco)tourism illustrate the potential – and limits – of applicability of the concept. Measurement issues for natural capital are then considered in detail. Finally, the concept is applied to agricultural strategy in fragile lands, where the tradeoff between the environment and development is likely to be most severe. Some implications for future research and policy are developed.     

Institutions, Forest Management, and Sustainable Human Development – Experiences from India

New institutional economists have argued that there are many categories of institutions, including market and non-market institutions, which may prove economically efficient, specifically for public goods and common pool goods. The Government of India introduced a non-market community-based institution, known as Joint Forest Management (JFM), for forest management and protection in 1990. JFM is a sharing mechanism for forest planning and management based on sharing of rights and duties, control and decision-making authority over forestlands, between forest departments and local user groups. By 2001, 42 000 Village Forest Committees established under JFM were managing over 11.5 million ha forestland. These institutions have proved very useful, and have contributed to forest management as well as four aspects of sustainable human development (SHD) – ecological output, income generation, village infrastructure development, and community empowerment. In the long-term, community-based institutions will prove to be a foundation of SHD and participatory democracy.     

可持续发展下的生态经济学理论透视

生态经济学是一门正在蓬勃发展的新兴交叉学科，可持续发展是生态经济学研究的中心问题。人类对可持续发展问题的极大关注推动了生态经济学的发展。本文从宏观角度分析了可持续发展问题的凸显和生态经济学的兴起，着重指出生态经济学是关于可持续发展的科学的认识；阐述了可持续发展条件与状态的生态经济学理论内涵；论述了生态经济系统的本质特征及其可持续发展评估的核心内容；概括了可持续发展评估与绿色国民经济核算的框架及其目标和衡量方法。     

中国经济增长对碳排放的影响分析

通过相关分析探讨了中国国内生产总值(GDP)的增长与碳排放量的关系.结果表明,二者有明显的相关性(R2＝0.958 1).进一步研究认为,由于中国投资率在35%～40%以上,且工业增加值占GDP的比重超过50%,因此中国过分依赖投资的经济增长方式和以第二产业(工业)为主的经济结构在很大程度上是导致温室气体排放量增加的主要原因.未来在全球化背景下,经济增长可转变为更多地依靠科技创新、技术进步和制度的改进,因此,调整经济增长方式和产业结构,可以在保持发展经济的同时,使碳排放强度呈逐渐下降的趋势.     

行为经济学视角下矿工不安全行为仿真分析

为了分析影响矿工不安全行为决策的成本收益因素，扩展不安全行为的研究方向，基于行为经济学，构建矿工不安全行为决策模型，模型包括矿工属性、管理者属性以及矿工之间的交互影响规则。利用Netlogo工具进行仿真模拟，探讨不同影响因素对不安全行为产生的影响程度。结果表明:正向激励水平对抑制不安全行为效果显著，同时，维持合理的工作时间对保障安全生产意义重大，从而为煤矿企业控制不安全行为提供思路。