内蒙古西部生态建设与植物种选择

从内蒙古西部地区生态环境恶化严重制约着区域经济发展的实际出发,介绍了生态环境恶化的严重性以及生态建设中应该高度重视优良植物品种选择的重要性,并在对植物种选择进行了长期的试验研究,并汇总和分析的基础上,提出了植物种选择的建议。     

Ecosystem and Economy: An Integrated Dynamic General Equilibrium Approach

A dynamic general equilibrium model is developed for analyzing economy-ecosystem interactions. It includes stock-flow relations of natural resources, species populations and pollution, and it provides a microfoundation of the growth of populations. Humans and (other) species compete for natural resources and (prey) biomass. Resource stocks, pollution and populations determine public ecosystem services which in turn affect all agents in both the ecosystem and the economy. We establish a benchmark market system encompassing Lindahl markets for ecosystem services and emission markets. We also analyze a system where those two types of markets break down (laissez-faire) and propose efficiency restoring policies.     

An ambient tax approach to invasive species

Invasive species have become an issue of increasing concern in recent years. Invasive species are species that are not native to an area but are imported either intentionally or unintentionally and become established. A primary pathway for introduction is the ballast water of ships. Although not all imported species become invasive, those that do cause extensive damage to ecosystems and have been blamed for the endangerment of numerous native species. In many cases, release of non-native species can be prevented, either through open-ocean ballast water exchange, retention of ballast water, or other biosecurity measures. However, policies designed to encourage such actions face several specific challenges. The difficulty of linking an invasion to a specific vessel and of monitoring individual vessels' care makes using standard environmental liability plans difficult if not impossible. In this paper, we present an alternative policy option, that of an ambient tax. Building on the work of Segerson [Segerson, Kathleen, 1988. Uncertainty and incentives for nonpoint pollution control. Journal of Environmental Economics and Management, 15: 87-98.], we show that an ambient tax can ensure socially optimal behavior in both the short-run and the long-run with minimal vessel specific information.     

四川省龙泉山脉蝴蝶资源调查报告

经过标本鉴定,可确认四川省龙泉山脉境内有蝴蝶82种,隶属于10科47属,其中凤蝶科Papilionidae 3属10种,粉蝶科Pieridae 4属7种,斑蝶科Danaidae 1属1种,环蝶科Amathusiidae 2属2种,蛱蝶科Nymphalidae 19属32种,眼蝶科Satyridae 5属13种,珍蝶科Acraeidae 1属1种,蚬蝶科Riodinidae 1属1种,灰蝶科Lycaenidae 5属7种,弄蝶科Hesperiidae 6属8种。     

NDVI在农作物监测中的研究与应用

归一化差值植被指数(normalized difference vegetation index,NDVI)是农作物监测中应用最为广泛的光谱参数之一,在农作物生产与管理中具有重要的实际指导意义.该文就NDVI在作物产量、生物量、收获指数、叶面积指数、营养状况、作物冻害等方面的研究与应用作一综述,并总结当前研究中存在的问题与不足,提出了NDVI在今后作物监测中进一步的研究重点.     

2000—2018年西辽河流域植被覆盖度时空变化特征及影响因素研究

目的 研究“退耕还林”“退牧还草”及“镰刀弯”等生态政策实施以来西辽河流域植被覆盖时空变化趋势及驱动因素，探究各类驱动因子对区域植被覆盖的影响，为区域生态建设和环境保护提供参考。方法 文章采用像元二分模型，估算西辽河流域植被覆盖度，归纳了植被覆盖变化的驱动因素，利用一元线性回归和Pearson相关系数等方法，定性定量分析2000—2018年西辽河流域植被覆盖时空变化趋势及其与气候、地形、农村居民点分布和土地利用变化等驱动因子的响应关系。结果 19年来，西辽河流域植被覆盖度呈波动增加趋势。分区看，农区植被覆盖度最高，其次是半农半牧区，牧区植被覆盖度最低。全区植被覆盖空间变化趋势较为稳定，96.63%面积植被覆盖无明显变化，2.07%面积植被覆盖极显著改善，1.30%面积植被覆盖显著改善，基本无退化区域。结论 （1）植被覆盖度与降水、气温因子正向相关，降水对植被覆盖度的影响高于气温。（2）高程、坡度和农村居民点密度均与植被覆盖度正向相关，其中农区人类农业种植活动正向促进作用要大于生产建设活动的负向抑制作用。（3）林地和作物种植面积长势的增加促进了全区植被覆盖的改善。“退耕还林”和“镰刀弯”生态实施促进了全区植被覆盖的改善，但“退牧还草”生态工程效益有待提高。应注重区域植被覆盖变化监测与预警，充分发挥生态政策的积极导向作用，优化生态工程实施结构，提高生态脆弱区抵御风险能力。     

我国西部灌木植被的生态经济价值

灌木具有防风固沙、保持水土、改良土壤及生物量大、饲用营养价值高等生态经济价值。众多灌木品种是西部干旱半干旱地区极其重要的植被恢复与重建的资源，应在西部大开发的生态保护与建设中得到足够的重视。     

Protectionism, Trade, and Measures of Damage from Exotic Species Introductions

Unintentional introductions of nonindigenous plants, animals, and microbes cause significant ecological and agricultural crop damage worldwide. Trade in both manufactured and agricultural goods is a primary vector for such introductions. Fusing simple models of trade and biological introductions, we explore the links between trade, protectionism, and damage arising from exotic species introductions. We show that it is possible for freer trade to reduce damage arising from exotic species invasions. We also show how current measures of damage—heavily weighted toward agricultural damage—serve as misleading indicators of how restrictions to trade affect total losses arising from exotic species introductions.     

Preservation of Species and Genetic Diversity

This article presents a mathematical programming approach to determine a conservation strategy that maximizes preserved species' diversity under limited resource availability. Diversity is defined as the negative of total diversity loss given by the sum of genetic distances between extinct species and their closest surviving relatives. The model incorporates both species richness and genetic diversity as the conservation criteria when determining species preservation and site selection decisions. The article also presents two empirical applications to the conservation of 15 crane species and 208 genera including most of the endangered or threatened North American bird species.     

Factors determining awareness and knowledge of aquatic invasive species

Public perceptions of invasive species may influence policies and programs initiated by public and private stakeholders. We investigate the determinants of the public's awareness and knowledge of invasive species as few studies have examined this relationship. We focus on aquatic invasive species (AIS) and employ survey data from property owners in a lake district. A major contribution is that we estimate a mixed trivariate binary-ordered probit regression model that accommodates correlations among unobserved characteristics, produces statistically more efficient estimates, and allows a more proper investigation of the probability of knowledge conditional on awareness. Our results provide insights for invasive species education and management programs. We find that individuals are more likely to be aware of AIS if they participate in water-based recreation, visit lakes outside their area, have a boat, belong to a lake association, or are college educated. This has a policy implication: Given high levels of AIS awareness by those most involved in activities around lakes and those with a higher education, it may be beneficial to target informational campaigns at those who do not display these characteristics, so that they can better make informed decisions about whether to support and expend money on invasive species management programs.