Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.     

Theory and practice of monetary policy

Summary. We consider an optimally managed renewable resource with stochastic non-concave growth function. We characterize the conditions under which the optimal policy leads to global extinction, global conservation and the existence of a safe standard of conservation. Our conditions are specified in terms of the economic and ecological primitives of the model: the biological growth function, the welfare function, the distribution of shocks and the discount rate. Our results indicate that, unlike deterministic models, extinction and conservation in stochastic models are not determined by a simple comparison of the growth rate and the discount rate; the welfare function plays an important role.Received: 20 October 2004, Revised: 28 February 2005, JEL Classification Numbers: D90, O11, O41, Q32.Santanu Roy: Correspondence toResearch on this paper was completed when the second author visited Cornell University in July, 2003. We thank the Center for Analytic Economics and the Department of Economics at Cornell University for making this research visit possible. The current version has gained considerably from the comments made by an anonymous referee.     

The value of nonindigenous species risk assessment in international trade

Managing the introduction of nonindigenous species is becoming a major goal of policy-makers at regional, national and international scales. Here we investigate, at the national level, the ideal design and expected net benefits of a risk assessment program for evaluating the desirability of nonindigenous species imports. We show how to enhance the statistical rigor of such a system by correcting a common non-random sampling problem encountered in the data. This correction enables model output to be interpreted in an economically relevant way and facilitates a theoretically rigorous characterization of the balance between trade and nonindigenous species establishment risk. Using reptiles and amphibians imported to the U.S. as a case study, we characterize economic outcomes over a range of cases and demonstrate substantial expected returns to such a screening program, relative to the current effectively open-door policy. Our results are informative for the current debate in the U.S. about whether to require federal agencies to apply risk assessment before allowing a species for import. The framework presented decomposes a complex argument about risk management into component economic and statistical parts, allowing for debate and improved understanding over each element to inform the overall program in a transparent fashion.     

Competitive selection, self-organisation and Joseph A. Schumpeter

Post-Schumpeterians have tended to use biological analogies to understand economic evolution, in contrast to Schumpeter himself. In this paper it is argued that the biological analogies used tend to be outdated and that Schumpeter espoused an intuitive understanding of the evolutionary economic process that is closely related to modern conceptions of self-organisation, suitably adapted for application in socioeconomic systems. Using a self-organisation approach, competition can be understood without recourse to biological analogy, in terms of general systemic principles that operate in the presence of variety. Viewing economic evolution in terms of complex adaptation in self-organising systems yields nonequilibrium and nonlinear perspectives that parallel Schumpeter's own intuitions, reinvigorating them as the basis of evolutionary economic thinking in the new Millennium.     

自然保护区生态旅游设计发展潜力分析——以吉林省长白山自然保护区为例

生态旅游是一种将可持续发展理念贯穿于整个旅游系统的发展方式,它是可持续旅游宏观指导思想的一种操作上的落实。自然保护区生态旅游,是在自然保护区内开展的、以自然保护为核心的、高度责任化的高层次旅游活动。长白山自然保护区是我国重要的旅游地区,自然环境独特,旅游资源丰富多样,长白山自然保护区生态旅游具有很大的发展潜力。因此应制定生态旅游规划,建立“吉林省长白山管理区”,建立健全的旅游环境容量调控系统。     

美国生物医学研究概况

美国国立卫生研究院（NIH）专司是美国唯一一家国家级公立生物医学研究机构，负责生物医学领域的研究和管理。在关联邦机构中，NIH掌管的研发经费仅次于国防部。本文对NIH的科研投入情况、资助计划和发展方向进行介绍和分析，旨在从宏观上把握美国生物医学的总体发展水平和重点方向。     

《医学生物实验学》教学改革的探索与实践

通过优化重组实验教材,增加综合性和探索性实验内容,改革教学手段,开展师生座谈会及时反馈教学效果等一系列教学改革措施,最终建立由医学细胞生物学、医学遗传学、医学生物实验学组成的相互支撑、紧密联系的课程体系,提高学生跨学科知识综合运用的能力和实验操作的能力。     

浅谈新课改要求下的高中生物教学

新课程改革下的中学生物教学,要求教师进一步更新教育观念,提高业务理论水平、实行探究式教学、推动素质教育等以适应新时期、新要求。     

四川省生物资源开发利用战略

生物资源利用已成为当今世界“朝阳产业”,由于特殊的自然环境。四川生物资源特别丰富,为此可将坑害民为中国生物产品中心,分析了四川生物资源在中医药工业、食品工业,旅游业,生物用品产业和生物种产业的利用方面。提出了加快四川资源利用的一些措施。     

Inequality and living standards under early communism: Anthropometric evidence from Czechoslovakia, 1946–1966

A sample of adolescent heights and weights from the Czechoslovak city of Liberec is analyzed to shed light on the changes in biological standard of living between 1946 and 1966, the early years of Communist rule in Czechoslovakia. The long-term trend in average height was upwards for all social groups but differences in stature between social groups were about as large as in Communist Czechoslovakia as in market economies, such as the UK. Sons of blue-collar fathers and of parents employed in agriculture were generally shorter than sons of clerks and professional employees (teachers, doctors, lawyers). The anthropometric record also suggests that in the immediately post-war years inequality was greater than in the late 1950s and early 1960s.