关于中国西部“山川秀美”再造的思考——兼论西部生态安全建设中的防灾减灾

再造一个“山川秀美”的大西北 ,展现出一幅理想的人与自然依存的场景。笔者为此给出独特的思考和科学的见解 :要实现这一目标 ,必须研讨“山川秀美”的科学内涵 ,以恢复大西北自然生态安全环境为基础 ,以防灾减灾 ,保护人与自然为手段 ,依靠科技进步 ,坚持可持续发展战略 ,从长远利益并结合地区实际 ,才能真正实现人与自然和谐共存的“山川秀美”     

Sperm precedence and sperm storage in multiply mated red flour beetles

In insects, the last male to mate with a female often gains access to a disproportionate number of subsequent fertilizations. This study examined last-male sperm precedence patterns in doubly and triply mated Tribolium castaneum females. Sperm storage processes were investigated by measuring the quantity of sperm stored within the female spermatheca following single, double, and triple matings. Both doubly mated and triply mated females exhibited high last-male sperm precedence for progeny produced during the first 48 h following the last mating, with females in both groups exhibiting parallel declines in sperm precedence 1 and 2 weeks later. The number of sperm stored by females increased by 33% between singly mated and doubly mated females, indicating that the spermatheca is filled to only two-thirds capacity following insemination by the first male. Based on the proportion of stored sperm from first and second matings, we tested predictions about sperm precedence values based on models of random sperm mixing. High initial last-male sperm precedence strongly supports stratification of last-male sperm. By 1–2 weeks after double matings, sperm precedence declined to levels indistinguishable from values expected under random mixing. These results provide insight into mechanisms of sperm storage and utilization in this species. Received: 20 August 1997 / Accepted after revision: 24 May 1998     

Investigating the embryo/larval toxic and genotoxic effects of γ irradiation on zebrafish eggs

Eggs/larval of freshwater fish (Danio rerio) were exposed to low dose rates of external gamma radiation (from 1 to 1000 mGy d⁻¹) over a 20-day period, with the objective of testing the appropriateness of the 10 mGy d⁻¹ guideline suggested by the IAEA. The present study examines different endpoints, mortality and hatching time and success of embryos as well as the genotoxicity of γ-irradiations (after 48 h). The 20-day embryo-larval bioassay showed an enhanced larval resistance to starvation after chronic exposure to γ irradiation (from low 1 mGy d⁻¹ to high dose rate 1000 mGy d⁻¹) and an acceleration in hatching time. Gamma irradiation led to increased genotoxic damage Ito zebrafish egg (40-50% DNA in tail in Comet assay) from the lowest dose rate (1 mGy d⁻¹). Possible mechanisms of γ radiotoxicity and implications for radioprotection are discussed.     

三峡工程对长江中游湖泊生态影响及监测因子优选

分析了三峡工程的兴建对长江中游湖泊生态环境的影响,为保护长江中游湖泊生态环境,优选出了８类指标的监测因子,以期通过这些因子的监测,可以较全面,准确地反映了三峡工程对长少中游湖泊生态环境状况的影响及其动态变化趋势,为保持长江中游湖泊生态系统的良性特环境提供科学依据。     

Interdependence with the environment: Commitment,interconnectedness, and environmental behavior

Do individuals’ perceptions of their interdependence with the natural environment affect their environmental behaviors? From the perspective of interdependence theory, we introduce a scale to measure commitment to the natural environment. In Study 1, higher levels of commitment to the environment and greater inclusion of nature in the self separately predicted higher levels of pro-environmental behavior, even when controlling for social desirability and ecological worldview. In Study 2, participants primed to experience high commitment to the environment reported greater levels of pro-environmental behavioral intentions as well as pro-environmental behavior relative to participants primed to experience low commitment to the environment. Commitment to the natural environment is a new theoretical construct that predicts environmental behavior.     

Adaptation as a Political Process: Adjusting to Drought and Conflict in Kenya’s Drylands

In this article, we argue that people’s adjustments to multiple shocks and changes, such as conflict and drought, are intrinsically political processes that have uneven outcomes. Strengthening local adaptive capacity is a critical component of adapting to climate change. Based on fieldwork in two areas in Kenya, we investigate how people seek to access livelihood adjustment options and promote particular adaptation interests through forming social relations and political alliances to influence collective decision-making. First, we find that, in the face of drought and conflict, relations are formed among individuals, politicians, customary institutions, and government administration aimed at retaining or strengthening power bases in addition to securing material means of survival. Second, national economic and political structures and processes affect local adaptive capacity in fundamental ways, such as through the unequal allocation of resources across regions, development policy biased against pastoralism, and competition for elected political positions. Third, conflict is part and parcel of the adaptation process, not just an external factor inhibiting local adaptation strategies. Fourth, there are relative winners and losers of adaptation, but whether or not local adjustments to drought and conflict compound existing inequalities depends on power relations at multiple geographic scales that shape how conflicting interests are negotiated locally. Climate change adaptation policies are unlikely to be successful or minimize inequity unless the political dimensions of local adaptation are considered; however, existing power structures and conflicts of interests represent political obstacles to developing such policies.     

The dimensions of land use change in rural landscapes: lessons learnt from the GB Countryside Surveys

Rural landscapes are highly dynamic and their change impacts on a number of ecological processes such as the dynamics of biodiversity. Although a substantial amount of research has focused on quantifying these changes and their impact on biodiversity, most studies have focused on single dimensions of land use change. This lack of integration in land use change studies can be explained by the fact that data on the spatial, temporal, and ecological dimensions of land use are seldom available for the same geographical location. In this paper, the benefits of taking into account these three dimensions are illustrated with results derived from the Great Britain Countryside Surveys (CS), a large-scale monitoring programme designed to assess change in the extent and ecological condition of British habitats. The overview of CS results presented in this paper shows that (1) changes in land use composition will translate into a variety of spatial patterns; (2) the temporal stability of land use is often lower than can be expected; and (3) there can be large-scale shifts in the ecological condition of the land use types that form our rural landscapes. The benefits of integrated rural landscape studies are discussed in the context of other national monitoring programmes.     

Predicting the effects of ionising radiation on ecosystems by a generic model based on the Lotka–Volterra equations

The present work describes a model for predicting the population dynamics of the main components (resources and consumers) of terrestrial ecosystems exposed to ionising radiation. The ecosystem is modelled by the Lotka–Volterra equations with consumer competition. Linear dose–response relationships without threshold are assumed to relate the values of the model parameters to the dose rates. The model accounts for the migration of consumers from areas characterised by different levels of radionuclide contamination. The criteria to select the model parameter values are motivated by accounting for the results of the empirical studies of past decades. Examples of predictions for long-term chronic exposure are reported and discussed.     

Factors influencing wastewater management performance: case study of housing estates in suburban Bangkok, Thailand

As population densities have risen and settlements become increasingly crowded, wastewater effluent volumes have, not unexpectedly, also risen. The adverse impacts of effluent from housing estates (HEs) in suburban areas of Thailand, served by local wastewater management (WWM) systems, are of particular concern. Because of this problem, which reflects the poor performance of WWM systems, it has become increasingly important that the pivotal factors that hinder WWM improvements be identified and effective solutions be proposed and implemented. The goal of the research described in this paper was to determine the critical factors influencing WWM performance at HEs in suburban Bangkok, using multiple regression analysis. Three significant factors encompassing financial, social, institutional and general aspects were identified for each type of WWM system (community centralized and onsite). For the community centralized system, the key factors were house price, type of organization managing the HE, and the attitudes of the organization. For onsite systems, the three factors were total number of house units, direct experience with water pollution and percentage of occupied houses. These findings reflect the importance of having a WWM that employs an integrated approach rather than focusing on specific aspects in isolation from other factors. WWM performance could be improved if significant factors indicating high priority concerns were to be identified and properly applied. Addressing the priority concerns could, consequently, contribute to the development of appropriate environmental management measures, plans, and policies related to HE WWM.     

Human perceptions of landscape change: The case of a monodominant forest of <Emphasis Type="Italic">Attalea speciosa</Emphasis> Mart ex. Spreng (Northeast Brazil)

From the perception of human populations, we can assess the changes occurring in certain landscapes and the factors that cause those changes. Such studies have proven helpful in increasing the knowledge of the history of a landscape, recognizing past formations and projecting its future. Our research objective was to determine how a landscape dominated by the palm tree Attalea speciosa, a species of ecological, economic, and cultural importance, has been changing over time by synthesizing and comparing historical documents and local perceptions. This study was conducted in Araripe Environmental Protection Area, Northeast Region, Brazil. To understand local landscape change, we interviewed active harvesters in four communities in which A. speciosa use has been documented. Historical documents were evaluated as a complement to the interview data. According to local informants, areas previously used for cultivation and animal husbandry that were abandoned or decimated by droughts in the region may have fostered the expansion of a monodominant A. speciosa forest. Furthermore, other forms of landscape management resulting from human population growth may also have affected the current and past distribution of this forest.