循环经济的微观理论基础——生态效用论及人类选择理性

生态环境资源的日益稀缺,凸显了物质效用理论的局限。循环经济理念的产生体现了人类效用选择的理性回归。以生态效用理论为基础,揭示了人类效用选择的理性,从而构建了循环经济的微观理论基础,进一步分析了人口增长以及技术进步对循环经济发展的影响。     

河南省农业人口、资源对生态环境的影响及对策

河南省由于农业人口基数大,农业人口增长迅速,人口素质和结构不够合理。土地、水及其它自然资源没有得到充分的利用,且污染比较严重,对河南省脆弱的农业生态环境造成了严重的不良影响。要改善河南省农业生态环境现状,促进河南省农业人口、资源与生态环境的协调发展,就要从控制人口的增长,提高农业劳动者科技文化素质;推广绿色农业技术,保护农业资源;发展综合养殖生态工程,合理回收利用生物质资源;健全环境保护机制,加强监控力度四个方面入手。     

四川辖曼自然保护区黑颈鹤(Grus nigricollis)的数量及分布

通过１９９７０７２４～１９９７０８１７对四川辖曼自然保护区的调查,发现黑颈鹤２６９只．通过平均密度法估算整个保护区有４０７只,其主要分布在伏流宽谷沼泽和湖泊洼地沼泽,其最适生境是湿润及水体沼泽区,偶见于草坡．由于自然环境的变迁及人为活动的干扰,黑颈鹤的栖息繁殖环境及整个湿地生态系统的稳定性正受到极大的威胁,需进一步加强保护     

Phylogeography and Limited Genetic Connectivity in the Endangered Boring Giant Clam across the Coral Triangle

Abstract: The Coral Triangle is the global center of marine biodiversity; however, its coral reefs are critically threatened. Because of the bipartite life history of many marine species with sedentary adults and dispersive pelagic larvae, designing effective marine protected areas requires an understanding of patterns of larval dispersal and connectivity among geographically discrete populations. We used mtDNA sequence data to examine patterns of genetic connectivity in the boring giant clam (Tridacna crocea) in an effort to guide conservation efforts within the Coral Triangle. We collected an approximately 485 base pair fragment of mtDNA cytochrome c oxidase 1 (CO1) from 414 individuals at 26 sites across Indonesia. Genetic structure was strong between regions (φ_ST=0.549, p < 0.00001) with 3 strongly supported clades: one restricted to western Sumatra, another distributed across central Indonesia, and a third limited to eastern Indonesia and Papua. Even within the single largest clade, small but significant genetic structure was documented (φ_ST=0.069, p < 0.00001), which indicates limited gene flow within and among phylogeographic regions. Significant patterns of isolation by distance indicated an average dispersal distance of only 25–50 km, which is far below dispersal predictions of 406–708 km derived from estimates of passive dispersal over 10 days via surface currents. The strong regional genetic structure we found indicates potent limits to genetic and demographic connectivity for this species throughout the Coral Triangle and provides a regional context for conservation planning. The recovery of 3 distinct evolutionarily significant units within a well‐studied taxonomic group suggests that biodiversity in this region may be significantly underestimated and that Tridacna taxa may be more endangered than currently recognized.     

Lyapunov stability for an age-structured population model

This is a short notice on the McKendrick equation that I actually learned from Yu.M. Svirezhev in the 1990s. This McKendrick equation modelling the evolution in time of an age-structured population has received attention recently from mathematicians. The initial and boundary conditions for the McKendrick equation imposed by the population model are not the standard side conditions one sees in PDE theory for an evolution equation. In the simplest case, the problem reduces to a well-known model in demography, the Lotka integral equation.     

Model of coral population response to accelerated bleaching and mass mortality in a changing climate

We model coral community response to bleaching and mass mortality events which are predicted to increase in frequency with climate change. The model was parameterized for the Arabian/Persian Gulf, but is generally applicable. We assume three species groups (Acropora, faviids, and Porites) in two life-stages each where the juveniles are in competition but the adults can enter a size-refuge in which they cannot be competitively displaced. An aggressive group (Acropora species) dominates at equilibrium, which is not reached due to mass mortality events that primarily disadvantage this group (compensatory mortality, >90% versus 25% in faviids and Porites) roughly every 15 years. Population parameters (N individuals, carrying capacity) were calculated from satellite imagery and in situ transects, vital rates (fecundity, mortality, and survival) were derived from the model, field observations, and literature. It is shown that populations and unaltered community structure can persist despite repeated 90% mortality, given sufficiently high fecundity of the remaining population or import from connected populations. The frequency of disturbance determines the dominant group—in low frequency Acropora, in high frequency Porites. This is congruent with field observations. The model of an isolated population was more sensitive to parameter changes than that of connected populations. Highest sensitivity was to mortality rate and recruitment rate. Community composition was sensitive to spacing of disturbances and level of catastrophic mortality. Decreased mortality led to Acropora dominance, increased mortality led to Acropora extinction. In nature, closely spaced disturbances have severely disadvantaged Acropora populations over the last decade. Unless a longer (>10 years) disturbance-free interval can be maintained, a permanent shift away from Acropora dominance will be observed. A mortality rate of 99% in Acropora, as observed in 1996, is not sustainable if repetitive and neither is a disturbance frequency <15 years—each leading to population collapse. This shows that the severity and/or the spacing of the 1996–1998–2002 disturbances were unusual in frequency and duration.     

Data-directed modelling of Daphnia dynamics in a long-term micro-ecosystem experiment

The micro-ecosystem under consideration consists of three compartments forming a closed chain in which water circulates. Three trophic levels are represented in different compartments: autotrophs (algae, mainly Chlorella vulgaris), herbivores (Daphnia magna) and microbial decomposers. From a 20 years experiment with this system, data has been selected for this study. The dynamics of algae and Daphnia magna in only one of the compartments were modeled by different systems of differential and difference equations. We describe the successive steps in the process of model development, and the fitting of parameters using a Nelder-Mead simplex calibration method. Identification problems were overcome by taking values for physiological parameters in agreement with the literature. It turned out that a logistic type of model gives the best result for the structured Daphnia population because of the set up of the experiment: algae grow and reproduce in the upstream compartment. For this reason well-known plant–herbivore models did not comply with the data. The results of the parameter estimation procedure are discussed. The estimated grazing rate by Daphnia was smaller than expected. Possibly the Daphnia fed also on detritus and decomposing algae which were not measured.     

Habitat Change and Plant Demography: Assessing the Extinction Risk of a Formerly Common Grassland Perennial

Abstract:  An important aim of conservation biology is to understand how habitat change affects the dynamics and extinction risk of populations. We used matrix models to analyze the effect of habitat degradation on the demography of the declining perennial plant Trifolium montanum in 9 calcareous grasslands in Germany over 4 years and experimentally tested the effect of grassland management. Finite population growth rates (λ) decreased with light competition, measured as leaf-area index above T. montanum plants. At unmanaged sites λ was <1 due to lower recruitment and lower survival and flowering probability of large plants. Nevertheless, in stochastic simulations, extinction of unmanaged populations of 100 flowering plants was delayed for several decades. Clipping as a management technique rapidly increased population growth because of higher survival and flowering probability of large plants in managed than in unmanaged plots. Transition-matrix simulations from these plots indicated grazing or mowing every second year would be sufficient to ensure a growth rate ≥1 if conditions stayed the same. At frequently grazed sites, the finite growth rate was approximately 1 in most populations of T. montanum . In stochastic simulations, the extinction risk of even relatively small grazed populations was low, but about half the extant populations of T. montanum in central Germany are smaller than would be sufficient for a probability of survival of >95% over 100 years. We conclude that habitat change after cessation of management strongly reduces recruitment and survival of established individuals of this perennial plant. Nevertheless, our results suggest extinction processes may take a long time in perennial plants, resulting in an extinction debt. Even if management is frequent, many remnant populations of T. montanum may be at risk because of their small size, but even a slight increase in size could considerably reduce their extinction risk.     

Invasion, Disturbance, and Competition: Modeling the Fate of Coastal Plant Populations

Abstract:  Wetland habitats are besieged by biotic and abiotic disturbances such as invasive species, hurricanes, habitat fragmentation, and salinization. Predicting how these factors will alter local population dynamics and community structure is a monumental challenge. By examining ecologically similar congeners, such as Iris hexagona and I. pseudacorus (which reproduce clonally and sexually and tolerate a wide range of environmental conditions), one can identify life-history traits that are most influential to population growth and viability. We combined empirical data and stage-structured matrix models to investigate the demographic responses of native ( I. hexagona ) and invasive ( I. pseudacorus ) plant populations to hurricanes and salinity stress in freshwater and brackish wetlands. In our models I. hexagona and I. pseudacorus responded differently to salinity stress, and species coexistence was rare. In 82% of computer simulations of freshwater marsh, invasive iris populations excluded the native species within 50 years, whereas native populations excluded the invasive species in 99% of the simulations in brackish marsh. The occurrence of hurricanes allowed the species to coexist, and species persistence was determined by the length of time it took the ecosystem to recover. Rapid recovery (2 years) favored the invasive species, whereas gradual recovery (30 years) favored the native species. Little is known about the effects of hurricanes on competitive interactions between native and invasive plant species in marsh ecosystems. Our models contribute new insight into the relationship between environmental disturbance and invasion and demonstrate how influential abiotic factors such as climate change will be in determining interspecific interactions.     

青藏高原东部原始云杉林及其系列采伐迹地3个林地藓类种群结构与生物量的差异性评估

森林采伐对地表藓类种群的发育具有重要影响,但很少有人评估这种影响后迹地上的藓类种群状况.本研究调查了四川壤塘县4个系列采伐迹地和附近原始云杉林下3种林地优势藓类种群[锦丝藓(Actinothuidium hookeri)、塔藓(Hylocomium splendens)和大羽藓(Thuidium cymbifolium)]的发生频率和盖度、生物量以及维管束植物盖度和凋落物盖度,通过方差分析检验比较分析了3个藓类种群的盖度和生物量在不同采伐迹地及原始林之间的差异,评估了其自然发展趋势,揭示了维管束植物结构参数与藓类种群盖度和生物量之间的相互关系.发现:1)3种藓类种群的盖度和生物量在采伐迹地和附近原始林间有显著差异,但在系列采伐迹地之间没有明显差异,证实森林采伐后林生地表藓类种群显著衰退,随着迹地自然恢复进程这些藓类种群并未能逐渐恢复;2)微环境尺度上的藓类盖度和生物量在系列采伐迹地之间有较大的波动,Spearman相关分析显示乔木和草本层盖度是影响藓类种群生物量的主要因子.综合分析表明,采伐导致的环境变化以及藓类自身的牛态适应性和繁殖策略综合决定着藓类种群的自然恢复能力;如果仅仅依靠迹地自然恢复过程,顶极藓类种群(塔藓和锦丝藓)是难以自然复壮的.图6表4参44