INTEGRATING DEMOGRAPHIC AND LANDSAT (TM) DATA AT A WATERSHED SCALE1

ABSTRACT: Recurrent calls for integrated resource management urge that an understanding of human activities and populations be incorporated into natural resource research, management, and protection efforts. In this paper, we hypothesize that watersheds can be a valuable geography for organizing an inquiry into the relationship between humans and the environment, and we present a framework for conducting such efforts. The framework is grounded in the emerging field of landscape ecology and incorporates demographic theory and data. Demography has been advanced by technological capabilities associated with the 1990 Census. Employing Geographic Information System (GIS) tools, we couple Landsat Thematic Mapper (TM) land cover data with census‐derived housing density data to demonstrate the operation of our framework and its utility for better understanding human‐landscape interactions. In our investigation of the Kickapoo Watershed and two sub‐ watersheds, located in southwestern Wisconsin, we identify relationships between landscape composition and the distribution and social structure of human populations. Our findings offer insight into the interplay between people and biophysical systems.     

Forest growth in the light of the thermodynamic theory of ecological systems

The observed growth of a particular forest stand can be described by many models and explained by some of them. The forest growth models are also successfully applied for extrapolating the growth curve. However, the known models of forest growth are not “one-point” models. They are not designed to predict the future growth of a forest stand from its current state: the model parameters either are not directly measurable or cannot be measured with relevant accuracy. This article is an attempt to use Jørgensen–Svirezhev theory as a new clue to the choice of variables that determines forest growth. The postulates of this theory combined with the pipe theory of tree growth lead to conclusion that biomass of a stand should be proportional to the four-fifths power of its age. Empirical validation, however, disclosed that calendar age is rather approximate measure of ecosystem ontogeny. Delayed development or intensive thinning of a forest stand at the early stages leads to rejuvenation bias. Thus derived 4/5-law model approximates well-known Chapman–Richards model in the neighborhood of the inflection point, and is applicable to middle-aged forest stands.     

城市滨水区的生态恢复研究

城市滨水区的生态恢复具有着重要的生态、经济和社会意义。通过探讨和分析城市滨水区生态恢复的基础理论和主要内容,综述了国内外城市滨水区生态恢复的研究现状,指出我国为做好城市滨水区生态恢复工作尚需加强滨水区生态恢复的基础理论、关键技术、景观生态学的应用和示范推广等方面的研究,以滨水区的生态恢复带动开发,保证城市的可持续发展。     

资源学的学科属性及定位问题讨论

资源学属于应用理学,以地球科学、生物学、天文学为其学科理论基础。资源学、环境学、生态学是同一层次的学科。资源经济学建立在资源学和理论经济学基础之上。     

Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon

River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1) upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions. However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies.     

浅谈我校生态综合实验室的合理利用和管理

我校生态综合实验室由实验室、仪器设备储藏室和教师预备室组成。本文针对该实验室在运行中由于教学任务的逐年增加导致的实验室软硬件建设相对滞后等问题,在实验室的管理建设方面提出了提高综合利用率等建议。     

生态校园建设现状分析

生态校园建设的类型主要有:景观园林设计型、生态技术型、教育管理型.通过在校园内建立生态环境体系,使校园内有限的资源得到循环、合理、科学的使用,提高学校生态环境质量.     

Effects of Riparian Vegetation and Watershed Urbanization on Fishes in Streams of the Mid‐Atlantic Piedmont (USA)1

Abstract: The joint influences of riparian vegetation and urbanization on fish assemblages were analyzed by depletion sampling in paired forested and nonforested reaches of 25 small streams along an urbanization gradient. Nonforested reaches were narrower than their forested counterparts, so densities based on surface area differ from linear densities (based on reach length). Linear densities (based on number or biomass of fish) of American eel, white sucker and tesselated darter, and the proportion of biomass of benthic invertivores were significantly higher in nonforested reaches, while linear densities of margined madtom and the number of pool species were significantly higher in forested reaches. Observed riparian effects may reflect differences in habitat and algal productivity between forested and nonforested reaches. These results suggest that relatively small‐scale riparian restoration projects can affect local geomorphology and the abundance of fish. Dense vegetative cover in riparian zones and similar or analogous habitats in both forested and nonforested reaches, the relatively small scale of the nonforested reaches, and the low statistical power to detect differences in abundance of rare species may have limited the observed differences between forested and nonforested reaches. There was a strong urbanization gradient, with reductions of intolerant species and increases of tolerant species and omnivores with increasing urbanization. Interactions between riparian vegetation type and urbanization were found for blacknose dace, creek chub, tesselated darter, and the proportion of biomass of lithophilic spawners. The study did not provide consistent support for the hypotheses that responses of fish to riparian vegetation would be overwhelmed by urban degradation or insignificant at low urbanization.     

Should Habitat Trading Be Based on Mitigation Ratios Derived from Landscape Indices? A Model-Based Analysis of Compensatory Restoration Options for the Red-Cockaded Woodpecker

Many species of conservation concern are spatially structured and require dispersal to be persistent. For such species, altering the distribution of suitable habitats on the landscape can affect population dynamics in ways that are difficult to predict from simple models. We argue that for such species, individual-based and spatially explicit population models (SEPMs) should be used to determine appropriate levels of off-site restoration to compensate for on-site loss of ecologic resources. Such approaches are necessary when interactions between biologic processes occur at different spatial scales (i.e., local [recruitment] and landscape [migration]). The sites of restoration and habitat loss may be linked to each other, but, more importantly, they may be linked to other resources in the landscape by regional biologic processes, primarily migration. The common management approach for determining appropriate levels of off-site restoration is to derive mitigation ratios based on best professional judgment or pre-existing data. Mitigation ratios assume that the ecologic benefits at the site of restoration are independent of the ecologic costs at the site of habitat loss. Using an SEPM for endangered red-cockaded woodpeckers, we show that the spatial configuration of habitat restoration can simultaneously influence both the rate of recruitment within breeding groups and the rate of migration among groups, implying that simple mitigation ratios may be inadequate.     

Natterer’s bat (Myotis nattereri Kuhl, 1818) hawks for prey close to vegetation using echolocation signals of very broad bandwidth

We present a hitherto unknown prey perception strategy in bats: Myotis nattereri (Vespertilionidae, Chiroptera) is able to perceive prey by echolocation within a few centimeters of echo-cluttering vegetation, by using frequency-modulated search signals of very large bandwidth (up to 135 kHz). We describe the species’ search behavior and echolocation repertoire from the field and from experiments in a flight tent. In the field, bats varied signal parameters in relation to their distance from vegetation and usually flew close to vegetation. In the flight tent, M. nattereri detected and localized prey by echolocation alone as close as 5 cm from vegetation. Apparently, the bats were able to tolerate some overlap between prey and clutter echoes. Passive prey cues (vision, olfaction, prey-generated sounds) were not used in prey perception. The bats selected prey by size. The animals performed aerial catches and produced approach sequences typical for aerial hawking bats, but were able to do so within a few centimeters of the substrate. M. nattereri thus has access to silent, suspended prey very close to vegetation (e.g., spiders, and caterpillars on threads). Received: 29 September 1999 / Received in revised form: 12 February 2000 / Accepted: 12 February 2000