石灰石和菱镁矿对酸化森林土壤修复作用的研究

以重庆铁山坪马尾松林下典型的酸化土壤为修复介质,将土壤溶液pH值和主要阴阳离子浓度作为测试指标,对石灰石和菱镁矿这2种化学修复剂的修复效果进行了为期1a的野外实验研究.结果表明:与未投加修复剂的土壤相比,投加石灰石和菱镁矿后土壤溶液的pH值和相应阳离子(Ca²⁺或Mg²⁺)浓度显著上升,而且无机单体铝(Al_i)浓度明显下降,从而起到了缓解土壤酸化并降低其对植被危害的效果.但是,修复剂的投加导致NO₃^{-相似文献}   

旱区城市扩展过程区位因素研究——以中国呼包鄂榆城市群为例

认识城市扩展过程的区位因素特征对旱区城市可持续发展具有重要意义。为此,以中国呼包鄂榆城市群为例,利用随机森林方法量化区位因素对城市扩展过程的影响。研究发现:随机森林方法能够有效地量化旱区城市扩展过程区位因素的基本特征,模型的AUC(area under curve)值达到0.97。同时,到城市中心距离对区域1980—2017年城市扩展过程影响最大,重要性达到42.62%。国道、高速公路和铁路等交通因素也有重要的影响,重要性均大于10%。此外,所有区位因素对区域城市扩展过程的影响均存在尺度效应,其中地形、气候和河流对城市扩展过程影响的尺度效应相对比较明显。地形、气候和河流对大城市影响的重要性分别为27.17%、20.23%和8.12%,分别是其对小城市影响的4.02倍、3.91倍和2.36倍。因此,建议在旱区城市建设中,应该高度重视地形、气候和河流等自然要素的约束作用,因地制宜地进行城市规划和建设。     

Predicting and setting conservation priorities for Bolivian mammals based on biological correlates of the risk of decline

The recognition that growing proportions of species worldwide are endangered has led to the development of comparative analyses to elucidate why some species are more prone to extinction than others. Understanding factors and patterns of species vulnerability might provide an opportunity to develop proactive conservation strategies. Such comparative analyses are of special concern at national scales because this is the scale at which most conservation initiatives take place. We applied powerful ensemble learning models to test for biological correlates of the risk of decline among the Bolivian mammals to understand species vulnerability at a national scale and to predict the population trend for poorly known species. Risk of decline was nonrandomly distributed: higher proportions of large‐sized taxa were under decline, whereas small‐sized taxa were less vulnerable. Body mass, mode of life (i.e., aquatic, terrestrial, volant), geographic range size, litter size, home range, niche specialization, and reproductive potential were strongly associated with species vulnerability. Moreover, we found interacting and nonlinear effects of key traits on the risk of decline of mammals at a national scale. Our model predicted 35 data‐deficient species in decline on the basis of their biological vulnerability, which should receive more attention in order to prevent their decline. Our results highlight the relevance of comparative analysis at relatively narrow geographical scales, reveal previously unknown factors related to species vulnerability, and offer species‐by‐species outcomes that can be used to identify targets for conservation, especially for insufficiently known species. Predección y Definición de Prioridades de Conservación para Mamíferos de Bolivia con Base en Correlaciones Biológicas del Riesgo de Declinación     

Effectiveness of Community Forestry in Prey Long Forest,Cambodia

Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005–2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context‐specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18–20 randomly placed variable‐radius plots and fixed‐area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income. Efectividad de la Silvicultura Comunal en el Bosque Prey Long, Camboya     

Improving Environmental and Social Targeting through Adaptive Management in Mexico's Payments for Hydrological Services Program

Natural resource managers are often expected to achieve both environmental protection and economic development even when there are fundamental trade‐offs between these goals. Adaptive management provides a theoretical structure for program administrators to balance social priorities in the presence of trade‐offs and to improve conservation targeting. We used the case of Mexico's federal Payments for Hydrological Services program (PSAH) to illustrate the importance of adaptive management for improving program targeting. We documented adaptive elements of PSAH and corresponding changes in program eligibility and selection criteria. To evaluate whether these changes resulted in enrollment of lands of high environmental and social priority, we compared the environmental and social characteristics of the areas enrolled in the program with the characteristics of all forested areas in Mexico, all areas eligible for the program, and all areas submitted for application to the program. The program successfully enrolled areas of both high ecological and social priority, and over time, adaptive changes in the program's criteria for eligibility and selection led to increased enrollment of land scoring high on both dimensions. Three factors facilitated adaptive management in Mexico and are likely to be generally important for conservation managers: a supportive political environment, including financial backing and encouragement to experiment from the federal government; availability of relatively good social and environmental data; and active participation in the review process by stakeholders and outside evaluators. Mejorando los Objetivos Ambiental y Social Mediante el Manejo Adaptativo en el Programa de Pagos por Servicios Hidrológicos en México     

Thermal Physiology,Disease, and Amphibian Declines on the Eastern Slopes of the Andes

Rising temperatures, a widespread consequence of climate change, have been implicated in enigmatic amphibian declines from habitats with little apparent human impact. The pathogenic fungus Batrachochytrium dendrobatidis (Bd), now widespread in Neotropical mountains, may act in synergy with climate change causing collapse in thermally stressed hosts. We measured the thermal tolerance of frogs along a wide elevational gradient in the Tropical Andes, where frog populations have collapsed. We used the difference between critical thermal maximum and the temperature a frog experiences in nature as a measure of tolerance to high temperatures. Temperature tolerance increased as elevation increased, suggesting that frogs at higher elevations may be less sensitive to rising temperatures. We tested the alternative pathogen optimal growth hypothesis that prevalence of the pathogen should decrease as temperatures fall outside the optimal range of pathogen growth. Our infection‐prevalence data supported the pathogen optimal growth hypothesis because we found that prevalence of Bd increased when host temperatures matched its optimal growth range. These findings suggest that rising temperatures may not be the driver of amphibian declines in the eastern slopes of the Andes. Zoonotic outbreaks of Bd are the most parsimonious hypothesis to explain the collapse of montane amphibian faunas; but our results also reveal that lowland tropical amphibians, despite being shielded from Bd by higher temperatures, are vulnerable to climate‐warming stress. Fisiología Termal, Enfermedades y Disminuciones de Anfibios en las Laderas Orientales de los Andes     

EVALUATION OF BEST MANAGEMENT PRACTICES FOR CONTROLLING NONPOINT POLLUTION FROM SILVICULTURAL OPERATIONS1

ABSTRACT: Fifteen years of streamflow and water quality data were evaluated to determine the effectiveness of Best Management Practices (BMP's) in controlling nonpoint source pollution from an 110. acre commercial clearcut located in the Ridge and Valley Province of central Pennsylvania. The analyses addressed both short- and long-term changes in the physical and chemical properties and the hydro-logic regime of the stream draining this 257-acre watershed. Overall, the BMP's employed on this commercial clearcut were very effective in preventing serious deterioration of stream quality as a result of forest harvesting. Although statistically significant increases in nitrate and potassium concentrations and temperature and turbidity levels were measured the first two years following harvesting, the increases were relatively small and, with the exception of turbidity, within drinking water standards. Nevertheless, such increases may violate EPA's anti-degradation policy. Nitrate and potassium concentrations and turbidity levels remained above pre-harvesting levels for as long as nine years following harvesting. Clearcutting also significantly increased water yield, which in turn initially lowered the concentrations of most solutes because of dilution. Increased water yields returned to pro-harvesting levels within four years as a result of rapid regrowth. The export of some ions increased; however, the increased export appeared to be insufficient to affect site fertility. Implementation of periodic post-harvest inspections of harvested areas, increasing the width of the buffer zone, and utilizing buffer zones on all perennial and intermittent channels would reduce further impacts of silvi-cultural activities on water quality.     

Bird Extinctions in Atlantic Forest Fragments of the Viçosa Region, Southeastern Brazil

Abstract:   We studied the conservation status of Atlantic forest birds in 43 forest fragments ranging in size from 1 to 384 ha in the Viçosa region of southeastern Brazil. We compared data from 15 years of field work with historical records from the region, mainly originating from specimens collected by João Moojen during the 1930s. We used published studies associated with museum data and current field work to assess the decline of forest birds during the last 70 years and to relate their disappearance to forest fragmentation and destruction. At least 28 bird species have become locally extinct, 43 are critically endangered, and 25 are vulnerable, representing 60.7% of the original forest bird community known to exist in the region. Vulnerability to fragmentation differed among guilds, forest strata, and endemicity status. Birds that feed on fruit and seeds, and those that feed on insects, were more threatened than omnivores and carnivores. Nectarivorous species were less threatened than other guilds. Moreover, terrestrial and understory birds or birds using only one forest stratum also were more likely to have been threatened. Finally, Atlantic forest endemics were more likely to have become extinct than nonendemic species. In general, sensitivity to environmental disturbance at the local level was similar to the predicted vulnerability to regional disturbance derived from the literature. Our results indicate that a serious decline of Atlantic forest birds is underway and that many other species of birds, not previously recognized as threatened, are of conservation concern .     

Using the guild concept in the assessment of tree harvesting effects on understory herbs: A cautionary note

To help determine whether plants should be grouped into guilds for environmental impact assessment, the responses of six members of a guild of deciduous forest herbs to selective tree harvesting were compared. Harvesting operations themselves (tree cutting and skidding) had little effect on five of the six species but the sixth species decreased more in cut plots than in uncut plots. Subsequent microclimatic changes, resulting from tree cutting, also affected guild members differently. In the first year after cutting, two species increased more in cut plots than in uncut plots, while three other species did not change in frequency of occurrence and the sixth species decreased more in cut plots than in uncut plots. This inconsistent response of guild members to tree harvesting suggests that caution should be exercised in using guilds to assess plant response to environmental change.     

西南地区卫星林火监测系统的建立

本文对建立ＧＩＳ支持的ＮＯＡＡ卫星林火监测系统进行了分析．内容包括：监测区ＧＩＳ的形成；ＮＯＡＡ卫星图像叠加经纬度网格；ＧＩＳ与ＮＯＡＡ卫星图像的复合．１９９４年春天，我们对西南林区林火进行了１个多月的实时监测，证明了该系统具有林火分辨率高和定位准确的特点．是一个较为理想的林火监测系统。