纯化方式和保存条件对改性落叶松单宁絮凝性的影响

选择一种典型植物多酚——落叶松单宁,研究了纯化方式和保存条件对改性植物多酚絮凝性的影响,通过测定相对黏度和红外谱图分析稳定性变化的原因.对于1 g.L-1的高岭土模拟水样,未纯化落叶松单宁改性后的最佳投加量为10 mg.L-1;经过抽滤、萃取、离心后的纯化样,改性后最佳投加量降低到1 mg.L-1,且以液体或固体形式在4℃或25℃条件下保存30 d后仍具有较好絮凝性;而只经抽滤、离心,未经萃取的纯化样,其改性产物只有保存于4℃才有絮凝性;只经抽滤、萃取,未经离心或只经抽滤的纯化样,对应改性产物只有以固体形式在4℃保存才有絮凝性.以4℃保存的固体样相对黏度变化最小,且相对黏度的变化越小,絮凝性能的稳定性越强.红外结果显示,落叶松单宁中含有大量的酚羟基基团,改性后,叔胺基团加成到芳环上,但保存前后红外谱图变化不大.     

Climate Change, Elevational Range Shifts, and Bird Extinctions

Abstract:  Limitations imposed on species ranges by the climatic, ecological, and physiological effects of elevation are important determinants of extinction risk. We modeled the effects of elevational limits on the extinction risk of landbirds, 87% of all bird species. Elevational limitation of range size explained 97% of the variation in the probability of being in a World Conservation Union category of extinction risk. Our model that combined elevational ranges, four Millennium Assessment habitat-loss scenarios, and an intermediate estimate of surface warming of 2.8° C, projected a best guess of 400–550 landbird extinctions, and that approximately 2150 additional species would be at risk of extinction by 2100. For Western Hemisphere landbirds, intermediate extinction estimates based on climate-induced changes in actual distributions ranged from 1.3% (1.1° C warming) to 30.0% (6.4° C warming) of these species. Worldwide, every degree of warming projected a nonlinear increase in bird extinctions of about 100–500 species. Only 21% of the species predicted to become extinct in our scenarios are currently considered threatened with extinction. Different habitat-loss and surface-warming scenarios predicted substantially different futures for landbird species. To improve the precision of climate-induced extinction estimates, there is an urgent need for high-resolution measurements of shifts in the elevational ranges of species. Given the accelerating influence of climate change on species distributions and conservation, using elevational limits in a tested, standardized, and robust manner can improve conservation assessments of terrestrial species and will help identify species that are most vulnerable to global climate change. Our climate-induced extinction estimates are broadly similar to those of bird species at risk from other factors, but these estimates largely involve different sets of species.     

Land-use planning for sustainable resource development in Kumaon Lesser Himalaya—a study of the Gomti watershed

SUMMARY

The Lesser Himalaya, as the most densely populated part of the tectonically active and ecologically sensitive Himalayan mountain ranges, deserves specific attention to the conservation of the environment and the sustainable development of natural resources. Rapid growth of the human population during recent years, and the absence of any viable means of livelihood other than uneconomic crop farming have led to the uncontrolled exploitation of land areas and the consequent degradation and depletion of critical biophysical resources in the region. The need for sustainable development in Himalaya, therefore, makes it imperative to adopt a comprehensive land-use policy based on land capacity analysis that is scientific and practical. The main objective of this paper is to evolve an optimal land-use framework for the Gomti Watershed, situated in Kumaon, Lesser Himalaya. A detailed study of the traditional land use, regional agricultural system and the areas prone to environmental hazards was made throughout the watershed, through the preparation of large scale topographical forest and land record maps, field surveys and mapping. The average slope was considered as the principal parameter of land capacity, the potential for landslides and the intensity of erosion. Recognising the drastic changes that have taken place in the traditional land use, the watershed area has been proposed to be defined as protected forests (33.41%), community forests (32.86%), cultivation (23.33%) and horticulture (8.30%).     

广州市南沙区海岸防护林群落构建技术研究

森林是稳固和改善生态环境的重要载体,因其能提供巨大的生态服务功能而备受各国政府和学界的关注。珠江三角洲地区城市化进程的步伐逐渐加快,带来一系列环境问题。以广州市南沙区海岸景观防护林（也即河涌水网林、公路隔离林、海岸防风林）建设为例,主要研究了防护林的关键构建模式、林分群落结构等方面内容。结果显示,采用多层次的乔灌草配置,遵循适地适树的原则,以本土树种为主,搭配部分优良的引进树种,采取适合的营林措施,可构建出具有一定防护功能的人工林群落。广州南沙防护林建设是珠三角地区城市森林建设的一个缩影和代表,为我国南方城市森林建设理论的创建提供了一定的参考经验。破解城市化危机,创建宜居城市环境,实现城市可持续发展,应综合考虑城市的人口集中程度,经济发展规模,环境污染模式,针对具体的水分、气候和土壤等要素,运用多学科理论和技术,制定合适的森林构建模式,并需要政府、社会组织、以及公众的协同努力。     

Ground Fires as a Factor of Maintenance of Pine–Larch Forests in the Southern Urals

Russian Journal of Ecology -     

ATMOSPHERIC CONTRIBUTIONS TO FOREST NUTRIENT CYCLING1

The atmosphere is a significant source of plant nutrients that partially replenishes losses due to timber harvesting. The relative importance of wet and dry deposition depends upon the specific nutrient and site. Nitrogen in bulk precipitation (wetfall and dryfall) is equivalent to at least 70 percent of the nitrogen incorporated annually in above-ground woody tissues of some temperate hardwood forests. Atmospheric sources of calcium and potassium supply between 20 and 40 percent of the nutrients sequestered in woody increments. Annual nutrient inputs in bulk precipitation can exceed removals associated with sawiog harvest over a rotation period. Atmospheric inputs of nitrogen are only slightly less than hydrologic losses immediately after timber harvesting. The deposition of nutrients is highly variable in both time and space; interpretations of nutrient inputs and forest management impacts require quantification of inputs for a variety of ecosystems over long periods of time.     

WATER YIELD IMPROVEMENT BY VEGETATION MANAGEMENT1

ABSTRACT: Vegetation management aimed at increasing the amount of usable water yield from precipitation falling on upstream watersheds may be one alternative for supplementing water supplies. Indications are that water yields can be increased within a multiple-use framework, which can benefit or at least be compatible with other natural resource objectives. Through changes in vegetation on a watershed, it is possible to reduce evaporation losses only slightly but significantly increase streamflow runoff. In an assessment of potentials for water yield improvement in Arizona, experimental studies on various vegetation zones are reviewed. Because of either limited acreage or limited rainfall, the alpine, grassland, aspen, and desert shrub vegetation zones are not realistic management areas for Arizona. Furthermore, manipulation of pinyon-juniper woodlands does not appear promising at this time. Conversion of chaparral to grasses and forbs does appear to be a possible treatment for water yield improvement, as well as various silvicultural treatments of mixed conifer and ponderosa pine forests. Streamflow increases are given for experiments in chaparral, mixed conifer, and ponderosa pine vegetation zones. However, complete information on possible constraints for these zones is not currently available. Specific assessment of water yield management options for riparian vegetation is difficult to make, due to incomplete knowledge of water yield changes and other constraints for this vegetation zone. Prior to the final adoption of management practices, results of experimental work must be coupled with economic and social considerations.     

Recreation impacts in some riparian forests of the Eastern United States

Ecological impacts on camp and picnic sites were examined in three National Park Service units along the Delaware and New rivers, in the eastern United States. All sites experienced pronounced impact to trees, groundcover vegetation, and soils. The nature and magnitude of impacts in these riparian forests were quite similar to those reported in wilderness areas in the mountainous western states and northern Minnesota, despite more favorable growing conditions. The relationship between amount of use and amount of impact and the importance of differences in type of use and environment were also roughly comparable. High-use sites were more heavily impacted than low-use sites, but differences were small when compared with differences in amount of use. The areal extent of impact was the major difference between sites in different environments and sites used by different clienteles. This suggests that the effectiveness of basic strategies for managing impact should not differ greatly between regions. Here, as elsewhere, actions taken to control the areal extent of impact appear to be particularly important.     

Invasion of Gleditsia triacanthos in Lithraea ternifolia Montane Forests of Central Argentina

Gleditsia triacanthos and the native dominant Lithraea ternifolia in montane forests of central Argentina, considering life history and demographic traits of both the alien and the native species and different site conditions for population growth (good and bad sites). Matrix models are applied to project the consequences of differences in vital rates for population growth. Analyzing these models helps identify which life cycle transitions contributed most to population growth. Obtained population growth rates are considered to assess predicted rates of spread using the reaction-diffusion (R-D) model. G. triacanthos presents many of the life history traits that confer plants high potential for invasiveness: fast growth, clonal and sexual reproduction, short juvenile period, high seed production, and high seed germinability. These traits would ensure G. triacanthos invasive success and the displacement of the slow-growing, relatively less fecund native L. ternifolia. However, since disturbance and environmental heterogeneity complicate the invasibility pattern of G. triacanthos in these montane forests, the outcome of the invasion process is not straightforward as could be if only life history traits were considered. Great variation in demographic parameters was observed between populations of each species at good and bad sites. Though both good and bad sites signified increasing or at least stable populations for G. triacanthos, for L. ternifolia bad sites represented local extinction. Analyzing the results of matrices models helps design the optimal management for the conservation of L. ternifolia populations while preventing the invasion by G. triacanthos. The predicted asymptotic rate of spread for G. triacanthos at the good site was fourfold greater than the predicted one for L. ternifolia, although the difference was much smaller considering the bad site. The usefulness of the R-D model to study this invasion system is discussed.     

Discourses of Place: Environmental Interpretation about Vermont Forests

Motivated by a lack of scholarly attention to the substance of interpretive messages and materials, this study examines discursive aspects of interpretative brochures available at forest recreation and tourism sites in Vermont, United States. Directive statements that instruct and guide visitor experiences—and the discourses to which they contribute—were analyzed for content, form, and meaning. Across the interpretive brochures, four broad discourses were identified: the natural forest, the recreational forest, the productive forest, and the dependent forest. Consideration of intertextuality revealed a fifth, hybrid discourse that linked forests to meanings of Vermont as a distinctive place. The convergence of these discourses across the set of brochures gives insight into the ways interpretation serves to both direct individual visitor experiences at particular sites, and to influence the development of larger-scale place meanings.