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971.
Epiphytes, air plants that are structurally dependent on trees, are a keystone group in tropical forests; they support the food and habitat needs of animals and influence water and nutrient cycles. They reach peak diversity in humid montane forests. Climate predictions for Central American mountains include increased temperatures, altered precipitation seasonality, and increased cloud base heights, all of which may challenge epiphytes. Although remaining montane forests are highly fragmented, many tropical agricultural systems include trees that host epiphytes, allowing epiphyte communities to persist even in landscapes with lower forest connectivity. I used structural equations models to test the relative effects of climate, land use, tree characteristics, and biotic interactions on vascular epiphyte diversity with data from 31 shade coffee farms and 2 protected forests in northern Nicaragua. I also tested substrate preferences of common species with randomization tests. Tree size, tree diversity, and climate all affected epiphyte richness, but the effect of climate was almost entirely mediated by bryophyte cover. Bryophytes showed strong sensitivity to mean annual temperature and insolation. Many ferns and some orchids were positively associated with bryophyte mats, whereas bromeliads tended to establish among lichen or on bare bark. The tight relationships between bryophytes and climate and between bryophytes and vascular epiphytes indicated that relatively small climate changes could result in rapid, cascading losses of montane epiphyte communities. Currently, shade coffee farms can support high bryophyte cover and diverse vascular epiphyte assemblages when larger, older trees are present. Agroforests serve as valuable reservoirs for epiphyte biodiversity and may be important early-warning systems as the climate changes.  相似文献   
972.
Tropical forests are experiencing enormous threats from deforestation and habitat degradation. Much knowledge of the impacts of these land-use changes on tropical species comes from studies examining patterns of richness and abundance. Demographic vital rates (survival, reproduction, and movement) can also be affected by land-use change in a way that increases species vulnerability to extirpation, but in many cases these impacts may not be manifested in short-term changes in abundance or species richness. We conducted a literature review to assess current knowledge and research effort concerning how land-use change affects species vital rates in tropical forest vertebrates. We found a general paucity of empirical research on demography across taxa and regions, with some biases toward mammals and birds and land-use transitions, including fragmentation and agriculture. There is also considerable between-species variation in demographic responses to land-use change, which could reflect trait-based differences in species sensitivity, complex context dependencies (e.g., between-region variation), or inconsistency in methods used in studies. Efforts to improve understanding of anthropogenic impacts on species demography are underway, but there is a need for increased research effort to fill knowledge gaps in understudied tropical regions and taxa. The lack of information on demographic impacts of anthropogenic disturbance makes it difficult to draw definite conclusions about the magnitude of threats to tropical ecosystems under anthropogenic pressures. Thus, determining conservation priorities and improving conservation effectiveness remains a challenge.  相似文献   
973.
Next-generation sequencing (NGS) has significantly increased knowledge of microbial communities and their distribution. However, it is still not common to apply NGS technology to microbial conservation. We sought to use NGS technologies to evaluate conservation strategies for wood-inhabiting fungi. Evaluating a deadwood experiment 3 years after it was established, we specifically examined which tree species combinations promoted the highest richness of wood-inhabiting fungi. Deadwood enrichment was an effective strategy and logs of 6 tree species, either those with the highest wood-inhabiting fungal α and γ diversity or those with the highest β diversity, maintained >1,000 operational taxonomic units (OTUs) spread over a wide range of taxonomic groups. In comparison, a conservation strategy based only on the results of sporocarp surveys yielded 591 OTUs. This result highlights the need to use NGS approaches to inform microbial conservation strategies. We also determined that 5 tree species with the highest saproxylic beetle γ diversity simultaneously conserved wood-inhabiting fungi. Apart from deadwood volume, we suggest data on deadwood quality and species also be included as indicators, especially for wood-inhabiting fungal diversity, and incorporated quickly in forest assessment and monitoring systems in Central Europe.  相似文献   
974.
We aspired to set conservation priorities in ways that lead to direct conservation actions. Very large‐scale strategic mapping leads to familiar conservation priorities exemplified by biodiversity hotspots. In contrast, tactical conservation actions unfold on much smaller geographical extents and they need to reflect the habitat loss and fragmentation that have sharply restricted where species now live. Our aspirations for direct, practical actions were demanding. First, we identified the global, strategic conservation priorities and then downscaled to practical local actions within the selected priorities. In doing this, we recognized the limitations of incomplete information. We started such a process in Colombia and used the results presented here to implement reforestation of degraded land to prevent the isolation of a large area of cloud forest. We used existing range maps of 171 bird species to identify priority conservation areas that would conserve the greatest number of species at risk in Colombia. By at risk species, we mean those that are endemic and have small ranges. The Western Andes had the highest concentrations of such species—100 in total—but the lowest densities of national parks. We then adjusted the priorities for this region by refining these species ranges by selecting only areas of suitable elevation and remaining habitat. The estimated ranges of these species shrank by 18–100% after accounting for habitat and suitable elevation. Setting conservation priorities on the basis of currently available range maps excluded priority areas in the Western Andes and, by extension, likely elsewhere and for other taxa. By incorporating detailed maps of remaining natural habitats, we made practical recommendations for conservation actions. One recommendation was to restore forest connections to a patch of cloud forest about to become isolated from the main Andes. Establecimiento de Prioridades Prácticas para la Conservación de Aves en los Andes Occidentales de Colombia  相似文献   
975.
Fuelwood is one of the major sources of energy in the domestic sector across the rural areas,especially in the developing regions across the world.The Northeastern Himalayan state of Manipur is dominated by the tribal population that largely depends on fuelwood from the nearby forest area.The entire dependence on forests for energy resources is affecting the sustainability of the forest ecosystem in the region,thus indicating the livelihood conditions.Since land-use land-cover change is the key driver to the change in resource availability of a region,the present study has tried to analyze the landcover changes over a period 28 years.The second major component affecting resource availability is the increasing population pressure that leads to changes in the land dynamics,which directly affect the resource production.Based on the existing consumption pattern,the total consumption of fuelwood in the watershed ranges fiom a minimum of 289.992 tons/year to a maximum of 3545.719 tons/year with an average of 1561.956 tons/year in the year 2009 and simulated fuelwood consumption for the year 2021 is around 1469.260 tons/year.Nine different probable scenarios of resource are proposed to calculate the stress value that can be used by the policy-makers and planners for suitable policy implementation at the micro level with a complex social system.  相似文献   
976.
In connection with the change in economic principles and disintegration of big industrial enterprises, the environmental pollution in Baltic States decreased considerably in 1991-1996. Although there are still many things waiting to be done, the improvement of the Baltic environmental situation during the years of independence gives us a cause to be optimistic.  相似文献   
977.
Forest management in south eastern Nigeria has changed hands from the forest communities to foreign technology. As a result the sustainable, conservative and cyclical use that characterised the communities that lived in balance with their forest resources are no longer practised. Consequently, a great deal of the region's valuable timber trees has been lost and the environmental influences of the forest grossly reduced. The local communities have not only been deprived of a multitude of non-timber forest resources upon which they depend for their survival and well-being but have also lost their knowledge of traditional forest management. Although these consequences are far-reaching, the neglected majority in the rural areas bear the brunt. To save what is left of the once vast forest areas, communities in and around the biome need to be empowered to manage their forest resources. Empowerment will challenge their responsibility and their ability to function for the common good—themselves, the State and the world at large.  相似文献   
978.
The mushroom Macrocybe gigantea collected from the native stands in the Yunnan Province of China can be considered a species that efficiently bioconcentrates mercury (Hg) because the values of the bioconcentration factor (BCF) calculated for this element were well above unity, i.e., for caps, the BCF ranged from 4.8 to 24 and, for stipes, from 3.6 to 18. The Hg content of the composite samples of caps of the fruit bodies collected in the wild ranged from 0.48 to 1.78 mg kg?1 dry matter and of stipes from 0.36 to 1.70 mg kg?1 dry matter, whereas 0.37 and 0.25 mg kg?1 dry matter were observed for farmed specimens. M. gigantea, because of a large biomass of the fruit bodies that emerge in a cluster, is an important food item in Yunnan, but knowledge on mineral composition and content of this species is largely absent. This study estimated the lifetime average daily dose intake of Hg through mushroom as well as the incremental lifetime cancer risk and non-cancer health hazard to consumers of this mushroom.  相似文献   
979.
加勒比松1a生幼林氮磷钾不同配比的追肥试验表明,追肥后6a,肥效都极显著;其中以第2a的效果最显著,最大树高、胸径、材积分别比不追肥增加39.1%~52.6%、45.4%~109.3%和34.1%~405.6%;6a后肥效下降,但追肥仍比不追肥的树高、胸径、材积增长8.7%~20%、10.9%~17.9%、31.5%~54.7%。氮磷钾配合施用的效果最佳,施氮磷而缺钾有负效应。当氮磷钾相同配比(N30P30K30)时有特殊的低效应。  相似文献   
980.
河流污染类型优控顺序确定方法及其在海河流域的应用   总被引:1,自引:0,他引:1  
建立河流污染类型优控顺序方法并将其应用于海河流域,结合海河流域主要河流站点水质监测数据和沉积物分析数据,对各水系河流的耗氧污染、富营养化及沉积物重金属污染状况进行整体评估,确定海河流域河流污染优先控制顺序.结果表明,海河流域有36%河长耗氧污染严重,重污染河流主要分布在黑龙港运东水系、子牙河水系和徒骇马颊河水系,重度污染河长比例分别为100%、54%和68%.重度富营养化河流主要分布在子牙河水系、北三河水系(北运河、潮白河、蓟运河)和徒骇马颊河水系,重度污染河长比例分别为50.0%、52.3%和39.7%;沉积物重金属生态风险普遍较低,子牙河水系、滦河水系和漳卫河水系重度污染河长比例分别为26.5%、21.6%和28.0%.海河流域河流中度以上的耗氧污染、富营养化及重金属污染河长分别为8203 km、6927 km和6733 km,由此确定流域河流污染优控顺序应该是首先关注耗氧污染,然后再控制河流富营养化,最后再治理重金属污染.分水系优控顺序研究表明永定河水系、大清河水系、黑龙港运东水系、子牙河水系和徒骇马颊河水系主要面临耗氧污染问题;北三河水系应首先控制富营养化;滦河水系、海河干流和漳卫河水系应关注沉积物重金属污染.  相似文献   
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