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1.
Chile has more than half of the temperate forests in the southern hemisphere. These have been included among the most threatened eco-regions in the world, because of the high degree of endemism and presence of monotypic genera. In this study, we develop empirical models to investigate present and future spatial patterns of woody species richness in temperate forests in south-central Chile. Our aims are both to increase understanding of species richness patterns in such forests and to develop recommendations for forest conservation strategies. Our data were obtained at multiple spatial scales, including field sampling, climate, elevation and topography data, and land-cover and spectrally derived variables from satellite sensor imagery. Climatic and land-cover variables most effectively accounted for tree species richness variability, while only weak relationships were found between explanatory variables and shrub species richness. The best models were used to obtain prediction maps of tree species richness for 2050, using data from the Hadley Centre’s HadCM3 model. Current protected areas are located far from the areas of highest tree conservation value and our models suggest this trend will continue. We therefore suggest that current conservation strategies are insufficient, a trend likely to be repeated across many other areas. We propose the current network of protected areas should be increased, prioritizing sites of both current and future importance to increase the effectiveness of the national protected areas system. In this way, target sites for conservation can also be chosen to bring other benefits, such as improved water supply to populated areas. 相似文献
2.
普通小麦与山羊草叶绿体基因组长度热点突变区的核苷酸序列分析 总被引：2，自引：0，他引：2
检测了Ae. speltoides和Ae. ovata叶绿体基因组的一个长度热点突变区的核苷酸序列，并与普通小麦、四倍体Ae. crassa 以及Ae. squarrosa的相应序列进行了比较分析。从rbcL基因的终止密码子到cemA基因内的HindIII位点，Ae. speltoides和Ae. ovata的核苷酸序列长度分别为2 808 和 2 810bp。与四倍体Ae. crassa的序列相比，在普通小麦和Ae. speltoides中各有一个791 bp的大片段缺失，在Ae. ovata中存在一个793 bp的大片段缺失。Ae. ovata的缺失片段比普通小麦和Ae. speltoides的长2个碱基，推测Ae. ovata的大片段缺失在进化上是独立发生的。Ae. speltoides的大片段缺失与普通小麦的完全相同，支持Ae. speltoides是普通小麦叶绿体基因组供体的假说。除了大片段缺失外，在这个区域还检测到了7 个插入/缺失和15个碱基替换突变。研究结果表明，这个长度热点突变区的核苷酸序列分析是研究小麦与山羊草叶绿体基因组之间遗传变异关系的一个非常有效的途径。 相似文献
3.
戴志强 《农业环境科学学报》2012,31(2)
介绍了国际著名评论期刊——Natural Product Reports 的“Hot off the Press”评价系统的宗旨、演进、现状和学术背景及其取得成功的基本要素,利用ISI Web of Science数据库验证了“Hot off the Press”评价系统的客观价值,指出了该评价系统的局限性,以期对相关领域的科研人员和情报、编辑工作者有所帮助。 相似文献
4.
Human-wildlife conflict in the Kingdom of Bhutan: Patterns of livestock predation by large mammalian carnivores 总被引：1，自引：0，他引：1
We examined predation activity throughout Bhutan by tiger (Panthera tigris), common leopard (Panthera pardus), snow leopard (Uncia uncia) and Himalayan black bear (Ursus thibetanus) on a variety of livestock types using data gathered over the first two years (2003-2005) of a compensation scheme for livestock losses. One thousand three hundred and seventy five kills were documented, with leopards killing significantly more livestock (70% of all kills), than tigers (19%), bears (8%) and snow leopards (2%). About 50% of livestock killing were of cattle, and about 33% were of horses, with tigers, leopards and snow leopards killing a significantly greater proportion of horses than predicted from availability. Examination of cattle kills showed that leopards killed a significantly greater proportion of smaller prey (e.g., calves), whereas tigers killed a significantly greater proportion of larger prey (e.g., bulls). Overall, livestock predation was greatest in summer and autumn which corresponded with a peak in cropping agriculture; livestock are turned out to pasture and forest during the cropping season, and subsequently, are less well guarded than at other times. Across Bhutan, high horse density and low cattle and yak density were associated with high rates of livestock attack, but no relationship was found with forest cover or human population density. Several northern districts were identified as ‘predation hotspots’, where proportions of livestock lost to predation were considerable, and the ratio of reported kills to relative abundance of livestock was high. Implications of our findings for mitigating livestock losses and for conserving large carnivores in Bhutan are discussed. 相似文献
5.
Using summed individual species models and state-of-the-art modelling techniques to identify threatened plant species hotspots 总被引：1，自引：0，他引：1
Miia Parviainen Mathieu Marmion Miska Luoto Wilfried Thuiller Risto K. Heikkinen 《Biological conservation》2009,142(11):2501-2509
Reliable identification of hotspot areas with high numbers of threatened plant species has a central role in conservation planning. We investigated the potentiality of identifying the distribution, richness and hotspots of threatened plant species at a 25 ha resolution using eight state-of-the-art modelling techniques (GLM, GAM, MARS, ANN, CTA, GBM, MDA and RF) in a taiga landscape in north-eastern Finland. First, the individual species models developed based on occurrence records of 28 species in the 1677 grid squares and derived from different statistical techniques were extrapolated to the whole study area of 41 750 km2. Second, the projected presence/absence maps were then combined to create species richness maps, and the top 5% of grid cells ranked by species richness were classified as hotspots. Finally, we created an overall summary map by combining the individual hotspot maps from all eight modelling techniques and identified areas where the individual hotspots maps overlapped most. There were distinguishing differences in projections of the geographic patterns of species richness and hotspots between the modelling techniques. Most of the modelling techniques predicted several hotspot locations sporadically around the study area. However, the overall summary map showed the highest predictive performance based on Kappa statistics, indicating that the locations where the hotspot maps from the eight models coincided most harboured highest observed species richness. Moreover, the summary map filtered out the patchy structures of individual hotspot maps. The results show that the choice of modelling technique may affect the accuracy and prediction of hotspot patterns. Such differences may hamper the development of useful biodiversity model applications for conservation planning, and thus it is beneficial if the conservation decision-making can be based on sets of alternative maps and overlaying of predictions from multiple models. 相似文献
6.
生物基因组中简单重复序列的多态性是同源染色体不对等交换的结果之一,因此明确不对等交换的热点区域具有重要的理论意义。利用来源于优良玉米杂交种豫玉22的一套重组近交系(RIL)群体,对其遗传组成进行了SSR标记分析,发现40个不对等交换的SSR标记,不对等交换在群体间发生的概率介于0.34%~14.63%之间,每世代发生的频率为10-2~10-1,其中(AG)n重复的标记占发生不对等交换总标记的58.3%。有31个不对等交换标记分布于染色体上的11个热点区域,位于第9染色体以外的其它染色体上,其中第3和第5染色体上各分布2个不对等交换的热点区域。 相似文献
7.
Invertebrates play important roles in ecosystem functioning, but with the decline in biodiversity worldwide, it has become increasingly evident that our knowledge of invertebrate diversity distributions and of how to adequately integrate many invertebrates into conservation strategies is insufficient. We analyzed congruence between patterns of total as well as of endemic species richness of twelve invertebrate taxa across Europe and compared these patterns to those of so far predominantly studied vertebrates and plants. Coarse-scale centers of high collective diversity were identified, all in southern European regions. However, the strength of covariation between diversity patterns strongly depended on the respective taxa, with ground beetles emerging as one of the invertebrate taxa significantly reflecting endemism and total species richness distributions of many invertebrates, vertebrates and plants. Plants and ants showed similarly strong cross-taxon correlations. In contrast, correlations of vertebrates with invertebrates were in part less strong, questioning whether conservation strategies based on the former adequately account for diversity of invertebrates as a whole. Moreover, as the potential impact of environmental factors on diversity distributions varies among taxa, future climate change might affect relationships between richness patterns of different taxa. Our findings draw attention to the necessity of incorporating invertebrates, represented for instance by the highly diverse ground beetles, into national and international conservation decisions. They also highlight the importance of individual countries in maintaining European biodiversity and the responsibility of these countries for specific invertebrate taxa within international conservation frameworks, emphasizing the need for adequate consideration of invertebrates in the implementation of conservation actions. 相似文献
8.
The diversity of future landscapes might depend on our ability to predict their potential species richness. The predictability
of patterns of vascular plant species richness in a Finnish agricultural river landscape was studied using generalized linear
modeling, floristic records from fifty-three0.25-km grid squares in the “core” study area, and environmental variables derived
from Landsat TM images and a digital elevation model. We built multiple regression models for the total number of plant species
and the number of rarities, and validated the accuracy of the derived models with a test set of 52 grid squares. We tentatively
extrapolated the models from the core study area to the whole study area of 601 km2 and produced species richness probability maps using GIS techniques. The results suggest that the local ‘hotspots’ of total
flora (grid squares with > 200species) are mainly found in river valleys, where habitat diversity is high and a semi-open
agricultural-forest mosaic occurs. The ‘hotspots’ of rare species (grid squares with > 4 rare species) are also found in river
valleys, in sites where extensive semi-natural grasslands and herb-rich deciduous forests occur on steep slopes. We conclude
that environmental variables derived from satellite images and topographic data can be used as approximate surrogates of plant
species diversity in agricultural landscapes. Modeling of biological diversity based on satellite images and GIS can provide
useful information needed in land use planning. However, due to the potential pitfalls in processing satellite imagery and
model-building procedures, the results of predictive models should be carefully interpreted.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Tree diversity is one of the most important components of urban ecosystems, because it provides multiple ecological benefits and contributes to human well-being. However, the distribution of urban trees may be spatially segregated and change over time. To provide insights for a better distribution of tree diversity in a socially segregated city, we evaluated spatial segregation in the abundance and diversity of trees by socioeconomic group and their change over a 12-year period in Santiago, Chile. Two hundred vegetation plots were sampled across Santiago in 2002 and 2014. We found that overall abundance and diversity of urban trees for the entire city were stable over 12 years, whereas species richness and abundance of native tree species increased. There was segregation in tree species richness and abundance by socioeconomic group, with wealthier areas having more species and greater abundance of trees (for all tree species and native species) than poorer ones. Tree community composition and structure varied with socioeconomic group, but we found no evidence of increased homogenization of the urban forest in that 12 years. Our findings revealed that although tree diversity and abundance for the entire city did not change in our 12-year period, there were important inequities in abundance and diversity of urban trees by socioeconomic group. Given that 43% of homes in Santiago are in the lower socioeconomic areas, our study highlights the importance of targeting tree planting, maintenance and educational programs in these areas to reduce inequalities in the distribution of trees. 相似文献
10.
Ecosystems services sustain humans all over the world. The unsustainable use of ecosystem services around the world has led to widespread degradation which now threatens human health and livelihoods. Although the maintenance of ecosystem services is often used to justify biodiversity conservation actions, it is still unclear how ecosystem services relate to different aspects of biodiversity and to what extent the conservation of biodiversity will ensure the provision of services. The aim of this study was to find out whether biodiversity priorities, biomes, species richness and vegetation diversity hotspots co-occur in space with ecosystem services. The distribution of the ranges and hotspots of five ecosystem services (surface water supply, water flow regulation, carbon storage, soil accumulation, and soil retention) was assessed in South African biomes. Coincidence, overlap, and correlation analyses were used to assess spatial congruence between ecosystem services and species richness (plants and animals) and vegetation diversity hotspots. The grassland and savanna biomes contained significant amounts of all five ecosystem services. There was moderate overlap and a generally positive but low correlation between ecosystem services hotspots and species richness and vegetation diversity hotspots. Species richness was mostly higher in the hotspots of water flow regulation and soil accumulation than would be expected by chance. The water services showed varying levels of congruence with species richness hotspots and vegetation diversity hotspot. These results indicate that actions taken to conserve biodiversity in South Africa will also protect certain ecosystem services and ecosystem services can be used to strengthen biodiversity conservation in some instances. 相似文献