关键词： Cullenia exarillata   non-flying mammals   pollination   Western Ghats  

摘要： Many non-flying mammals help in the pollination of plant species in tropical forests. However, this remains poorly documented from India. Here we demonstrate with Cullenia exarillata, a canopy tree in the Western Ghats, how a wide range of visitors frequent flowers of the tree and how among them a few select mammals are important in pollination. Since Cullenia also uses bats as a pollinating vector, we further discuss how the dual strategy of using non-flying mammals and bats could have evolved in the wet forests of the Western Ghats.

关键词： browsing damage   Eucalyptus globulus   forestry   marsupial   plantation   repellent   thistles   vegetation management  

摘要： Browsing of commercial tree seedlings by mammalian herbivores can reduce long-term plantation productivity, and is an economic problem worldwide. Characteristics of both tree seedlings and their neighbours can influence browsing on the former, particularly by generalist herbivores. The nature of the combined effects of seedlings and their neighbours is, however, unknown. If effects are additive, it should be possible to exploit the capacity of herbivores to make foraging decisions at multiple scales in order to manage browsing of tree seedlings in forestry plantations. We conducted a field trial that focussed on browsing of Eucalyptus globulus seedlings by native marsupial herbivores. Our aim was to determine the absolute and relative importance of characteristics of both seedlings and neighbouring vegetation on browsing of seedlings. Seedlings with and without a chemical repellent were planted in vegetation patches that varied in the abundance and height of thistles. Browsing of seedlings was assessed over 16 weeks. Characteristics of both seedlings and neighbouring vegetation were shown to influence the degree to which seedlings were browsed, and the effects were additive. Repellent-treated seedlings received less browsing than those without repellent;and browsing decreased with increasing thistle cover. The presence of thistles also increased the time it took for browsers to find seedlings. Results are consistent with the associational plant refuge hypothesis, and vegetation effects may be manifested via an alteration in plant apparency. These results have applications in the forestry industry. They demonstrate the principle that the use of less palatable seedlings combined with tall, unpalatable vegetation can reduce browsing on plantation seedlings in the short-term, and that the effects are additive. (c) 2006 Elsevier B.V. All rights reserved.

关键词： distance sampling   efficiency   African mammals   cluster sampling  

摘要： Effective management and conservation of wildlife populations require reliable estimates of population size, which can be difficult and costly to obtain. We evaluated how precision in estimates of herd size and abundance varies with sample size and strip width using two field surveys and bootstrap resampling of the field data. We also examined precision under distance sampling and evaluated the cost-effectiveness of both survey techniques. Precision in estimates of abundance increased with increasing sample size and varied with strip width independently of sample size. The hazard rate key function was best for five species in two surveys with contrasting visibility conditions. Precision in density was more sensitive to the number of herds sighted than to variation in herd size and effective strip width for distance sampling. Strip counts produced lower abundance estimates but higher precision than distance sampling. We estimated that distance sampling would cost about US$3.1 km(-1) of transect. Strip counts deserve serious consideration for surveys of species that occur at high densities and form large, loose agglomerations but distance methods are suitable for species occurring at moderate to low densities in areas where visibility varies substantially. Distance sampling may thus need to be supplemented by strip counts to efficiently estimate densities of rare, abundant and highly clustered multi-species assemblages of African savanna mammals. In small areas, it may often prove necessary to conduct several surveys to obtain adequate sample sizes for distance models.

关键词： ants   birch   enemy-free space   Epirrita autumnata   plant structure   spiders   tritrophic interactions  

摘要： 1. Vegetation structural complexity is an important factor influencing ecological interactions between different trophic levels. In order to investigate relationships between the architecture of trees, the presence of arthropod predators, and survival and parasitism of the autumnal moth Epirrita autumnata Borkhausen, two sets of experiments were conducted. 2. In one experiment, the architectural complexity of mountain birch was manipulated to separate the effects of plant structure and age. In the other experiment the trees were left intact, but chosen to represent varying degrees of natural complexity. Young autumnal moth larvae were placed on the trees and their survival was monitored during the larval period. 3. The larvae survived longer in more complex trees if predation by ants was prevented with a glue ring, whereas in control trees smaller canopy size improved survival times in one experiment. The density of ants observed in the trees was not affected by canopy size but spider density was higher on smaller trees. The effect of canopy structure on larval parasitism was weak-, larger canopy size decreased parasitism only in one year. Until the fourth instar the larvae travelled shorter distances in trees with reduced branchiness than in trees with reduced foliage or control treatments. Canopy structure manipulation by pruning did not alter the quality of leaves as food for larvae. 4. The effect of canopy structure on herbivore survival may depend on natural enemy abundance and foraging strategy. In complex canopies herbivores are probably better able to escape predation by ambushing spiders but not by actively searching ants.

关键词： Forestry  

摘要： Newly established plantations are often damaged by heavy browsing. This is a major economic problem. Vegetation management involving the use of cover crops is a potential method for reducing browsing damage to plantation seedlings. An important first step in determining whether this is feasible is to determine the relative preferences of browsing herbivores for seedlings and crops. We conducted a no-choice feeding trial with red-bellied pademelons (Thylogale billardierii) and common brushtail possums (Trichosurus vulpecula) to determine their relative preferences for two common plantation species: Eucalyptus nitens and Pinus radiata, and three potential legume cover crops: bitter lupin (Lupinus albus), sweet lupin (L. angustifolius) and broad bean (Vicia faba L. cv Coles Dwarf). Pademelons exhibited a strong preference for P. radiata, but did not eat much of the legumes. Possums showed no significant preferences for any of the plants offered. A paired-choice feeding trial with pademelons demonstrated that bitter lupin was less preferred and oats (Avena sativa variety Esk) were more preferred than E. nitens. These results can now be integrated with an understanding of feeding behaviour at higher scales (e.g. vegetation patch) in order to design effective vegetation management for reducing browsing damage.

关键词： canopy arthropods   Eucalyptus obliqua   forest entomology   geographic distance   tree age   Tasmania   invertebrate trapping  

摘要： Despite the anthropogenically-induced changes to forest tree demographics, few studies have examined the differences in arthropod species composition between the crowns of trees of different ages. We tested for differences in the taxonomic composition of the canopy arthropod faunas of 100 y.o. and old-growth trees, using eight pairs of trees in an Eucalyptus obliqua tall open-forest with a rainforest understorey in the Warra Long Term Ecological Research Site in southern Tasmania and compared these differences to those related to geographic distances. Sticky traps, hanging flight-intercept traps and bark funnel traps were used to sample the canopy arthropods in different placement situations. There were no significant differences between 100 y.o. and old-growth trees at the tree level, but several at the trap and placement levels. Ordination analyses and correlation analyses indicated that high inter-pair variability related to the geographic distance between trees was partially masking tree age effects. The age of E. obliqua does influence canopy arthropod species composition, but this effect was weaker than the geographic effect that was evident in a relatively uniform forest with a maximum distance between trees of only 324 m. This implied high beta diversity in the forest type has implications for the planning of conservation reserves. Further work is needed to see if age effects are stronger in forests of the ages created by silvicultural treatment. (c) 2006 Elsevier B.V. All rights reserved.

关键词： 疾病动物模型   树鼩   亚热带地区   亚洲东南部   啮齿类动物   哺乳动物   大体解剖   新陈代谢   发病机理   灵长类  

摘要： 树鼩(tupaia,tree shrew)是最低等的灵长类哺乳动物,主要分布于亚洲东南部的热带和亚热带地区.由于具有体小、比较容易饲养、价廉及新陈代谢和大体解剖远比啮齿类动物更接近人类等优点,树鼩已广泛用于病毒、细菌、寄生虫和神经、内分泌、泌尿、肿瘤等方面的研究.疾病动物模型为研究疾病的发病机理、治疗及防治提供了平台.本文对树鼩作为疾病动物模型的研究作一概述。

关键词： 疾病动物模型   树鼩   亚热带地区   亚洲东南部   啮齿类动物   哺乳动物   大体解剖   新陈代谢   发病机理   灵长类  

摘要： 树鼩(tupaia,tree shrew)是最低等的灵长类哺乳动物,主要分布于亚洲东南部的热带和亚热带地区.由于具有体小、比较容易饲养、价廉及新陈代谢和大体解剖远比啮齿类动物更接近人类等优点,树鼩已广泛用于病毒、细菌、寄生虫和神经、内分泌、泌尿、肿瘤等方面的研究.疾病动物模型为研究疾病的发病机理、治疗及防治提供了平台.本文对树鼩作为疾病动物模型的研究作一概述.

关键词： HURRICANES   TREE islands   FOREST canopy gaps   EXOTIC plants   ARTHUR R. Marshall Loxahatchee National Wildlife Refuge (Fla.)  

摘要： Tree islands-small, wetland forest communities imbedded in a matrix of freshwater marsh-characterize Arthur R. Marshall Loxahatchee National Wildlife Refuge in South Florida. The establishment and spread of invasive exotic plant species were hypothesized to alter tree-island communities and prolong recovery times from hurricane disturbances. During the fall of 2004, two hurricanes, Frances and Jeanne, caused damage to these tree islands. We examined the spatial extent of damage to tree islands and tree species across the Refuge by sampling 74 islands. Each tree island was assigned an overall damage rating based on both the openness of the canopy and the type and quantity of damage received. Distance from the eye-wall of the hurricanes, tree-island size, average tree height on the island, and relative abundance of invasive exotic plants were examined as predictors of damage. Over 85% of the sampled tree islands had damage, with most of the damage occurring in the center of the Refuge. Most tree islands were found to have moderate damage, (i.e., snapped large branches and less than 50% canopy cover removed). Persea palustris (swamp bays) had more snapped trunks than Ilex cassine (dahoon holly) and Myrica cerifera (wax myrtle). Islands with larger trees had heavier damage than islands with shrubs or smaller trees. Fifty-eight percent of the tree islands sampled had either Lygodium microphyllum (lygodium) and/or Melaleuca quinquenervia (melaleuca). The only island with severe damage had abundant lygodium that appeared to have caused the entire canopy to collapse. These hurricanes present a unique opportunity to investigate recovery patterns of tree islands in an ecosystem impacted by invasive exotics. They also provide an opportunity to examine patterns of spread and recruitment of lygodium and melaleuca.

关键词： 随机广义Cookie-Cutter集   弱收敛   紧测度   记忆函数   系统发育树   线粒体完全基因组   傅立叶变换   Kullback-Leibler散度距离  

摘要： 我们首先在构造随机广义Cookie-Cutter集的过程中，通过记忆函数，研究了这种随机概率测度序列的紧测度的收敛性。方法是首先构造了[0，T]上的随机广义Cookie-Cutter集KT。令K_n为构造KT中的第n级集合，并在K_n上定义记忆函数。基于这个记忆函数，我们定义了K_n上的随机概率测度φ_n（Υ）。令Ψ_n（·）=Eφ_n（·），其中Ψ_n为随机测度φ_n的紧测度。最后证明了序列Ψ_n是弱收敛的且有Ψ=limΨ_n。 对生物信息问题的研究，我们主要是不通过序列比对，讨论64种脊椎动物的线粒体完全基因组之间的联系，用快速的傅立叶变换（FFT）作用于由蛋白质序列得到的组分向量，然后计算Kullback-Leibler散度距离，用PHYLIP软件包中的NJ（neighbour-joining）方法构造发育树。从系统发育树可以看出这64种线粒体基因组可以被分为两大部分。一部分是哺乳动物，另一部分包含两个子部分，分别是鱼类和古生物类（包括鸟类和爬行类）。由此建立的树的拓扑结构在很大程度上与已有的脊椎动物的系统发育树是吻合的。