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991.
Many animals can adjust their behavioral strategies to reduce predation risk. We investigated whether rain forest monkeys and duikers alter their antipredatory behavior in response to hunting by humans in southwestern Gabon. We compared monkey and duiker responses to human observers in an area where hunting is prohibited, to those in a nearby area where hunting pressure is moderate but spatially variable. The results of our study indicate that monkeys become more secretive when hunted, commencing alarm calls only when at a certain distance (typically > 50 m) from humans. We found no difference in monkey group size between hunted and no-hunting areas. In no-hunting areas, duikers often freeze in response to approaching observers, but in hunted areas they abandon this strategy and rapidly flee from humans. Duikers also whistle more often in areas where they are hunted frequently. Our findings have at least two important implications. First, behavioral observations of monkeys and duikers may be useful in gauging local hunting intensity in African rain forests. Second, duiker densities are likely to be overestimated in hunted areas, where they more readily flee and whistle, and underestimated in no-hunting areas, where they rely on freezing behavior to avoid detection. Because behavioral adaptations to hunting vary both among species and localities, these differences should be considered when attempting to derive population-density estimates for forest wildlife.  相似文献   
992.
Aim  To assess whether spatial variation in sampling effort drives positive correlations between human population density and species richness.
Location  British 10 × 10 km squares.
Methods  We calculated three measures of species richness from atlas data of breeding birds in Britain: total species richness, species richness standardised for sampling effort, and the number of species only recorded in supplementary casual records in a manner not standardised for survey effort. We then assessed the form of the relationship between these richness estimates and human population density, both with and without taking spatial autocorrelation into account.
Results  Both total and standardised species richness exhibit similar species richness–human population density relationships; species richness generally increases with human population density, but decreases at the very highest densities. Supplementary species richness is very weakly correlated with human population density.
Main conclusions  In this example, sampling effort only slightly influences the form of species richness–human population density relationships. The positive correlation between species richness and human population density and any resultant conservation conflicts are thus not artefactual patterns generated by confounding human density and sampling effort.  相似文献   
993.
Here, I examine overlapping resource use of forest and cultivated resources by villagers and tonkean macaques (Macaca tonkeana) in Lore Lindu National Park, Sulawesi, Indonesia. An integrative research design was employed, using methods from primatology and cultural anthropology, in conjunction with quantitative measurements of cacao crop loss. The results indicate that the current patterns of overlapping resource use may not be severely affecting the tonkean macaques or villagers in Lindu. The research does, however, point to possible future difficulty if cacao crop raiding by macaques increases, and as changing socioeconomic trends and loss of traditional folklore result in further modification of macaque habitat. Successful strategies to ameliorate human–macaque conflict may require efforts aimed at the adoption of alternative buffer zone crops that use shade-management systems, the deliberate protection of important macaque food species, and increasing local tolerance to crop raiding by exploring the role of macaques in forest regeneration.  相似文献   
994.
Background For veterinary management of non‐human primates in captivity, and conservation of wild‐living primates, management of their health risks is necessary. Incidences of pathogenic bacteria in the fecal specimens are considered as one of the useful indicators for non‐invasive health monitoring. Methods We carried out the detection of Clostridium perfringens in feces from captive and wild chimpanzees by the rapid polymerase chain reaction method. Results The bacterium was detected in most fecal specimens (80%) in captive chimpanzees. Contrarily, the detection rate in the wild chimpanzees was low, with 23% (n = 12) of 53 fecal samples from the Bossou group, Guinea, and 1.2% (1/81) in the Mahale group, Tanzania. Conclusions These results show that the intestinal microflora differs between Pan populations under various living conditions, being influenced by their diet and environment.  相似文献   
995.
Understanding microsite requirements is critical for restoring sustainable rare plant populations and creating meaningful management plans that will enhance native species’ population viability. Natural areas bordered by urban communities have restricted size and constrained management options that confound goals of preserving biodiversity. Using geographical information systems and observational and experimental studies, we determined that current microsites required for seedling establishment within existing habitat of the federally endangered Crenulate leadplant are few and spatially restricted, resulting in little wild seedling recruitment. Experimental and wild seedlings had highest germination rates in litter layers 1–2 cm in depth and survived the longest in litter 0.5–2 cm deep. Fire suppression and aggressive native and exotic plants have accumulated litter up to 33 cm near some of the wild adult Crenulate leadplant. Only 9% of habitat occupied by this taxon at its largest population is conducive to seedling establishment. Similarly, 30% is conducive to seedling establishment in the second largest population. Fire plays a critical role in South Florida ecosystem dynamics and the restoration and preservation of its landscape and biodiversity. When fire is not possible, other management is needed. Manual litter and downed debris removal are recommended at both population sites to improve the probability of Crenulate leadplant seedling establishment and population persistence.  相似文献   
996.
The first population ecology study of the endangered Magnolia sargentiana Rehder & Wilson (Magnoliaceae) is reported in the paper. It is a protected species in China but little is known about its present status in the field. In 2007 and 2008 we surveyed the population and conservation status of M. sargentiana in the Provincial Mamize Nature Reserve and the National Meigu Dafengding Nature Reserve, Sichuan Province, southwestern China. Natural regeneration is poor because of unfavorable environmental conditions and anthropogenic disturbances. Flower buds and bark of M. sargentiana are used in traditional Chinese medicine and their collection by local people from 1983 to 1994 has led to dramatic population declines. The collection of flower buds and bark is now banned, but hewing branches for firewood and grazing continues to have a negative impact on the recovery of M. sargentiana populations. To protect the species we require a ban on hewing branches, closure of primary forest to reduce humans and ungulates, better education of local people, and increased awareness of wildlife conservation.  相似文献   
997.
To effectively conserve sour orange (Citrus aurantium L.) germplasm on two islands at the estuary of the Yangtze River in China, we estimated genetic variation and relationships of the known parental trees and their proposed descendents (young trees) using the fingerprints of random amplified polymorphic DNA (RAPD). Results based on RAPD analyses showed considerable genetic diversity in the parental populations (He = 0.202). The overall populations including the parental and young trees showed slightly higher genetic diversity (He = 0.298) than the parents, with about 10% variation between populations. An unweighted pair group method with arithmetic mean analysis dendrogram based on cluster analysis of the Jaccard similarity among individuals demonstrated a more complicated relationship of the parental and young trees from the two islands, although the young trees showed a clear association with parental trees. This indicates a significant contribution of parental trees in establishing the sour orange populations on the two islands. According to farmers' knowledge, conservation of only one or two parental trees would be sufficient because they believed that the whole populations were generated from a single mother tree. However, this study suggests that preserving most parental trees and some selected young trees with distant genetic relationships should be an effective conservation strategy for sour orange germplasm on the two islands.  相似文献   
998.
The introduction of a predatory flatworm, Platydemus manokwari, has been considered a cause of the decline of endemic land snails on the tropical oceanic islands. To clarify the effect of P. manokwari on land snail survival in the field, we examined survival rates of snails experimentally placed in areas where snails are absent (i.e., P. manokwari is present) on Chichijima, Ogasawara (Bonin) Islands. We found that over 50 and 90 percent of the snails were dead after 3 and 11 d, respectively, and that the main cause of mortality was predation by P. manokwari.  相似文献   
999.
Habitat fragmentation has resulted in many species becoming geographically restricted, as dispersal among subsequent isolates becomes compromised. This study investigated the effects of historical fragmentation on the genetic diversity and differentiation of Australia's Bunya Pine (Araucaria bidwillii) using random amplified DNA (RAPD) markers. High diversity characterises all Bunya populations sampled, regardless of population size or degree of isolation, which may be either due to similar effective population size among populations, or the lagging effects of the detection of contemporary genetic signal in long-lived conifer species. Large genetic differentiation characterises the northern and southern populations, although all sampled populations are significantly differentiated from each other. The northern population, at Mt Lewis, is responsible for the majority of variation detected among populations, and as such represents a significant genetic reservoir. The conservation of the genotypes of the Mt Lewis population may be imperative for the future of the species, given predicted models of accelerated climate change over the coming decades.  相似文献   
1000.
保护性耕作对稻田土壤有机质的影响   总被引:9,自引:0,他引:9  
邵景安  唐晓红  魏朝富  谢德体 《生态学报》2007,27(11):4434-4442
研究使用常规犁耕-休闲(DTF),常规犁耕-小麦(DTW),保护耕作-休闲(CTF),保护耕作-小麦(CTW)4个处理,评价连续实验10a后保护性耕作对稻作区SOM的影响。结果表明:垄作、免耕和小麦种植的结合是稻作区一种较好的保护性耕作实践。它不仅显著增加SOM在土壤表层的聚集,而且它也通过改变SOM的组成和结构显著影响土壤胡敏酸的光谱和热解特性。相比其他处理,垄作免耕(稻麦)在0~10cm土层拥有最多的SOM含量,但随着土层厚度的增加,这一含量下降的也较为迅速。垄作免耕(稻麦)土壤胡敏酸在波长665nm处的光密度为0.122,465nm处为0.705,而常规平作(中稻)在这两个波长处却分别为0.062和0.321。垄作免耕土壤胡敏酸DTA曲线在360~365℃处放热峰的焓变值比常规平作低,1000~1050cm-1吸收峰常规平作也比垄作免耕强。垄作免耕土壤腐殖质的氧化稳定系数增高,表明长期垄作免耕土壤腐殖酸的缩合度增高,芳构化程度增强。通过保护性耕作和作物实践可以管理稻田土壤,维持充分的SOM积累,缓解土壤有机碳的丢失。  相似文献   
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