关键词： Logging damage   Rodent ecology   Rain-forest   Reserve   Uganda   Model   Uganda   Road   Secondary road   Central African Republic   Rainforest   Rodent   Primary highways   Access roads  

摘要： Despite increasing pressure to harvest timer from African tropical forests, the short- and long-term ecological effects of qualitative and quantitative variation in extraction practices rarely have been examined. At a site in the southwestern Central African Republic, we surveyed rodent and tree communities and vegetation structure in unlogged forest and along skid trails and secondary and primary access roads at 12 and 19 years after logging. The most important source of variation among transects was the type of logging road: primary and secondary access roads showed the greatest change and skid trails the least. An intercorrelated suite of changes occurred along the margins of the roads, including changes in rodent community composition, increases in rodent abundance and diversity, changes in the height distribution of rodent abundance, increases in understory foliage density, and decreases in sapling density and tree species richness. Ecological changes along the secondary roads were nearly as strong as those along primary roads, despite the fact that secondary roads had been abandoned immediately after logging, whereas primary roads had been traveled up to the time of the research. Continuing edge-induced effects along graded road margins at between 12 and 19 years after logging were indicated by differences in tree species composition, sapling and tree densities, and understory density. Our results support conclusions of increased disturbance to rainforest communities with increasingly destructive road construction techniques and suggest that canopy damage rather than stem damage is the most appropriate measure of logging damage. Although minimizing the length of access roads is important in reducing ecological effects, it should not be achieved at the expense of increased canopy damage. Rodent communities appear to be an easily measured indicator of these ecological changes and may be responsive to landscape-level changes in forest cover and degradation.

关键词： ants   Camponotus   mangrove   Sonneratia  

摘要： The distribution and density of the ant fauna in the canopy of the mangrove tree Sonneratia alba J. Smith were investigated in Darwin Harbour, Australia. Ten ant species were found on Sonneratia but on the experimental trees only Camponotus sp. A. Crematogaster sp. A, Tetraponera punctulata Smith and Tapinoma spp. occurred at high densities. Camponotus sp. A was by far the most common species and is only known from Sonneratia. Samples of Sonneratia branches were taken at l-m intervals from 4 to 10 m above the lowest astronomical tide (LAT) level. A total of 278 nest chambers was dissected from the branches and the contents identified and counted. All observed nests were inferred to have been excavated by Camponotus sp. A queens, which were often observed excavating small cavities in the green shoots. The nest chambers were all small (5.2 +/- 0.6 cm), normally covering only one internode, and the mean number of workers of Camponotus sp. A per nest was only 15.9. Chambers have only one small entrance, which can be blocked by a major worker or the queen with their head during high tide. The percentage of twigs hollowed out and inhabited by ants ranged from 2% at 4-5 m to more than 25% higher than 9 m above LAT. Queens were never observed in internodes that were more than 1 year old, although workers and brood were present. It is therefore assumed that the queens die shortly after colony founding and that the workers take over reproduction through some sort of thelytokous parthenogenesis.

关键词： patch size   edge-effects   arthropod communities   habitat heterogeneity   pyrethrum knockdown  

摘要： Fragmentation and management of temperate forests has resulted in the creation of isolated patches of habitat ranging in size from the single tree to large stands of forest and plantation. Pyrethroid knockdown sampling of canopy arthropods in Pinus sylvestris in a British heathland matrix revealed larger forest patches (10 ha) supported greater populations of certain arthropod specialists than small patches (1 ha), and that individual trees support a qualitatively different fauna with a stronger heathland influence. Further, patch edges differ from patch interiors, particularly with respect to woodland specialist spiders. Feeding guilds differ between edges and interiors. Scaffold-web building spiders prefer larger patches, whilst aphid species with long rostra capable of penetrating thick exposed cuticle predominate on exposed single trees (P = 0.007) and patch edges. Predator densities were lower on single trees (P = 0.024), but there was little evidence of a compensatory increase in density of herbivores. No evidence was found for species-area or density-area effects, suggesting patch heterogeneity with respect to edge and interior may be relatively important at the scales examined. The taxa examined in greatest detail were the Homoptera, Lepidoptera, Symphyta, Coleoptera and Araneae, with the latter group identified to species level to examine relationships between feeding guild and patch character. Microclimatic variables related to exposure are proposed to be an important determinant of the patterns observed. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： granivory   ants   birds   rodents   woodland-savanna habitat  

摘要： Seed removal from bait stations was studied in miombo habitat in western Zimbabwe. Previous studies of seed predation in southern Africa have largely been conducted in desert ecosystems. However, this woodland-savanna habitat is more mesic and has relatively predictable rainfall patterns. The experiment was conducted in grassy and woody microhabitats in the hot, dry season and early wet season, and followed a year in which precipitation was 69 % of the long-term average. Birds removed the greatest quantity of seeds, followed by ants and then rodents. Previous studies in northern hemisphere mesic environments emphasize the importance of rodents and minor role of invertebrates in seed predation. Although our site appears to have more in common with southern hemisphere desert sites than with northern hemisphere mesic sites, we recognize that our results are likely to reflect a lower limit of consumption by rodents.

关键词： avian frugivores   genetic diversity   plant recruitment   RAPD   seed dispersal   spatial variation  

摘要： We examined the patterns of random amplified polymorphic DNA (RAPD) variation among seven Prunus mahaleb (Rosaceae) populations extending over approximate to 100 km(2) to examine local differentiation in relation to spatial isolation due to both geographical distance and differences in elevation. No less than 51.4% of the RAPD loci were polymorphic, but very few were fixed and among-population variation accounted for 16.46% of variation in RAPD patterns. Mean gene diversity was 0.1441, with mean Nei's genetic diversity for individual populations ranging between 0.089 and 0.149. Mean G(ST) value across loci was 0.1935 (range, 0.0162-0.4685), giving an average estimate for Nm of 1.191. These results suggest extensive gene flow among populations, but higher G(ST) and lower Nm values relative to other outcrossing. woody species with endozoochorous dispersal, also suggest a process of isolation by distance. The combined effect of both geographical and elevation distances and nonoverlapping flowering and fruiting phenophases on the G(ST) matrix was partially significant, revealing only marginal isolation of the P. mahaleb populations. The matrix correlation between estimated Nm values among populations and the geographical + elevation distance matrices (r = -0.4623, P = 0.07), suggests a marginal trend for more isolated populations to exchange less immigrants. Long-distance seed dispersal by efficient medium-sized frugivorous birds and mammals is most likely associated to the high levels of within-population genetic diversity. However, vicariance factors and demographic bottlenecks (high postdispersal seed and seedling mortality) explain comparatively high levels of local differentiation.

关键词： nematodes   earthworms   acidification   enchytraeids   agroforestry  

摘要： Pinus radiata was planted in a grazed pasture at Tikitere, New Zealand in 1973;final tree stocking rates were 0, 50, 100, 200 and 400 stems ha(-1);trees were harvested in 1999. We sampled the loamy sand for chemistry, earthworms, enchytraeids and nematodes during crop growth. There were no visible changes in the soil profile between years 2 and 25 of the P. radiata rotation, but marked changes in soil chemistry with pH declining at all depths. Topsoil pH declined but plant-available P and the soil C:N ratio increased. That similar trends occurred in pasture may have reflected reduced inputs. Lumbricid earthworms declined with increasing time and tree stocking rate;significant populations were found only in pasture at 25 years;no related changes in soil bulk density were detected. Enchytraeids were abundant but declined in the plots with 200 and 400 stems ha(-1). The composition of the nematode fauna at a soil depth of 0-10 cm varied, and there were changes in the "control" pasture. Pratylenchus sp. and Pungentus sp. were characteristic of pasture;Diphtherophora sp. appeared at higher tree stocking rates. In addition to changes related to the change in landuse there were temporal changes that affected faunal composition across tree stocking rates: Heterodera sp. and Paratylenchus sp. were rare after year 6;Prismatolaimus sp. was most abundant in years 2, 13 and 25;Axonchium sp. occurred in year 6 and Alaimus sp. mainly in year 25. Overall, the changes in soil chemistry reflected the change from pasture to forest. Parallel changes in soil microfauna and macrofauna also reflected the change in landuse, from fertilised pasture to coniferous forest, and are considered reversible.

关键词： 反刍动物   种系发生树   亚目分类   乳蛋白基因序列  

摘要： 依据牛的4种乳蛋白（α-乳清蛋白、β-乳球蛋白、和к-酪蛋白）基因已知序列设计引物，用PCR的方法扩增并克隆测定了牦牛α-乳清蛋白全序列（2999bp），水牛的α-乳清蛋白基因全序列（2784bp），东北马鹿的α-乳清蛋白基因部分序列（1582bp），β-酪蛋白基因的5’侧翼序列（987bp）和第4～第9外显子区序列（1090bp）、β-乳球蛋白5’侧翼序列（2167bp），3’端侧翼序列（1096bp）、к-酪蛋白第4外显子序列（780bp）。依据。酷蛋白第4外显子363bp的片段构建了1个包含20个物种（或亚种）的反刍动物种系发生树，该种系发生树中牛科动物具有典型的单源发生关系。据此种系发生树对牦牛及糜鹿的分类与起源进行初步探讨。依据其他几种奶蛋白基因不同区段所构建的种系发生树表明，这些区段至少适于亚科间种系发生分析。

关键词： herbivory   lepidopteran larvae   oak   polyphagy   Quercus   reciprocal replacement   seedling survival  

摘要： The acorn-producing oak Quercus crispula Blume is shade-tolerant and its seedlings were found to be underdispersed on the forest floor, forming seedling aggregations near fertile canopy trees. However, 84.4% of the seedlings were dead within 2 years, with the highest mortality near the adult canopy trees of Q. crispula. This was mostly due to the high levels of herbivory by lepidopteran larvae. The most serious damage was caused by spring consumers, which fed on the leaves of canopy trees in June and, when the food quality of the leaves declined, fell down to the forest floor to consume the juveniles, including the seedlings. Contrary to the expectation of the herbivore-host arms race theory, most of the herbivores were polyphagous. The most dominant spring consumer Telorta edentata (Leech) was also polyphagous, and its distribution on the forest floor showed a high level of association with the distribution of dead oak seedlings.

关键词： mitochondrial ND5 gene   phylogenetic tree   ground beetles   geohistory   Japanese Carabina fauna  

摘要： Phylogenetic analyses based on the mitochondrial ND5 gene comparisons and the geohistory of the Japanese Islands suggest that each Japanese species belonging to the subtribe Carabina has its own history for the establishment of its present habitat in the Japanese Islands. It can be roughly classified into two categories: (1) species which were derived from the ancestry that inhabited ancient Japan at the time of its split from the Eurasian Continent [ca, 15 million years ago (MYA)], followed by diversification within the Japanese Islands;and (2) species which invaded Hokkaido from the Eurasian Continent through land-bridges from Sakhalin and/ or the Kuriles or from western Japan from the Korean Peninsula during the glacial era (<2 MYA).

关键词： 链脲佐菌素   树qu   糖尿病模型   患病率  

摘要： 目的:探讨链脲佐菌素(STZ)树(qu)糖尿病(DM)动物模型的空腹血糖(FBG)标准和最佳药剂量.结论:树(qu)DM模型标准为FBG≥11.1mmol/L,最佳STZ剂量为150mg/kg.