关键词： biodiversity   ecological indicators   green-tree retention   small mammals   mountain pine beetle   Pinus contorta   Pseudotsuga menziesii   salvage harvest   stand structure  

摘要： We report on a retrospective investigation of the impacts of salvage harvesting of lodgepole pine (Pinus conform var. latifolia Engelm. ex S. Wats.), killed by an outbreak of mountain pine beetle (Dendroctonus ponderosae Hopk.) in the 1970s, with variable retention of Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco). Our inference to biodiversity was coniferous stand structure and four mammal species: the southern red-backed vole (Myodes gapperi Vigors), common shrew (Sorex cinereus Kerr), red squirrel (Tamiasciurus hudsonicus Erxleben) and northern Hying squirrel (Glaucomys sabrinus Shaw). We tested hypotheses that, at 30 years after salvage harvest of beetle-killed lodgepole pine trees, (1) abundance and diversity of stand structure, and (2) abundance of mammal species, will increase with higher levels of green-tree retention (GTR). Stand structure attributes and small mammals were sampled during 2005-2008 in young pine stands, with a range of GTR seed-trees (none, dispersed, and aggregated Douglas-fir), and uncut forest in south-central British Columbia, Canada. Diameters and heights of Douglas-fir and lodgepole pine and basal area of total conifers supported hypothesis (1). Mean abundance of the red-backed vole was consistently higher (2.3 to 6.4 times) in the uncut forest than other stands. Overall mean patterns of abundance for common shrews, red squirrels, and northern flying squirrels were similar among treatment stands. Mean abundance of the red-backed vole supported hypothesis (2), but numbers of the other three species did not. There is "life after the beetle" at 30 years after salvage harvesting, and this was enhanced by GTR.

关键词： Acacia drepanolobium   allocation   ant symbiont   defense   herbivory   photosynthesis   tritrophic interactions  

摘要： A letter to the editor is presented in response to the article on the interaction of herbivores and mutualistic ants in modifying tree photosynthesis.

关键词： 脊椎动物   晚二叠世   树栖   陆地生态系统   生活环境   食物来源   生态空间   猎食  

摘要： 纵贯脊椎动物在陆地上的历史，它们不断地填充和分割着陆地生态系统，不断占据新的、先前未曾开发过的生活环境。由于树冠能提供新的食物来源和保护它们免受地面猎食者的捕杀，树栖生态空间对脊椎动物的进化显得很重要。

关键词： Termites   Cerrado   Habitat Simplification   Diversity   Abundance   Feeder group  

摘要： The advance of agricultural frontier may cause the Cerrado (Brazilian savanna) to disappear before 2030. This work focuses on measuring the impact of pasture implantation on a cerrado's termite fauna. Termites were sampled in a cerrado sensu stricto and a pasture, originally cerrado. All species were classified as their feeder group, accumulation curves were made and Shannon-Wiener indexes and beta diversity were calculated for both areas. Cerrado was richer than pasture and species composition differed considerably, leading beta diversity to a high value. The humivorous was the most representative species, followed by grass/litter feeders, xylophagous and, less representative, the intermediates. There were more xylophagous and intermediates species on cerrado than in pasture;the grass/litter feeders were more abundant in pasture, but didn't differed in number or species;and humivorous didn't differed neither in richness nor in abundance. This work shows that the simplification of the habitat is indeed causing the extinction of populations that depend on some specifics resource.

关键词： Animals   Arthropods/metabolism   Brazil   Conservation of Natural Resources   Ecology   Ecosystem   Ecosystem   Fires   Geography   Plant Leaves/metabolism   Population Density   Population Dynamics   Seasons   Soil   Trees  

摘要： Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade) were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover) and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover). Although these effects were transitory, there is evidence that the increasingly prevalent fire return interval of o

关键词： Bayesian   cladistics   eutheria   hidden branch support   homoplasy   mammalia   molecular phylogenetics   morphological phylogenetics   partitioned branch support   placentalia  

摘要： The emerging molecular evolutionary tree for placental mammals differs greatly from morphological trees, leading to repeated suggestions that morphology is uninformative at this level. This view is here refuted empirically, using an extensive morphological and molecular dataset totalling 17 431 characters. When analysed alone, morphology indeed is highly misleading, contradicting nearly every clade in the preferred tree (obtained from the molecular or the combined data). Widespread homoplasy overrides historical signal. However, when added to the molecular data, morphology surprisingly increases support for most clades in the preferred tree. The homoplasy in the morphology is incongruent with all aspects of the molecular signal, while the historical signal in the morphology is congruent with (and amplifies) the historical signal in the molecular data. Thus, morphology remains relevant in the genomic age, providing vital independent corroboration of the molecular tree of mammals.

关键词： Land fragmentation   Rangeland   Maasai   Settlement   Conservation   Kenya  

摘要： This study looks at the impact of subdivision and sedentarization of pastoral lands on wildlife numbers and production in a savanna ecosystem of southern Kenya. The study uses aerial counts over a period of 33 years to compare changes in wildlife populations on two adjacent and ecologically similar Maasai group ranches. During the period under study, one group ranch was subdivided and settled. The other remained communally owned under shifting seasonal use. Wildlife populations decreased sharply on the privatized ranch following subdivision and increased steadily on the adjacent ranch where pastoralists continued mobile pastoralism. The results of multivariate analysis show that sedentarization and settlement distribution accounts for wildlife declines on the subdivided ranch. Both the direct displacement of wildlife and the reduction in grass production following a switch from seasonal to permanent grazing associated with sedentarization are discussed as causes of wildlife loss. Given the demand for title deeds among pastoralists to counter land losses, the resulting sedentarization is likely to become the biggest threat to wildlife in the East African savannas. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Bivalves   Pisidioidea   reservoirs   estuary   Kola Peninsula  

摘要： The fauna of bivalves of superfamily Pisidioidea from the coastal zone of the Lower Tuloma Reservoir and the estuary of the Tuloma River was studied in 2004-2005. Seventeen species mollusks were found. The influence of some ecological factors on the mollusks is analyzed. The most important factor in the Lower Tuloma Reservoir is the tidal rise;in the estuary of the Tuloma River, it is the time of coast exposure and water salinity.

关键词： African savanna   community interactions   herbivore exclusion   large herbivores   predation risk   savanna rodents   South Africa  

摘要： Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to hares) from sixteen 40 x 40-m plots of vegetation by using different fence types. We determined grass species composition and vegetation height and collected capture-mark-recapture data on murid rodents. Nutrient concentrations of the dominant grass species and rodent diet compositions were analysed. We found that herbivore species of different body sizes had different effects on murid rodents. The exclusion of medium-sized herbivores, such as warthog, impala and nyala increased the abundance of high-quality grass species, especially Panicum maximum. However, the dominant rodent species Lemniscomys rosalia preferred the most abundant grass species, rather than high-quality grasses. The absence of large bulk feeders, such as zebra, buffalo and white rhino led to an increase in vegetation height. In response. tall vegetation promoted both rodent abundance and species diversity and altered rodent species composition. Ultimately, our results indicate that the greatest effect on murid rodents came from the reduction of vegetation cover by large bulk feeders, which likely increased rodent predation risk.

关键词： acropetal dispersal   haplodiploid   Hymenoptera   intraplant heterogeneity   Pikonema alaskensis   Picea mariana   Tenthredinidae   black spruce   yellowheaded spruce sawfly   defoliation  

摘要： Heterogeneity in the quality of oviposition and feeding sites within plants can significantly influence the distribution and abundance of herbivorous insects, but remains poorly understood. Field surveys and a manipulative study were conducted to evaluate the influence of variation within the crown of black spruce, Picea mariana (Mill.) B. S. P. (Pinaceae), on adult oviposition and larval feeding behavior of yellowheaded spruce sawfly, Pikonema alaskensis Rohwer (Hymenoptera: Tenthredinidae). Most eggs were laid in the mid to lower crown of 1.5-2 m tall trees. However, most of the few eggs that were laid in the upper crown (i.e., whorl 2) were female. Fourth and fifth instars dispersed acropetally, from the mid and lower to the upper crown, causing high defoliation in the upper crown. Late-instar females were generally more abundant than males on the leader, the most apical shoot on a tree where eggs and early instars rarely occurred, strongly suggesting that more females than males disperse acropetally. This hypothesis was supported in a manipulative experiment, where only 15-20% of larvae in all-male broods, but almost three-quarters of larvae in mixed broods, dispersed to the upper crown. To our knowledge, this is only the second study to explicitly demonstrate preferential allocation of progeny sex through oviposition site selection by a herbivorous insect, and the first study to unambiguously demonstrate sex-biased dispersal by the juveniles of an insect whose adult females can fly. This study emphasizes the important role of intra-plant variation in shaping both oviposition site selection and the dispersal behavior of juvenile phytophagous insects within their hosts, and suggests that sex-biased foraging behaviors may be necessary for some insects to accommodate the respective needs of immature females and males within heterogeneous host plants.