共查询到4条相似文献,搜索用时 0 毫秒
1.
LINCOLN P. BROWER ERNEST H. WILLIAMS DANIEL A SLAYBACK LINDA S. FINK M. ISABEL RAMÍREZ RAÚL R. ZUBIETA M. IVAN LIMON GARCIA PAUL GIER JENNIFER A. LEAR TONYA VAN HOOK 《Insect Conservation and Diversity》2009,2(3):163-175
Abstract. 1. Survival of overwintering monarch butterflies following severe wet winter storms in Mexico is substantially higher for butterflies that form clusters on the oyamel fir tree trunks than for those that form clusters on the fir boughs. 2. Thermal measurements taken at similar elevations with a weather station on the Sierra Chincua and within a Cerro Pelon and a Sierra Chincua overwintering area indicated that clustering on the fir trunks provides dual microclimatic benefits for the butterflies. a. At night, the minimum surface temperatures of all firs combined averaged 1.4 °C warmer than ambient forest temperatures, thereby enhancing protection against freezing for monarchs that are either wet or dry. We term this the ‘hot water bottle effect.’ b. During the day, the maximum surface temperatures of all firs combined averaged 1.2 °C cooler than ambient, a difference sufficient to lower the loss of the butterflies’ lipid stores over the 154‐day wintering season. 3. Larger diameter trees increase both microclimate benefits. 4. The results add a new dimension to improving the conservation management guidelines for the Monarch Butterfly Biosphere Reserve. Strict enforcement against culling of larger trees and in favour of promoting old‐growth oyamel forests will enhance two microclimatic benefits: butterfly mortality during severe winter weather will be reduced, and the butterflies’ lipid savings over the winter will be enhanced. 相似文献
2.
Extensive tropical forest loss and degradation have stimulated increasing awareness at the international policy level of the need to undertake large‐scale forest landscape restoration (FLR). Natural regeneration offers a cost‐effective way to achieve large‐scale FLR, but is often overlooked in favor of tree plantations. The studies presented in this special issue show how natural regeneration can become an important part of FLR and highlight the ecological, environmental, and social factors that must be considered to effectively do so. They also identify major knowledge gaps and outline a research agenda to support the use of natural regeneration in FLR. Six central questions emerge from these studies: (1) What are the ecological, economic, and livelihood outcomes of active and passive restoration interventions?; (2) What are the tradeoffs and synergies among ecological, economic, and livelihood outcomes of natural regeneration, restoration and productive land uses, and how do they evolve in the face of market and climate shocks?; (3) What diagnostic tools are needed to identify and map target areas for natural regeneration?; (4) How should spatial prioritization frameworks incorporate natural regeneration into FLR?; (5) What legal frameworks and governance structures are best suited to encourage natural regeneration and how do they change across regions and landscapes?; (6) What financial mechanisms can foster low‐cost natural regeneration? Natural regeneration is not a panacea to solve tensions and conflicts over land use, but it can be advantageous under some circumstances. Identifying under what conditions this is the case is an important avenue for future research. 相似文献
3.
In closed‐canopy tropical forest understory, light availability is a significant determinant of habitat diversity because canopy structure is highly variable in most tropical forests. Consequently, variation in canopy cover affects the composition and distribution of plant species via creating variable light environments. Nevertheless, little is known about how variation in canopy openness structures patterns of plant–animal interactions. Because of the great diversity and dominance of ants in tropical environments, we used ant–plant interactions as a focal network to evaluate how variation in canopy cover influences patterns of plant–insect interactions in the Brazilian Amazon rain forest. We observed that small increases in canopy openness are associated with increased diversity of ant–plant interactions in our study area, and this change is independent of plant or ant species richness. Additionally, we found smaller niche overlap for both ants and plants associated with greater canopy openness. We hypothesize that enhanced light availability increases the breadth of ant foraging sources because variation in light availability gives rise to plant resources of different quality and amounts. Moreover, greater light availability promotes vegetative growth in plants, creating ant foraging ‘bridges’ between plants. In sum, our results highlight the importance of environmental heterogeneity as a determinant of ant–plant interaction diversity in tropical environments. 相似文献
4.
Shamira Vzquez‐Castillo Antonio Miranda‐Jcome Ernesto Ruelas Inzunza 《Ecology and evolution》2019,9(3):1268-1277
In the frugivory networks of many arid and semi‐arid Mesoamerican ecosystems, columnar cacti act as keystone species that produce fruits with a high content of water and nutrients attractive to numerous vertebrates. The aim of this investigation was to assess the fruit removal patterns of two guilds of frugivores on the fruits of the woolly torch Pilosocereus leucocephalus. We assessed fruit pulp removal in two ways: by estimating the consumption of seeds given the amount of pulp removed per visit and by estimating the percentage of pulp removal over time. We put exclosures on unripe, intact fruits to keep frugivores from removing material. Once ripe, we removed the exclosures and tracked animal visitation of 69 fruits using camera traps. We obtained a total of 2,162 hr of footage (14:47 hours of them with effective pulp removal). The highest number of visitors is that of diurnal species (n = 12, all birds) versus only four nocturnal (three bats, one rodent). The most effective species in pulp removal are birds. Bats play a modest role in frugivory of this cactus. The significance of this work is twofold: (a) birds and bats consume the fruit pulp of this cactus and likely disperse its seeds, and (b) although bats rank high in pulp removal effectiveness, birds as a guild far outweigh their importance in this system, as they are not only more frequent but also remove more pulp and seeds. Both groups are known to be important in cacti seed dispersal, and our findings are essential in understanding the population dynamics of the woolly torch and in elucidating its seed dispersal ecology. 相似文献