Restrepo, CarlaDelgado, DianaDebrot, Adolphe O.Vries, Albert J....
14页
查看更多>>摘要：Tropical dry forests experience pronounced seasonal changes in precipitation manifested in varied plant phenologies. At landscape scales, geologic substrate-one of the least understood abiotic factors interacting with precipitation-may modulate phenological responses in these forests through a combination of mechanisms regulating water and nutrient use. We leveraged a phenological dataset from the semiarid island of Curacao to examine the extent to which plant phenology at multiple levels of biological organization diverge under different geologies. Monthly observations over a 30-month period of leaves, flowers, and fruits of 69 plant species of different life forms at three nearby sites differing in their underlaying geology were used to examine intra- and inter-annual plant responses at species, community, and system levels. The integration of leaf, flower, and fruit observations at intra-annual scales revealed diverse phenological strategies among species, broad associations with geologic substrate, and the extent of intra-specific variation as a function of geology. The community- and system-level analyses at inter-annual scales showed a reduction in mean leaf scores during the 30-month period, a weak and strong leafless period in 1993 and 1994, respectively, and differences among geologic substrates. Finally, we observed significant and positive relationships between precipitation and the phenophase scores; the strength of the relationships varied with phenophase and geologic substrate. Results of this work emphasize the importance of geologic substrate, and more broadly speaking landscape heterogeneity, in modulating plant phenological responses in tropical dry forests. Ultimately, this information will become important to understand and mitigate global climate change impacts. Abstract in Spanish is available with online material.
Amponsah-Mensah, KofiCunningham, Andrew A.Wood, James L. N.Ntiamoa-Baidu, Yaa...
12页
查看更多>>摘要：Urbanization is driving many species to inhabit modified landscapes, but our understanding of how species respond to this remains limited. Bats are particularly vulnerable due to their life-history traits but have received little attention. We describe the roosting behavior and roost site selection, including maternity roosts, for the Gambian epauletted fruit bat (Epomophorus gambianus) within a modified forest-savannah transition ecological zone in Ghana, West Africa. We compared characteristics of roost and non-roost sites to test the hypotheses that roost site selection is non-random and that maternity roost site selection differs from non-maternity roosts. Male bats were more likely to switch roost (mean = 0.49 +/- 0.23 bat days, N = 23) than females (mean = 0.33 +/- 0.18 bat days, N = 7) while linear distances between roosts used by males (255 +/- 254 m) were significantly longer than for females (102 +/- 71 m) (t = 4.50, df = 86, p < .0001). Roost trees were more likely than non-roost trees to be bigger, taller, occur closer to buildings, and be in relatively open and less mature plots; maintaining such trees in modified landscapes could benefit the species. Lactating bats selected a subset of roost trees but significantly, those that contained a greater number of bats, a strategy which may reflect predator avoidance, or other social co-operation benefits. Although there was a preference for five tree species, other trees with preferred characteristics were also used. Our findings contribute to the understanding of how species utilize modified landscapes, which is important in the management of biodiversity in the Anthropocene.
查看更多>>摘要：Nest location is a decision that presumably affects predation probability, thus, it directly impacts offspring survival. Those locations could be near animals that deter potential nest predators, like acacia ants. We tested whether the preference of three neotropical bird species (Icterus pustulatus, Tolmomyias sulphurescens and Pitangus sulphuratus) for nesting in swollen-thorn acacias (Vachellia) shifted in human-modified landscapes. Because natural predators deterred by ant-defended acacias in protected forest may decrease or be replaced by other predators in human-modified landscapes, we predicted a potential loss of preference for swollen-thorn acacias in those landscapes. Swollen-thorn acacias can be inhabited by defending Pseudomyrmex ants (ant-defended acacias) or by non-defending ants (non-defended acacias). Hence, a preference for nesting on ant-defended acacias was expected in natural habitats but not in anthropogenic habitats. All three bird species preferred to nest in swollen-thorn acacias in forests, but only P. sulphuratus showed a preference for ant-defended acacias. However, this nesting preference of all three species was lost in human-modified landscapes, where birds switched to large trees, and included utility poles or power lines, although acacias remained a common species. The preference of P. sulphuratus for ant-defended acacias in the forests was also lost in anthropic areas. The habitat-dependent shift in preference for nesting trees indicates a potential change in the benefits of tree traits and the selective forces (e.g., predators) at those sites. Our results demonstrate that birds who seem strongly dependent on a tree when studied in natural habitats may shift their preferences in altered habitats. Abstract in Spanish is available with online material.
NSTL
Wiley