2016-12-23T18:52:10

Cave ecosystems are subterranean biodiversity hotspots, but limited knowledge of the distribution of diversity among caves hampers their conservation. Surveys of surrogate taxa (e.g., keystone species) can identify hotspots of biodiversity when knowledge about an ecosystem is lacking. Bats are keystone species in cave ecosystems because their guano is the primary energy source supporting diverse assemblages of cave-dependent wildlife. However, directly measuring bat diversity is time-consuming and requires expert knowledge; instead, we suggest the use of correlates of bat diversity that can be derived from readily accessible data (e.g., land-use maps) and straightforward methods not requiring expert knowledge (e.g., cave surveys, interviews) as a foundation for prioritizing caves. To identify easily measurable correlates of bat diversity, we compared assemblage composition and species abundances of 21 bat species captured in 56 caves on Bohol Island, Philippines, along gradients in environmental factors and human disturbance. Model-and distance-based methods indicated that surface-level disturbance (i.e., percent non-forested habitat, degree of urbanization and road development) along with cave complexity (i.e., available roosting area, structural heterogeneity, number of entrances and temperature range) were the most influential factors governing cave-roosting bat assemblages, thus representing correlates of bat diversity. Prioritization schemes based on these correlates select combinations of caves with greater species richness than both random selection and selection of caves based on observed richness from intensive bat surveys. The use of easy-tomeasure environmental and disturbance correlates of bat diversity is an effective tool to prioritize caves to protect cave-roosting bats and the cave-dependent wildlife they support.

No abstract

Ecological thresholds represent a critical tipping point along an environmental gradient that, once breached, can have irreversible consequences for species persistence and assemblage structure. Thresholds can also be used to identify species with the greatest sensitivity to environmental changes. Bats are keystone species yet are under pressure from human disturbances, specifically landscape and cave disturbances (i.e., reduced forest cover, urbanization, hunting, tourism). We compared bat assemblages across environmental and disturbance gradients measured at 56 caves in the Philippines to identify species-specific thresholds and assess congruence among species responses. All species exhibited significant responses to one or more gradients, with 84% responding to more than one gradient. Yet mixed responses of sensitivity to some gradients but tolerance to others hindered identification of assemblage thresholds to all gradients except landscape disturbance. However, we identified credible indicator species that exhibit distinct thresholds to specific gradients and tested for differences in ecological and morphological traits between species groups with shared responses (i.e., negative or positive). Few traits were useful for discriminating the direction of a species response, with some exceptions. Species that responded positively to increased landscape disturbance and hunting had greater body mass, whereas species that responded negatively to mining emitted higher peak call frequencies.

Rajah Sikatuna Protected Landscape (RSPL), considered the last frontier within the Central Visayas region, is an ideal location for flora and fauna research due to its rich biodiversity. This recent study was conducted to determine the plant species composition and diversity and to select priority areas for conservation to update management strategy. A field survey was carried out in fifteen (15) 20 m x 100 m nested plots established randomly in the forest over limestone of RSPL from July to October 2019. Three hundred and sixty eight (368) species of plants were identified up to species level. This represented 327 angiosperms, one gymnosperm and 40 pteridophytes. Common plant families with more than 10 representative species were Moraceae, Meliaceae, Lauraceae, Dipterocarpaceae, Rubiaceae, Myrtaceae, Phyllanthaceae, Annonaceae, Araceae and Lauraceae. There were 93 (28%) endemic and 46 (14%) threatened species (vulnerable to critically endangered) observed. The cluster analysis and species accumulation curve suggests that plant species are not homogeneously distributed which implies that different management and conservation strategies should be implemented across RSPL. These results not only indicate the importance of RSPL, but also highlights areas with higher diversity and concentration of threatened and endemic species as a special area of concern. Furthermore, areas with high biodiversity value were recommended for immediate protection, while areas with low biodiversity value were recommended for reforestation programmes using species with high importance value.