The impact of rubber plantations on the diversity and activity of understorey insectivorous bats in southern Thailand

Abstract

Although a large proportion of tropical rain-forest in South-east Asia has been replaced by rubber plantations, there is very little information about the impact of such forest conversion on bat diversity. To address this deficiency, trapping and acoustic monitoring programmes were carried out in Ton Nga Chang and Khao Ban That wildlife sanctuaries in southern Thailand with the purpose of comparing species diversity and activity of understorey insectivorous bats at sites in forest and in nearby monoculture rubber plantations. Insect biomass in both habitats was assessed. Bat species diversity and activity were found to be much lower in rubber plantations than in forested areas and mean insect biomass was determined to be more than twice as high in the latter habitat than in the former. Bats utilising forest were shown to have significantly higher call frequencies but marginally lower wing loadings and aspect ratios than bats found in both habitats. Management strategies to increase biodiversity in rubber plantations are discussed.

How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

“…Leaf‐gleaning bats are less abundant in agricultural systems than in natural forest (Phommexay et al . ) suggesting natural forests are sources of bats for nearby agroforests, but we did not find any evidence for forest distance‐dependent effects of bats.…”

Ultrasonic monitoring to assess the impacts of forest conversion on Solomon Island bats

“…Note, this is in contrast to studies in shade cocoa agroforests, which are structurally complex habitats, that have found these areas to support similar levels of bat species richness to forests (Harvey and Villalobos 2007). Given the insectivorous diet of most echolocating bats (Fenton 1982), monocultures, such as cacao plantations are likely to make poor habitats for Paleotropical bats (Fukuda et al 2009;Phommexay et al 2011). In addition, cacao plantations on Makira are relatively open habitats, which also poses an increased predation risk for bats (i.e.…”

“…In addition to testing these hypotheses, our study supplements the limited literature for bat acoustics in the Paleotropics (Phommexay et al 2011) and provides the first acoustic characterizations and morphological data of bat species common and/or endemic for a data-deficient region of the Solomon Islands. Through this study we also document some of the challenges of using ultrasonic bat detection in a remote and poorly studied region, which are common features of many conservation priority areas; we hope this work will help guide future assessments in similar challenging regions.…”

“…Reasons for this include high food availability, high level of habitat heterogeneity and low risk of predation in these habitats (Estrada et al 2004). However, we expect bat activity to be lower in cacao plantations because monocultures tend to be bat-poor (Estrada et al 1993;Harvey and Villalobos 2007;Fukuda et al 2009;Phommexay et al 2011). Because food gardens have higher plant diversity than cacao plantations, but more open canopies than forest areas, we hypothesize that gardens will exhibit intermediate bat activity levels.…”

Responses of Tropical Bats to Habitat Fragmentation, Logging, and Deforestation

“…Acoustic surveys could potentially contribute additional information concerning bat activity and the structure of bat assemblages in these habitats. The first insights from the Old World come from southern Thailand, where Phommexay et al (2011) sampled bats in forest and neighboring rubber plantations using bat detectors, mist nets, and harp traps. Although diversity and overall bat activity were much lower in plantations than in forests, differences between the two habitat types were not as severe as indicated by capture-based surveys.…”