Review: Biodiversity of forests over limestone in Southeast Asia with emphasis on the Philippines

Abstract

Abstract. Tolentino PJS, Navidad JRL, Angeles MD, Fernandez AP, Villanueva ELC, Obena RDR, Buot Jr IE. 2020. Review: Biodiversity of forests over limestone in Southeast Asia with emphasis on the Philippines. Biodiversitas 21: 1597-1613. A comprehensive review of literature was carried out to determine the status of plant and animal diversity on forests over limestone in Southeast Asia (SEA), particularly in the Philippines. Angiosperm records are available in Peninsular Malaysia (1216 spp.); West Java and Seram Indonesia (101 and 149 spp., respectively); Laos (135 spp.); Thailand and Myanmar (1 sp.); and Limestone areas in Vietnam. Pteridophytes were recorded in Malaysia (32 spp.) while Bryophytes are recorded in Peninsular Malaysia (59 spp.). In the Philippines, there are plant records in: Masbate (61 spp.); Isabela (169 spp. Pteridophytes); Bohol (12 spp.), and Samar forests over limestone (29 spp. palms and 20 spp. orchids). A floral assessment in Samar Island Natural Park (SINP) includes species (212 spp.) that can possibly be found but are not limited to karsts. New Philippine endemic species are also recorded in Cebu, Palawan, and Panay Island. There are animal records in SEA including Vietnam (Bats-36, Bird-1, and Langurs-5 spp.); Malaysia (Sciuridae-1, Bats-28, Birds-129, Reptiles-17, and Invertebrates-74 spp.); Thailand (Murids-12, Reptiles-11, and Amphibian-1 sp.); and Myanmar (Reptiles-15 spp.). Records in the Philippines include: Mammals (Bicol-9, Mt. Irid-24, Mt. Aruyan-1, and Cebu-1 species), and; Birds (Cebu-1 sp.). A terrestrial faunal assessment in SINP includes species (182 spp.) that can possibly be found but are not limited to karsts. Forests over limestone are still largely understudied and the potential of discovering species is high. Further research is critical to establish science-based initiatives and policies that will protect and conserve limestone ecosystem biodiversity while allowing the utilization of its biological resources at a sustainable level.

Karstic Landscapes Are Foci of Species Diversity in the World’s Third-Largest Vertebrate Genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata; Gekkonidae)

“…This pattern is particularly strong in Indochina and less so on islands throughout the Indo-Australian Archipelago, reflecting the sharp contrast in the extent of karstic landscapes between these regions (Figure 8). These data clearly underscore the importance of karstic habitats to this hyper-diverse genus and continue to amplify the work of many other authors indicating that the high levels of biodiversity and rangerestricted endemism in karstic habitats rivals that of most other habitats throughout the tropics (see discussions in [1,4,5,10,[56][57][58][59][60][61]). The sad irony is that, although these are some of the most imperiled ecosystems on the planet due to unregulated and unsustainable quarrying practices, only 1% of these terrains throughout Asia are afforded any form of legal protection.…”

“…The dramatic topography of karstic landscapes composes some of the most surreal images of our world and has stirred the emotions of ancient artisans and natural historians for time on end. But not only are these crenulated, repeating layers of rugged terrain steeped in natural beauty (Figure 1), they are the only refuge for some of the most seriously endangered species on the planet [1]. Asia contains 8.35 million km 2 of karstic habitat with some of the most extensive concentrations ranging from China to western Melanesia (Figure 2).…”

A checklist and conservation status of vascular plants in the Limestone forest of Metropolitan Ilocos Norte Watershed Forest Reserve, Northwestern Luzon, Philippines

“…The forest structure in MINWFR showed differences in vegetation just a few kilometers apart from one area to another; (i) some portions of the forest are open brushland, while others have been converted into agroforestry and reforestation areas, (ii) other areas are observed as seasonal dry with tall trees and small understory trees, (iii) to forested thickets with the presence of ferns, herbaceous plants, and shrubs in dense population with high growing trees, which makes the upper canopy, at the same time, limestone is present on the ground scape, (iv) while another site is dominated by sparse and small stunted trees over rocky ridges with numerous herbaceous plants on the ground, which indicate drought-tolerant population, some of the trees and shrubs tend to have leathery and thick leaves. This diverse ecological niches, specific vegetation and complex terrains that could be found existing within the limestone landscape (Clements et al 2006;Saw et al 2010;Tolentino et al 2020) is similarly observed in the area. According to Perez-Garcia et al (2009), the observed high environmental heterogeneity found within the forest is attributed to its unusual soil condition.…”

“…The high floral richness recorded on forest over limestone is considered still as underestimated (Clements et al 2006). Moreover, according to Tolentino et al (2020), a few existing studies focusing on limestone forests in the country were conducted. The forest structure in MINWFR showed differences in vegetation just a few kilometers apart from one area to another; (i) some portions of the forest are open brushland, while others have been converted into agroforestry and reforestation areas, (ii) other areas are observed as seasonal dry with tall trees and small understory trees, (iii) to forested thickets with the presence of ferns, herbaceous plants, and shrubs in dense population with high growing trees, which makes the upper canopy, at the same time, limestone is present on the ground scape, (iv) while another site is dominated by sparse and small stunted trees over rocky ridges with numerous herbaceous plants on the ground, which indicate drought-tolerant population, some of the trees and shrubs tend to have leathery and thick leaves.…”

“…Among the considered remaining intact and important limestone areas found in Luzon (Tolentino et al 2020), is the Metropolitan Ilocos Norte Watershed Forest Reserve (MINWFR). It is part of the Ilocos Mountains and described as one of the critical ecosystems by Calaramo et al (2016).…”