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Karst areas in the Philippines shaded in black (based on Balázs 1973; Restificar et al. 2006)

Karst areas in the Philippines shaded in black (based on Balázs 1973; Restificar et al. 2006)

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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...

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... studies indicate that the Philippine karst landscapes have a total area of 35 000 km² (Figure 1) which is about 11.7% of the country's total land area (BMB-DENR 2019) and about 29% is protected by law (Wagner 2013). However, there are no existing legislation that directly addressed the protection and conservation of karst areas in the country, and its protection is mainly indirect. ...

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... Accounting for approximately only 10 % (460,000 km 2 ) in Southeast Asia, karst ecosystems are still considered an 'ark' of biodiversity, containing an extraordinarily high level of endemism (Day and Urich, 2000;Clements et al., 2006;Luo et al., 2016;Tolentino et al., 2020). Giving an example of the gekkonid genus Cyrtodactylus, comprising approximately 300 species mostly native to South East Asia, the karstic habitats (which far out-number all others) are not simply refugia but rather a mosaic of unique micro-niches forcing speciation in disjunct outcrops (Clements et al., 2006;Grismer et al., 2020). ...
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Human impact is considered the major threat to the global decline of biodiversity, especially for threatened endemic species in karst ecosystems. Studies assessing a species' demography based on temporal and spatial indicators of population size, density and structure are expected to evaluate the level of impact of threats and are therefore becoming increasingly important for species conservation efforts. Goniurosaurus huuliensis, an endemic species in Vietnam, is one of the most threatened reptiles in the world. This karst–adapted species is classified by the IUCN Red List as Critically Endangered and listed under CITES Appendix II due to habitat loss and over–exploitation for the international pet trade. Here we provide the first evaluation of the population status of G. huuliensis. We applied a 'capture mark–recapture' method to estimate the population size and identify the population density and structure. The total population size was estimated to comprise a maximum of 1,447 individuals in integrated suitable habitats, possibly reaching up to 2,855 individuals exclusively in karst habitats within the total extension of occurrence. This is exceedingly lower than the threshold for a minimum viable population. Furthermore, G. huuliensis is documented to occur in extremely small mean population densities of only 6.4 indiv./km and 2.5 indiv./km/day along the surveyed transects. Based on the demographic information, the ongoing severe human impact (e.g. wildlife exploitation and limestone quarrying) is driving G. huuliensis to the brink of extinction. In situ conservation measures are therefore urgently required. We recommend that in-situ actions should be increased, and a plan should be developed to establish a species and habitat conservation area for G. huuliensis.
... The existing studies on plant diversity which includes forest over limestone showed varying results in different regions. Clements et al. (2006) and Paul-John et al. (2020) supported the view when they reported that the high species diversity of flora in limestone areas is due to varied ecological niches and intricate terrains that can be found within the limestone landscapes. In this study, the most speciose family was Euphorbiaceae with 13 species (11.9%), followed by Moraceae and Annonaceae with nine species (8.3%) and eight species (7.3%), respectively (Table 2). ...
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A study was conducted to determine the tree species composition, stand structure, diversity and to estimate biomass at Gunung Payang in the Serian-Padawan-Tebedu limestone areas, Sarawak. Twenty-five plots of 20 m x 20 m (1 ha) were established and all trees with diameter at breast height (DBH) of ≥5 cm were enumerated. A total of 607 individual trees was enumerated and identified to 37 families, 89 genera and 109 species. Euphorbiaceae is the largest family comprises 10 genera and 13 species. Based on stem density, Euphorbiaceae recorded the highest density with 206 individuals/ha. The Importance Value Index (IVi) of Euphorbiaceae was 23.81%. The Shannon-Weiner Diversity Index (H') indicated a value of 3.81. The total above-ground biomass of trees was estimated at 278.59 t/ha. This study showed that three species were listed as vulnerable by IUCN Red Data Book and their population trends decreased. The floristic composition implies that the study area can serve as a conservation site for the threatened plant species.
... Karst forest or limestone forest is a type of forest formation growing on karst outcrops. It is a forest formation type in the Philippines (Fernando et al., 2008) which serves as a habitat to unique fauna and flora (Tolentino et al., 2020). ...
Article
A comprehensive list of plant and animal biodiversity is necessary as a basis for local government and concerned agencies to enact local policies on species conservation. This article provides an enumeration of the vascular flora and vertebrate fauna in the karst forests of Basey, Samar, Philippines. A review of literature concerning plants and animals of Basey, Samar Island Natural Park, from various published sources was done. A total of 67 plants, represented by 54 genera and 38 families were included in this list, with 23 threatened and 28 Philippine endemic species. For the vertebrates, a total of 70 species were enumerated, which was composed of 6 amphibian, 12 reptile, 43 bird, and 9 mammal species. Among these, 21 were threatened and 14 were endemic to the Mindanao Pleistocence Aggregate Island Complex (PAIC). This checklist can be used as a reference in crafting local conservation policies and strategies for protection and sustainable use of this ecotourism site.
... Studying the forests over limestone in Samar Island Natural Park (SINP), Samar Island, Philippines expands our current knowledge on leaf analysis studies to other forest types. SINP has been nominated to be a UNESCO World Natural Heritage site, recognizing its unique physical and biological treasures (Tolentino et al., 2020;Obeña et al., 2021;Villanueva et al., 2021a;2021b). Plant species new to science had been reported in scientific literature such as Calamus warayanus Adorador & Fernando (Adorador & Fernando 2020), Orania zheae Adorador & Fernando (Adorador & Fernando 2020) (Villanueva et al., 2021a). ...
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Leaf size is one of the plant functional traits that can explain ecosystem function. This study identified the leaf size classes of trees in the forest over limestone ecosystems of Samar Island Natural Park, Samar Island, Philippines. One-sided surface leaf areas of voucher specimens from 18 sites in SINP were measured and data obtained were calculated and further classified based on the Raunkier-Webb classification. Most of the leaf sizes recorded were mesophyll (15 spp.), followed by notophyll (11 spp.), microphyll (4 spp.), and megaphyll (2 spp.). Moreover, leaf size classes are highly diverse among the sampling plots, a characteristic that can enhance the diversity of faunal populations dependent on plants for food and shelter. The dominance of large leaf sizes in SINP confirms the results of similar studies in forests over limestone.
... 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). ...
... 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. ...
... Therefore, the diversity of the karst-associated species in general-and Cyrtodactylus in particular-are, for the most part, without legal protection. Unfortunately, the immense financial returns from cement manufacturing makes the challenge of karst conservation difficult and many governments from developing nations that are willing to overlook sustainable quarrying policies in order to expand their economy [1]. Continued exploitation of karstic habitats for limestone shows no signs of abating. ...
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Karstic landscapes are immense reservoirs of biodiversity and range-restricted endemism. Nowhere is this more evident than in the world’s third-largest vertebrate genus Cyrtodactylus (Gekkonidae) which contains well over 300 species. A stochastic character mapping analysis of 10 different habitat preferences across a phylogeny containing 345 described and undescribed species recovered a karst habitat preference occurring in 25.0% of the species, whereas that of the other eight specific habitat preferences occurred in only 0.2–11.0% of the species. The tenth category—general habitat preference—occurred in 38.7% of the species and was the ancestral habitat preference for Cyrtodactylus and the ultimate origin of all other habitat preferences. This study echoes the results of a previous study illustrating that karstic landscapes are generators of species diversity within Cyrtodactylus and not simply “imperiled arks of biodiversity” serving as refugia for relics. Unfortunately, the immense financial returns of mineral extraction to developing nations largely outweighs concerns for biodiversity conservation, leaving approximately 99% of karstic landscapes with no legal protection. This study continues to underscore the urgent need for their appropriate management and conservation. Additionally, this analysis supports the monophyly of the recently proposed 31 species groups and adds one additional species group.
... Unfortunately, karst forests are largely understudied and considered one of the most threatened forest types in the Philippines due to mining and conversion of land to agriculture (Fernando et al. 2008;Tolentino et al. 2020). ...
... The abundance of endemic and forest-dependent birds, as well as the presence of threatened species in FF1 highlight the conservation value of karst habitats. In the Philippines, existing policies and laws do not directly address the protection of karst areas but instead focused mainly on the protection of caves and cave features to boost tourism (Tolentino et al. 2020). However, the high level of endemism and presence of threatened species in karst habitats underlines the importance of protecting the forests surrounding the caves for these species to continually thrive in the area. ...
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Little is known on the effects of degradation and disturbance on bird assemblage in lowland karst forests in the Philippines. In this study, we determined diversity patterns and distribution of birds along the vertical strata in two karst forest fragments adjacent to and one reforestation area within an active limestone quarry area in Bulacan province, Luzon island. Surveys were conducted using mist nets set in the understory (0-3 m) and sub-canopy (4-10 m) from November 2013 to October 2016. A total of 617 individuals belonging to 63 species and 13 feeding guilds were recorded from a mist-netting effort of 654,264.8 mist-net hours (m2•h); of these, 32 are Philippine endemics and six are threatened species. We recorded the highest number of species in the reforestation area, most of which are generalist and disturbance-tolerant species. Results from permutational multivariate analysis of variance (PERMANOVA) and non-metric multidimensional scaling (NMDS) indicate differences in bird assemblage between the three habitat types and between the two vertical strata within habitat types. Meanwhile, similarity percentage analyses and Mann-Whitney U tests showed that species and guilds that contributed to the observed dissimilarity in the two strata have higher capture rates in the understory. These observations provide insights into the effect of disturbance and habitat alteration in the vertical movement of birds, as evidenced by the shift of some arboreal species to the understory layer in more disturbed habitats. Understanding the behavior and habitat use of birds will, thus, help in identifying appropriate conservation measures to ensure proper resource partitioning among the different bird assemblages in fragmented habitats.
... 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). ...
... 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. ...
... 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. ...
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The Metropolitan Ilocos Norte Watershed Forest Reserve (MINWFR) is among the remaining intact limestone formations and a critical protected area in Northwestern Luzon. There have been few published floristic studies despite its undeniable rich biological importance. Therefore, this paper primarily aims to provide a preliminary checklist of vascular plants in MINWFR and their conservation status. Consequent field visits and surveys were made from April 2019 to March 2020. Results revealed a total of 173 species distributed in 140 genera belonging to 59 families. The most represented families are Rubiaceae, Fabaceae, Orchidaceae, and Malvaceae. This forest supports 49% or 28.65 % local endemics, five of which are narrow endemics, namely Cyanometra warburgii, Pyrostria triflora, Syzygium ilocanum, Thrixspermum nicolasiorum, and Antirhea microphylla. The latter, however, extends up to Ilocos Sur. Based on IUCN criteria and DENR records, a total of 18 species are threatened, one species is recorded as critically endangered, five endangered, nine vulnerable, three other threatened, two near threatened, 55 as least concern, and the rest are not evaluated. Other noteworthy species present in the area are the two dominant endangered species, Podocarpus costalis, and Podocarpus polystachyus. An interesting spinescent Rubiaceae species were recorded and currently under examination to establish its identity. This checklist serves as a basis to effectively manage this vulnerable area surrounded by human-induced disturbances and threats.
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Pla-ard M, Hoonheang W, Kaewdee B, Panganta T, Charaspet K, Khoiesri N, Paansri P, Kanka P, Chanachai Y, Thongbanthum J, Bangthong P, Sukmasuang R. 2021. Abundance, diversity and daily activity of terrestrial mammal and bird species in disturbed and undisturbed limestone habitats using camera trapping, Central Thailand. Biodiversitas 22: 3620-3631. This study on the abundance, diversity and daily activity of terrestrial mammal and bird species was conducted in the limestone mountainous area of Central Thailand, located on the east of Dong Phaya Yen-Khao Yai forest complex. Camera traps were placed in both habitats disturbed by limestone mining and undisturbed habitat areas. From the study, a total of 38 species of mammals and birds from 27 families in 13 orders were recorded, including 15 species of mammals from 6 orders, 12 families and 23 species of birds from 14 families in 7 orders. Fifteen species of mammals were recorded in the undisturbed area and 11 were recorded in the disturbed area, with the Malayan Pangolin, Small Indian Civet and Grey-bellied Squirrel found in the undisturbed area. However, the number of bird species in the limestone mining area was larger than in the undisturbed area. It was also found that there was no difference in the overall abundance and diversity of mammalian species between disturbed and undisturbed areas, which is not in accordance with the hypothesis. But in the case of wild birds, the relative abundance of wild birds was found to differ significantly between areas. A high number was found in the areas with mining activities, although there was no difference in the diversity index of the two areas. However, it was found that when the combined data was analyzed, there was a significant difference in the daily activity of both mammals and wild birds in both areas. Many rare wildlife species were recorded during this study, for example, the Malayan Pangolin, Serow, Northern Pig-tailed Macaque, Rufous Limestone-babbler, Golden Jackal, Leopard Cat, Large-toothed Ferret Badger, Small Asian Mongoose, Common Palm Civet, Small Indian Civet, Malayan Porcupine. The key measure proposed is to preserve some natural habitats within the areas with mining activities, as wildlife remains in the area.
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Hakim L, Widyorini R, Nugroho WD, Prayitno TA. 2021. Radial variability of fibrovascular bundle properties of salacca (Salacca zalacca) fronds cultivated on Turi Agrotourism in Yogyakarta, Indonesia. Biodiversitas 22: 3594-3603. Fibrovascular bundles have properties variability not only based on species and varieties but also parts of species. This study, therefore, aims to characterize the FVB fundamental properties (anatomical, chemical, physical and mechanical) of Salacca zalacca (Gaertn.) Voss fronds, based on radial direction. The salacca fronds were divided into three parts, outer, middle as well as inner positions. Then the FVB's anatomical and physical properties were observed by light microscope and gravimetry analysis, respectively. Meanwhile, the variability of chemical and mechanical properties was investigated based on the ASTM standard. According to the results, the outer position has a higher variability of diameter, density, cellulose, lignin, and mechanical properties than the inner position, but has a lower hemicellulose value than the middle and inner position. Furthermore, the relationships between the anatomical, physical, chemical, and mechanical properties were discovered to form a pattern where increasing the mechanical properties is influenced by density and ratio vascular tissue area to total transverse area. Based on the results, the fibrovascular bundle of S. zalacca frond was concluded to possess anatomical, physical, chemical, and mechanical properties variability on the radial direction. There was a correlation between anatomical properties and mechanical properties.