Nevertheless, many species extinctions have probably gone unnoticed on karsts that were destroyed before they could be sampled. Unless biodiversity surveys of karsts are intensified, the true magnitude of extinctions will never be ascertained. Large-scale operations involving the mining of limestone and basement minerals e. To estimate the magnitude of limestone-quarrying activities in the tropics, we compiled mineral statistics over a five-year period — for four regions. Southeast Asia appears to have greater mean annual increases in limestone quarrying rates 5.
Furthermore, quarrying rates for each region are likely to be underestimates because they do not include statistics from village-level quarries. The gravity of these figures will become clear only when remaining limestone resources for the whole of Southeast Asia have been quantified.
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Nevertheless, they suggest a bleak outlook for the future of regional karst biodiversity. Quarrying rates in Southeast Asia appear to be the highest relative to other regions. Calculations excluded countries with incomplete statistics for all five years. Land clearing for development is another major threat to karst biota. Logging activities around karsts a reduce shade and humidity and endanger sensitive plants Kiew , b drive away cave-visiting animals such as mammals and arthropods that supply organic matter to guano communities Culver et al.
The land surrounding karsts is sometimes burned to facilitate crop cultivation e. Burnt karsts subsequently experience prolonged desiccation due to higher solar radiation and are more susceptible to further fires Schilthuizen et al. The resulting depauperate secondary vegetation that grows on burnt karsts not only takes decades to recover Kiew , but also results in population declines in taxa that are sensitive to disturbance Schilthuizen et al. Unsustainable collection of endemic plants of medicinal and ornamental value can also result in population extinctions, and the indiscriminate harvesting of swiftlet nests in Borneo has reduced swiftlet populations Lim and Cranbrook Excessive nest-harvesting activities may have indirectly contributed to the decline of bat populations as well; the abundance of naked bats Cheiromeles torquatus at the Niah karsts in Sarawak fell from approximately 30, to over a year period Hutson et al.
Hunting pressure can also deplete populations of certain karst-associated animals if it continues unregulated. Bats from karst caves are sold for consumption in the markets of Thailand and Indonesia, and horn trophies of the threatened serow C. Other threats to karst species include the quarrying of speleothems mineral formations in caves, such as stalactites , insecticide use, flooding caused by the damming of nearby rivers, treasure hunting, and spelunking Kiew , Davison Poverty and resource shortages resulting from overpopulation are likely to continue to marginalize karst conservation issues.
Concepts of population extinctions and unsustainable extractions are usually of little concern to the poor. For cash-strapped governments, royalties from cement manufacture are so substantial that policies for sustainable limestone quarrying are generally overlooked. To alleviate poverty and resource overexploitation in karst areas, land-use planning must be improved using a landscape-scale conservation approach to consider the welfare of poorer communities. For example, the managing agencies of the Pu Luong-Cuc Phuong karst conservation project in Vietnam allocated land to local residents for sustainable agroforestry and involved them in ecotourism projects to generate income GEF In Malaysia, karsts that were preserved as aesthetic backdrops for a resort township figure 1d have not only attracted multimillion-dollar investments but also opened up job opportunities for local residents.
In most countries, karsts have been preserved on the basis of anthropocentric criteria e. While such an approach may seem pragmatic to conservation planners, the distinctiveness of a karst's biodiversity and geomorphology must not be neglected. During karst EIAs, high species richness and the presence of IUCN threatened species may function only as secondary indicators; the former does not reflect species rarity, and the latter often excludes uncharismatic organisms.
Instead, endemism levels of range-restricted taxa e. If governments deem limestone quarrying to be necessary, groups of small and isolated karsts should not be selected, because these are more likely to harbor high numbers of endemic species; larger and more extensive karsts may instead be made open to quarrying prospects Vermeulen and Whitten However, such percentages do not necessarily correspond to species representation Rodrigues et al. As karst protection in some countries is still absent or minimal e. For example, the state government of Sarawak has extended the coverage of the Gunung Mulu National Park by km2 to include other karsts IUCN , while organizations such as the World Bank and The Nature Conservancy have helped protect karst landscapes in Vietnam e.
The impressive biodiversity at some of these sites table 3 suggests that protected areas containing karsts may help reduce the number of gap species species with distributions not covered by protected areas; Rodrigues et al. Taxonomic breakdown of species recorded in four of the eight World Heritage natural sites that contain karsts in Southeast Asia.
Current laws that protect karsts in Southeast Asia, however, appear ad hoc, ineffective, or in some cases simply nonexistent.
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For example, many karsts in Malaysia receive protection only by virtue of being located within the boundaries of national parks Kiew In Borneo, agricultural activities often proceed unchecked toward the bases of protected karsts, while localized bans on swiftlet nest harvesting have only served to divert poachers to other unprotected karsts MacKinnon et al. Laws to protect karst species are severely lacking Kiew , Lim and Cranbrook ; the only known case is a cave fish from central Java, Indonesia Vermeulen and Whitten Moreover, mining companies often exploit the uncertain demarcation of legal authority arising from the involvement of too many agencies.
Evidently, additional legislative measures need to be formulated. For example, the retention of forested buffer zones around karsts to prevent fires and maintain habitat integrity should be made compulsory, and mining companies should be prohibited from starting small-scale operations elsewhere if the karsts allocated to them have not been completely quarried. To curb unnecessary limestone quarrying e. Existing wildlife laws must also be amended to protect certain keystone species that can serve as umbrellas for the entire karst community Vermeulen and Whitten For the above-mentioned laws and policies to work, however, governments must clamp down on corruption, resolve conflicting jurisdictions, and provide administrators with greater incentives e.
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The paucity of biological information on karsts ultimately weakens justifications for their conservation in the long run. To support this argument, we screened internationally peer-reviewed articles from the Biological Abstracts database for biodiversity-related articles over a year period — For example, a paper by Chapman is the only known ecological study of karst caves from the region thus far Deharveng and Bedos To promote research on karsts, governments must commit more funds for capacity building in biodiversity research, and regional institutions should form collaborative efforts with international scientific agencies.
It is encouraging that community-based educational programs and workshops on karsts have been carried out with ARCBC and other conservation initiatives e. Percentage of global black bars and Southeast Asian gray bars biodiversity research conducted in major terrestrial and freshwater ecosystems over a year period — These percentages suggest a paucity of biological information on karsts relative to other ecosystems.
Data were obtained from article searches within the abstract, title, and keywords of citations in the Biological Abstracts database using hierarchically nested combinations of relevant keywords and wild cards available from Reuben Clements upon request. We have shown that karsts are major foci for speciation and important biodiversity arks. Considering the immense financial returns from cement manufacturing, their continued exploitation for limestone cannot be stopped.
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In Southeast Asia, karsts warrant greater conservation attention, given the relatively high limestone quarrying rates. The question now is this: Can habitat loss at karsts be slowed down long enough for scientists to get a better handle on the challenges ahead? Unfortunately, given the lack of baseline data on karst biota and their extinction rates, this is a conservation battle we may well lose. We are especially grateful to Tony Whitten for his constructive comments, which greatly improved this article. We also thank Elery Hamilton-Smith for granting us permission to modify his map.
This project was supported by research grants from the Singapore Zoological Gardens, the National University of Singapore R , and research permit no.
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Sign In or Create an Account. Sign In. Advanced Search. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents. Biodiversity arks.
Importance to humanity. Conservation status. Anthropogenic threats. Conservation challenges. References cited. Oxford Academic. Google Scholar. Navjot S. Menno Schilthuizen. Peter K. Reuben Clements rclements nus. Sodhi is an associate professor in the Department of Biological Sciences, National University of Singapore, Singapore , where he work on the conservation and systematics of various animals Peter K. Ng is a professor in the Department of Biological Sciences, National University of Singapore, Singapore , where he work on the conservation and systematics of various animals Menno Schilthuizen is a professor at the Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Locked Bag , Kota Kinabalu, Malaysia, where he studies the evolutionary biology, systematics, and ecology of tropical land snails.
Cite Citation. Permissions Icon Permissions. Abstract The overexploitation of the world's biomes for natural products calls for the prioritization of biologically important ecosystems for conservation. Figure 1. Open in new tab Download slide. Figure 2. Figure 3. Figure 4. Figure 5. Table 1. Figure 6. Table 2. Table 3. Figure 7. Table 4. Bat thought to be extinct rediscovered in southwestern Negros Island, Philippines. Search ADS. Google Preview.
A new genus and species in Cupressaceae Coniferales from northern Vietnam, Xanthocyparis vietnamensis. Poor reproduction in forest passerines from decline of snail abundance on acidified soils. A new family, genus, and species of bat Mammalia: Chiroptera from Thailand. Origins of lepidopteran faunas in high mountains of the Indo-Australian tropics. Morphological and molecular investigations of a new family, genus and species of rodent Mammalia: Rodentia: Hystricognatha from Lao PDR. Two species of cavefishes from northern Thailand in the genera Nemacheilus and Homaloptera Osteichthyes: Homalopteridae.
Cancrocaeca xenomorpha, new genus and species, a blind troglobitic freshwater hymenosomatid Crustacea: Decapoda: Brachyura from Sulawesi, Indonesia. Galapagos Islands troglobites: The questions of tropical troglobites, parapatric distributions with eyed-sister species, and their origin by parapatric speciation. Global gap analysis: Priority regions for expanding the global protected-area network. The evolution and conservation of limestone biotas in Malaysia, with special reference to land snails. Population structure in a snail species from isolated Malaysian limestone hills, inferred from ribosomal DNA sequences.
Effects of karst forest degradation on pulmonate and prosobranch land snail communities in Sabah, Malaysian Borneo. Notes on the non-marine molluscs of the island of Borneo 6. The genus Opisthostoma Gastropoda: Prosobranchia: Diplommatinidae , part 2. Sarawak Bau Limestone Biodiversity. Sarawak Museum Journal. Download all figures. View Metrics.
Living on limestone: Land use policy and practice in karst terrains
Email alerts New issue alert. I think it is one of the unfortunate aspects of our news that we do not tend to hear about these kind of disasters simply because they do not occur in densely populated areas. I think if news about geological events were proliferated by the press regardless of how remote the are people would be better prepared to deal with them and also more likely to avoid hazard areas to start off with. Tuesday, April 14, Sinkholes and subsidence. Sinkholes occur where the rock situated below the land surface is limestone, carbonate, salt beds or rocks that can be naturally dissolved by groundwater circulating through them.
Sinkholes are definitely more of a regular occurrence in Romania than I thought, although we normally don't tend to hear much about them. Thus, the Apuseni Mountains and the Padurea Craiului Mountains where bauxite bodies were discovered to be close enough to the surface present countless sinkholes. Most likely we don't hear about these particular ones, as they are not located in densely populated areas.
The entire village was sucked into a giant sinkhole and a state of emergency was declared for the region. The sinkhole covered near square meters. Many people slept in the streets out of fear that their houses could collapse in the night and city officials feared that land subsidence could extend to other localities and called in experts to see if there is danger of the collapse spreading outside the region.
Thus, the hole opened up because the ground under the tarmac had been washed away by powerful underground floods.
Related Land Use Policy and Practice on Karst Terrains: Living on Limestone
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