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Use of limestone karst forests by Bornean orangutans (Pongo pygmaeus morio) in the Sangkulirang Peninsula, East Kalimantan, Indonesia
Abstract
The Indonesian province of East Kalimantan is home to some of the largest remaining contiguous tracts of lowland Dipterocarp forest on the island of Borneo. Nest surveys recently conducted in these forests indicated the presence of a substantial population of Eastern Bornean orangutans (Pongo pygmaeus morio) in the Berau and East Kutai regencies in the northern half of the province. The Sangkulirang Peninsula contains extensive limestone karst forests in close proximity to the lowland Dipterocarp forests inhabited by orangutans in these regencies. Orangutans have been sighted in these limestone karst forests, but the importance of this forest type for orangutans has been unclear. Therefore, we conducted 49 km of nest surveys in limestone karst forest to obtain the first quantitative estimates of orangutan densities in this habitat, and walked 28 km of surveys in nearby lowland Dipterocarp forests for comparison. We also gathered basic ecological data along our transects in an attempt to identify correlates of orangutan abundance across these habitat types. Undisturbed limestone karst forests showed the lowest orangutan densities (147 nests/km(2), 0.82 indiv/km(2)), disturbed limestone forests had intermediate densities (301 nests/km(2), 1.40 indiv/km(2)), and undisturbed lowland Dipterocarp forests contained the highest density (987 nests/km(2), 5.25 indiv/km(2)), significantly more than the undisturbed limestone karst forests. This difference was not correlated with variation in liana abundance, fig stem density, or stump density (an index of forest disturbance). Therefore, other factors, such as the relatively low tree species diversity of limestone karst forests, may explain why orangutans appear to avoid these areas. We conclude that limestone karst forests are of low relevance for safeguarding the future of orangutans in East Kalimantan.
... Although there is some variation in its precise application (Lambert, 2007), the term fallback foods is generally used to refer to abundant foods of relatively low quality that are used during periods of low overall food availability (Wrangham et al., 1998; Hanya, 2004; Lambert et al., 2004; Yamakoshi, 2004; Knott, 2005; Laden and Wrangham, 2005). The most commonly applied operational definition of fallback foods describes them as foods whose use is significantly negatively correlated with the abundance of preferred foods (Wrangham et al., 1998; Doran et al., 2002a; Marshall and Wrangham, 2007). For example, our studies of gibbons at GPNP demonstrate that figs are a major fallback food for this taxon. ...
... We advocate more general use of the term ''fallback food'' when referring to foods that are consumed by a particular taxon in inverse proportion to the availability of their preferred foods. We feel this would avoid confusion that might arise from the fact that the term ''keystone,'' as applied by some primatologists to foods used by a particular species , is a misuse of a term that had an earlier and different meaning among ecologists and primatologists, one that related to interactions among species, typically across multiple trophic levels (Paine, 1969; Hemingway and Bynum, 2005; Marshall and Wrangham, 2007) and the fact that, in contrast to the use of the term ''staple'' in common parlance, fallback foods may be completely ignored for extended periods (Marshall and Wrangham, 2007). Discussion of the importance of fallback foods rests implicitly , sometimes explicitly, on the concept of ecological crunch periods. ...
... We advocate more general use of the term ''fallback food'' when referring to foods that are consumed by a particular taxon in inverse proportion to the availability of their preferred foods. We feel this would avoid confusion that might arise from the fact that the term ''keystone,'' as applied by some primatologists to foods used by a particular species , is a misuse of a term that had an earlier and different meaning among ecologists and primatologists, one that related to interactions among species, typically across multiple trophic levels (Paine, 1969; Hemingway and Bynum, 2005; Marshall and Wrangham, 2007) and the fact that, in contrast to the use of the term ''staple'' in common parlance, fallback foods may be completely ignored for extended periods (Marshall and Wrangham, 2007). Discussion of the importance of fallback foods rests implicitly , sometimes explicitly, on the concept of ecological crunch periods. ...
Physical anthropologists use the term "fallback foods" to denote resources of relatively poor nutritional quality that become particularly important dietary components during periods when preferred foods are scarce. Fallback foods are becoming increasingly invoked as key selective forces that determine masticatory and digestive anatomy, influence grouping and ranging behavior, and underlie fundamental evolutionary processes such as speciation, extinction, and adaptation. In this article, we provide an overview of the concept of fallback foods by discussing definitions of the term and categorizations of types of fallback foods, and by examining the importance of fallback foods for primate ecology and evolution. We begin by comparing two recently published conceptual frameworks for considering the evolutionary significance of fallback foods and propose a way in which these approaches might be integrated. We then consider a series of questions about the importance of fallback foods for primates, including the extent to which fallback foods should be considered a distinct class of food resources, separate from preferred or commonly eaten foods; the link between life history strategy and fallback foods; if fallback foods always limit primate carrying capacity; and whether particular plant growth forms might play especially important roles as fallback resources for primates. We conclude with a brief consideration of links between fallback foods and primate conservation.
... Different types of forest differ in their suitability for orangutans because they differ in these aspects of food productivity (seeTable 2). Marginal produce less orangutan food due to relatively low productivity and/or low tree species diversity [59] ; probably cannot support permanent populations [40 ] . Orangutans seen in these habitats are probably dispersing males [14] or individuals that can also access better habitat types nearby to meet nutritional needs [59] ;. ...
... Marginal produce less orangutan food due to relatively low productivity and/or low tree species diversity [59] ; probably cannot support permanent populations [40 ] . Orangutans seen in these habitats are probably dispersing males [14] or individuals that can also access better habitat types nearby to meet nutritional needs [59] ;. ...
Reintroduction is an increasingly common approach to protecting displaced wildlife and a useful conservation tool. Reintroduction is especially important for great apes, humans’ closest living biological relatives, who are seriously threatened with extinction. Orangutans are among the most threatened ape species and have been subject to the most extensive reintroduction efforts. Orangutan reintroduction success rates are commonly considered unsatisfactory, however, so improving success is a high priority. Behavioral rehabilitation, the greatest and slowest of these processes, is critical to success. Age-graded forest schools may be among the most effective programs for rehabilitation. This document offers guidelines and standards for orangutan forest schools that should (a) improve methods for encouraging adaptive learning and discouraging counterproductive learning, (b) respect current international standards for reintroduction, and (c) improve the evaluation of progress in individual orangutans, facilitate early identification and remediation of problems, and assess forest school effectiveness. We focus Bornean orangutans; considerations differ somewhat for Sumatrans. Our aims were to design forest schools that are ethically, scientifically, and practically credible.
... Ground nests are often poorly constructed, since they are usually used temporarily during the day for resting (Brownlow et al. 2001;Koops et al. 2007). Site-specific differences are not surprising given that nest decay times vary over space and time and with sample period, tree species, forest type, nest height and position, soil pH, and average rainfall (Ancrenaz et al. 2004;Buij et al. 2003;Johnson et al. 2005;Kouakou et al. 2009;Marshall et al. 2007;Mathewson et al. 2008;van Schaik et al. 1995;Walsh and White 2005). ...
Increased human activities such as commodity-led deforestation, extension of agriculture , urbanization, and wildfires are major drivers of forest loss worldwide. In Camer-oon, these activities cause a loss of suitable primate habitat and could ultimately threaten the survival of chimpanzees (Pan troglodytes). We derived independent estimates of the population size of the Endangered Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti) in Kom-Wum Forest Reserve, Cameroon, and surrounding unprotected forest areas through 1) direct observations, 2) camera trapping, 3) distance sampling, 4) marked nest counts, and 5) standing crop nest counts. In addition, we georeferenced signs of chimpanzee and human activity along line transects. We used a generalized linear mixed model to predict the occurrence of chimpanzees in response to edge length (measured as the perimeter of core forest patches), core area of forest patches (measured as area of forest patches beyond an edge width of 100 m), habitat perforation (measured as the perimeter of nonforested landscape within core forest patches), patch size(measured as area of forest patches), and forest cover. Chimpanzee density estimates ranged from 0.1 (direct observation) to 0.9 (distance sampling) individuals km −2 depending on estimation method with a mean nest group size of 7 ± 5.4 (SD). The mean encounter rate for signs of chimpanzee activity was significantly higher in mature forests (2.3 signs km −1) than in secondary forests (0.3 signs km −1) and above 1000 m elevation (4.0 signs km −1) than below 1000 m (1.0 signs km −1). The mean encounter rate for signs of human activity was significantly higher in secondary (8.0 signs km −1) than in mature forests (0.9 signs km −1). Secondary forests, habitat perforation, and edge length had a significant negative effect on the occurrence of chimpanzee signs. Overall, human activity and forest degradation affected the number of observed chimpanzee signs negatively. Regular antipoaching patrols and reforestation programs in degraded areas could potentially reduce threats to populations of endangered species and may increase suitable habitat area.
... Considering the location of fossiliferous deposits and the geological context of the area in northern Vietnam (Duringer et al., 2012), it is highly plausible that they lived in the limestone forests on hills and tower karsts. Today, limestone karst forests are inhabited by wild populations of low density, due to relatively low tree species diversity and limited productivity (vs forested habitats such as peat-swamp forests, lowland Dipterocarp forests or dry forests) (Marshall et al., 2007;Husson et al., 2009). ...
The Coc Muoi fauna provides a good example of the type of tropical mammalian communities that existed in northern Vietnam during the late Middle Pleistocene. The first results of the analysis of hypoplasia indicated that rhinoceroses and wild cattle were exposed to multiple physiological and psychological stress events specific to age [Bacon et al., 2018. A rhinocerotid-dominated megafauna at the MIS6-5 transition: The late Middle Pleistocene Coc Muoi assemblage, Lang Son province, Vietnam. Quat. Sci. Rev. 186, 123–141].
In this paper, we aim to supplement the study of hypoplasia in the orangutans (Pongo) from Coc Muoi and, more widely, from different Pleistocene faunas. To address this issue, we conducted a macroscopic analysis of linear enamel hypoplasia [LEH] on Pongo from three collections: Coc Muoi (148–117 ka), Duoi U'Oi (70–60 ka), and Tham Khuyen (>475 ka).
Such comparative analysis based on isolated teeth is constrained by numerous biases including: the small datasets; the differential representation of tooth types; the difficulty in distinguishing first from second molars; the small number of individuals [MNI]; the differential representation of males versus females. The data analysis has been divided into two parts: (1) an analysis of the frequency and expression of LEH on incisors, premolars, and molars (three sites), and (2) an analysis of the frequency and expression of LEH on a set of canines (Tham Khuyen). We used a reference sample composed of 17 adult and 10 immature Pongo individuals to determine the age range of fossil Pongo individuals, at the time of the defects.
Results show that hypoplasia was a common phenomenon in Pleistocene Pongo: two individuals at Coc Muoi; 2 out of 3 individuals at Duoi U’Oi; and 4 out of 6 individuals at Tham Khuyen. They experienced multiple stresses between ∼2 and 5 years of age, a period of great vulnerability for immature individuals. The occurrence of accentuated lines of hypoplasia on canine crowns of Tham Khuyen suggests a greater intensity of the stressor, in a time range consistent with the long dietary and behavioral transition of the weaning. In terms of paleoecology, Pleistocene orangutans from the Asian mainland could survive in different environmental conditions than those they occupy today. Various sources (archaeozoology, geological context, and ecology of wild populations), suggest that they might have been larger apes than extant orangutans, living in limestone forests on hills and tower karsts.
... Studies on endangered primates inhabiting karst habitats generally describe karst forests as nonpreferred habitats, likely due to the inadequate food resource availability in these forests (for white-headed langur, Trachypithecus leucocephalus, see Li and Rogers 2005; for Delacour's langur, Trachypithecus delacouri, see Workman 2010). In their study of Bornean orangutans (Pongo pygmaeus morio) in the forests of East Kalimantan (Indonesia), for example, Marshall et al. (2007) suggested that the relatively low tree species diversity of limestone karst forest may explain why orangutans avoid these areas, and they concluded that karst forest should be considered suboptimal habitat. ...
Primate behavior can be responsive to the different ecological pressures associated with different habitats, as well as to the effects of direct and indirect anthropogenic disturbance. The karst forest ecosystem of South Sulawesi (Indonesia) represents one of the few intact forests available for residual populations of the moor macaque, but our understanding of its habitat use is limited. In the present study, this gap in knowledge was addressed by observing the activity and habitat use of two groups of moor macaques and by assessing the suitability of different habitats in the karst forest. Through a fine-scale vegetation analysis of 1 ha of forest in Bantimurung Bulusaraung National Park, we identified the presence of two distinct habitats that differ in terms of forest structure and composition. The karst plain forest (KPF) provided a greater abundance and diversity of food resources than the karst tower forest (KTF). In addition, anthropogenic disturbance was high in the KPF but low in the KTF. Behavioral data collected via group scans indicate that the macaques devoted more time to feeding activities when in the KPF, suggesting an ability to adjust their feeding behavior to meet their nutritional needs. However, the larger of the two groups used the food-rich KPF more than expected, implying that the KTF may represent a valuable refuge for the smaller group, as it is a less risky portion of its home range. The results of this study therefore provide novel information on the ecology of moor macaques and their habitats that can inform conservation planning for remnant populations.
... In Marang their leftovers, such as bark and lianas, were also found scattered on the forest floor. The occurrence of this species in Marang karst forest has been reported before by Marshall et al. (2007) through an orangutan nest survey. The existence of this ape in other karst forest in East Kalimantan, such as in Beriun, has been reported in previous surveys by Kusrini & Bukhori (2011). ...
The Sangkulirang-Mangkalihat Karst is an area in Kutai Timur and Berau regencies of East Kalimantan province, Indonesia, on the island of Borneo. The peninsula is dominated by limestone geology, and it covers an area of over 18,000 square kilometres. Brief primate surveys were conducted in karst areas in seven locations spanning from Sangkulirang to Mangkalihat. A total of nine primate species were found. Diurnal surveys were made in Suaran (5 days), Karangan Dalam (5 days), Tepian Langsat (Marang) (5 days), Biatan Ulu (4 days), Lobang Kelatak (5 days), Lobang Belanda (Teluk Sulaiman) (3 days) and Danau Sigending (Teluk Sulaiman) (2 days). Night surveys were also carried out to observe nocturnal primates. This activity was part of the TFCA Kalimantan Project, led and managed by the Karst Research Group of the Faculty of Geography, Gadjah Mada University. A total of nine species of primate were seen: Nycticebus sp.,
... However, very few nests were recorded in limestone habitats and in forests growing on ultra basic soils originating from Bidu Bidu and similar associations. The lack of sodium and the relative abundance of nickel, chromium and cobalt characteristic of these soils limits the growth of many plant species, resulting in a less diverse tree community with fewer food resources than other forest types, which accounts for the lower nest abundance in these suboptimal orang-utan habitats (Marshall et al., 2007). ...
Orang-utans, Asia’s only great ape, occur solely in the tropical forests of Borneo and Sumatra
(great apes include chimpanzees, gorillas, bonobos and orang-utans). Their populations are
declining fast: the Sumatran orang-utan (Pongo abelii) is critically endangered and the Bornean
species (Pongo pygmaeus) is considered endangered in the IUCN Red List. The major drivers
for the species declines include poaching for meat and traditional medicine; pet trade;
destruction, degradation and fragmentation of their habitat; and natural causes such as
diseases and global climate change. In this thesis I present results from the research I designed
and conducted to guide some of the conservation efforts that have contributed to slowing down
the decline of the species in the Malaysian state of Sabah (Borneo) over the past 17 years. I
also discuss some of the new challenges and threats faced by the species in the newly created
multiple-use landscapes that are currently found throughout most of the species’ range. Last but
not least, I discuss new technology and opportunities that are currently available to
conservationists and that need to be used in order to secure the future of orang-utans
throughout its range. My thesis is articulated around five major orang-utan conservation
questions that I have been exploring for the past 17 years. These topics are crucial to secure
the future of the species. They include:
1. The possible function of reduced-impact logging and sustainable practices for
orang-utan survival in commercial forest reserves
Without any doubt, destruction of forests following large-scale conventional logging practices
can result in the local extinction of orang-utan populations. However the surveys that I led in
Sabah have established that sustainable logging can be compatible with orang-utan survival as
long as diligent planning, proper implementation of reduced-impact practices and a zero-hunting
policy are all strictly enforced. Consequently, implementing better management practices for
commercial forest reserves exploited for timber might contribute to securing the future of the
species in some areas.
2. The need to reconcile the agro-industrial landscape with orang-utan survival
In eastern Sabah, orang-utans are seen more and more frequently roaming into large industrial
oil palm plantations. Although oil palm plantations cannot sustain viable populations of orangutans,
these observations warrant further studies to design better landscapes where we can
reconcile agriculture practices and orang-utan survival.3. New evidence showing that orang-utans are more terrestrial than previously
thought – an insight with a host of implications for the design of future
conservation efforts
The use of new technologies, such as camera-traps, reveal new facts about orang-utan
behavior and ecology, one of the species scientists thought they understand well. The study I
co-supervised showed that orang-utans move on the ground more often than we thought. These
new findings open new thinking for orang-utan conservation that need to be incorporated in
management and conservation strategies in non-protected areas.
4. The need to consider risks of disease transmission as a result of wildlife tourism
and increased contact with people in human-transformed landscapes
The promotion of nature-based tourism is seen as a way to incorporate local communities in
conservation. It has the potential to promote wildlife conservation, increase public awareness
and raise local revenue for protecting endangered species such as great apes. However,
regular habitat penetration of the orang-utan habitat by people and repeated close proximity
between apes and people can also be counterproductive to conservation goals: behavioral
disorders, increased stress levels and disease transmission can all result from bad tourism
practices. These negative impacts need to be addressed and minimized in order to develop
successful conservation strategies in the long-term.
5. The need to engage with a wide variety of stakeholders
Since orang-utans are found in different forests which are exploited by a wide range of
stakeholders, their conservation warrants a novel, multi-disciplinary approach which must go
beyond the traditional view of conserving species by designating protected areas. Therefore,
orang-utan conservation must encompass the needs and aspirations of people who are sharing
and exploiting the same habitat, and must include both commercial interests as well as local
communities in their management, rather than solely adopting a single-species conservation
approach.
The research presented in this thesis shows that although protected areas should remain
the heart of orang-utan conservation, the protection of orang-utans in Sabah requires a
paradigm shift: the traditional approach of protecting primary pristine habitat empty of
people is insufficient. Orang-utan conservation must incorporate improved management
of multiple-use habitats where wildlife and people can co-habit, while minimizing the
risks of pathogen transmission which might arise from this close cohabitation.
... Orangutans mainly live in primary tropical rain forest and old secondary forest at low elevations that include peat swamp forests and lowland mixed dipterocarp forests (Rodman, 1988). Bornean orangutan density is low in most populations, ranging from 0.8 to 4.3ind/km² on average (van Schaik et al., 2005;Marshall et al., 2007). On Sumatra, the average density seems to be slightly higher in similar habitats as on Borneo (Delgado and van Schaik, 2000; for a review see Husson et al., 2009Husson et al., ). ...
... In 2007, rainforest still covered more than half of the drainage basin, although the rainforest cover is rapidly decreasing due to economic development (Ekadinata et al., 2010). The rainforest supports high densities of the Bornean orangutan (Marshall et al., 2007). The adjacent Berau continental shelf is host to an extremely diverse coral community (de Voogd et al., 2009) that shows a marked zonation with more turbid coastal reefs west of the Derawan reef chain, and oceanic reefs east of the chain (Fig. 1). ...
Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in the tropics. The increasing sediment fluxes pose a threat to coastal marine ecosystems such as coral reefs. This study presents observations of suspended sediment fluxes in the Berau river (Indonesia), which debouches into a coastal ocean that can be considered the preeminent center of coral diversity. The Berau is an example of a small river draining a mountainous, relatively pristine basin that receives abundant rainfall. Flow velocity was measured over a large part of the river width at a station under the influence of tides, using a Horizontal Acoustic Doppler Current Profiler (HADCP). Surrogate measurements of suspended sediment concentration were taken with an Optical Backscatter Sensor (OBS). Tidally averaged suspended sediment concentration increases with river discharge, implying that the tidally averaged suspended sediment flux increases non-linearly with river discharge. Averaged over the 6.5 weeks observations covered by the benchmark survey, the tidally averaged suspended sediment flux was estimated at 2 Mt y-1. Considering the wet conditions during the observation period, this figure may be considered as an upper limit of the yearly averaged flux. This flux is significantly smaller than what could have been expected from the characteristics of the catchment. The consequences of ongoing clearing of rainforest were explored using a plot scale erosion model. When rainforest, which still covered 50-60 % of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment flux in the Berau river would impose a severe sediment stress on the global hotspot of coral reef diversity. The impact of land cover changes will largely depend on the degree in which the Berau estuary acts as a sediment trap.
... The relative opportunity costs of preserving karst forests to conserve orangutans are unclear. While karsts host significant species endemism, they support low orangutan densities and are not considered an important focus for orangutan conservation (Marshall et al., 2007). Although some, not all, karst forests have rich and productive soils suitable for agriculture, such as for rice production and oil palm, they are most valued economically for mining and are quarried for cement, marble and lime for agriculture (e.g., to reduce the acidity of peat soils) (Schilthuizen et al., 2005). ...
... In 2007, rainforest still covered more than half of the drainage basin, although the rainforest cover is rapidly decreasing due to economic development (Ekadinata et al., 2010). The rainforest supports high densities of the Bornean orangutan (Marshall et al., 2007). The adjacent Berau continental shelf is host to an extremely diverse coral community (de Voogd et al., 2009) that shows a marked zonation with more turbid coastal reefs west of the Derawan reef chain, and oceanic reefs east of the chain (Fig. 1). ...
Forest clearing for reasons of timber production, open pit mining and
the establishment of oil palm plantations generally results in
excessively high sediment loads in tropical rivers. The increasing
sediment loads pose a threat to coastal marine ecosystems, such as coral
reefs. This study presents observations of suspended sediment loads in
the Berau River (Kalimantan, Indonesia), which debouches into a coastal
ocean that is a preeminent center of coral diversity. The Berau River is
relatively small and drains a mountainous, still relatively pristine
basin that receives abundant rainfall. In the tidal zone of the Berau
River, flow velocity was measured over a large part of the river width
using a horizontal acoustic Doppler current profiler (HADCP). Surrogate
measurements of suspended sediment concentration were taken with an
optical backscatter sensor (OBS). Averaged over the 6.5 weeks covered by
the benchmark survey period, the suspended sediment load was estimated
at 2 Mt yr-1. Based on rainfall-runoff modeling though, the
river discharge peak during the survey was supposed to be moderate and
the yearly averaged suspended sediment load is most likely somewhat
higher than 2 Mt yr-1. The consequences of ongoing clearing
of rainforest were explored using a plot-scale erosion model. When
rainforest, which still covered 50-60% of the basin in 2007, is
converted to production land, soil loss is expected to increase with a
factor between 10 and 100. If this soil loss is transported seaward as
suspended sediment, the increase in suspended sediment load in the Berau
River would impose a severe stress on this global hotspot of coral reef
diversity.
... The areas of the different habitat types were calculated with Geographic Information System (GIS) software, except the areas planted between mid-2003 and the end of 2006 which were directly obtained from plantation company maps. Data were collected by teams of at least two experienced surveyors [23,47,48]. Each transect was censused twice, in opposite directions, to minimize the chance that nests were missed [43]. ...
Ecological studies of orangutans have almost exclusively focused on populations living in primary or selectively logged rainforest. The response of orangutans to severe habitat degradation remains therefore poorly understood. Most experts assume that viable populations cannot survive outside undisturbed or slightly disturbed forests. This is a concern because nearly 75% of all orangutans live outside protected areas, where degradation of natural forests is likely to occur, or where these are replaced by planted forests. To improve our understanding of orangutan survival in highly altered forest habitats, we conducted population density surveys in two pulp and paper plantation concessions in East Kalimantan, Indonesia. These plantations consist of areas planted with fast-growing exotics intermixed with stands of highly degraded forests and scrublands. Our rapid surveys indicate unexpectedly high orangutan densities in plantation landscapes dominated by Acacia spp., although it remains unclear whether such landscapes can maintain long-term viable populations. These findings indicate the need to better understand how plantation-dominated landscapes can potentially be incorporated into orangutan conservation planning. Although we emphasize that plantations have less value for overall biodiversity conservation than natural forests, they could potentially boost the chances of orangutan survival. Our findings are based on a relatively short study and various methodological issues need to be addressed, but they suggest that orangutans may be more ecologically flexible than previously thought.
... The relative economic benefit of preserving karst forests is unclear. While karsts host significant species endemism, they support low orangutan densities and are not considered an important focus for orangutan conservation (Marshall et al., 2007). Although some, not all, karst forests have rich and productive soils suitable for agriculture such as for rice production and oil palm, they most valued economically for mining and are quarried for cement, marble and lime for agriculture (e.g., to reduce the acidity of peat soils) (Schilthuizen et al., 2005). ...
... However, very few nests were recorded in limestone habitats and in forests growing on ultra basic soils originating from Bidu Bidu and similar associations. The lack of sodium and the relative abundance of nickel, chromium and cobalt characteristic of these soils limits the growth of many plant species, resulting in a less diverse tree community with fewer food resources than other forest types, which accounts for the lower nest abundance in these suboptimal orang-utan habitats [26]. Large bodies of water, such as the Segama River, represent a barrier to orang-utans dispersal [27,28]. ...
Today the majority of wild great ape populations are found outside of the network of protected areas in both Africa and Asia, therefore determining if these populations are able to survive in forests that are exploited for timber or other extractive uses and how this is managed, is paramount for their conservation.
In 2007, the "Kinabatangan Orang-utan Conservation Project" (KOCP) conducted aerial and ground surveys of orang-utan (Pongo pygmaeus morio) nests in the commercial forest reserves of Ulu Segama Malua (USM) in eastern Sabah, Malaysian Borneo. Compared with previous estimates obtained in 2002, our recent data clearly shows that orang-utan populations can be maintained in forests that have been lightly and sustainably logged. However, forests that are heavily logged or subjected to fast, successive coupes that follow conventional extraction methods, exhibit a decline in orang-utan numbers which will eventually result in localized extinction (the rapid extraction of more than 100 m(3) ha(-1) of timber led to the crash of one of the surveyed sub-populations). Nest distribution in the forests of USM indicates that orang-utans leave areas undergoing active disturbance and take momentarily refuge in surrounding forests that are free of human activity, even if these forests are located above 500 m asl. Displaced individuals will then recolonize the old-logged areas after a period of time, depending on availability of food sources in the regenerating areas.
These results indicate that diligent planning prior to timber extraction and the implementation of reduced-impact logging practices can potentially be compatible with great ape conservation.
... The relative economic benefit of preserving karst forests is unclear. While karsts host significant species endemism, they support low orangutan densities and are not considered an important focus for orangutan conservation (Marshall et al., 2007). Although some, not all, karst forests have rich and productive soils suitable for agriculture such as for rice production and oil palm, they most valued economically for mining and are quarried for cement, marble and lime for agriculture (e.g., to reduce the acidity of peat soils) (Schilthuizen et al., 2005). ...
Human-induced land-use change has resulted in substantial loss and degradation of habitat for forest-dwelling wildlife. The moor macaque Macaca maura, an Endangered primate endemic to Sulawesi, Indonesia, has been observed in a wide array of habitats, including heavily modified areas, but little is known about the quality of these habitats. Here we compared the habitat quality of two areas occupied by moor macaque populations: a previously human-modified karst forest now located within a national park and a heavily modified forest located in an unprotected area. We assessed habitat quality by measuring specific indicators of potential food availability derived from vegetation data and quantified the nutritional environment based on macronutrient analysis of fruit samples collected at the two sites. Although the species richness, diversity and overall stem density of macaque food trees were greater in the protected area forest, total basal area and mean diameter at breast height were greater in the heavily modified forest. Mean metabolizable energy concentrations of fruits eaten by macaques were similar between forests, as were the proportions of protein, lipids and total non-structural carbohydrates. These results provide further support for the notion that heavily modified habitats should not be overlooked for their potential conservation value. To further augment their value, conservation efforts should focus on forest restoration, specifically the planting of fast-growing species that are utilized by both wildlife and people.
Indonesia hosts a vast area of karst landscapes that expand from the island of Sumatra to Papua. Along with the implementation of the World Heritage List and Global Geopark Network, karst environment has become essential topics in Indonesia. By using SCOPUS and Google Scholar database, this paper examined trends of karst research in Indonesia. The result showed that karst related publications have shown to be increasing from 1994 to 2010, and grow more massively after 2010. Also, the publications can be classified into 1) conservation and biodiversity, 2) geophysical studies of karst, 3) environment and resource management, 4) forestry and agriculture, 5) archaeology and prehistoric life, 6) socio-cultural and education aspects. A wide gap occurred in research about conservation strategies at a more comprehensive and integrated scale, such as in a landscape, that takes a multidisciplinary and transdisciplinary approach at achieving sustainability. In terms of environmental education, the use of karst as a natural laboratory remained limited in subjects. Yet, it had excellent potential to be developed as a model for a multidisciplinary and transdisciplinary approach to environmental studies, to achieve the goal of Education of Sustainable Development (ESD).
Pongo pygmaeus pygmaeus is a subspecies of Bornean orangutan whose distribution is restricted to the northern part of the Kapuas River, West Kalimantan, and is categorized as Critically Endangered. In October 2017 we carried out a survey to estimate orangutan density in the peat-swamp forests of the Sungai Palin watershed, of the upper Kapuas river, Kapuas Hulu, West Kalimantan, Indonesia. Surveys for orangutans in 1991, in nearby Nanga Awen, had indicated the presence of orangutans in the peat-swamp forests of this area. We used distance sampling techniques to estimate orangutan densities from nest observations. We recorded 76 orangutan nests along 4.5 km transects in Sungai Palin in 2017, and 71 orangutan nests were observed along 4.3 km transects in Nanga Awen in 1991, giving densities of 1.29 and 2.62 individuals/km ² , respectively. The results of this orangutan survey can be used as a baseline for monitoring of orangutan populations for conservation and management of this watershed landscape.
This research try to describe how local NGO in East Kalimantan, Jatam (Mining Advocacy Network) and Walhi (Friends of the Life) pursue their interest in the politics of environmental management in Sangkulirang-Mangkalihat Karst Area in East Kutai and Berau Regency in East Kalimantan Province. How do they strive for their interest? What kind of strategy they deploy? And why? The result shows that there are several strategies that Jatam and Walhi use. They are: 1) Protest, 2) Seminar/FGD, and 3) Campaign. Those strategies are influenced by internal and external factors. For the internal factors, both Jatam and Walhi�s structure of organization creates possibilities to collaborate with other party with the same agenda to achieve the goal. The second internal factor is the funding. Is is widely known that local NGO in East Kalimantan, especially those who strive for environmental protection lack the financial resources to fund their agenda. Both Jatam and Walhi�s financial resources are relatively small compared to the resources of related actors such as the Government and corporations. With such conditions, street protests, seminar and campaign become the rational instruments to be deployed. The last is external factor that considers the social and political context of East Kalimantan society that make them choose those strategies.
This newsletter was published from 2005 to 2009 and provided regular updates about The Nature Conservancy's conservation work in the forests of East Kalimantan and Sulawesi
This newsletter was published from 2005 to 2009 and provided regular updates about The Nature Conservancy's conservation work in the forests of East Kalimantan and Sulawesi
This book describes one of our closest relatives, the orangutan, and the only extant great ape in Asia. It is increasingly clear that orangutan populations show extensive variation in behavioral ecology, morphology, life history, and genes. Indeed, on the strength of the latest genetic and morphological evidence, it has been proposed that orangutans actually constitute two species which diverged more than a million years ago — one on the island of Sumatra the other on Borneo, with the latter comprising three subspecies. This book has two main aims. The first is to carefully compare data from every orangutan research site, examining the differences and similarities between orangutan species, subspecies and populations. The second is to develop a theoretical framework in which these differences and similarities can be explained. To achieve these goals the book synthesizes and compares the data, quantify the similarities or differences, and seeks to explain them.
Lianas are becoming an increasingly prominent component of tropical forests. This chapter evaluates the use of lianas by primates an abundant, species-rich, and ecologically important order of mammals. The great majority of primate species are highly arboreal, and they depend on the different strata above the forest floor for feeding, traveling, resting, breeding, and protection from predators. Lianas represent an important food resource for primates, as many different primate species use a large number of liana species. Lianas often reproduce during periods that are unfavorable to trees, and have a much higher growth rate during the dry season than trees. Lianas are important structural elements during locomotion, as the systems of bridges that lianas form among trees facilitate the movement of arboreal primate. Lianas may affect the distribution of primates through their positive effect on the abundance of preferred food sources.
A critical review of orangutan survey methodology: with a focus on the proposed link between soil pH and nest decay rate.
The human footprint is increasing across the world's natural habitats, causing large negative impacts on the survival of many species. In order to successfully mitigate the negative effects on species' survival, it is crucial to understand their responses to human-induced changes. This paper examines the effect of one such disturbance, logging, on Sumatran orangutans – a critically endangered great ape. Orangutan population densities may decrease or remain stable after logging, but data on the effects of logging on the behavior of individuals is scant. Here, we provide individual-level behavioral data based on direct observations in 2003–2008 at the Ketambe (Sumatra, Indonesia) research area (partly subject to intense selective logging) in order to assess responses of Sumatran orangutans to logging. Logging significantly negatively affected forest structure and orangutan food resources, specifically important fallback and liana-derived foods. Individual orangutans behaved differently between logged and pristine forest; they moved more and rested less in logged forest. With the exception of figs, diet composition remained overall similar. Altogether, life after logging seems energetically more expensive for orangutans. Based on the results of this study, we provide recommendations for conservation research and guidelines for reduced-impact logging.
Summary The aim of this project is to determine the impact of illegal logging on orangutan behaviour, ecology and survival at the Ketambe research site, northern Sumatra, Indonesia. To design sustainable logging systems it is of critical importance to determine the effect that logging has on a forest's inhabitants and whether or not the logging ultimately threatens their long-term survival. Conservation decision makers also need accurate information on species' ability to endure logging in order to identify priority areas for protection. The Ketambe research site offers a unique opportunity to investigate this issue due to the existence of a wealth of data from the past 30 years (covering orangutan behaviour, demography, density and food availability) providing a comprehensive pre-logging database, with which we can compare the post-logging data. Initially we seek funding to establish this study for two years, but with the ultimate aim being to extend this period considerably because long-term data after logging is critical to evaluate how orangutans respond to logging. By comparing pre and post logging data we will be able to identify any significant changes in orangutan behaviour and feeding ecology that have resulted from logging. Furthermore, we will identify and monitor changes to the population density using repeated nest censuses at the same locations were pre-logging census work has been conducted. Food availability changes will be determined by examining the long-term vegetation plot data that has been collected pre-logging and now also post-logging. These will provide accurate information on which tree species have been removed and damaged in the process. This will allow us to identify by how much the potential food resources of the orangutans (and other species) have been reduced. We will also continue to monitor fruit availability in these plots, and by surveying and collecting fruits from trails on a monthly basis. The unique value of this study is that it will take place in an area that has been
http://www.primate-sg.org/best_practice_surveys/
In recognition of the fact that orang-utans (Pongo spp.) are severely threatened, a meeting of orang-utan experts and conservationists, representatives of national and regional governmental and non-governmental organizations, and other stakeholders, was convened in Jakarta, Indonesia, in January 2004. Prior to this meeting we surveyed all large areas for which orang-utan population status was unknown. Compilation of all survey data produced a comprehensive picture of orang-utan distribution on both Borneo and Sumatra. These results indicate that in 2004 there were c. 6,500 P. abelii remaining on Sumatra and at least 54,000 P. pygmaeus on Borneo. Extrapolating to 2008 on the basis of forest loss on both islands suggests the estimate for Borneo could be 10% too high but that for Sumatra is probably still relatively accurate because forest loss in orang-utan habitat has been low during the conflict in Aceh, where most P. abelii occur. When those population sizes are compared to known historical sizes it is clear that the Sumatran orang-utan is in rapid decline, and unless extraordinary efforts are made soon, it could become the first great ape species to go extinct. In contrast, our results indicate there are more and larger populations of Bornean orang-utans than previously known. Although these revised estimates for Borneo are encouraging, forest loss and associated loss of orang-utans are occurring at an alarming rate, and suggest that recent reductions of Bornean orang-utan populations have been far more severe than previously supposed. Nevertheless, although orang-utans on both islands are under threat, we highlight some reasons for cautious optimism for their long-term conservation.
The six limestone langur taxa of Southeast Asia inhabit the rugged limestone karst mountains, although the reason for their current restriction to this habitat is unclear. From August 2007 to July 2008, I collected data on the diet and feeding behavior of the critically endangered Delacour's langur (Trachypithecus delacouri) in Van Long Nature Reserve, Vietnam. I used these data to evaluate the hypothesis that limestone langurs are found on karst habitat because they depend on endemic limestone plants. Feeding accounted for 29% of the langurs' activity budget. Young leaves dominated the diet monthly, seasonally, and annually. The annual diet consists of nearly 79% foliage with almost 60% young leaves. Despite a distinct wet and dry season, over the study period, seasonal variation in plant part consumption was slight. Fruit and seeds were a small contribution to the diet. Delacour's langurs ate 42 of 145 available species, and they concentrated on a subset of this number. Five plant species comprised more than 60% of the diet and 16 species comprised more than 93%. More than half of the diet came from climbers. Delacour's langurs are among the most highly folivorous of studied colobines and, along with the closely related T. leucocephalus of southern China, the most folivorous of the Asian langurs. Whether high folivory is owing to a lack of available fruits and seeds in limestone habitats is unknown. What is certain, however, is that the plant species most important in the Delacour's langurs' diet at VLNR, throughout the study, were not plants endemic to limestone. Feeding dependence alone, therefore, cannot explain the current distribution of limestone langurs on karst habitat.
An accurate estimate for orangutan nest decay time is a crucial factor in commonly used methods for estimating orangutan population size. Decay rates are known to vary, but the decay process and, thus, the temporal and spatial variation in decay time are poorly understood. We used established line-transect methodology to survey orangutan nests in a lowland forest in East Kalimantan, Indonesia, and monitored the decay of 663 nests over 20 months. Using Markov chain analysis we calculated a decay time of 602 days, which is significantly longer than times found in other studies. Based on this, we recalculated the orangutan density estimate for a site in East Kalimantan; the resulting density is much lower than previous estimates (previous estimates were 3-8 times higher than our recalculated density). Our data suggest that short-term studies where decay times are determined using matrix mathematics may produce unreliable decay times. Our findings have implications for other parts of the orangutan range where population estimates are based on potentially unreliable nest decay rate estimates, and we recommend that for various parts of the orangutan range census estimates be reexamined. Considering the high variation in decay rates there is a need to move away from using single-number decay time estimates and, preferably, to test methods that do not rely on nest decay times as alternatives for rapid assessments of orangutan habitat for conservation in Borneo.
The main concerns in this report are biodiversity and cultural property associated with limestone in East Asia. These areas of interest are rarely paired, but do have common features: both are largely untraded goods, although some elements are highly valued by some but not by others. The World Bank finds that their loss or damage in the course of economic development is a significant issue, and that limestone areas are very important sites for both biodiversity and cultural property. Other limestone- related issues are dealt with relatively briefly insofar as they are relevant to the purpose of the report. In this way, the report is a first step to redress the balance in favor of concern for limestone biodiversity and cultural property, which are under-represented in the literature on limestone. Although such topics karst formation, karst features, hydrology, and geological features are discussed only very briefly, no lack of their importance is implied. This report deals primarily with limestone areas in East Asia, which in World Bank parlance comprises its client countries of Mongolia, China, the Republic of Korea, Thailand, the Lao People's Democratic Republic (Lao PDR), Vietnam, Cambodia, Malaysia, the Philippines, Indonesia, and Papua New Guinea. Many of the conclusions and recommendations are nonetheless applicable to tropical and subtropical karst areas worldwide. Fifteen environmental assessments of World Bank and International Finance Corporation (IFC) projects from the last 10 years involving major infrastructure and cement factory investments were reviewed. None of the assessments mentions the unique aspects of limestone biodiversity, adequately addresses biodiversity issues, or proposes measures to mitigate and monitor the impact on local biodiversity. However, one report mentions the aesthetic and wilderness values of the limestone areas that would be affected by the project. There was no indication that cultural remains or values related to limestone were assessed.
The effects of the fires that burned over 4.7 million ha of Indonesia's tropical forests during 1997 and 1998 are largely unknown. We assess the immediate impacts of these fires on five forest areas representing several different habitats in Kalimantan 1-2 months after the fires went out. Comparisons of transects in burned and unburned forest areas were conducted at three sites: Tanjung Puting National Park, Kutai National Park, and Sungai Wain Nature Reserve. In general, burned forests had reduced canopy and ground cover, lower tree species richness and diversity, and higher canopy tree, seedling, and sapling mortality than unburned forests. Species richness in peat swamp forests at Tanjung Puting was reduced by 59% by the fires, and in two lowland dipterocarp forests by 24% (Sungai Wain) and 57% (Kutai). Resurveying of transects at Tanjung Puting 8 months after the first survey showed that burned forests suffer higher tree mortality and further species loss in the months following fires. In addition, species richness was lower in forests that had been logged prior to burning than in forests that had been undisturbed before the fires. The long-term ecological effects of burning on forest diversity, structure, and species composition are discussed, and the conservation implications of the high fire hazard in Indonesia are considered.
Offers a comprehensive introduction to distance sampling, a statistical method used by many biologists and conservationists to estimate animal abundance. The text discusses point transect sampling and line transect sampling and also describes several other related techniques. There are updates on study design and field methods, laser range finders, theodolites and the GPS and advice is given on a wide range of survey methods. Analysis methods have also been generalized, through the use of various types of multiplier and exercises for students in wildlife and conservation management are included.
The southwestern Chinese provinces and neighbouring upland areas in Burma, Thailand, Laos and Vietnam form a geographical region with an expanding Palaeolithic record. The area was a gateway for the dispersion of populations into East Asia and Island Southeast Asia. It is therefore important to examine the diversity of environments and resources that the earliest inhabitants encountered, and to identify adaptations and technologies that may have shaped subsequent exploitations of Asian environments. This paper synthesizes the evidence for the early human occupations of the region, beginning over one million years ago and continuing through the Upper Pleistocene.
In 1997-98, fires associated with an exceptional drought caused by the El Niño/Southern Oscillation (ENSO) devastated large areas of tropical rain forests worldwide. Evidence suggests that in tropical rainforest environments selective logging may lead to an increased susceptibility of forests to fire. We investigated whether this was true in the Indonesian fires, the largest fire disaster ever observed. We performed a multiscale analysis using coarse- and high-resolution optical and radar satellite imagery assisted by ground and aerial surveys to assess the extent of the fire-damaged area and the effect on vegetation in East Kalimantan on the island of Borneo. A total of 5.2 +/- 0.3 million hectares including 2.6 million hectares of forest was burned with varying degrees of damage. Forest fires primarily affected recently logged forests; primary forests or those logged long ago were less affected. These results support the hypothesis of positive feedback between logging and fire occurrence. The fires severely damaged the remaining forests and significantly increased the risk of recurrent fire disasters by leaving huge amounts of dead flammable wood.
Great apes are threatened with extinction, but precise information about the distribution and size of most populations is currently lacking. We conducted orangutan nest counts in the Malaysian state of Sabah (North Borneo), using a combination of ground and helicopter surveys, and provided a way to estimate the current distribution and size of the populations living throughout the entire state. We show that the number of nests detected during aerial surveys is directly related to the estimated true animal density and that a helicopter is an efficient tool to provide robust estimates of orangutan numbers. Our results reveal that with a total estimated population size of about 11,000 individuals, Sabah is one of the main strongholds for orangutans in North Borneo. More than 60% of orangutans living in the state occur outside protected areas, in production forests that have been through several rounds of logging extraction and are still exploited for timber. The role of exploited forests clearly merits further investigation for orangutan conservation in Sabah.
Sites of 1 ha were established in each of 4 contrasting types of primary lowland rain forest: alluvial forest (AF); dipterocarp forest (DF); heath forest (HF) and forest over limestone (LF). The total above-ground forest biomass (t ha-1 dry weight) was calculated as: AF,250; DF,650; HF,470; LF,380. There were at least 223 species ha-1 in the AF; 214 in the DF; 123 in the HF; and 78 in the LF. The AF soil was heterogenous, with gley soils of high base status in the lower, occasionally flooded, part and podzols and peats in the higher part. The DF soil was acid and very low in Ca. It was lower in total exchangeable bases than the very acid podzolic soils of the HF. The LF soils were shallow, highly organic, of high base status, and neutral to mildly acid pH. The species-rich DF occurred on very poor soils but there was no simple relationship between soil nutrient element concentrations and biomass of species richness. The causes of the distinctive sclerophyllous leaves of the heath forest are discussed. Extreme soil acidity in the organic soils may limit N-mineralization and low levels of biologically active nitrogen favour sclerophylly. Features of heat forest which reduce transpiration may be important in reducing the mass flow of soil toxins to the root surfaces.-from Authors English
We examine why demographic models should be used cautiously in Population Viability Analysis (PVA) with endangered species. We review the structure, data requirements, and outputs of analytical, deterministic single-population, stochastic single-population, metapopulation, and spatially explicit models. We believe predictions from quantitative models for endangered species are unreliable due to poor quality of demographic data used in most: applications, difficulties in estimating variance in demographic rates, and lack of information on dispersal (distances, ages, mortality, movement patterns). Unreliable estimates also arise because stochastic models are difficult to validate, environmental trends and periodic fluctuations are rarely considered, the form of density dependence is frequently unknown but greatly affects model outcomes, and alternative model structures can result in very different predicted effects of management regimes. We suggest that PVA (1) evaluate relative rather than absolute rates of extinction, (2) emphasize short-time periods for making projections, (3) start with simple models and choose an approach that data can support, (4) use models cautiously to diagnose causes of decline and examine potential routes to recovery (5) evaluate cumulative ending functions and alternative reference points rather than extinction rates, (6) examine all feasible scenarios, and (7) mix genetic and demographic currencies sparingly. Links between recovery options and PVA models should be established by conducting; field tests of model assumptions and field validation of secondary model predictions.
A survey of the density and population size of Bornean orang-utan (Pongo pygmaeus) was carried out in 1995 and 1996 in an area of peat swamp forest in the Sungai (River) Sebangau catchment, Central Kalimantan, Indonesia. Densities were calculated for four forest sub-types by counts of orang-utan sleeping platforms (nests) along line transects. Densities were found to be highest in the tall interior and mixed swamp forest sub-types. Low pole forest supported the lowest density. Habitat disturbance caused by logging was shown to affect orang-utan density within mixed swamp forest. The orang-utan population for a larger peat covered landscape unit (9200 km2), including the Sebangau catchment, was estimated to be between 5671 (±955) and 8951 (±1509) individuals, based upon the area of each forest type, the level of disturbance in each area and corrected to prevent overestimates. This study identifies the presence of a very large, self-sustaining orang-utan population in this region and emphasises the urgent requirement for greater protection of Kalimantan's peat swamp forests in the light of recent and rapid habitat degradation.
Due to its practical relevance to conservation, considerable efforts have been devoted to understanding the effects of logging on orangutan (Pongo spp.) population densities. Despite these efforts, consistent patterns have yet to emerge. We conducted orangutan nest surveys and measured forest quality and disturbance level at 108 independent locations in 22 distinct sites in the forests of the Berau and East Kutai regencies of East Kalimantan, Indonesia. Survey locations varied substantially in orangutan density, forest structure, distance to villages, and logging intensity. We incorporated site-specific nest tree composition into our estimates of nest decay rates to reduce errors associated with inter-site differences in nest tree selection. Orangutan nest densities were uncorrelated with altitude, fig density, or any other ecological measure. Multivariate analyses demonstrated that densities were not significantly affected by logging intensity (at the relatively light levels we report here) or the distance to the nearest village, but were positively correlated with the distance from the nearest village known to hunt orangutans. These results indicate that provided hunting is absent, lightly to moderately degraded forests retain high conservation value for orangutans. Widespread incorporation of degraded areas into management plans for orangutan populations would substantially increase the size of populations that could be protected, and thereby improve their changes for long-term survival.
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