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1.
We investigated the population density of Bornean orangutans Pongo pygmaeus pygmaeus and aspects of habitat quality in a selectively hand-logged peat swamp forest in West Kalimantan, Indonesia, and in a comparable unlogged forest nearby. We conducted orangutan nest surveys, measured different parameters of forest structure, recorded monthly changes in fruit availability, and noted the sex and the stage of maturity of orangutans encountered. Nest density, an index of orangutan population density, was 21% lower in the logged area. The forest, logged 2 years previously, had fewer large food trees and a greater number of canopy gaps. We discuss these differences in relation to the lower orangutan nest density in the logged forest. Significantly fewer adult orangutans were observed in the logged study area. We hypothesize that fully adult orangutans, particularly females, are the most severely affected by hand-logging.  相似文献   

2.
We conducted the first orangutan population census of Gunung Palung National Park, West Kalimantan, Indonesia, between April and September 2001. We used a refined line-transect nest-count methodology utilizing transect recounts to survey 69 km at 14 sites within the park and 14.2 km in the buffer zone. We present the first Bornean orangutan density estimate using complete site-specific parameters and long term monitoring of nest decay rates. Average orangutan density was 3.0 individuals/km2, with densities ranging from 2.4 ind/km2 in montane forest to 4.1 ind/km2 in primary peat swamp. In addition, we tested alternative approaches to calculation of the nest-duration parameter. The second count of each transect resulted in 30% higher density estimates overall. We conclude that recounts should be incorporated into standard line-transect methodology. We estimate there to be ≈2500 individual orangutans in Gunung Palung, indicating the importance of this site in plans to conserve a network of viable orangutan populations. While logging may reduce densities, disturbed forest both inside and adjacent to the park has high conservation value as orangutan habitat. Further research into long-term orangutan population persistence in disturbed forest is needed.  相似文献   

3.
Peat swamp forest is a unique wetland ecosystem covering extensive areas in Southeast Asia that has received relatively little scientific attention and is now being lost at a rapid pace. This study examines the effects of anthropogenic degradation on bird communities in disturbed peat swamp forest habitats – namely, intact logged forest, a degraded forest fragment, and non-forest regrowth – in Central Kalimantan, Indonesia. Results show that species richness was significantly higher and species composition significantly different in intact logged forest in comparison to the degraded forest fragment and non-forested area. Nectarivore and tree foliage-gleaning insectivore abundance declined outside the intact forest, while the regrowth was dominated by the yellow vented bulbul, an open country insectivore–frugivore. Surveys reveal that large intact tracts of logged peat swamp forest can harbour threatened and near threatened bird species (36% of records) and thus play a role in their conservation, especially for a few habitat specialists. Given the extent of unmanaged degraded peatlands and continuing pressure to development them, urgent conservation actions are needed to rehabilitate and protect this ecosystem.  相似文献   

4.
The western Amazon is experiencing unprecedented levels of oil and gas exploration, a trend of particular concern given the high levels of biodiversity found in this relatively pristine and unstudied region. Despite the widespread use of seismic reflection technology for exploration, no studies have investigated the response of wildlife populations to this disturbance in the tropics. We conducted a trail camera survey inside a large oil concession (Block 39) in the Peruvian Amazon near the Ecuador border with ongoing 2D seismic explorations to investigate its effects on ocelot (Leopardus pardalis) activity and abundance. The estimated size of the ocelot population within our 22 km2 study area was the same before (control period: 34 ± 6.9 ocelots) and during exploration operations (disturbance period; 34 ± 4.6 ocelots) and we detected no change in activity patterns between the two periods. Ocelot capture rate was unaffected by the presence of seismic crews, and distance to the nearest seismic line was not correlated with capture rate at individual stations. Our density estimates (ocelots/100 km2) from the control (75.2) and disturbance period (94.7) include the highest reported for the species, and represent the first ocelot density estimates from the northwest Amazon forest. These high values conform to recent research showing a positive association between ocelot density, annual rainfall, and proximity to the equator (this study: >2500 mm annual rainfall; <200 km from equator). We discuss the potential short- and long-term environmental impacts of seismic operations, particularly as they relate to large mammal populations.  相似文献   

5.
A field experiment in managed woodland was set up to examine the effects of manipulated population density and resource availability on spatial distribution and dispersal of the anecic earthworm Lumbricus terrestris. Experiments over 2 years, made use of 1 m2 field enclosures with associated trapping units to assess emigration rates at control and enhanced L. terrestris densities and different levels of leaf litter availability. Densities were manipulated twice; at the outset and again after 1 year when visually tagged animals obtained from 2 origins were introduced. Population density had a significant effect on dispersal (p < 0.01, p < 0.05 in Year 1 and Year 2 respectively) with more captures (pro rata) at the higher density compared with controls over the experimental period. Food availability only had a significant effect during the initial week of the experiment. L. terrestris midden arrangement was found to be regular across 1 m2 plots and regularity increased with an increase in midden number. Mean (±S.E.) midden number was 30.34 ± 0.77 m−2 and 28.06 ± 0.5 m−2, during the first and second year of the experiment respectively and this was unaffected by additions. Inter-midden distance was recorded at 0.13 ± 0.0014 m. Results suggest that L. terrestris dispersal can be affected by population density and resource availability.  相似文献   

6.
Several studies have shown that there is a strong decline in orang-utan densities shortly after logging. Nevertheless, there is little information on whether orang-utan densities return to their pre-logging values when logged forest is left to recover. This study investigates the orang-utan density in a 22-year-old selectively logged forest and compares it with the orang-utan density in a nearby ecologically similar primary forest. The results show that the orang-utan density did not differ significantly between primary forest and the selectively logged forest. Since we found no difference in fruit availability between the selectively logged and primary forest, we suggest that the selectively logged forest regenerated sufficiently well to sustain pre-logging levels of orang-utans. This study confirms previous studies that suggest fruit availability is the best ecological predictor of orang-utan densities and found a positive overall correlation between orang-utan density and fruit availability. The food attraction hypothesis, which explains local fluctuations in orang-utan density as a result of variation in fruit availability, was not supported.  相似文献   

7.
To conserve species it is essential to understand which factors determine their distribution and density. Here we focus on the critically endangered Sumatran orang-utan and examine factors that influence the distribution and density in the Batang Toru area, the southernmost area where wild orang-utans occur on Sumatra. We contrast a scenario in which orang-utan distribution is mainly determined by ecological, and topographic variables with a model that includes hunting and human impact. We show that orang-utan distribution and density are best explained by hunting pressure and elevation. These results indicate that an assessment of anthropogenic factors that might influence density such as hunting needs to be included in surveys that aim to predict orang-utan distribution and density. As anthropogenic impact becomes higher with increasing human population density and increased forest access in most areas where orang-utans occur the consequence is that orang-utan conservation will have to be achieved in an environment modified by humans. In such areas the potential for a range of conflicts such as hunting that lead to human-caused mortality for orang-utans will remain a constant threat and need to be mitigated.  相似文献   

8.
Fen‐soil cultivation in NE Germany resulted in severe peat degradation; therefore present and future management is aimed to restore degraded sites by re‐wetting. Evidence in the literature indicates that decreasing redox potentials in re‐wetted fens may result in an increased risk of diffuse water pollution with P. However, little is known about the impact of different fen‐preserving land‐management schemes on the redox potential in soil and on the P dynamics in adjacent surface water. We investigated effects of peat degradation and re‐wetting on redox potential and P mobilization on extensive grassland, re‐wetted intensive grassland, and alder swamp forest in the Drömling (Saxony‐Anhalt, Germany). The results showed that the redox potentials of peat lands were almost below the theoretical stability fields of Fe(III)‐containing minerals. The re‐wetted site was characterized by the highest concentrations of soluble reactive P (SRP) in surface water. Average SRP concentrations up to 0.36 mg l–1 indicated an increased P load. The concentration of SRP in the Ohre river, which is the central drainage channel of the Drömling catchment, significantly increased since 1996. The P concentrations of surface water were found to be indirectly correlated with the redox potentials.  相似文献   

9.
Soil microbial biomass was analyzed in a rapidly subsiding coastal bottomland forest at three sites along an elevation change of ∼1 m and an associated hydrologic gradient of 400 m from rare (ridge site), to occasional (intermediate site), to frequent flooding (swamp site). Given the current rate of relative sea-level rise in this area (subsidence+global mean sea-level rise ∼1.2 cm y−1), this gradient may represent a space-for-time substitution for about one century of future sea-level rise. Along the hydrologic gradient, microbial biomass carbon (MBC) in the upper 20 cm of mineral soil was 157±26 (ridge), 134±14 (intermediate), and 90±20 (swamp) g C m−2. MBC was positively correlated with soil organic matter (r2=0.76, P=0.002) and the ratio of MBC to soil organic C ranged from 0.008 to 0.017 depending on soil depth and site. Generally, MBC decreased with increasing soil moisture from the ridge to the swamp site. Although MBC was statistically similar overall in the ridge and intermediate sites, the intermediate site had the largest fraction (45%) at 0-5 cm, whereas the ridge site had the largest fraction (40%) below 10-20 cm. Based on a space-for-time substitution model using non-linear regression analysis, we predict that MBC in the upper 20 cm of soil is likely to decrease by about one-third along the transect over the next century as a result of subsidence and sea-level rise.  相似文献   

10.
Water balance and leaching of plant nutrients, with special reference to N, were described for a 46-ha catchment consisting mainly of coniferous forest (one third of it clear-cut) during the period January 1982-August 1988. The atmospheric N load in this region is high compared with most other parts of Scandinavia. On average, annual N leaching amounted to 9.5 kg ha?1 in the form of NO3-N (83%), org-N (15%) and NH4-N (2%). The highest monthly rate of N transport observed was 3.9 kg ha?1. The NO3-N levels in groundwater in the 60-yr-old coniferous stand ranged from 0.5 to 3.1 mg L?1. The effect of clear-cutting on groundwater-NO3-N levels lasted 4 yr. The highest annual NO3-N transport from the clear-cut area observed was 18 kg ha?1. The groundwater in the spruce forest was very acidic (pH=4.3) in contrast to the stream water (pH=6.3). The relatively higher pH-value of the stream water was probably a result of chemical and biological processes occurring in the highly humified, periodically waterlogged peat soil (alder swamp) in the vicinity of the small stream.  相似文献   

11.
Twenty eight samples of peat, clay and silty clay from a tin mine exposure near Pantai Remis, Perak, Malaysia, were palynologically analyzed. Six pollen zones and eight subzones were delineated based on the dominant floral components. Accelerator mass spectrometry (AMS) radiocarbon and thermoluminescence datings on selected samples indicate late Pleistocene and older age. The occurrence ofPodocarpus imbricatus pollen suggests that the deposit is no older than late Pliocene. The fluctuation of sea level during the late Pleistocene is believed to be the main factor that influenced the development of vegetation at the Pantai Remis area. The presence of mangrove peat at depths between 13.0 m and 14.0 m, which overlies a freshwaterPandanus peat, indicates the position of a former shoreline at Pantai Remis when the area was inundated sometime during the last interglacial marine incursion. During this period of high sea level, thePandanus swamp was probably being gradually replaced by mangrove vegetation. The mangrove sequence is regarded as equivalent to the Kempadang formation. A slight drop in sea level sometime during the last glacial interstadial stage probably caused a small, open alluvial swamp to be developed over the mangrove forest. This freshwater deposit may be the equivalent of the Simpang formation.  相似文献   

12.
Using a soilless culture system mimicking tropical acidic peat soils, which contained 3 mg of gellan gum and 0.5 mg NO3?-N per gram of medium, a greenhouse gas, N2O emitting capability of microorganisms in acidic peat soil in the area of Palangkaraya, Central Kalimantan, Indonesia, was investigated. The soil sampling sites included a native swamp forest (NF), a burnt forest covered by ferns and shrubs (BF), three arable lands (A-1, A-2 and A-3) and a reclaimed grassland (GL) next to the arable lands. An acid-tolerant Janthinobacterium sp. strain A1-13 (Oxalobacteriaceae, β-proteobacteria) isolated from A-1 soil was characterized as one of the most prominent N2O-emitting bacteria in this region. Physiological characteristics of the N2O emitter in the soilless culture system, including responses to soil environments, substrate concentration, C-source concentration, pH, and temperature, suggest that the N2O emitting Janthinobacterium sp. strain A1-13 is highly adapted to reclaimed open peatland and primarily responsible for massive N2O emissions from the acidic peat soils. Regulation of N2O emitters in the reclaimed peatland for agricultural use is therefore one of the most important issues in preventing the greenhouse gas emission from acidic peat soil farmlands.  相似文献   

13.
Freshwater species and ecosystems are gravely imperiled, particularly within urban landscapes of tropical Asia. In one of the region’s most urbanized landscapes (i.e., Singapore), we determined: (1) the importance of six different habitats (i.e., catchment reservoirs, estuarine reservoirs, forest streams, rural streams, ponds and monsoon canals) for conserving the diversity of freshwater molluscs; (2) key environmental factors (e.g., pH) affecting molluscan distribution; (3) important biogeographical determinants (e.g., area) of molluscan richness within each habitat; and (4) the habitat affinities of introduced species. High sampling saturation was achieved at most study habitats with minimal sampling effort, suggesting that the utilization of molluscs as bioindicators can expedite freshwater conservation initiatives. Estuarine reservoirs (6.0 ± 2.0) had the highest molluscan richness, vis-à-vis catchment reservoirs, forest streams, rural streams, ponds and monsoon canals (3.0 ± 1.5; 0; 3.3 ± 2.0; 1.8 ± 0.5 and 3.5 ± 0.5 respectively). Both reservoir types possessed species compositions distinct from other habitats and contained majority (76%) of the sampled species. Reservoirs therefore serve to conserve the bulk of local freshwater malacofauna, especially if they are maintained at near-neutral pH levels (i.e., ∼7.3) and contain large substrates (i.e., rocks). Area was the best predictor of molluscan richness across all habitats, implying that larger freshwater habitats require higher conservation priorities than smaller ones. Introduced (non-native) species (e.g., Pomacea canaliculata) had high affinities for reservoirs, which are in need of monitoring to curb population expansions. The interminable growth of human settlements urgently requires a reconciliatory approach, which includes the ecologically-sound design and management of modified habitats to complement reserves in sustaining native freshwater species.  相似文献   

14.
The occupancy probability of 35 large-bodied bird and mammal species was examined in relation to patch- and landscape-scale habitat and disturbance variables in 147 forest patches distributed throughout the Mexican Yucatán Peninsula. Occupancy was assessed on the basis of interviews with local informants. The most important predictors of vertebrate species richness, composition, and patch occupancy were human population density and the extent and quality of forest cover. Most forest species responded positively to forest extent, while felids in particular were sensitive to human population density. However, the effects of human density on patch occupancy operated at extremely local scales. Effects were stronger at a smaller grain size, offering optimistic prospects for conservation strategies that incorporate human population effects. Three arboreal frugivores (Ateles geoffroyi, Alouatta pigra, and Ramphastos sulfuratus) were strongly associated with total basal area of trees bearing fleshy fruits. The degree of hunting pressure was not related to human population density, and affected the occupancy probability of three game species, two of which (Mazama spp., Crax rubra) are among the most preferred prey across the Yucatán Peninsula. Levels of patch occupancy across this region varied considerably among species, and were best explained by body size and degree of forest habitat specificity, large-bodied species and habitat specialists being the most vulnerable. This study provides a quantitative assessment of the conservation potential of large vertebrates in Mesoamerica and identifies disturbance-sensitive species. This can inform regional-scale conservation planning at a time when low deforestation in parts of the Yucatán Peninsula still provides a narrow window of conservation opportunity given the rapid human population growth.  相似文献   

15.
The extent to which complex interrelationships between plants and microorganisms influence organic matter dynamics is critical to our understanding of global C cycles in changing environments. We examined the hypothesis that patterns of soil microbial activity and functional composition differ among vegetation types in northern peatland ecosystems. Microbial characteristics were compared among peatlands differing in plant growth form (tree, shrub/moss, sedge) in two regions (New York State and West Virginia). Microbial activity (basal respiration) was greater in surface (0-15 cm) than subsurface (15-30 cm) peat and from sites dominated by shrubs and Sphagnum moss (3.9±0.65 μg C g−1 h−1) compared to forested (1.8±0.20 μg C g−1 h−1) or sedge-dominated sites (1.9±0.38 μg C g−1 h−1). Microbial activity was not related to decomposability of peat organic matter among vegetation types, and activity was unexpectedly higher in sites with lower peat pH and higher water table level. Substrate-induced respiration (SIR) did not show a clear pattern among vegetation types, but was greater in surface than subsurface peat. Microbial responsiveness to added glucose was very low. The ratio of basal respiration to SIR varied between 0.39 and 0.72 and, like activity, was highest in shrub/Sphagnum sites. Microbial substrate utilization patterns (assayed with BIOLOG® GN plates) also differed between shrub/Sphagnum sites and forest or sedge sites, suggesting that C fluxes were mediated by different assemblages of microorganisms in shrub/Sphagnum peatlands. Principal component (PC) scores indicated more utilization of N-containing compounds and carboxylic acids, and less utilization of carbohydrates by microbial communities in shrub/Sphagnum sites. PC scores were much more variable both within and among vegetation types for sites in West Virginia than in New York State, and a greater diversity of C sources were utilized in WV (57±3) than NYS (47±2) peat. Our results suggest a link between microbial respiratory activity and microbial functional composition as they vary among these peatland vegetation types.  相似文献   

16.
An eight-year-long census and habitat evaluation of the Macaca sylvanus population was conducted in a 484-km2 area of the central region of the Middle Atlas Mountains in Morocco between June 1994 and October 2002. The authors walked a 93.5-km circuit - divided into 16 transect segments - 30 times with teams of trained research assistant volunteers, collecting data on a total of 2,805 linear km. Previous studies had reported an average density of 44-70 individuals per km2, while data from the present study indicate a progressive population decline, from 25 to 30 individuals per km2, down to a current average density of 7-10 I/km2. The population decline is attributed to the loss of prime habitat, mainly cedar forest, which has significantly decreased from 1994 to 2002, due to the growing impact of overgrazing by mixed flocks of goats and sheep and consequent forest degradation. At present, human-caused habitat deterioration in the Middle Atlas risks further compromising the future of the world’s only remaining large M. sylvanus population.  相似文献   

17.
In southern Africa the samango monkey Cercopithecus mitis is confined to small (< 500 ha) forest fragments and is considered a locally rare species. Monkey populations from 17 of Natal's forests were visited and 14 of these were censused using King's strip transect method. Enviromental correlates and disturbance factors affecting samango population density are examined. The results of this provincial census show that it may be possible to predict samango density according to the plant species richness and diversity of a forest. The potential effect of the latter on the vagaries of food abundance and availability and hence the primate carrying capacity of a forest are considered. The important conclusion is that forests in Natal with very high species richness and diversity values do not necessarily support high samango densities. In fact these forests appear to maintain population densities similar to those forests with low plant species richness and diversity (swamp and sand forests). This has important implications for the conservation and management of the species, since it high-lights the importance to its survival, of those, often young, forests that can maintain high population densities (coastal dune and coastal lowland forest). Furthermore, results of this study permit a more objective interpretation of the evaluation of the observed abundance of samango monkeys in different forest types, and in so doing may form the basis for sound management proposals in the future.  相似文献   

18.
We assessed the response of the tomato variety “Tiny Tom” to the application of copper (Cu) and zinc (Zn) fertilizers in three tropical peat soils of Sarawak: mixed swamp forest, Alan forest and Padang Alan forest. Limed soils were used because peat soils in their natural condition are unsuitable to sustain healthy growth of most crops. Yield responses were correlated with added Cu and Zn using Mitscherlich model. Adequate levels of applied Cu and Zn were calculated as those which resulted in 90% of the maximum obtainable shoot dry weight. Application of Cu and Zn significantly (P ≤ 0.05) increased the shoot dry weight and the shoot Cu and Zn concentrations of tomato. Application of the equivalent of 8.3 kg Cu and 5.2 kg Zn per ha was required to achieve 90% of the maximum shoot dry weight. In tomato shoots, the critical concentration for Cu was 18 mg/kg and for Zn, 92 mg/kg. The corresponding concentrations for diethylenetriaminepentaaceticacid (DTPA) extractable Cu and Zn in the soils were 2.3 mg Cu kg ?1 and 3.6 mg Zn kg ?1 . However, the addition of Cu fertilizer also increased Zn uptake by tomato plant, probably by displacing native Zn that was weakly sorbed to the soil solid phase.  相似文献   

19.
The ongoing conversion and degradation of insular Southeast Asian peat swamp forests causes globally important carbon emissions and leads to loss of unique biodiversity. Little quantitative information is available on the dynamics of peat swamp forest conversion. In this case study, we present a time‐series of peatland conversion and degradation in the Air Hitam Laut peatlands in Jambi Province (Sumatra, Indonesia), which included the Berbak National Park. High‐resolution (10–60 m) satellite imagery was used to map land cover and degradation status for nine time slices between the 1970s and 2009. Nearly‐pristine forest cover was shown to have declined in the study area from 90 to 43 per cent, inside the Berbak National Park from 95 to 73 per cent and outside the National Park from 86 to 25 per cent. Outside the protected area, 66 per cent of former nearly‐pristine forests turned into degraded forests or unmanaged deforested areas. Large‐scale oil palm plantations accounted for 21 per cent of the formerly nearly‐pristine areas and small‐holder agriculture for 8 per cent. The conversion to plantation has fast accelerated since 2002. Conversion from nearly‐pristine forest to plantation typically took around 6 years, at times up to 10 years. Better understanding of conversion and degradation dynamics will allow for improved estimates of the implications of management planning decisions taken in peatland areas. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
Pools and fluxes of N in wetland vegetation and soils were compared with an adjacent upland site to assess the relative importance of wetland versus upland landscapes in watershedN-retention in the Adirondack Mountains of New York (U.S.A.).The majority of N storage occurred in forest soils and wetlandpeat deposits (96 and 99% of total N in upland forests andwetlands, respectively). Annual N-uptake (49 kg N ha-1yr-1) was greater for wetland vegetation than that ofupland vegetation (30 kg N ha-1 yr-1). In the wetlandthe supply of N from mineralization (36 kg N ha-1yr-1) was less than N-uptake; in contrast, upland Nmineralization (76 kg N ha-1 yr-1) exceeded Nvegetation uptake. Annual N-storage in peat was small due to low peat accretion rates. Wetlands acted as a sink for N andstored a disproportionally high fraction (15%) of catchment Nin relation to their relatively small surface area (～4%)within the catchment.  相似文献   

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