Livestock predation by carnivores in Jigme Singye Wangchuck National Park, Bhutan

Villages in Jigme Singye Wangchuck National Park, central Bhutan, report livestock depredation by wild carnivores including leopard (Panthera pardus), tiger (Panthera tigris), Himalayan black bear (Ursus thibettanus), and dhole (Cuon alpinus). In a survey of 274 households in six different geogs (sub-districts) within the park, 21.2% of households surveyed reported losses of a total of 2.3% of their domestic animals to wild predators over 12 months. This loss equated to an average annual financial loss equal to 17% (US$ 44.72) of their total per-capita cash income. Total reported losses during 2000 amounted to US$ 12,252, of which leopard and tiger kills accounted for 82% (US$ 10,047). Annual mean livestock loss per household (of those that reported loss) was 1.29 head of stock, equating to more than two-thirds of their annual cash income of $250. Lax herding, inadequate guarding practices, and overgrazing may have contributed to livestock losses. Approximately 60% of the households lacked proper stables for corralling their livestock at night and there was a significant correlation between the number of livestock lost and the distance between the household and the grazing pasture. Overall, reported predation rates have increased since the inception of the park in 1993 and since implementation of the Forest and Nature Conservation Act in 1995, which prioritises some of Bhutan’s key livestock predators for conservation. We propose livestock intensification programmes, including pasture improvement, and financial compensation as short-term measures to reduce conflict between people and predators. In the long-term, we recommend that the feasibility of an insurance scheme should be tested, the possibility of relaxing the resource use restrictions in the Forest and Nature Conservation Act of 1995 be explored, and that farmers should be involved in managing human-wildlife conflicts - particularly through improving their own herding and guarding practices, and building proper corralling facilities and adopting reliable corralling procedures.     

Spatial, temporal, and physical characteristics of livestock depredations by large carnivores along a Kenyan reserve border

Most large mammalian carnivores are in global decline, largely due to their involvement in livestock depredation. Research that advances our understanding of predator-livestock interactions is crucial to conflict mitigation and carnivore conservation. Here we investigated the influence of environmental and socio-ecological factors on livestock depredation by carnivores in pastoral villages adjacent to the Maasai Mara National Reserve, Kenya during a 14-month period. We attempted to identify factors associated with temporal and spatial variation in depredation rates, incorporating data on a closely monitored spotted hyena (Crocuta crocuta) population known to be involved in depredation events. Spotted hyenas, leopards (Panthera pardus) and lions (Panthera leo) were responsible for 53%, 32%, and 15% of attacks on livestock, respectively. Monthly depredation frequency was correlated positively with rainfall and negatively with natural prey abundance. Radio-telemetry revealed that hyenas defending a group territory within the Reserve spent more time outside the Reserve during months when hyena attacks on livestock were most frequent. Results of logistic regression models, which indicated spotted hyenas were most likely to attack large villages, were supported by behavioral observations of hyenas near villages. Leopards however, selected villages that were spatially isolated from other villages. Hyenas were more likely to attack livestock enclosures constructed of local bush material than those of more sturdy “pole” timber, but use of pole material more than doubled the probability of leopard attack. Selection of fence type should therefore depend on the size and relative isolation of villages. Overall, improved fences, more watch dogs, and high levels of human activity were not associated with lower livestock losses to predators.     

Evaluation of a compensation scheme to bring about pastoralist tolerance of lions

Lions (Panthera leo) are in decline throughout most of their range due to human persecution, largely provoked by depredation on livestock, and there is debate as to the usefulness of financial instruments to mitigate this conflict. Intending to reduce local lion-killing, the Mbirikani Predator Compensation Fund compensates members of Mbirikani Group Ranch for livestock depredation at a flat rate (close to average market value), after the kill has been verified and with penalties imposed for poor husbandry. Despite penalizing claimants, 55% of claims arose because livestock were lost in the bush. Between 1st April 2003 and 31st December 2006, 754 cattle, 80 donkeys and 1844 sheep/goats were killed (2.31% of the total livestock herd each year). Forty-three percent of kills were ascribed to spotted hyaenas (Crocuta crocuta); leopards (Panthera pardus) and cheetahs (Acinonyx jubatus) were blamed for 37% of cases, lions 7%, jackals (Canis mesomelas) 7% and buffalo (Syncerus caffer) and elephants (Loxodonta africana) together 6%. Significantly more attacks took place during months of lower rainfall but the rate of attacks was not related to the density of livestock on the ranch, or the ratio of wild herbivores to domestic stock. There was no correlation between local market prices and the number of claims per month. Despite compensation, at least one lion per year was killed in 2004, 2005 and 2006. We describe some features of large carnivore depredation in the study area and suggest that regional recovery of the lion population may require compensation on a wider scale.     

Cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) in central-western Brazil

In this study, data on cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) were recorded for six years (1998-2003) in a cattle ranch in central-western Brazil. Depredation represented 18.9% of the overall cattle mortality, being predominant on calves. In biomass, kills represented 0.4% (63.8 kg/km²) of the ranch’s annual stock. In economic loss, kills represented 0.3% of the cattle stock value. Depredation was mainly associated with cattle’s age class and location along with the time of birth of calves. The proportion of pastures next to forest with depredation (n = 33, 48.5%) was not distinguished to the proportion of pastures not bordering forest with depredation (n = 35, 51.5%). However, the proportion of pastures next to forest with depredation represented 54% (n = 33) of the 61 total pastures that were at least partially surrounded by forest patches or riparian forests that comprised eight continuum blocks of forest fragments of different sizes in the ranch and adjacent areas. No kills occurred in the central portion (main house) of the farm, close to the headquarters where the pastures not bordering forest. The distances of the kills in relation to areas of native forest was 1317.48 ± 941.03 m. In order to reduce depredation, calves should be kept as far as possible from forest areas and concentrated cattle breeding and calving seasons should be encouraged.     

Human-wildlife conflict in the Kingdom of Bhutan: Patterns of livestock predation by large mammalian carnivores

We examined predation activity throughout Bhutan by tiger (Panthera tigris), common leopard (Panthera pardus), snow leopard (Uncia uncia) and Himalayan black bear (Ursus thibetanus) on a variety of livestock types using data gathered over the first two years (2003-2005) of a compensation scheme for livestock losses. One thousand three hundred and seventy five kills were documented, with leopards killing significantly more livestock (70% of all kills), than tigers (19%), bears (8%) and snow leopards (2%). About 50% of livestock killing were of cattle, and about 33% were of horses, with tigers, leopards and snow leopards killing a significantly greater proportion of horses than predicted from availability. Examination of cattle kills showed that leopards killed a significantly greater proportion of smaller prey (e.g., calves), whereas tigers killed a significantly greater proportion of larger prey (e.g., bulls). Overall, livestock predation was greatest in summer and autumn which corresponded with a peak in cropping agriculture; livestock are turned out to pasture and forest during the cropping season, and subsequently, are less well guarded than at other times. Across Bhutan, high horse density and low cattle and yak density were associated with high rates of livestock attack, but no relationship was found with forest cover or human population density. Several northern districts were identified as ‘predation hotspots’, where proportions of livestock lost to predation were considerable, and the ratio of reported kills to relative abundance of livestock was high. Implications of our findings for mitigating livestock losses and for conserving large carnivores in Bhutan are discussed.     

Livestock predation by endangered African wild dogs (Lycaon pictus) in northern Kenya

Most large mammalian carnivores are in global decline, principally due to conflict with livestock farmers. Because endangered African wild dogs (Lycaon pictus) range widely, often beyond the boundaries of protected areas, they may be particularly exposed to lethal control by farmers, even where nominally protected by reserves. Hence, effectively conserving wild dogs demands resolution of their conflicts with farmers. We investigated livestock depredation by African wild dogs living outside protected areas in northern Kenya. Scat analysis confirmed the distribution of depredation events reported by local farmers, indicating that farmer reports - collated by local Community Liaison Officers - gave a reasonably good index of the true pattern of depredation. Although livestock were abundant throughout the study area, depredation was exceedingly uncommon (approximately one attack per 1000 km² per year) and the costs of tolerating wild dogs were very low (US $3.40/wilddog/year) where wild prey remained, even at low densities. However, where wild prey were seriously depleted, wild dogs killed livestock repeatedly, and the cost of sustaining them rose to US $389/wilddog/year. Hence, although wild dogs had a negligible economic impact in the region, their impact was locally severe. Conservation activities for wild dogs are most likely to be successful if targeted at areas where wild prey remain, and where traditional herding practices have been retained.     

Mountain lion depredation in southern Brazil

Mountain lion (Puma concolor) depredation incidents on livestock herds were recorded at 15 ranches in southern Brazil from 1993 to 1995. Maximum losses to mountain lions were 78% for goats, 84% for sheep, and 16% for cattle. Cattle mortality arising from causes other than depredation assumed a greater importance in herd productivity. In contrast, attacks on sheep and goats were more frequent than losses to other causes, but could be reduced to acceptable levels when flocks were corralled at night. Most depredation incidents occurred when weather and light conditions were unfavorable to human activity. We explain these patterns and inter-ranch variation in depredation rates on the basis of a risk-avoidance strategy by the mountain lions. Stock losses can be minimized by understanding these patterns and by applying appropriate herd husbandry, thus reducing the urge to persecute this protected species.     

The impact of trophy hunting on lions (Panthera leo) and other large carnivores in the Bénoué Complex, northern Cameroon

In West and Central Africa large carnivores have become increasingly rare as a consequence of rapid habitat destruction and lack of resources for protected area management. The Bénoué Complex (23,394 km²) in northern Cameroon is a regionally critical area for large mammal conservation. In the complex lions (Panthera leo), leopards (Panthera pardus) and spotted hyenas (Crocuta crocuta) are formally protected in three national parks and 28 hunting zones. Over-hunting may be having a strong additive effect precipitating declines in large carnivore numbers across the complex. We used a coarse level track index method to estimate the relative abundance of these three species both in hunting zones and national parks. The results were interpreted with respect to ungulate abundance, and hunting impact. There was no significant difference between the densities of medium to larger species of ungulates in the hunting zones and the national parks, and no difference in leopard and spotted hyena densities in the respective areas. However, lions occurred at significantly lower densities in the hunting zones, and even in the national parks occurred at significantly lower densities than prey biomass would predict.     

Lions and Warriors: Social factors underlying declining African lion populations and the effect of incentive-based management in Kenya

African lion (Panthera leo) populations are in decline throughout most of Africa, but the problem is particularly acute in southern Kenya, where Maasai people are spearing and poisoning lions at a rate that will ensure near term local extinction. Lion killing is shaped by Maasai perception of livestock depredation, socio-economic factors, and the complex relationship between Maasai and conservation. These all affect tolerance for lions and consequently Maasai behavior towards conservation initiatives and carnivores in general. We used an in-depth quantitative questionnaire and participatory rural appraisals (PRAs) to identify the social and ecological predictors of lion killing and to investigate the effect of a compensation scheme on individual tolerance. Individuals who lose a greater proportion of their livestock to predators relative to their overall livestock loss, those affiliated with an evangelical church, and those who mainly sell rather than accumulate livestock all reported a higher propensity to kill carnivores. The future of carnivore conservation in this region depends on a better understanding of the nuances of human–carnivore conflict and a concerted effort to address appropriate cultural and community-level institutions, chiefly by providing economic benefits to local people who engage in positive conservation activities.     

Community, lions, livestock and money: A spatial and social analysis of attitudes to wildlife and the conservation value of tourism in a human–carnivore conflict in Botswana

We quantified livestock (cattle, shoats, horses and donkeys) losses to lions (Panthera leo) and attitudes to lions, livestock losses and tourism among livestock owners, village residents and tourism workers around Makgadikgadi Pans National Park in Botswana. Losses were not correlated with the size or structure of livestock enclosures, numbers of dogs or herders. Rather losses increased with the amount of livestock owned. Most were stray animals preyed upon at night. Attitudes to wildlife, conservation and lions were also not consistently distributed within the society we studied. Negative attitudes to lions were almost ubiquitous among cattleposts but less widespread among people living in the more urbanized society of villages or among people working in tourism.Although four tourist camps were operating in the area, benefits from these operations were largely limited to employees. Despite considerable sums of money being paid to Botswana by local tourist facilities few respondents viewed tourism as valuable and most felt that the government and not they or their community was the main beneficiary of tourism. Tourism employees made up a small sub-section of the adult population drawn predominately from larger villages while the costs of livestock losses were spread among cattleposts near the park boundary. These same cattlepost respondents were not prepared to improve stock care to protect livestock, but indicated a willingness to kill lions instead. If tourism is to play a role in reducing human–wildlife conflict, communities must not be regarded as homogenous entities into which to distribute benefits evenly. Benefits might usefully be distributed in relation to the costs of coexisting with wildlife or used as incentives to better protect livestock or other human resources.     

Free-ranging domestic dogs (Canis familiaris) as predators and prey in rural Zimbabwe: threats of competition and disease to large wild carnivores

Domestic dogs (Canis familiaris) arrived in Zimbabwe ca. 1000 years ago. Numbers of free-ranging dogs have reached unprecedented levels in communal lands (agro-pastoralist rural areas), and interact with large wild carnivores along boundaries with wildlife reserves as predators and prey. This study examined a population of 236 dogs in a 33-km² section of Gokwe Communal Land (GCL) bordering the Sengwa Wildlife Research Area (SWRA) in north-western Zimbabwe in 1995-1996. Dogs were found up to 6 km within the SWRA, and were the most common carnivore on the GCL-SWRA boundary. Observations of 16 radio-collared dogs showed that they were inefficient predators. Only 20 kills were recorded amongst the remaining dog population, of which three were wild ungulates. Dogs were unsuccessful predators due to their small group size (mean 1.7) and body mass (mean 14.7 kg), and the abundance of alternative food. It is therefore unlikely that they compete with large carnivores for wild prey. However, leopards (Panthera pardus), lions (P. leo) and spotted hyaenas (Crocuta crocuta) preyed on dogs in GCL, removing ?6% of the dog population in 1993. Such predation provides ideal circumstances for disease transmission. Canid disease was prevalent in the study area; including rabies and probably distemper. The risk of infection is greatest during the dry season (May-October), when peaks in rates of disease, carnivore incursions into GCL, and predation on dogs coincided. The role of jackals (Canis adustus and Canis mesomelas) and spotted hyaena predation of dogs is discussed in relation to disease epidemics within wildlife reserves. With a dog population growth rate of 6.5% per annum, and the prevalence of canid diseases, the conservation threat posed by dogs is escalating on communal land-wildlife reserve boundaries in Zimbabwe. Measures to control dog numbers and improve vaccination coverage of dogs are discussed.     

Conflicts between Amur (Siberian) tigers and humans in the Russian Far East

In 1999, the Russian Federation created a Tiger Response Team (TRT) to investigate and intervene in human–tiger conflicts. We examined data collected on human-Amur tiger (Panthera tigris altaica) conflicts from January 2000 through February 2009 to: (1) summarize and characterize human–tiger conflicts in the area, (2) examine causes of human–tiger conflicts, and (3) attempt to evaluate the effectiveness of the TRT. The team investigated 202 conflicts. Both attacks on humans and depredations were greatest in winter (X² = 9, df = 3, P = 0.03 and X² = 64, df = 3, P < 0.001, respectively). Tiger depredation on domestic animals was the most common type of conflict reported (57%), followed by tigers near human habitations (22%), miscellaneous conflicts (12%), and attacks on humans (9%). Dogs were killed more commonly than other domestic animals (63% of 254 animals), likely because livestock were well managed. Nineteen attacks on humans were recorded resulting in 11 injuries and 2 deaths. Nearly four tigers per year (n = 32 tigers) died, were killed, or were removed from the wild, and all but 1 of 20 tigers killed or removed from the wild by the TRT were considered unfit to survive in the wild. Attacks on humans (n = 19) were most often (77%) by wounded tigers (80% of injuries were human-caused) and commonly provoked (47% of attacks). The effectiveness of interventions focused on reducing depredation on domestic animals was unclear, but data suggested that removal of injured and other unhealthy tigers from the wild by the Tiger Response Team resulted in fewer human deaths. Our recommendations include that the TRT continues to work to reduce conflict by rapidly removing debilitated tigers from the wild, explores different methods and technologies for reducing depredation on domestic animals, and increases their efforts to maintain tigers in the wild through telemetry monitoring, translocation, and rehabilitation of orphaned cubs. Further, standardized data should be collected to evaluate all interventions, with information from evaluation guiding an adaptive management component of their human–tiger conflict mitigation activities. This process should occur across tiger landscapes in Asia to allow rapid assessment of interventions.     

Farmer attitudes toward wolves: Implications for the role of predators in managing disease

The potential for disease transmission between wild and domestic animals may interfere with wildlife and habitat conservation on lands surrounding protected areas. Recently, possible transmission of bovine tuberculosis (Mycobacterium bovis) from wild ungulates to domestic livestock has affected the Riding Mountain National Park region in Manitoba, Canada. Wolf (Canis lupus) predation on ungulate populations may help lessen the risk of disease transmission to livestock. We conducted an exploratory analysis of causal factors associated with farmer attitudes toward observing wolves on their farms. A survey to 4 220 farms within 50 km of the Park resulted in an adjusted response rate of 25%. We constructed several logistic regression models with factors hypothesized to influence whether farmers agreed with the statement “I enjoy seeing wolves on my land”, and three candidate models received reasonable support. Factors most affecting attitudes were, in order of importance, perceived wolf population size, frequency of seeing wolves, perceived seriousness of wolf damage, distance to Park boundary and number of beef cattle (Bos taurus) owned. The factors least influential on attitudes were education and age. Concern over bovine tuberculosis in wild elk also had minimal influence. Of respondents who perceived the wolf population as “too high”, 60% were extremely concerned about bovine tuberculosis in wild elk. Although the role of wolf predation as a potential natural regulator of disease in wild ungulates might not be widely recognized in many areas, we believe this provides a unique opportunity to re-examine the significance of maintaining viable wolf populations.     

A Lysimeter Study to Investigate the Effect of Dairy Effluent and Urea on Cattle Urine n Losses, Plant Uptake and Soil Retention

Loss of nitrate (NO₃ ^?) from grazing land is a major cause of surface and groundwater contamination. These losses increase when N sources such as fertilizer are applied to grazing land. The objectives of this work were to (1) study the impact of dairy effluent (DE) or urea on N losses and plant uptake when DE or urea was applied with and without cattle urine and; (2) determine the effect of organic C rich DE on the fate of urine N. The experiment was conducted using lysimeters that contained Templeton sandy loam soil extracted from a pasture in New Zealand. Application of DE resulted in significantly less (p < 0.05) NO₃ ^? leaching compared with urea in the first year, but not in the second year. Differences between years could be attributed to the comparatively lower C:N ratio of applied DE in the second year, causing relatively greater N mineralization and greater NO₃ ^? leaching. Differences could also be due to cumulative effects of DE (first year applied) on second year NO₃ ^? leaching. Total annual pasture N uptake was similar for DE and urea treatments. During the first year, the average NO₃ ^? concentration was lower when DE was combined with urine compared to urine alone, but not in the second year. The combination of DE with urine resulted in significantly greater (p < 0.01) annual pasture N uptake compared with the urine alone treatment in both years. Urine plus urea resulted in the greatest leaching losses in both years, but its impact on pasture N uptake was mixed. The total leaching loss of N from urine plus DE (90 kg N ha^?1) was similar to urine alone (77 kg N ha^?1) in the second year. Likewise, the annual percentage of ¹⁵N recovered in the leachate from urine plus DE (9%) was not significantly different from urine alone (6%). However, ¹⁵N recoveries revealed that the contribution of urine N to NO₃ ^? leaching was greater when urine was combined with DE (98.8%) compared to urine alone (83%). The greater NO₃ ^? leaching from urine when combined with DE could be a result of greater nitrification due to the low C:N ratio of DE. Additionally, the annual percentage of urine N uptake by the pasture from urine plus DE (29%) was significantly less than from urine alone (39%) (p < 0.01). The application of organic C rich DE had no significant effect on soil N retention or denitrification when combined with urine.     

Population trends in northern spotted owls: Associations with climate in the Pacific Northwest

We used reverse time capture-mark-recapture models to describe associations between rate of population change (λ) and climate for northern spotted owls (Strix occidentalis caurina) at six long-term study areas in Washington and Oregon, USA. Populations in three of six areas showed strong evidence of declining populations, while populations in two additional areas were likely declining as well. At four areas, λ was positively associated with wetter-than-normal conditions during the growing season, which likely affects prey availability. Lambda was also negatively associated with cold, wet winters and nesting seasons, and the number of hot summer days. The amount of annual variation in λ accounted for by climate varied across study areas (3-85%). Rate of population change was more sensitive to adult survival than to recruitment; however, there was considerable variation among years and across study areas for all demographic rates. While annual survival was more closely related to regional climate conditions, recruitment was often associated with local weather. In addition to climate, declines in recruitment at four of six areas were associated with increased presence of barred owls. Climate change models predict warmer, wetter winters and hotter, drier summers for the Pacific Northwest in the first half of the 21st century. Our results indicate that these conditions have the potential to negatively affect annual survival, recruitment, and consequently population growth rates for northern spotted owls.     

Local perceptions of jaguars (Panthera onca) and pumas (Puma concolor) in the Iguaçu National Park area, south Brazil

Jaguars (Panthera onca) have been killed by local residents within the boundaries and lands surrounding Iguaçu National Park (INP), Brazil. Both jaguars and pumas (Puma concolor) occur in the region, however, livestock predation by pumas has rarely been reported. Our objective was to assess the local perceptions about jaguars and pumas. We identified two major factors that distinguished the perceptions towards the two species: less people feared the puma than the jaguar; and most people believed that jaguars, but not pumas, were released into INP by local authorities. Interestingly, despite those major differences in these perceptions, feelings towards the two species tended to be the same. Perceptions towards jaguars were not influenced by the predation history of the properties, suggesting that the predation impact was not remarkable enough to influence local perceptions towards carnivores. This is apparently the first study on local perceptions towards large carnivores in Brazil.     

Relationship between fluoride contents and loss of lichens near an aluminium works

The relationship between F contents and damage to previously unpolluted saxicolous lichens (Ramalina sp) was examined in the vicinity of an Al works on the island of Anglesey, North Wales. Damage was greatest <2 km from the works, where 41% of Ramalina thalli showed >50% chlorosis and necrosis. Loss of lichens (measured by changes in percent cover in 58 permanent quadrats) decreased with increasing distance from the works. Lichens well-exposed to emissions had the largest F content and 20 to 30% more losses than those less-exposed. Well-exposed lichens had rates of loss of cover of 4.9% km^?1 yr^?1, whereas more sheltered thalli had losses of 3.7% km^?1 yr^?1. In contrast, relatively uncontaminated lichens increased in % cover. Content of F reflected both distance from the works and exposure to emissions; losses, and F content, were closely related (r²=0.90). Lichens containing 300, 100 and 50 μg F g^?1 dry weight lost 46, 15 and 10% of cover yr^?1, respectively.     

Residue cover and rainfall intensity effects on runoff soil organic carbon losses

Soil cover and rainfall intensity (RI) are recognized to have severe impacts on soil erosion and an interaction exists between them. This study investigates the effect of rainfall intensity (RI) and soil surface cover on losses of sediment and the selective enrichment of soil organic carbon (SOC) in the sediment by surface runoff. A field rainfall simulator was used in the laboratory to produce 90 min rainfall events of three rainfall intensities (65, 85 and 105 mm h^− 1) and four cover percentages (0%, 25%, 50% and 75%) on soil material at 9% slope. A strong negative exponential relation was observed between cover percentage and RI on sediment loss under 85 and 105 mm h^− 1 of rain, while under RI of 65 mm h^− 1, the highest sediment loss was observed under 25% cover. Overall, higher RI and lower cover produced higher sediment and consequently higher nutrient loss, but resulted in a lower SOC enrichment ratio (ER_SOC) in the sediment. The amount of runoff sediment rather than the ER_SOC in the sediment was the determinant factor for the amount of nutrients lost. The values of ER_SOC were high and positively correlated with the ER values of particles smaller than 20 µm (p < 0.01). Although the sediment contained substantially more fine fractions (fine silt and clay, < 20 µm), the original soil and runoff sediment were still of the same texture class, i.e. silt clay loam.     

Core terrestrial habitat for conservation of local populations of salamanders and wood frogs in agricultural landscapes

Pond-breeding amphibians require aquatic and terrestrial habitats to complete their lifecycles, and preservation of both habitats is necessary for maintaining local populations. Current wetland regulations focus primarily on aquatic habitats, and criteria to define critical upland habitats and regulations to protect them are often ambiguous or lacking. We examined the association between the presence of seven pond-breeding amphibian species and the landscape composition surrounding 54 wetlands located within the Till Plains and the Glaciated Plateau ecoregions of Ohio, USA. We quantified landscape composition within 200 m of the wetland (“core terrestrial zone”) and the area extending from 200 m to 1 km from the wetland (“broader landscape context zone”). We constructed binary logistic regression models for each species, and evaluated them using Akaike Information Criterion. Presence of spotted salamanders (Ambystoma maculatum), Jefferson's salamander complex (A. jeffersonianum) and smallmouth salamanders (A. texanum) was positively associated with the amount of forest within the core zone. Presence of wood frogs (Rana sylvatica) was positively associated with the amount of forest within the core zone and the amount of forest within the broader landscape context zone. Presence of tiger salamanders (A. tigrinum tigrinum) was negatively associated with the cumulative length of paved roads within 1 km of the site, and presence of red-spotted newts (Notophthalmus v. viridescens) was negatively associated with the average linear distance to the five nearest wetlands. Overall salamander diversity was positively associated with the amount of forest within the core zone, and negatively associated with the presence of predatory fish and cumulative length of paved roads within 1 km of the site. Our results confirm the strong association between the structure of surrounding upland areas and amphibian diversity at breeding ponds, and stress the importance of preserving core terrestrial habitat around wetlands for maintaining amphibian diversity.     

南水北调中线水源地土壤侵蚀经济损失估算

在GIS的支持下,通过气象数据分析、实地调查、野外采样及室内分析、DEM计算、遥感解译等,构建了南水北调中线水源地丹江口水库库区流域地理信息数据库,并利用USLE估算了研究区的土壤侵蚀量。以1990年的价格为基准,利用市场价格法、机会成本法和影子工程法估算了水源区年均土壤侵蚀带来的经济损失。结果表明,水源区的年均土壤侵蚀模数为2394 t/(km²·a)。研究区表土流失造成的全氮、全磷、全钾和有机质损失量在分别换算成标准化肥磷酸二铵、氯化钾及薪柴后的经济损失分别为1.64×10⁸,7.25×10⁷,1.17×10⁹和2.97×10⁷元;年均侵蚀的土壤相当于61.94 km²的土地被废弃,经济损失为3.71×10⁷元。土壤侵蚀导致的涵养水分、泥沙淤积和泥沙滞留方面的经济损失分别为3.22×10⁵,1.88×10⁷和1.95×10⁶元。水源区年均土壤侵蚀总经济损失达1.50×10⁹元,其中养分损失占96.11%。