Plantation clearcut size and the persistence of early-successional wildlife populations

Plantation clearcuts represent an important habitat for many open-area wildlife species – including conservation-concern species – in landscapes dominated by industrial forests. However, due to the ephemeral nature of clearcuts, species using this type of environment face a “shifting mosaic” in which their ability to successfully relocate to another habitat patch may play a crucial role in the species’ persistence in the landscape. Although several studies have shown a positive effect of patch size on the persistence of open-habitat species, forest clearcutting represents a special case in which, on average, larger patches also tend to be more isolated from each other, likely creating a trade-off between area and isolation effects. We developed an individual-based spatially-explicit model to test the effect of clearcut size (a critical management variable in plantation forestry) on the persistence of generic early-successional wildlife species in a landscape dominated by forest plantations. We simulated a landscape covered with a plantation harvested regularly over a 25-year rotation and different versions of a wildlife population whose habitat was constituted only by 1–4 year-old patches. We observed that when the species could perceive the attributes of the neighboring pixels persistence time was higher at intermediate clearcut sizes agreeing with our prediction. Also, species with a high dispersal capacity were less limited by connectivity and reached their maximum persistence at higher clearcut sizes. Results also showed a positive effect of habitat lifetime on persistence. Our results suggest large clearcuts may be incompatible with the conservation of many early-successional vertebrates that have limited dispersal capacity, unless additional conservation measures, such as the use of corridors or special spatial arrangement of clearcuts, are taken to overcome the lack of connectivity.     

Bayesian spatial modeling of data from avian point count surveys

We present a unified framework for modeling bird survey data collected at spatially replicated survey sites in the form of repeated counts or detection history counts, through which we model spatial dependence in bird density and variation in detection probabilities due to changes in covariates across the landscape. The models have a complex hierarchical structure that makes them suited to Bayesian analysis using Markov chain Monte Carlo (MCMC) algorithms. For computational efficiency, we use a form of conditional autogressive model for modeling spatial dependence. We apply the models to survey data for two bird species in the Great Smoky Mountains National Park. The algorithms converge well for the more abundant and easily detected of the two species, but some simplification of the spatial model is required for convergence for the second species. We show how these methods lead to maps of estimated relative density which are an improvement over those that would follow from past approaches that ignored spatial dependence. This work also highlights the importance of good survey design for bird species mapping studies.     

Health surveillance in wildlife reintroductions

Reintroductions and translocations are increasingly used as conservation tools. However, despite guidelines recommending that health-screening be an integral part of such programmes, few reports are available. For most species, even baseline data, against which to compare future results, are not published. Here we report two case studies of health surveillance in wildlife reintroduction programmes - for water voles (Arvicola terrestris) in Australia, and for marsupial dibblers (Parantechinus apicalis) in the UK. These illustrate the potential importance of even basic screening strategies in helping to avoid disease transfer and identifying predictors of survival. Factors to be considered in the design of future monitoring schemes are also discussed.     

Isolation and extirpations in wildlife reserves

Recent evidence implies that reserve faunal communities may experience species depletion as a result of isolation from contiguous gene pools. Although we could find no species-area relation between reserve size and the number of extant large mammal species in 13 East African savanna reserves, certain tenets of biogeographic theory still apply. Available data from one such area reveal four extirpations in recent times. This may support the hypothesis that isolated reserves may be experiencing species depletion due to isolation from surrounding natural habitat.     

Accuracy of sedimentgraph modeling from topography map scale and DEM mesh size

The evaluation of scale effects on modeling performance of sedimentgraphs as the ultimate outputs of the hydrological simulation is vital for adaptive watershed management. The present study therefore analyzed effectability of simulated sedimentgraphs components in association with different topographic maps with various vector scales. The whole procedure was materialized to select the critical scale and cell size for the Galazchai Watershed, Iran. To this end, the stormwise sedimentgraphs were modeled for 23 recorded events using the Clark's Instantaneous Unit Hydrograph (IUH) model stemmed for developing Instantaneous Unit Sedimentgraphs (IUSGs) incorporated with dimensionless sediment concentration distribution (DSCD) based on the vector scales of 1:25000, 1:50000, 1:100000 and 1:250000 and cell sizes of 5, 10, 20 30, 50, 100 and 200 m. Some 644 direct sedimentgraphs (DSGs) were then evaluated based on Relative Errors (REs) for sediment volume, peak sediment, time to peak, base time and the Coefficient of Efficiency (CE). The results confirmed that REs for peak sediment, time to peak and CE were sensitive to cell size. The results further verified that the cell sizes of 5, 20, 30, 50 and 100 m were critical cell sizes in viewpoint of time to peak. In addition, the vector scales of 1:50000 with cell size of 50 m, and 1:100000 with cell sizes of 5 and 10 m were critical vector scales and cell sizes based on RMSE evaluation criterion. It is concluded from the current research that the accuracy of simulation of sedimentgraph was influenced by map scales and mesh sizes.     

Realities of documenting wildlife corridors in tropical countries

Connectivity is regarded as vital in conservation planning but the whereabouts of remaining wildlife corridors and dispersal areas in most tropical countries are poorly documented. With local experts, we compiled an annotated list of the most important wildlife corridors remaining on mainland Tanzania, information on the status of each corridor, wildlife using these corridors, and threats to them. We discovered that the concept of a wildlife corridor differs greatly between different people working in the same country, so we divided these into five working categories. The most common categories were those identified by known movements of animals between two protected areas, or simply proposed connections between important habitats. In Tanzania, the majority of documented corridors now seem to be in a critical condition, that is, they may have less than 5 years remaining before they disappear, judging by current rates of land use change. Five corridors are in extreme condition and could disappear within 2 years unless immediate action is taken. These pressing problems – and our experience in Tanzania – indicate that surveys of remaining wildlife corridors may need urgent documentation in other countries too and that collators should maintain loose definitions of corridors, accept data of variable quality and give information to authorities as soon as possible in order to maximize the chances of saving these conservation assets.     

植物化感作用研究概况

近年来植物化感物质的提取、纯化、鉴定及其生物检测方法的研究取得很大进展。化感作用物质主要来自植物的次生代谢产物，它通过影响植物膜系统、激素水平、矿质吸收、呼吸和光合作用等对植物的生长产生影响。并阐述了植物化感作用及其机理、化感作用的研究方法，指出植物化感作用研究中存在的问题和研究方向。     

Bayesian approach in agrochemical surveys

In the scheme of agrochemical surveys, sampling is one of the most costly stages. The use of a priori information about the distributions of properties (Bayesian approach) allows one to reduce the number of samples to be taken by 5–10% without deteriorating the accuracy of the estimation. The maintenance of regional soil-mapping databases is a necessary condition for applying the Bayesian approach.     

Hong Kong's trade in wildlife

Hong Kong, a city of $\text{4}\text{1}\text{4}$ million people situated near the mouth of the Pearl River in South China, consumes large numbers of wild birds, mammals, reptiles and amphibians imported from the People's Republic of China. Some are gourmet foods, but most are used for quasi-medicinal purposes. This paper is an attempt to assess the volume of this trade, and also to pinpoint certain areas in which there is potentially severe damage being done to the ecological balance of the regions in which the fauna originate.     

Use of highway undercrossings by wildlife in southern California

Roads, especially large highways, can have significant impacts on wildlife movement and survival. This is especially true for wide-ranging species, such as mammalian carnivores. Some of these impacts may be mitigated if wildlife can find and utilize passageways under highways. To determine if underpasses and drainage culverts beneath highways are used by wildlife as movement corridors, we monitored 15 such passages near Los Angeles, California using remotely triggered cameras and gypsum track stations. We found that passages were used by a variety of species, including carnivores, mule deer, small mammals, and reptiles. Many types of undercrossings were utilized, indicating that passages beneath highways, even when not originally designed for wildlife, can provide important safe avenues for animals to cross roads. For mammals of conservation concern, including native carnivores and deer, passage dimensions, surrounding habitat, and the extent of human activity were assessed to determine if these factors influenced passage use by these species. Our results show that while many native mammals used passages beneath highways, the presence of suitable habitat on either side of the passage was a particularly important factor predicting use. For deer and coyotes, passage dimensions were also important and should be considered with the presence of suitable habitat when wildlife passages are planned or evaluated. To increase the likelihood of utilization and to help prevent animals from crossing road surfaces, we suggest that simple improvements such as habitat restoration near crossing points and animal-proof fencing that serves to funnel wildlife to passages, can facilitate animal movement between fragmented habitats that are bisected by roads.     

Effects of industrial air pollution on wildlife

Air pollution is a recognized health hazard for man and domestic animals. Although industrial air pollutants have been known to cause sickness and death of the latter for over 100 years, little attention has been paid to their importance in the decline of wildlife. This paper reviews the existing information on the effects of industrial air pollutants on vertebrate wildlife. Air pollutants have had a worldwide effect on both wild birds and wild mammals, often causing marked decreases in local animal populations. The major effects of industrial air pollution on wildlife include direct mortality, debilitating industrial-related injury and disease, physiological stress, anaemia, and bioaccumulation. Some air pollutants have caused a change in the distribution of certain wildlife species.     

Poaching of Israeli wildlife by guest workers

Movement of people from third- to first-world countries frequently brings with it different, and often opposing, approaches to wildlife. About 22,000 Thai workers are currently employed in Israel, mostly in agriculture. Most of these workers originate from the poor Isaan region in northeast Thailand, where the major source of income is from agriculture, supplemented by gathering and hunting of animals. In Israel, many of them engage in illegal hunting and gathering of wildlife. At least 28 species of mammals (including six domestic ones), 25 species of birds, seven species of reptiles, three species of amphibians and various species of fish, molluscs and other invertebrates have been found mainly in traps (chiefly noose traps) laid by Thai workers. Other methods of capture used by the workers include the use of hand-held catapults, netting, the collection of bird eggs, and the gathering of slow-moving vertebrates and invertebrates. These activities have a serious deleterious effect on the wildlife in Israel.     

Difference in spatiotemporal patterns of wildlife road-crossings and wildlife-vehicle collisions

Human–wildlife conflicts like wildlife–vehicle collisions pose major challenges for the management and conservation of mobile wildlife in human-dominated landscapes, particularly when large species are involved. Mitigation measures to reduce risk of collisions may be based on information given by wildlife movement and collision data. To test whether movement and collision data indicate different spatiotemporal risk zones, we predicted year-around probabilities of road-crossings of GPS-marked female moose (Alces alces) (n = 102), and compared them with spatiotemporal patterns of police recorded moose-vehicle collisions (n = 1158). Probability of moose road-crossings peaked in May, June, and between mid November and the beginning of January, i.e. during moose migration. Moose-vehicle collisions were more likely during autumn and winter. Comparing environmental attributes of crossing and collision sites showed significant differences. The likelihood of collisions increased with the abundance of human-modified areas and higher allowed speed, and was lower on forest roads. We found that animal movement data alone are insufficient to predict collision risk zones, while analyses of collision data alone overestimate the collision risk in certain habitats. Our findings suggest that higher collision risk is largely due to low light and poor road surface conditions rather than to more animal road-crossings. This suggests that efforts to reduce wildlife collisions should focus on driver attitudes and road conditions rather than animal movement, and any efforts to model the collision risk will require actual collision data, and not just movement data.     

Illegal wildlife use and protected area management in Ghana

Starting in 2004, a system to monitor patrol staff performance, illegal wildlife use and trends in large-mammal populations was established in nine protected areas in Ghana. The main objectives were to use monitoring feedback as the foundation for informed decisions to aid adaptive and performance management, and to identify the most important factors contributing to wildlife conservation. The competitive management system resulted in a doubling of patrol performance. As a result, in the six savannah sites, poaching was reduced to acceptable levels by the end of 2007, but in the three forest sites, poaching remained high. To reverse poaching trends in the forest required a conventional patrol effort that was 10 times higher than that in the savannah.The relationship between the amount of illegal activity with the operational budget, senior staff performance, encounter rates with large mammals, human population densities and habitat, was investigated for 2005-2007. With three predictor variables, the model explained 63% of the variation in the encounter rates with illegal activity. Increasing human population densities gave higher levels of poaching. Increasing frequencies of camp visits by senior officers and increasing operational budgets gave lower levels of poaching.In the second model, elephant poaching was used as the response variable and relative elephant density as an additional predictor variable. One predictor variable - that is elephant density - explained 38% of the total variation in elephant poaching. Elephant density incorporated the effects of camp visit frequencies, human densities, and habitat. Commercial trophy hunting for ivory, as opposed to subsistence hunting, was more sensitive to the density of the target species and efforts to curtail the activity. Subsistence hunting was proportional to human densities, with mainly members of nearby communities involved, while elephant poaching was not, mainly involving specialised hunters from towns further away.     

Conservation of non-game wildlife in California: A model programme

Public interest prompted the California State Legislature to provide needed authority and precedent-setting mandates for the management and protection of its non-game wildlife resources. Newly established activities and regulations include: research and field surveys on species-specific problems; the introduction of protective categories for threatened or unique species; bag limits and seasons on the taking of any unprotected animal; a moratorium on mountain lion hunting; measures to promote increases in the numbers of the rare Tule elk; curtailment of imported wildlife; a ban on the trade in endangered species; protective measures for intertidal organisms; and land acquisition of areas with important habitats. These constitute a comprehensive programme that merits wider adoption in the USA.     

The conservation impact of commercial wildlife farming of porcupines in Vietnam

Commercial farming of wildlife, particularly in Southeast Asia, is currently the subject of much debate and to date, its conservation impact has been largely unexplored. This study used semi-structured interviews to build a detailed understanding of the dynamics of the commercial farming of Southeast Asian porcupine (Hystrix brachyura) in the northwest Vietnamese province of Son La. Although farm owners are obliged by law to propagate stock solely from farm-bred animals, 58% of farm owners admitted purchasing wild founder stock, with at least 19% continuing to buy wild individuals. Despite the number of farms, the primary demand on them is to supply other farms, and wild meat restaurants were still sourcing their meat from wild populations. Lower cost was a major factor driving the trade in wild animals, with wild adult porcupines being bought for half the price of farm-bred adults. With high demand from farms and restaurants, increased targeted hunting may be the cause of a dramatic decline in the wild population of porcupines across the region.     

Criteria used in assessing wildlife conservation potential: A review

The criteria which have been used for the assessment of wildlife conservation values during the last decade are reviewed. Nine studies, ranging from studies of particular sites to those of ecological evaluation methods, are examined. Five criteria — diversity, rarity, naturalness, area and threat of human interference—were used in more than half of these studies. The rationale for each of these is considered, and problems of definition, measurement and application are discussed. Other criteria, which are used less frequently, are reviewed briefly.Three groups of criteria are recognised. The first can be estimated during a site visit. The second relies on extensive survey data within the geographical area, thus demonstrating the important role of amateur naturalists and their conservation organisations. The third group relies for its estimation upon a collection of case histories: there is an urgent need, both nationally and internationally, for systems to store and retrieve such data.