A meta‐analysis of human disturbance impacts on Antarctic wildlife

Evidence‐based assessments are increasingly recognized as the best‐practice approach to determine appropriate conservation interventions, but such assessments of the impact of human disturbance on wildlife are rare. Human disturbance comprises anthropogenic activities that are typically non‐lethal, but may cause short‐ and/or longer‐term stress and fitness responses in wildlife. Expanding human activity in the Antarctic region is of particular concern because it increases the scope and potential for increased human disturbance to wildlife in a region that is often thought of as relatively untouched by anthropogenic influences. Here, we use a meta‐analytical approach to synthesise research on human disturbance to wildlife over the last three decades in the Antarctic and sub‐Antarctic region. We combine data from 62 studies across 21 species on the behavioural, physiological and population responses of wildlife to pedestrian, vehicle and research disturbances. The overall effect size indicated a small, albeit statistically significant negative effect of disturbance (?0.39; 95% CI: ?0.60 to ?0.18). Negative effects were found for both physiological and population responses, but no evidence was found for a significant impact on wildlife behavioural responses. Negative effects were found across pedestrian, vehicle and research disturbances. Significant and high among‐study heterogeneity was found in both disturbance and response sub‐groups. Among species, it remains unclear to what extent different forms of disturbance translate into negative population responses. Most current guidelines to limit wildlife disturbance impacts in Antarctica recommend that approaches be tailored to animal behavioural cues, but our work demonstrates that behavioural changes do not necessarily reflect more cryptic, and more deleterious impacts, such as changes in physiology. In consequence, we recommend that pedestrian approach guidelines in the Antarctic region be revisited. Due to the high heterogeneity in effects, management guidelines for different sites and species will need to be developed on a case‐by‐case basis, ideally in conjunction with carefully designed experiments. Guidelines to reduce the impact of research activities per se require development to reduce the potential impacts of conducting research. We identify research questions that, if answered, will further improve the evidence base for guidelines to manage human disturbance in Antarctica.     

Determinants of uncertainty in wildlife responses to human disturbance

Outdoor recreation is increasing in intensity and space. Areas previously inaccessible are now being visited by ever‐growing numbers of people, which increases human–wildlife encounters across habitats. This has raised concern among researchers and conservationists as, even in non‐aggressive encounters, animals often perceive humans as predators and mount physiological and behavioural responses that can have negative consequences. However, despite all the research in recent decades, not many general patterns have emerged, especially at the level of populations, and many studies have yielded seemingly contradictory or inconclusive results. We argue that this is partly due to incomplete knowledge of the number and complexity of factors that may modulate the responses of animals. Thus, we aim to provide a conceptual approach intended to highlight the reasons that make it difficult to detect general patterns. We present a comprehensive compilation of factors modulating animal responses to humans at increasing levels (from sensory detection and immediate behavioural and physiological reactions, to changes in fitness and population trends), which may help understanding the uncertainty in the patterns. We observed that there are many modulating factors, which can be categorized as reflecting characteristics of the recreational activity itself (e.g. intensity of human presence), of the animals concerned (e.g. age or antipredatory strategy), and of the spatio‐temporal context (e.g. habitat or timing of the encounter). Some factors appear to have non‐linear and complex effects, which, if not considered, may lead to erroneous conclusions. Finally, we conclude that the difficulty in finding general patterns will be amplified at higher levels (i.e. at the level of populations), since as we proceed from one level to the next, the number of potential modulating factors accumulates, adding noise and obscuring direct associations between recreation and wildlife. More comprehensive knowledge about which (and how) factors affect animal responses across levels will certainly improve future research design and interpretation, and thus, our understanding of human recreational impacts on wildlife.     

Long‐term persistence of wildlife populations in a pastoral area

Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case‐study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long‐term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework. By comparing density estimates of the road transect‐based long‐term monitoring to estimates derived from systematically distributed transects, we found that the bias associated with nonrandom placement of transects was nonsignificant. Overall, cattle and sheep and goat reached the greatest densities and several wildlife species occurred at densities similar (zebra, wildebeest, waterbuck, Kirk's dik‐dik) or possibly even greater (giraffe, eland, lesser kudu, Grant's gazelle, Thomson's gazelle) than in adjacent national parks in the same ecosystem. Generalized linear mixed models suggested that most wildlife species (8 out of 14) reached greatest densities during the dry season, that wildlife population densities either remained constant or increased over the 17‐year period, and that herbivorous livestock species remained constant, while domestic dog population decreased over time. Cross‐species correlations did not provide evidence for interference competition between grazing or mixed livestock species and wildlife species but indicate possible negative relationships between domestic dog and warthog populations. Overall, wildlife and livestock populations in Manyara Ranch appear to coexist over the 17‐year span. Most likely, this is facilitated by existing connectivity to adjacent protected areas, effective anti‐poaching efforts, spatio‐temporal grazing restrictions, favorable environmental conditions of the ranch, and spatial heterogeneity of surface water and habitats. This long‐term case study illustrates the potential of rangelands to simultaneously support wildlife conservation and human livelihood goals if livestock grazing is restricted in space, time, and numbers.     

高原鼠兔扰动对高寒草地植物群落特征的影响

高原鼠兔是青海湖流域高寒草地主要的啮齿动物.本文基于R-Vegan中的RDA排序方法,以有效洞口数差异将高原鼠兔扰动强度划分为4组,分析不同扰动强度下高寒草地植物群落特征,进而提出群落演替的概念模型,探究高原鼠兔扰动对高寒草地生态系统及放牧质量的影响.结果表明:随着扰动强度加大,出现以灯芯草为优势种的群落向以草地早熟禾、海乳草为优势种的群落演替.当扰动强度较小时,群落的总盖度、地上生物量、物种多样性和物种丰富度较高,但杂类草植物比例较高;当扰动强度较大时,各群落特征值较低且杂类草植物比例最高;当扰动强度适中时,各群落特征值比较高,禾本科和莎草科植物比例最大.因此,轻度扰动时,虽然群落特征值高但放牧质量低;过度扰动时出现草场植被退化;而扰动强度在阈值内可维持高寒草地生态系统稳定并提高放牧质量.     

Dynamics of fish in Australian desert springs: role of large-mammal disturbance

Human activities affect even the most remote and best preserved places on Earth. One of those places is Dalhousie Springs, Witjira National Park, in the arid centre of Australia. In 2003 we resurveyed the fish communities in springs to document changes since an earlier survey in 1991. Over the 12 years there were 18 population extirpations and only two colonizations, so total occurrences of five native species in 30 springs decreased from 83 to 67 populations. One species, the endemic Dalhousie goby, Chlamydogobius gloveri , accounted for 12 of the 18 population extirpations. Each fish species tended to persist in springs larger than some threshold size. Extirpations were related to spring size, with smaller springs more readily loosing populations, and to major habitat changes, which included large increases in the tropical reed Phragmites and concomitant decreases in open water, disturbed habitats, and dissolved oxygen. Extirpations of fish populations can be attributed primarily to habitat changes associated with reduced disturbance and herbivory as a result of the removal of feral livestock. These changes highlight the keystone impacts of large mammals on habitats and biotas of desert springs, and should be considered in management practices and policy decisions.     

A multispecies approach to manage effects of land cover and weather on upland game birds

Loss and degradation of grasslands in the Great Plains region have resulted in major declines in abundance of grassland bird species. To ensure future viability of grassland bird populations, it is crucial to evaluate specific effects of environmental factors among species to determine drivers of population decline and develop effective conservation strategies. We used threshold models to quantify the effects of land cover and weather changes in "lesser prairie‐chicken" and "greater prairie‐chicken" (Tympanuchus pallidicinctus and T. cupido, respectively), northern bobwhites (Colinus virginianus), and ring‐necked pheasants (Phasianus colchicus). We demonstrated a novel approach for estimating landscape conditions needed to optimize abundance across multiple species at a variety of spatial scales. Abundance of all four species was highest following wet summers and dry winters. Prairie chicken and ring‐necked pheasant abundance was highest following cool winters, while northern bobwhite abundance was highest following warm winters. Greater prairie chicken and northern bobwhite abundance was also highest following cooler summers. Optimal abundance of each species occurred in landscapes that represented a grassland and cropland mosaic, though prairie chicken abundance was optimized in landscapes with more grassland and less edge habitat than northern bobwhites and ring‐necked pheasants. Because these effects differed among species, managing for an optimal landscape for multiple species may not be the optimal scenario for any one species.     

Tropical Dry Forests of Venezuela: Characterization and Current Conservation Status1

Tropical dry forests are located predominantly in the northern portion of Venezuela, above 6°N. Although their potential extent covers ca 400,000 km² (44% of the land), they currently occupy about 10 percent of this area. The diversity and complexity of Venezuelan dry forests increases from north to south along a gradient of decreasing severity of the dry season. A typical dry forest in Venezuela presents ca 110–170 species of plants from ca 40 to 50 families within an area of approximately 10 ha. Species composition and forest structure, however, are dependent on local landscape conditions (e.g., soil type, topography), and nearby forest types can be very different. Our analysis of five dry forest variants showed a maximum family similarity of 67 percent, although most values fell in the 50–60 percent interval. They are currently considered as one of Venezuela's most threatened ecosystems, but only 5 percent of extant dry forests are included in protected areas; this represents 0.5 percent of their potential extent. It is fundamental to promote the creation of at least 3 or 4 more large protected areas (ca 5000 ha), with different climatic and orographic characteristics, in combination with the recovery of threatened species, the restoration of degraded systems, and the implementation of sustainable development projects. Their apparent high resilience suggests that with the proper management we can restore and maintain the integrity of Venezuelan dry forests.     

地面节肢动物营养类群对土地覆被变化和管理扰动的响应

近几十年来,黑河中游荒漠绿洲过渡带大面积天然沙质草地被转变为农田和防风固沙人工林,然而目前尚缺乏土地利用/覆被变化和管理措施对地面节肢动物多样性形成和维持影响的系统研究。以天然沙质草地转变为的人工梭梭灌木林、人工杨树林、人工樟子松林和农田为研究对象,以天然草地为对照,通过对5种样地地面节肢动物群落的调查及非生物环境因子的测定,采用典范对应分析(CCA)等方法,系统探讨了土地覆被和管理强度(天然草地和人工梭梭林实施零管理、杨树和樟子松人工林实施灌溉管理、农田实施灌溉和施肥管理)变化对地面节肢动物营养类群组成、数量和物种丰富度的影响。主要结果是:(1) 在干旱环境下,单纯改变土地覆被并不会导致土壤环境的显著变化,而高强度的管理扰动加速了土壤环境的演变过程。(2)不同土地覆被和管理措施对营养类群组成及其数量和丰富度的调控作用不同,将天然草地转变为杨树和樟子松人工林和农田后,显著提高了捕食性和植食性类群的比例,降低了'腐食性+杂食性’类群的比例;转变为人工梭梭林后显著降低了3种营养类群的数量;转变为人工杨树林后显著降低了'腐食性+杂食性’类群数量;转变为人工樟子松林后显著增加了植食性类群数量而降低了其它类群的数量;转变为农田后显著增加了植食性类群数量而降低了'腐食性+杂食性’类群数量。(3)影响捕食性动物分布的关键环境因子是地面温度、土壤硝态氮和田间持水量,影响植食性动物分布的关键因子是土壤粘粉粒、土壤硝态氮、土壤容重和pH值,影响'腐食性+杂食性’动物分布的关键因子是地面温度和田间持水量。主要结论是:土地覆被变化与管理措施相互作用对地面节肢动物群落组装过程及其多样性形成具有重要调控作用,尽管其相对重要性不同。     

植被、海拔、人为干扰对大中型野生动物分布的影响——以九寨沟自然保护区为例

利用九寨沟自然保护区内8条动物监测样线在2003—2010年的生态监测数据,分析了植被、海拔、人为干扰对大中型野生动物分布的影响,结果显示:1)本监测共记录到保护区内大中型野生动物26种,其中兽类18种,鸟类8种,属于我国Ⅰ级、Ⅱ级保护动物的分别有5种和11种。2)针阔混交林和针叶林是大中型野生动物种类最丰富的两种植被类型(分别有26种和17种),阔叶林和灌丛次之(分别为10种和12种),草地最少(2种)。3)海拔2400 m以下的地方,大中型野生动物种类稀少,为10种,2400—2599 m海拔段物种数增加至20种,之后随海拔上升物种丰富度下降。4)人为干扰显著影响大中型野生动物的空间分布:历史上的人类活动将原生森林植被转化为次生的落叶阔叶林、灌丛和草地,使树正、亚纳和尖盘等地下坡位(相对海拔0—199 m)的大中型野生动物的物种丰富度降低(分别为4、2、2种)。包括旅游活动和交通在内的人为干扰,可能导致附近50m海拔范围内保护动物的缺失,并使下坡位的某些物种向高海拔处移动。生境破碎化则使野生动物的种类组成发生改变,使原有森林内部优势种,如羚牛(Budorcas taxicolor),逐渐被适应能力强的物种,如豹猫(Prionailurus bengalensis)、雉鸡(Phasianuscolchicus)和野猪(Sus scrofa)等所取代,并将长期影响野生动物种群的存活。当前九寨沟自然保护区大中型野生动物的分布是植被、海拔与人为干扰综合作用的结果。     

The effect of forest disturbance on the leaf litter ant fauna in Ghana

In order to observe the effect of forest loss on the leaf litter ant fauna in Ghana, West Africa, samples were taken in primary forest, secondary forest and in cocoa plots. Ants were extracted from the leaf litter by sieving followed by suspension in Winkler bags. The species composition and species richness in the three different habitats were compared and no significant difference was found between them. It was concluded that most primary forest leaf litter ant species continue to survive in parts of the agricultural landscape which has largely replaced their original habitat.     

The effects of disturbance on forest butterflies using two methods of sampling in Trinidad

The butterfly assemblages of pairs of forest habitats, differing in disturbance level, within the Victoria Mayaro reserve of South-East Trinidad, are described using walk-and-count transects and canopy and understorey fruit traps. The concurrent use of these two butterfly censusing techniques, revealed major but conflicting differences in species accumulation rates under different disturbance conditions. The disturbed evergreen habitat had the significantly highest accumulation rate from walk-and-count data but the significantly lowest from fruit trap data. This reflects the specificity of much of the fruit-feeding guild for closed canopy forest. Disturbed habitats were found to lack a distinct canopy fauna. These results are discussed in light of the intermediate disturbance hypothesis. Within a region of forest, butterflies were found to be more characteristic of a disturbance level than of a particular forest type, lending weight to the belief that butterfly faunas can be used as bioindicators of forest disturbance. Several restricted geographic range species were not adversely affected by forest disturbance, at these levels of disturbance. The butterfly censuses in this study suggest that the optimal strategy for safeguarding butterfly species richness under natural forest management regimes would be to maintain a mosaic of habitats that included areas of undisturbed primary forest and a network of other forest patches, that varied in management regime and level of disturbance.     

Dental indicators of growth disturbance in a series of ancient Lower Nubian populations: Changes over time

Previous studies of accentuated striae of Retzius in tooth enamel suggest that early childhood growth disturbance tends to be severe in state-level agricultural societies. The present study investigates the diachronic stability of levels of growth disturbance with a series of Lower Nubian agricultural states broadly similar in terms of mode of subsistence and way of life. The sample consists of 114 first permanent molars from the Meroitic (100 B.C. to 300 A.D.) and X-Group (300 to 600 A.D.) cultures. These teeth were sectioned according to standard histological technique. Data on the frequency and severity of accentuated striae of Retzius were then used to derive estimates of the magnitude of individual growth disturbance. Populations were compared by means of a two-way ANOVA, with growth disturbance as the dependent variable, and age and population as the independent variables. The results show that those dying in childhood experienced significantly higher levels of early childhood growth disturbance than did those surviving to adulthood. The results also show a decline in growth disturbance levels over time. Both X-Group children and X-Group adults experience significantly less early childhood growth disturbance than their Meroitic counterparts. These results suggest an improvement in child health status from Meroitic to X-Group times. Tentative explanatory hypotheses imply an increase in village autonomy, an increase in helminthic disease related to a change in irrigation technology, or direct and indirect effects of consumption of naturally-occurring tetracyclines. These hypotheses are not mutually exclusive, and further research is needed before any of them can be tested.     

Developing a disturbance index for five East African forests using GIS to analyse historical forest use as an important driver of current land use/cover

A means of deriving a disturbance index reflecting forest use history is demonstrated here to establish a disturbance gradient and enable comparison of different forest areas within and across individual forests. Detailed reference is made to Kakamega Forest in western Kenya for which a long‐term time series has been established, although the study is spread to four further forests in Kenya and Uganda. A wide variety of sources are drawn upon for spatially resolved data that are integrated in a geographic information system. Three indices are derived: for commercial disturbance, local disturbance, and forest cover change. Results show a wide range of disturbance values (from low to heavy) for the research sites within Kakamega Forest, while results for Budongo and Mabira Forest sites show low and moderate levels, respectively. Correlations of low disturbance levels with nature or national reserves appear to be marked, while a correlation of disturbance with differing management authority is also suggested with Kenya Wildlife Service achieving the lowest disturbance levels. Results from the index are reviewed against other means of estimating disturbance with the conclusion that disturbance evaluations should be both spatially resolved and long‐term in nature.     

Habitat structure and disturbance affect small mammal populations in Mediterranean forests

Habitat structure, the physical arrangement of objects in space, affects animal populations, ecological interactions, species diversity, and ecosystem functioning. Conventional forest management practices that reduce habitat structural complexity are thus under reappraisal, and there are increasing efforts to understand how habitat structure affects functionally important species. We investigate here the effect of habitat structures on small mammal dens and their interactions with widespread antagonistic species (wild boars). Among habitat structures we considered tree dimension (diameter), shrub cover, rock cover, dead wood volume, and stump area. Ground cover with rooting signs measured wild boar disturbance. The number of small mammal dens was related positively to rock cover and tree diameter, and negatively to wild boar disturbance. Additionally, a positive interaction between wild boar disturbance and tree diameter emerged, showing that the effect of big trees on small mammal nesting was more evident with higher levels of disturbance. This study suggests that habitat structures that can be affected by forest management provide effective refuges for functionally important species. The effect of habitat structure on species survival and interactions thus needs to be addressed to understand ecosystem management and functioning.     

Myrmecochory in Australia's seasonal tropics: Effects of disturbance on distance dispersal

Abstract Successful ecosystem restoration requires the re-establishment of fundamental ecological processes, many of which involve plant-animal interactions. Myrmecochory (seed dispersal by ants) is a particularly important plant-animal mutualism in Australia, but little is known about its response to either disturbance or restoration following disturbance. Here we investigate the effects of disturbance on seed dispersal by ants, and the extent to which the ant-seed relationship has re-established at sites undergoing rehabilitation, at Ranger uranium mine in the seasonal tropics of Australia's Northern Territory. We focused on the composition of seed-dispersing ant assemblages, rates of seed removal by ants, and the dispersal curves generated by ants, as determined by observations of removal from seed depots. Ten sites were studied, comprising four ‘natural’ (undisturbed) sites representing a range of savanna habitats occurring in the region, four disturbed sites representing a range of habitat disturbance but with intact soil, and two waste rock sites subject to preliminary revegetation trials. A total of 22 ant species from 10 genera were observed during 154 observations of seed removal, most commonly Rhytidoponera aurata (53 records), Monomorium (rothsteini gp) sp. 1 (14), Iridomyrmex sanguineus (13), Iridomyrmex pallidus (12) and Pleidole sp. 3 (10). Removal rates (over 3 h) averaged 29% across all sites and time periods, varying markedly both between and within sites. However, mean rates of removal were similar between natural, disturbed and waste rock sites (29%, 28% and 31%, respectively). A high incidence (62% of all depots) of'aril robbing’ by ants (primarily Monomorium spp.) eating arils in situ, without removal, was observed. Dispersal distances varied markedly between ant species, with Iridomyrmex sanguineus having both the highest mean (7.25m) and maximum (13.08 m) dispersal distances. Species of Pheidole typically dispersed seeds less than 0.5 m, and Meranoplus, Monomorium and Tetramorium spp. only ever moved seeds a few centimetres, usually dropping and abandoning them before reaching the nests. The dispersal curves characteristic of each site varied markedly due to the different composition of seed-dispersing ants. The mean dispersal distance at disturbed sites (3.91 m) was significantly higher than at natural sites (2.19 m), and the curves were strongly skewed in the former, but relatively uniform in the latter. The implications of these differences for recovery following disturbance are unclear. At rehabilitated waste rock sites, all observed removals involved distances less than 0.5 m, with a mean of 17 cm. This lack of effective ant-seed relationships might represent a barrier to further vegetation development at rehabilitated sites.     

人类活动影响下的生物多样性保护:中欧的植被演化及其启示

对历史时期欧洲中部地区植被历史的研究表明,人类活动不仅破坏了自然、导致植被的单一化,同时也对植被与景观的丰富度(多样性)产生影响。人类或家畜的干预使得一些半自然、高多样性的生境类型及相应的植被类型得以保持和发展;但过度的干扰势必造成植被的单一化和贫乏化,威胁生物多样性的保存和保护。当今的中欧植被格局总体上是近几个世纪,某些地区甚至是上千年来,人为干扰叠加在气候变化影响之上的综合产物。中欧大部分地区的潜在植被多为森林,如果没有人为活动的强烈影响,除了岩石、水体、海滩、林线以上的高山以及高位沼泽等特定生境的分布区域以外,当今中欧的大部分地区应当仍覆盖着郁闭的阔叶林,而不会表现出今天的多样性景观。因此,自然保护的对象不应当仅仅是纯自然植被,保护手段也不仅仅是清除人为干扰。在保护多样性思想的指导下,各种典型植被类型都是值得保护的,除了高自然度的自然生态系统外,栽培植被也应当被保存和保护,否则,它们会随着特定耕作或管理方式的消失而消失。同时,既应保护当前植被,也要恢复潜在植被,使目前多样的景观类型、植被类型和栖息地类型得以维持和发展。本文结论为解决当前欧洲自然保护中的争议性问题提供了依据,也可以为中国的生物多样性保护战...     

Human-induced fear in wildlife: A review

Humans, like natural predators, can induce fear in wildlife, which has the potential to alter species-level survival and fitness. Though anthropogenic impacts on wildlife have been studied in detail, how wildlife respond behaviorally to human presence has been less studied. Here, we provide a literature review on how humans interact with wildlife populations through the ecology of fear framework. Fear responses can be proactive or reactive, and can go beyond behavioral changes to alterations in physiology (such as increases in stress) or alterations in individual chromosome structure. Wildlife are more likely to flee from humans if they possess a larger body size, are female, or have fear-associated genotypes. Intelligence and individual differences lead to variations in wildlife’s fear responses to humans that can make studying fear difficult. Wildlife fear responses to humans depend on environmental factors, including context-specific human presentation and whether the animal was in urban or rural habitats. Human-induced fear in wildlife may have cascading impacts on broader wildlife communities and habitat structure caused by changes in how individual species interact with other species and the environment.