The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 2. Paddock trees as stepping stones

The use of paddock trees as stepping stones by birds was assessedin a grazing landscape in southern New South Wales, Australia. A totalof 70 paddock tree sites was surveyed for 20 min each inthe morning, and 36 sites were surveyed again in the afternoon in March2000. During the surveys, the presence, direction of arrival, anddirection of departure to and from sites was recorded for each bird. Astepping stone effect of paddock trees was examined in two ways: (1) byanalysing the arrival and departure direction of birds relative tosurrounding vegetation cover, and (2) by analysing the departuredirection of birds relative to their arrival direction. An arrivaldirection was obtained for 150 independently acting groups of birds, anda departure direction was obtained for 203 independently acting groupsof birds. Both arrival and departure direction were obtained for 87independently acting groups. Foliage-foraging birds tended to followrelatively densely vegetated areas. There was some indication thatgranivores and nectarivores also preferred to move along denselyvegetated areas. This trend was absent for open-country species. Allgroups of birds examined tended to return to their place of origin ormove in the opposite direction of their arrival. This trend was mostpronounced for nectarivores and the foliage-foraging White-plumedHoneyeater (Lichenostomus penicillatus), and lesspronounced for open-country species and parrots. The results arediscussed in relation to the biology and ecology of the various speciesof birds. We conclude that paddock trees have the potential to enhancelandscape connectivity by acting as stepping stones to assist movement.This further highlights their conservation value as demonstrated in thefirst paper of this series.     

The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 1. Species composition and site occupancy patterns

The use of paddock trees by birds was assessed in a grazinglandscape in southern New South Wales, Australia. Seventy paddock treesites were surveyed for 20 min each in the morning, and 36sites were surveyed again at midday in March 2000. During this time, thepresence and abundance of birds was recorded. Several site and landscapevariables were measured at each site. These included tree species, atree size index, a measure of the crown cover density around the site,and proximity to the nearest woodland patch. During formal surveys, 31bird species, including several woodland species, were observed usingpaddock trees. Data from bird surveys in woodland patches that wereobtained in a separate study in November 1999 were used to comparewhether there was a relationship between the abundance of a given birdspecies in woodland patches and paddock trees. Many birds commonlydetected in woodland patches were also common in paddock trees. However,some birds with special habitat requirements were absent from paddocktrees although they were common in woodland patches. Site occupancypatterns were modelled for several guilds of birds using logisticregression. Foliage-foraging birds were more likely to occupy clumps oftrees and sites with a high tree size index. Nectarivores appeared to bemore likely to be detected at sites more than 200 m fromwoodland, although this result was marginally non-significant(P = 0.08). The probability of detecting granivoreswas higher at sites with a low tree size index. Open country specieswere most likely to occupy large trees and sites that were located morethan 200 m from the nearest woodland patch. The value ofpaddock trees may have been underestimated in the past because a widevariety of bird species use paddock trees on a regular basis. Ensuringthe continued survival of paddock trees should be an important aspect offuture conservation and revegetation efforts.     

Conservation value for birds of traditionally managed isolated trees in an agricultural landscape of Madagascar

Isolated trees have distinctive economic, social and cultural value for the Betsileo people living on the edge of the protected forest corridor between Ranomafana and Andringitra national parks, in South-East Madagascar. Many of these trees are Ficus spp., traditionally protected and respected. At the landscape level, they are isolated features in a heterogeneous mosaic, providing fruit, shade and aesthetic services in open cultivated areas. Within the current management system, isolated trees may also contribute significantly to the provision of ecological services by enhancing bird diversity in open areas outside the forest. We identified practices and values linked to isolated tree uses and management through ethnographic data collection. Bird presence and abundance were sampled by 338 point counts in isolated trees and open areas of the agricultural mosaic. Isolated trees were occupied by 18 out of 32 (56%) bird species in the agricultural mosaic, including 8 (25%) endemic forest species. Endemic forest birds were significantly more numerous in isolated trees than in open habitats, both in species richness and abundance (mean P value < 0.001). Overall bird species richness was significantly higher in open areas containing isolated trees, than in areas without isolated trees. Bird species richness in Ficus spp. was significantly higher than in other isolated tree species, although no differences were detected in abundance or within guilds. Community-based management of isolated trees may thus represent an opportunity for convergence between bird conservation goals outside protected areas and local management values and practices.     

区域农田景观格局对麦蚜种群数量的影响

明确农田景观格局对麦田蚜虫种群的影响,是开展区域性害虫生态调控的重要理论依据之一。以区域性小麦种植区为研究对象,基于遥感影像与土地覆盖分类数据以及田间调查的蚜虫种群数据,计算景观格局指数,使用负二项分布的广义线性模型从农田景观、非作物生境景观和区域景观3个方面分析了区域农田景观格局对麦田蚜虫种群的影响。结果表明,蚜虫种群的数量与草地的平均斑块面积和最大斑块指数显著正相关,与县域的平均几何最邻近距离和面积加权平均斑块面积显著负相关,与耕地的面积加权平均斑块面积显著负相关,与耕地的斑块密度显著正相关。草地斑块面积的增大、区域景观与耕地的破碎化、区域景观的聚集会促进蚜虫种群数量的增加。使用草地的斑块面积和最大斑块指数、区域景观的平均几何最邻近距离可以预测蚜虫种群的发生量。非作物生境草地的斑块面积、耕地的破碎化、区域景观的空间分布及破碎化是影响麦田蚜虫种群发生的重要景观因素。     

园林树木增湿降温生态功能评价方法

试验以吉林农业大学校园内的9种园林树木为研究对象,将树冠由外向内分为4个部位(分别记为表层A、外层B、中层C和内层D),分别测定各部位单位叶面积蒸腾降温量的变化规律,分析比较种内和种间不同部位单位叶面积增湿降温量的变化,以期探讨园林树木增湿降温生态功能评价的合理取样部位。结果表明:9种园林树木树冠各测定部位的单位叶面积增湿降温量均由树冠外围向树冠内部显著降低,树冠不同测定部位增湿降温量与平均值比较,种间SD和CV的变化大于种内。9个树种不同部位单位叶面积增湿量平均值为2.32 kg m-2d-1,降温量平均值为0.45℃。其中,表层A和外层B的增湿量较平均值分别提高了23.71%和10.77%,中层C和内层D分别较平均值下降了8.62%和26.46%;表层A和外层B的降温量较平均值分别提高了22.22%和11.11%,中层C和内层D分别较平均值下降了8.89%和26.67%;外层B和中层C平均增湿降温量为2.35 kg m-2d-1和0.46℃,与各测定部位平均值基本一致。9个树种各测定部位增湿降温量的偏离程度和和离散系数与平均值比较,外层B和中层C与各测定部位平均偏离程度接近,离散系数外层B最低。因此,在评价园林树木增湿降温生态功能时,提出用外层B或中层C偏向B点处的叶片作为取样部位更为合理。     

Metacommunities of spiders in grassland habitat fragments of an agricultural landscape

Arthropod communities in fragmented agricultural landscapes depend on local processes and the interactions between communities in the habitat islands. We aimed to study metacommunity structure of spiders, a group that is known for high dispersal power, local niche partitioning and for engaging in species interactions. While living in fragmented habitats could lead to nestedness, other ecological traits of spiders might equally lead to patterns dominated either by species interactions or habitat filtering. We asked, which community pattern will prevail in a typical agricultural landscape with isolated patches of semi-natural habitats. Such a situation was studied by sampling spiders in 28 grassland locations in a Hungarian agricultural landscape. We used the elements of metacommunity structure (EMS) framework to distinguish between alternative patterns that reveal community organization. The EMS analysis indicated coherent species ranges, high turnover and boundary clumping, suggesting Clementsian community organization. The greatest variation in species composition was explained by local habitat characteristics, indicating habitat filtering. The influence of dispersal could be detected by the significant effect of landscape composition, which was strongest at 500 m. We conclude that dispersal allows spiders to respond coherently to the environment, creating similar communities in similar habitats. Consistent habitat differences, such as species rich versus species poor vegetation, lead to recognisably different, recurrent communities. These characteristics make spiders a predictable and diverse source of natural enemies in agricultural landscapes. Sensitivity to habitat composition at medium distances warns us that landscape homogenization may alter these metacommunity processes.     

Scattered trees as modifiers of agricultural landscapes: the role of waddeessa (Cordia africana Lam.) trees in Bako area, Oromia, Ethiopia

Scattered trees in general and scattered waddeessa (Cordia africana Lam.) trees in particular are very common across the agricultural landscapes in Oromia, Ethiopia. A study on this scattered waddeessa trees commonly growing on farmers' agricultural fields was conducted at Bako in western Oromia, Ethiopia with the objective of assessing their role in modifying the soil properties in the agricultural landscape. Soil samples from surface layers (0–10 cm) were taken at three concentric transects (0.5, 2 and 4 m) around the tree and compared with soil samples from the adjacent open areas (15 m distance from the tree), and then analysed following the standard procedures. Results showed that scattered waddeessa trees significantly modified the overall properties of the soil in the agricultural landscape of Bako area. But soil texture was not affected, indicating that it is more related to parent material than the tree influence. Hence, the soil patches observed under these waddeessa trees can be important local nutrient reserves that may influence the rural agricultural landscape. They also play an important role in generating local household income from the sale of products and conserving biodiversity by providing habitats and resources that are otherwise absent or scarce in agricultural landscape.     

Small things are important: the value of singular point elements for birds in agricultural landscapes

Farmland birds belong to the most endangered group of vertebrates in Europe. They are an important component of farmland biodiversity considering the numerous functions they perform (e.g. seed dispersal, improving germination, increasing gene flow, nutrient recycling, and pest control). Therefore, their decline imposes substantial risks on agricultural ecosystems. In general, farmland bird conservation includes land-use and management alterations leading to less-intensive farming and land-sparing for breeding habitats (e.g. agri-environment-climate schemes, and organic farming). However, theoretical concepts describing farmland biodiversity maintenance and applied conservation measures usually ignore the role of singular, often very small, natural or man-made elements in an agricultural landscape. These elements play a role in the populations of certain species, their biology and in the general species richness of farmland. Furthermore, the importance of these elements has never been empirically tested, which means that conservationists and practitioners are not aware of their measurable value for birds. Herein, we define and identify singular point elements in the agricultural landscape (SPELs) which are potentially important for breeding farmland birds. We also describe each SPEL and evaluate its importance for birds in farmland based on a systematic review of the available literature. Using a horizon-scanning technique, we then polled field ornithologists about their personal observations of birds in relation to SPELs and the evaluation of the potential roles of such structures for birds. We identified 17 SPELs that vary in naturalness and age: singular trees, singular shrubs, erratic boulders, puddles, electricity pylons, wind turbines, spiritual sites, hunting platforms, fence and border posts, wells, road signs, scarecrows, piles of manure, piles of brushwood/branches, piles of stones/debris, piles of lime, and haystacks. Analysis of the literature revealed knowledge gaps, because some SPELs are frequently mentioned in ecological studies (e.g. trees, shrubs, pylons), but others such as spiritual sites, stones, hunting platforms, wells, road signs, or piles of lime are ignored. Despite the fact that some authors incorporate the effects of some SPELs in their studies, little research to date has aimed to assess the impact of various SPELs on farmland bird species numbers and distribution. Horizon scanning revealed that ornithologists often observe birds on various SPELs and thus, attribute to SPELs many functions that are important for maintaining bird populations. Horizon scanning also highlighted the importance of SPELs for many declining bird species and suggested possible mitigation of negative changes in the agricultural landscape by retaining SPELs within fields. We suggest that a better understanding of the role of SPELs for farmland birds is required. We also recommend that SPELs are considered as a potential tool for the conservation of birds, and existing conservation programs such as agri-environment-climate schemes and organic farming should be updated accordingly. Finally, we suggest that SPELs are included in predictive models that evaluate habitat suitability for farmland biodiversity.     

The value of scattered trees for wildlife: Contrasting effects of landscape context and tree size

Aim

The biodiversity value of scattered trees in modified landscapes is often overlooked in planning and conservation decisions. We conducted a multitaxa study to determine how wildlife abundance, species richness and community composition at individual trees are affected by (1) the landscape context in which trees are located; and (2) the size of trees.

Location

Canberra, south‐eastern Australia.

Methods

Trunk arthropod, bat and bird surveys were undertaken over 3 years (2012–2014) at 72 trees of three sizes (small (20–50 cm DBH), medium (51–80 cm), large (≥80 cm)) located in four landscape contexts (reserves, pasture, urban parklands, urban built‐up areas).

Results

Landscape context affected all taxa surveyed. Trunk arthropod communities differed between trees in urban built‐up areas and reserves. Bat activity and richness were significantly reduced at trees in urban built‐up areas suggesting that echolocating bats may be disturbed by high levels of urbanization. Bird abundance and richness were highest at trees located in modified landscapes, highlighting the value of scattered trees for birds. Bird communities also differed between non‐urban and urban trees. Tree size had a significant effect on birds but did not affect trunk arthropods and bats. Large trees supported higher bird abundance, richness and more unique species compared to medium and small trees.

Main conclusions

Scattered trees support a diversity of wildlife. However, landscape context and tree size affected wildlife in contrasting ways. Land management strategies are needed to collectively account for responses exhibited by multiple taxa at varying spatial scales. We recommend that the retention and perpetuation of scattered trees in modified landscapes should be prioritized, hereby providing crucial habitat benefits to a multitude of taxa.     

Seed removal patterns of pioneer trees in an agricultural landscape

The seeds of most tropical plants are dispersed by animals, many of which also act as seed predators. Shifts in animal community composition, such as those driven by the clearing of native vegetation, are therefore likely to drive changes in plant recruitment. We used manipulative experiments excluding ants, small rodents, and birds to quantify the relative impacts of these granivores on animal-dispersed pioneer trees (ADPT) in fragments of savanna vegetation and adjacent soy plantations in Brazil’s Cerrado. We found that ants were the main consumers of ADPT seeds, that the rates of seed removal varied with seed size, and that removal rates were higher in savanna fragments than in soy plantations. However, we also found significant interactions between habitat type, seed species, and the type of seed predator being excluded. Our results underscore how challenging it can be to predict the influence of human disturbances on the interactions between plant and animal communities. Because ants, rodents, and birds are Cerrado’s the main seed dispersers and granivores, seedling recruitment in Cerrado landscape mosaics will depend on how these distinct but related processes are each influenced by species-specific patterns of seed size and seed abundance.     

Genetic and landscape characterization of ancient autochthonous olive trees in northern Italy

Several ancient olive plants with different genetic, agronomic and morphological characteristics are widespread in the Emilia-Romagna region. In this study, details of 206 trees located in four provinces were collected and their phytometric traits were recorded. Easily recognizable varieties were identified, while plants of uncertain genetic identity were submitted for molecular analysis with SSR markers and compared with cultivars widespread in central Italy and Emilia-Romagna. The genetic analyses showed that most of the ancient olive trees belonged to 10 cultivars that are already characterized, with different cases of intra-varietal clones. The remaining accessions belonged to 19 different genotypes of unknown origin. The highest percentage of policormic trees was found in the Bologna and Rimini provinces. A high percentage of plants located under unfavourable aspects (west to east) was found only in the Rimini territory, which presents peculiar and milder climatic conditions compared to the other provinces. Slope appeared not to be a limiting factor for tree survival. The information obtained could help the rational reintroduction of olive growing in suitable areas of Emilia-Romagna, with the subsequent economic advantages, erosion preservation and germplasm enrichment.     

国际景观生态学研究新进展

20世纪90年代中期以来,国际景观生态学发展迅速.景观生态学研究最为活跃的地区集中在北美、欧洲、大洋洲(澳大利亚)、东亚(中国),表明景观生态学理论、方法和应用的广泛性和越来越高的认知度.从研究内容上看,景观生态评价、规划和模拟一直占居主导地位,其次是景观生态保护与生态恢复、景观生态学的理论探讨.随着景观生态学研究的深入,以科学和实践问题为导向的学科交叉与融合不断加强,促进了景观生态学新的学科生长点的形成和发展,主要包括水域景观生态学、景观遗传学、多功能景观研究、景观综合模拟、景观生态与可持续性科学.在全球化背景下,中国的景观生态学研究也已经取得了长足进展,国际同行开始关注并在重要学术刊物上评介中国的景观生态学研究,标志着中国景观生态学已逐步走上国际舞台.然而,中国景观生态学进一步发展的挑战和机遇并存.中国科学家需要抓住人类对可持续发展和可持续性科学的共同夙求,放眼国际前沿、服务本土需求,从中国自身的特色出发,关注受人类干扰的和以人为主导的景观,以景观格局与生态过程的多尺度、多维度耦合研究为核心,区域综合与区内分异并重,推动综合整体性景观生态学的建立和完善.     

Agricultural change and paddock tree loss: Implications for an endangered subspecies of Red-tailed Black-Cockatoo

Summary   Natural senescence and the intensification of agricultural practices are contributing to the continuing loss of paddock trees from agricultural regions in Australia. This is of particular concern in the southern Wimmera of western Victoria, where much of the endangered Buloke ( Allocasuarina luehmannii ) Woodland vegetation community is represented only by relict Buloke trees in paddocks, which also constitute critical feeding habitat for the endangered south-eastern subspecies of the Red-tailed Black-Cockatoo ( Calyptorhynchus banksii graptogyne ). I investigated the rate and correlates of loss of scattered Buloke trees in paddocks by examining aerial photographs taken over a period of 15 years in a region undergoing agricultural intensification. Tree loss over the period was measured using aerial photographs of five localities, covering a total of 7850 ha of agricultural land in the southern Wimmera. The average rate of loss (± 1 SE) was 25.8% ± 6.4% over the 15 years, or 1.7% per annum. The rate of tree loss was higher in areas under cultivation (32.5%) than areas under pasture (20.6%). A disproportionate number of trees was lost from locations where centre pivot irrigation systems were installed. Because of the slow growth rate of Buloke trees, revegetation efforts and offset planting are unlikely to compensate for losses of Red-tailed Black-Cockatoo habitat for approximately 100 years.     

Integrating species and habitat data for nature conservation in Great Britain: data sources and methods

1. Britain is unusual in the quantity and quality of species and habitat data available, at both national and regional scales. This paper reviews the sources, coverage and quality of these data. 2. Habitat and species data are used by conservation agencies in England, Scotland and Wales for site selection and for monitoring habitat quality. The paper argues, however, that neither habitat data nor species distribution data on their own are sufficient to locate and monitor habitats for nature conservation purposes effectively. 3. Differences in sampling methodologies between habitat and species surveys present methodological difficulties for the development of an integrated monitoring system that uses both types of data. These problems need to be overcome if habitat and species data are to be used more effectively for nature conservation in the wider countryside. 4. A more integrated system based on the concept of biotope occupancy is proposed and discussed. The implementation of the system would assist with understanding those factors that explain observed patterns in species distribution and diversity, thereby helping to improve the effectiveness of policies for nature conservation.     

The Shapley value of phylogenetic trees

Every weighted tree corresponds naturally to a cooperative game that we call a tree game; it assigns to each subset of leaves the sum of the weights of the minimal subtree spanned by those leaves. In the context of phylogenetic trees, the leaves are species and this assignment captures the diversity present in the coalition of species considered. We consider the Shapley value of tree games and suggest a biological interpretation. We determine the linear transformation M that shows the dependence of the Shapley value on the edge weights of the tree, and we also compute a null space basis of M. Both depend on the split counts of the tree. Finally, we characterize the Shapley value on tree games by four axioms, a counterpart to Shapley’s original theorem on the larger class of cooperative games. We also include a brief discussion of the core of tree games. Research of Francis Edward Su was partially supported by NSF Grants DMS-0301129 and DMS-0701308.     

Clumped and isolated trees influence soil nutrient levels in an Australian temperate box woodland

Isolated paddock trees are a common feature of agri-pastoral landscapes in south-eastern Australia. We assessed the impact of trees on soil nutrients by examining (1) changes in soil nutrients under clumped and isolated (living and dead) trees at four microsites corresponding with increasing distance from the trunk (trunk, mid-canopy, drip line, open), and (2) changes with depth under trees growing in clearly-defined clumps. We detected significantly greater concentrations of organic C, and total N and S under trees growing in clumps compared with either isolated living or dead trees. Levels of soluble Ca²⁺, K⁺ and Mg²⁺, pH, electrical conductivity (EC) and available P declined with increasing distance from the trees, but there were no significant trends for organic C, or total N and S. The concentration of most nutrients declined with depth, particularly at microsites close to the trunk, while pH increased with depth. We believe that differences in chemistry were largely driven by greater inputs of organic matter under the trees. This study reinforces the view that trees, whether scattered or in clumps, are important for soil nutrient conservation in agri-pastoral landscapes.     

The value of indicator species for landscape characterization

Given that different types of landscape are affected by different environmental factors, is it possible to identify plant species indicative of these landscape types? An analysis of indicator species was made using 140 vegetation samples distributed over five landscape types. A total of 30 indicator species were identified, displaying varying indicator value. The variation disclosed the existence of a gradient between landscape types in terms of the prevailing ecological conditions. The analysis of the results also led to a reflection on the hierarchical level of which species are indicative (landscape vs. ecosystem). Further 20 samples were taken to check the validity of the indicator species. The identification of the indicator species present in these samples enabled each sample to be assigned to one of the landscape types; that assignment was subsequently checked against the actual landscape from which samples were taken. Seventy-five percent of the 20 validation samples were correctly assigned; the misassignment of the remaining 25% was due largely to the heterogeneous nature of the landscapes. On the basis of these results, we concluded that it is possible to characterize landscapes on the basis of indicative plant species, although characterization becomes more incomplete as the internally heterogeneous nature of the landscape increases.