A multivariate analysis integrating ecological,socioeconomic and physical characteristics to investigate urban forest cover and plant diversity in Beijing,China

Understanding the factors driving the variation in urban green space and plant communities in heterogeneous urban landscapes is crucial for maintaining biodiversity and important ecosystem services. In this study, we used a combination of field surveys, remote sensing, census data and spatial analysis to investigate the interrelationships among geographical and social-economic variables across 328 different urban structural units (USUs) and how they may influence the distributions of urban forest cover, plant diversity and abundance, within the central urban area of Beijing, China. We found that the urban green space coverage varied substantially across different types of USUs, with higher in agricultural lands (N = 15), parks (N = 46) and lowest in utility zones (N = 36). The amount of urban green space within USUs declines exponentially with the distance to urban center. Our study suggested that geographical, social and economic factors were closely related with each other in urban ecological systems, and have important impacts on urban forest coverage and abundance. The percentage of forest as well as high and low density urban areas were mainly responsible for variations in the data across all USUs and all land use/land cover types, and thus are important constituents and ecological indicators for understanding and modeling urban environment. Herb richness is more strongly correlated with tree and shrub density than with tree and shrub richness (r = −0.472, p < 0.05). However, other geographic and socioeconomic factors showed no significant relationships with urban plant diversity or abundance.     

Anthropogenic noise reduces bird species richness and diversity in urban parks

Anthropogenic noise is becoming more prevalent in the world and has been shown to affect many animal species, including birds. The impact of such noise was measured in Neotropical urban parks to assess how the noise affects avifauna diversity and species richness. We sampled bird species, and concurrently measured sound pressure (noise) levels (L_eq, equivalent noise levels) in eight urban green areas or parks located in a large city (Belo Horizonte) in south‐eastern Brazil over a 1‐year period. The diversity of sampled points was measured by means of total species richness, Fisher's alpha and Shannon–Wiener diversity indices. Noise levels within all parks were greater than those in natural areas. We found that an increase in noise levels and the area of open habitats surrounding sampling points were negatively related to species richness. Social factors reflecting increased urbanization, such as higher incomes, were also negatively correlated with bird species richness. However, noise was the factor that explained most of the variance. These results suggest that anthropogenic noise can have a significant negative impact on the conservation value of urban parks for bird species.     

Landscape heterogeneity metrics as indicators of bird diversity: Determining the optimal spatial scales in different landscapes

Species distribution models are often used to study the biodiversity of ecosystems. The modelling process uses a number of parameters to predict others, such as the occurrence of determinate species, population size, habitat suitability or biodiversity. It is well known that the heterogeneity of landscapes can lead to changes in species’ abundance and biodiversity. However, landscape metrics depend on maps and spatial scales when it comes to undertaking a GIS analysis.We explored the goodness of fit of several models using the metrics of landscape heterogeneity and altitude as predictors of bird diversity in different landscapes and spatial scales. Two variables were used to describe biodiversity: bird richness and trophic level diversity, both of which were obtained from a breeding bird survey by means of point counts. The relationships between biodiversity and landscape metrics were compared using multiple linear regressions. All of the analyses were repeated for 14 different spatial scales and for cultivated, forest and grassland environments to determine the optimal spatial scale for each landscape typology.Our results revealed that the relationships between species’ richness and landscape heterogeneity using 1:10,000 land cover maps were strongest when working on a spatial scale up to a radius of 125–250 m around the sampled point (circa 4.9–19.6 ha). Furthermore, the correlation between measures of landscape heterogeneity and bird diversity was greater in grasslands than in cultivated or forested areas. The multi-spatial scale approach is useful for (a) assessing the accuracy of surrogates of bird diversity in different landscapes and (b) optimizing spatial model procedures for biodiversity mapping, mainly over extensive areas.     

Extinction thresholds and negative responses of Afrotropical ant-following birds to forest cover loss in oil palm and agroforestry landscapes

Afrotropical ant-following birds are vulnerable to forest loss and disturbance, but critical habitat thresholds regarding their abundance and species richness in human-dominated landscapes, including industrial oil palm plantations, have never been assessed. We measured forest cover through Landsat imagery and recorded species richness and relative abundance of 20 ant-following birds in 48 plots of 1-km², covering three landscapes of Southwest Cameroon: Korup National Park, smallholder agroforestry areas (with farms embedded in forest), and an industrial oil palm plantation. We evaluated differences in encounter frequency and species richness among landscapes, and the presence of critical thresholds through enhanced adaptive regression through hinges. All species were detected in Korup National Park and the agroforestry landscape, which had similar forest cover (>85%). Only nine species were found in the oil palm plantation (forest cover = 10.3 ± 3.3%). At the 1-km² scale, the number of species and bird encounters were comparable in agroforests and the protected area: mean species richness ranged from 12.2 ± 0.6 in the park and 12.2 ± 0.6 in the agroforestry matrix to 1.0 ± 0.4 in the industrial oil palm plantation; whereas encounters decreased from 34.4 ± 3.2 to 26.1 ± 2.9 and 1.3 ± 0.4, respectively. Bird encounters decreased linearly with decreasing forest cover, down to an extinction threshold identified at 24% forest cover. Species richness declined linearly by ca. one species per 7.4% forest cover lost. We identified an extinction threshold at 52% forest cover for the most sensitive species (Criniger chloronotus, Dicrurus atripennis, and Neocossyphus poensis). Our results show that substantial proportions of forests are required to sustain complete ant-following bird assemblages in Afrotropical landscapes and confirm the high sensitivity of this bird guild to deforestation after industrial oil palm development. Securing both forest biodiversity and food production in an Afrotropical production landscape may be best attained through a combination of protected areas and wildlife-friendly agroforestry.     

海口和三亚两城市破碎化林地中鸟类群落多样性与嵌套分布格局

城市化是生物多样性快速丧失的主要原因之一。鸟类作为城市生态系统的重要组成部分, 其生物多样性格局和物种保护已成为城市生态学研究的热点。为揭示城市化过程中城区和郊区破碎化林地中鸟类群落的多样性差异和嵌套格局, 本研究于2021年春、夏季鸟类繁殖期采用样线法对海口和三亚市的城区、郊区共13个林地斑块中的鸟类群落进行调查。使用NODF (nestedness metric based on overlap and decreasing fill)和WNODF (weighted nestedness metric based on overlap and decreasing fill)方法进行嵌套格局分析。研究发现: (1)共记录到林鸟100种, 隶属于11目39科, 其中三亚郊区的鸟类丰富度最高, 共8目29科68种。记录到国家重点保护鸟类共18种, 其中两城市郊区的国家重点保护鸟类物种数均多于城区, 海口郊区还记录到国家I级重点保护鸟类黄胸鹀(Emberiza aureola)。(2)鸟类群落多度、物种丰富度、Pielou均匀度指数和Shannon-Wiener多样性指数在不同区域中均存在差异。海口城区的鸟类群落多度显著高于海口郊区(P < 0.05), 三亚郊区的鸟类群落物种丰富度、Pielou均匀度指数和Shannon-Wiener多样性指数均显著高于三亚城区和海口郊区(P < 0.05)。(3)嵌套分析结果表明, 海口和三亚市的城区、郊区林地鸟类群落均呈现反嵌套分布格局。线性回归分析显示, 三亚市城区和郊区的斑块面积与鸟类物种丰富度呈显著正相关, 而物种丰富度与斑块距最近大面积林地的距离之间无显著相关性。研究表明, 两城市鸟类群落多样性都表现出郊区高于城区的特点, 少数优势种(如白头鹎 Pycnonotus sinensis)占据了城市中的主要生态位。受城市化的影响, 海口郊区与城区鸟类群落有同质化的趋势。鸟类在城区和郊区斑块间的高流动性、种间竞争和斑块中资源的可利用性等因素可能导致斑块间鸟类群落的反嵌套分布格局。我们建议应加强城区和郊区鸟类的保护, 减少对林地的破坏, 提高城市鸟类多样性。     

The effect of land type diversity and spatial heterogeneity on farmland birds in Norway

The decline in farmland birds observed throughout Europe during recent decades has attracted much attention. Agricultural intensification or land abandonment are commonly forwarded as key drivers. Several countries have established agri-environmental schemes (AES) to counter these negative trends among farmland birds. This paper reports a study of the relationship between land use and bird species in the agricultural landscape of Norway. The main objective was to investigate the effect of spatial heterogeneity and diversity of land use on total richness and abundance of farmland birds at a national level.Monitoring the distribution and abundance of birds is part of the Norwegian monitoring programme for agricultural landscapes. The monitoring programme is based on mapping of 1 × 1 km squares distributed across the entire agricultural landscape. Within these squares permanent observation points are established for bird monitoring. Detailed interpretation of aerial photographs provides the land classification. We tested the relationship between landscape metrics at different levels of land type detail and species richness and abundance of farmland and non-farmland birds.There was a positive relationship between species richness and abundance of farmland birds and agricultural area. For non-farmland birds the relationship was negative. Spatial heterogeneity of land use was a significant positive factor for both farmland and non-farmland species. High land type diversity was positive for farmland bird richness, but negative for abundance. Non-farmland bird richness was not affected by land type diversity, but abundance had a negative response.The results presented in this paper highlight the importance of a spatial heterogeneous landscape. However, we also found that land type diversity could negatively affect the abundance of both farmland and non-farmland birds. Our findings suggest a need for different management approaches depending on whether the aim is increased species richness or abundance. Achieving both aims with the same means might be difficult. We thus suggest a need for land use analyses before proper management strategies can be implemented.     

A habitat island approach to conserving birds in urban landscapes: case studies from southern and northern Europe

Wildlife conservation in urban habitats is increasingly important due to current urbanization trends. We review the different approaches to studying birds in urban landscapes, and point out the importance of the habitat island ecological theory as a research framework for the management and conservation of urban birds. Based on two comprehensive research projects conducted at urban parks in Spain (Madrid) and Finland (Oulu and Rovaniemi), several different issues related to bird conservation in cities are discussed, main findings of these projects are presented, and future research needs are suggested. Urban parks are important biodiversity hotspots in cities. Fragmentation conditions have the same deleterious effects to urban birds as in other fragmented landscapes. Park size accounts for species accumulation in urban parks; this pattern being highly nested. Urban parks of 10–35 ha would contain most of the species recorded in cities, but other indicators related to the probabilities of persistence of the target species should be obtained. Wooded streets can increase urban landscape connectivity by providing alternative habitat for feeding and nesting during the breeding season. Because increasing the size of parks is difficult in cities, enhancement of habitat diversity and resource availability for birds within parks (e.g. nest boxes, winter feeding tables, etc.) appears to be a straightforward way of increasing urban bird diversity. However, human disturbance (pedestrians) should be controlled since it can negatively influence many urban birds. We present a conceptual model for urban bird conservation, which includes three aspects (management, environmental education and research) and new alternatives to promote the involvement of different sectors of the society.     

Evaluating the effectiveness of overstory cover as a surrogate for bird community diversity and population trends

Landscape features are often used as surrogates for biodiversity. While landscape features may perform well as surrogates for coarse metrics of biodiversity such as species richness, their value for monitoring population trends in individual species is virtually unexplored. We compared the performance of a proposed habitat surrogate for birds, percentage cover of vegetation overstory, for two distinct aspects of bird assemblages: community diversity (i.e. species richness) and population trends. We used four different long-term studies of open woodland habitats to test the consistency of the relationship between overstory percentage cover and bird species richness across a large spatial extent (>1000 km) in Australia. We then identified twelve bird species with long-term time-series data to test the relationship between change in overstory cover and populations trends. We found percentage cover performed consistently as a surrogate for species richness in three of the four sites. However, there was no clear pattern in the performance of change in percentage cover as a surrogate for population trends. Four bird species exhibited a significant relationship with change in percentage overstory cover in one study, but this was not found across multiple studies. These results demonstrate a lack of consistency in the relationship between change in overstory cover and population trends among bird species, both within and between geographic regions. Our study demonstrates that biodiversity surrogates representing community-level metrics may be consistent across regions, but provide only limited information about individual species population trends. Understanding the limitations of the information provided by a biodiversity surrogate can inform the appropriate context for its application.     

Assessing the impact of revegetation and weed control on urban sensitive bird species

Nature in cities is concentrated in urban green spaces, which are key areas for urban biodiversity and also important areas to connect people with nature. To conserve urban biodiversity within these natural refugia, habitat restoration such as weed control and revegetation is often implemented. These actions are expected to benefit biodiversity, although species known to be affected by urbanization may not be interacting with restoration in the ways we anticipate. In this study, we use a case study to explore how urban restoration activities impact different bird species. Birds were grouped into urban sensitivity categories and species abundance, and richness was then calculated using a hierarchical species community model for individual species responses, with “urban class” used as the hierarchical parameter. We highlight variable responses of birds to revegetation and weed control based on their level of urban sensitivity. Revegetation of open grassy areas delivers significant bird conservation outcomes, but the effects of weed control are neutral or in some cases negative. Specifically, the species most reliant on remnant vegetation in cities seem to remain stable or decline in abundance in areas with weed control, which we suspect is the result of a simplification of the understorey. The literature reports mixed benefits of weed control between taxa and between locations. We recommend, in our case study site, that weed control be implemented in concert with replanting of native vegetation to provide the understory structure preferred by urban sensitive birds. Understanding the impacts of revegetation and weed control on different bird species is important information for practitioners to make restoration decisions about the allocation of funds for conservation action. This new knowledge can be used both for threatened species and invasive species management.     

近自然社区公园的生物多样性特征——以北京市中心城区为例

城市绿地为城市动植物提供了重要栖息地，对城市生物多样性保护具有重要意义。然而，传统社区公园绿地（"传统绿地"）主要围绕安全、景观和游憩功能，植物种类偏少，群落结构单一，为城市野生动物提供食源和栖息地的资源有限。北京市以2035规划"留白增绿"为政策背景，在中心城区建设一系列小型近自然社区公园绿地（"近自然绿地"），在植物物种组成、群落结构和管理方式上有别于以往的传统绿地。一般认为生物多样性在一定范围内随面积的增大而提高，那么对于受到高度干扰的小型绿地，"近自然"特征是否能够显著提高其包括昆虫、鸟类在内的生物多样性？为探究这类近自然绿地的生物多样性特征，在2020年8月至2021年3月，综合采用样方法、样线法，对北京市西城区2个近自然绿地及4个传统绿地的植物、昆虫和鸟类进行调查，分析比较其多样性特征。结果表明，近自然绿地的灌木和草本层丰富度和多样性显著高于传统绿地，均匀度则无显著差异；近自然绿地的昆虫和鸟类的丰富度、多样性显著高于传统绿地，均匀度则无显著差异。与传统绿地相比，近自然绿地具有更丰富的鸟类食源、蜜源植物，以及更为复杂的植被垂直结构。根据以上结果，近自然绿地具有比传统绿地更为显著的生物多样性优势，建议在进行城市绿地建设时，应增加植被结构复杂的近自然绿地的比例，增加绿地的灌木和草本层多样性。研究成果不仅丰富了小面积绿地的生物多样性内涵，且可为大都市近自然绿地营建提供理论依据。本研究还将为今后公园设计、改造和管理提供新的思路，引导绿地向基于生物多样性保护的方向可持续发展。     

Effects of windthrow disturbance on a forest bird community depend on spatial scale

Community structure is expected to be affected by spatial heterogeneity in a landscape. We examined the spatial-scale-dependent effects of windthrow caused by a large typhoon on a forest bird community. Typhoon events of this magnitude are rare in Hokkaido, Japan, occurring only once or twice a century. To assess the “functional spatial scale” at which bird groups (community, species, body-size class, and foraging guild) specifically responded to landscape heterogeneity, the canopy gap rate (CGR, gap percentage) was evaluated at different spatial scales by varying the radius of a circular landscape sector from 100 to 500 m stepwise by 10 m. We then analysed bird community responses, in terms of species richness and abundance, to CGR. Bird species richness did not significantly depend on CGR. In contrast, abundance was significantly dependent on CGR in many groups (species, body-size class, and foraging guild). The guild-level response was clearer than the species-level response, which suggests that the integration and filtration of species traits by guild can reveal a clear response of bird abundance to the extent of canopy gaps. For example, the scale dependence of responses to disturbance clearly varied among body-size classes, where larger birds had larger functional spatial scales. These results reveal that different groups of organisms have different functional spatial scales at which they respond to habitat heterogeneity. Our results also suggest that monitoring only a small number of species could be misleading for conserving biodiversity at the landscape level.     

Non‐linearities in bird responses across urbanization gradients: A meta‐analysis

Urbanization is one of the most extreme forms of environmental alteration, posing a major threat to biodiversity. We studied the effects of urbanization on avian communities via a systematic review using hierarchical and categorical meta‐analyses. Altogether, we found 42 observations from 37 case studies for species richness and 23 observations from 20 case studies for abundance. Urbanization had an overall strong negative effect on bird species richness, whereas abundance increased marginally with urbanization. There was no evidence that city size played a role in influencing the relationship between urbanization and either species richness or abundance. Studies that examined long gradients (i.e. from urban to rural) were more likely to detect negative urbanization effects on species richness than studies that considered short gradients (i.e. urban vs. suburban or urban vs. rural areas). In contrast, we found little evidence that the effect of urbanization on abundance was influenced by gradient length. Effects of urbanization on species richness were more negative for studies including public green spaces (parks and other amenity areas) in the sampled landscapes. In contrast, studies performed solely in the urban matrix (i.e. no green spaces) revealed a strong positive effect on bird abundance. When performing subset analyses on urban–suburban, suburban–rural and suburban–natural comparisons, species richness decreased from natural to urban areas, but with a stronger decrease at the urban–suburban interface, whereas bird abundance showed a clear intermediate peak along the urban–rural gradient although abundance in natural areas was comparable to that in suburban areas. This suggests that species loss happens especially at the urban–suburban interface, and that the highest abundances occur in suburban areas compared to urban or rural areas. Thus, our study shows the importance of suburban areas, where the majority of birds occur with fairly high species richness.     

Bird Richness and Abundance in Response to Urban Form in a Latin American City: Valdivia,Chile as a Case Study

There is mounting evidence that urban areas influence biodiversity. Generalizations however require that multiple urban areas on multiple continents be examined. Here we evaluated the role of urban areas on avian diversity for a South American city, allowing us to examine the effects of urban features common worldwide, using the city of Valdivia, Chile as case study. We assessed the number of birds and their relative abundance in 152 grid cells of equal size (250 m²) distributed across the city. We estimated nine independent variables: land cover diversity (DC), building density (BD), impervious surface (IS),municipal green space (MG),non-municipal green space (NG), domestic garden space (DG), distance to the periphery (DP), social welfare index (SW), and vegetation diversity (RV). Impervious surface represent 41.8% of the study area, while municipal green, non-municipal green and domestic garden represent 11.6%, 23.6% and 16% of the non- man made surface. Exotic vegetation species represent 74.6% of the total species identified across the city. We found 32 bird species, all native with the exception of House Sparrow and Rock Pigeon. The most common species were House Sparrow and Chilean Swallow. Total bird richness responds negatively to IS and MG, while native bird richness responds positively to NG and negatively to BD, IS DG and, RV. Total abundance increase in areas with higher values of DC and BD, and decrease in areas of higher values of IS, SW and VR. Native bird abundance responds positively to NG and negatively to BD, IS MG, DG and RV. Our results suggest that not all the general patterns described in previous studies, conducted mainly in the USA, Europe, and Australia, can be applied to Latin American cities, having important implications for urban planning. Conservation efforts should focus on non-municipal areas, which harbor higher bird diversity, while municipal green areas need to be improved to include elements that can enhance habitat quality for birds and other species. These findings are relevant for urban planning in where both types of green space need to be considered, especially non-municipal green areas, which includes wetlands, today critically threatened by urban development.     

城市化鸟类群落变化及其与城市植被的关系

持续而快速的城市化进程正在助长全球生物多样性的丧失,其中鸟类是城市生态系统的重要环节和城市生物多样性保护的重点目标,同时也是研究的热点内容。从城市环境变化压力下,鸟类群落组成与结构、空间分布和繁殖营巢方式的改变分析,重点介绍了支持城市地区鸟类多样性的植物环境因素与影响机制的最新研究成果。结果表明：1）城市中的植被和绿色空间为城市鸟类提供生存空间和食物资源,是城市鸟类最主要的栖息地。2）保留原生乡土植物和大型树木的地区能支持更丰富的鸟类物种。3）植被的结构和盖度对鸟类群落有显著影响。林冠覆盖率增加,复杂的垂直空间和多样的植物种类的组合产生各种不同类型的植物空间和栖息地类型,吸引不同的鸟类物种,相应地也会导致更丰富的鸟类群落。总之,保持和加强城市中植物环境良好和稳定是保护城市生物多样性的有效手段。据此,提出城市环境与鸟类群落关系研究的未来发展方向,指出了其在鸟类多样性保护和城市可持续发展等领域的应用前景。     

The reliability of a composite biodiversity indicator in predicting bird species richness at different spatial scales

Several biodiversity features can be linked to landscape heterogeneity, that, in turn, can be informative for management and conservation purposes. Usually, the more the landscape is complex the more the biodiversity increases. Biodiversity indicators can be a useful tool to assess biodiversity status, in function of landscape heterogeneity. In this study, we developed a biodiversity indicator, based on Shannon diversity index and built from distribution maps of protected species. With such an approach, we seek to evaluate the feasibility of using a combination of target species as a surrogate for assessing the status of the whole bird community. Our approach was spread over multiple spatial scales, to determine which was the most informative. We selected four species protected by European regulation and generated a presence-absence map from species distribution modelling. We, therefore, used the FRAGSTATS biodiversity metric to calculate Shannon index for the overlapped presence-absence maps, at two spatial scales (500 m and 1000 m). Then, the relationships with the whole community was assessed through generalised least square models, at the spatial scale of 4 ha, 9 ha and 25 ha. Results showed that the higher rate of variability of community was explained by the biodiversity indicator at 1000 m scale. Indeed, the more informative spatial scale for the whole bird community was 9 ha. In addition, a pattern emerged about the relationships between biodiversity indicator and community richness, that is worth of further research. Our study demonstrates that the usefulness of surrogate species for biodiversity and community assessment can become clear only at a certain spatial scales. Indeed, they can be highly predictive of the whole community, and highly informative for conservation planning. Moreover, their use can optimize biodiversity monitoring and conservation, focusing on a small number of noteworthy species.     

Effect of Urbanization and Seasonality in Bird Communities of Kathmandu Valley,Nepal

Kathmandu Valley, Nepal is undergoing rapid urbanization but its effects on the bird communities have not been reported till date. Kathmandu Valley was categorized into urban, sub-urban and rural to study the impact of urbanization in bird communities. By mobilizing volunteers, we monitored 24 transects each with one km long in summer and winter seasons of 2016. A total of 13,749 individuals of birds belonging to 102 species were recorded. Species richness and diversity of all birds declined from rural to urban areas and showed significant variation along urban–rural gradients. Insectivore was the most species-rich guild while nectarivore the least. The richness of insectivore, frugivore and carnivore guilds showed significant variations along the urban–rural gradients and higher preference towards the rural areas. Similarly, species richness of all birds and richness of insectivore and carnivore guilds showed significant seasonal variation and were higher in the winter season. Our results indicate that richness, diversity and feeding guilds of birds show different response towards the urbanization gradients and seasons. Sub-urban areas can function as bird refugia, however, habitat enrichments (like increasing green spaces, setting up new parks and gardens, plantation of native fruiting trees etc.) are utmost necessary to support the bird communities in urban areas of Kathmandu Valley.     

如何在北京充分实现受胁鸟类栖息地保护?

实现有效生物多样性保护的关键在于提升生物多样性丰富的人口密集区的保护效率。北京人口密集且生物多样性丰富, 存在3类具有生态保护功能的区划——自然保护区、生态保护红线和限制建设线。上述区域可视为生态保护潜力区。本文以在北京有分布的30种受胁鸟类为主要对象, 探讨现有生态保护潜力区对这些物种栖息地的覆盖程度, 并对如何改善上述受胁鸟类栖息地的保护状况进行了建议。根据物种对栖息地的选择, 基于高分辨率卫星解译的土地利用类型图, 利用最大熵模型(MaxEnt)掩膜栖息地分布图, 得到各受胁鸟类的预测空间分布。叠加这些分布获得北京受胁鸟类丰富度分布格局并进行验证。依据物种丰富度高低, 将受胁鸟类栖息地划分为一至四级(最重要的栖息地是一级栖息地, 以此类推)。同时, 依据地表覆盖类型和人类活动强度高低将北京市域划分为城市建成区、乡村生境区和自然生境区。分别计算3类保护潜力区对上述3类区域以及四级栖息地的覆盖面积比例。结果表明: (1) 95.64%的一级关键栖息地和86.32%的二级关键栖息地分布在乡村生境区, 但仅有0.69%和15.15%的乡村生境区分别被自然保护区和生态保护红线覆盖; (2)未受到自然保护区和生态保护红线覆盖的一、二级关键栖息地主要为水域和沼泽地等湿地、高覆盖度草地和部分耕地, 以及含有较高比例水体的大型城市绿地。基于以上结果, 我们建议至少在一定区域内试行如下保护措施: (1)严格保护湿地及其周边的高覆盖度草地, 确保面积不减少; (2)维持基本农田规模和粮食种植模式; (3)将乡村生境区位于河道附近的水域、沼泽地、高覆盖草地和灌木林纳入生态保护红线范围; (4)在公园绿地中划定生物多样性保护区; (5)优化平原地区林地结构。以上措施将使北京的受胁鸟类栖息地得到更好保护, 为中国东部人口密集区生物多样性保护提供示范。     

Grassland management for meadow birds in the Netherlands is unfavourable to pollinators

Agricultural intensification and loss of semi-natural grassland have contributed to biodiversity decline, including pollinator species, in pastures around the world. To reverse the decline, agri-environmental schemes have been implemented, varying widely in effectiveness. In addition, many countries, including the Netherlands, have established nature reserves in which semi-natural grasslands are restored and are often managed for specific groups of species, e.g. meadow birds or plants. The effects of such measures on insect biodiversity are not well known but recent reports on the dramatic decline of insect biomass in nature reserves have put even more attention to the impact of land use and management on biodiversity. This study compares pollinator abundance and species richness in three common semi-natural grassland management types in the Netherlands: (1) hay meadows, (2) herb-rich grasslands and (3) meadow bird grasslands. Pollinator abundance and species richness were assessed in eleven study areas, each with all three management types present. Standardized transects, insect sampling within a standard 20 min time frame and plot-based flower surveys were used in spring and summer to assess the relationships between management regime, floral abundance and diversity and pollinator communities. The results show that meadow bird grasslands have lower pollinator abundance and diversity and a less unique pollinator assemblage than both other types. Moreover, flower abundance has a positive effect on pollinator abundance and flower diversity has a positive effect on pollinator species richness. These results indicate that meadow-bird grasslands are a comparatively unfavourable habitat for bees, hoverflies and butterflies, which may be explained by a lack of flowers as well as unsuitable mowing practices. Measures benefitting both insectivorous birds and flower-visiting insects, such as rotational mowing, could remediate this imbalance.     

Remote sensing improves prediction of tropical montane species diversity but performance differs among taxa

Texture information from passive remote sensing images provides surrogates for habitat structure, which is relevant for modeling biodiversity across space and time and for developing effective ecological indicators. However, the applicability of this information might differ among taxa and diversity measures. We compared the ability of indicators developed from texture analysis of remotely sensed images to predict species richness and species turnover of six taxa (trees, pyraloid moths, geometrid moths, arctiinae moths, ants, and birds) in a megadiverse Andean mountain rainforest ecosystem. Partial least-squares regression models were fitted using 12 predictors that characterize the habitat and included three topographical metrics derived from a high-resolution digital elevation model and nine texture metrics derived from very high-resolution multi-spectral orthophotos. We calculated image textures derived from mean, correlation, and entropy statistics within a relatively broad moving window (102 m × 102 m) of the near infra-red band and two vegetation indices. The model performances of species richness were taxon dependent, with the lowest predictive power for arctiinae moths (4%) and the highest for ants (78%). Topographical metrics sufficiently modeled species richness of pyraloid moths and ants, while models for species richness of trees, geometrid moths, and birds benefited from texture metrics. When more complexity was added to the model such as additional texture statistics calculated from a smaller moving window (18 m × 18 m), the predictive power for trees and birds increased significantly from 12% to 22% and 13% to 27%, respectively. Gradients of species turnover, assessed by non-metric two-dimensional scaling (NMDS) of Bray-Curtis dissimilarities, allowed the construction of models with far higher predictability than species richness across all taxonomic groups, with predictability for the first response variable of species turnover ranging from 64% (birds) to 98% (trees) of the explained change in species composition, and predictability for the second response variable of species turnover ranging from 33% (trees) to 74% (pyraloid moths). The two NMDS axes effectively separated compositional change along the elevational gradient, explained by a combination of elevation and texture metrics, from more subtle, local changes in habitat structure surrogated by varying combinations of texture metrics. The application of indicators arising from texture analysis of remote sensing images differed among taxa and diversity measures. However, these habitat indicators improved predictions of species diversity measures of most taxa, and therefore, we highly recommend their use in biodiversity research.     

Validating bird diversity indicators on farmland in east-central Alberta,Canada

Birds can be used as indicators to monitor success of programs encouraging prairie landowners to increase biodiversity. Using a case study from Alberta, Canada, this paper compares bird diversity measures at the farm scale and examines their consistency across different habitat types to test for design, output, and end use validation. Based on 2005 point count data (two types) from 178 sites at 22 farms, we calculated bird species richness, abundance, Shannon index, and Inverse Simpson index.The 50 m radius data produced species richness and abundance measures about half the size as those produced by the unlimited radius data. The bird diversity measures were consistent across habitat types. The 50 m radius data showed differences among 3–5 habitat types, whereas the unlimited radius data showed differences between only two habitat types. Using any bird diversity measure, the wetland/riparian habitat scored highest, followed by homestead, upland forest, native prairie, tame pasture, and cultivated land habitats.Bird monitoring methods should favor fixed over unlimited radius point counts, because of the former's greater discriminating ability. Given that diversity measures are consistent across habitats and are highly correlated, the species richness measure, which is simple and easy to understand, can be used in conversations with landowners and policy-makers.