区域城市扩张对森林景观破碎化的影响——以粤港澳大湾区为例

森林生境丧失与景观破碎化是引起生物多样性下降,生态系统功能降低的重要原因。量化森林景观破碎化的时空特征及其与城市扩张格局的关系是开展区域生态修复与功能提升的重要基础。本文以快速城市化的典型区域——粤港澳大湾区为研究对象,基于遥感解译的1980年、1990年、2000年、2010年和2018年土地覆盖/利用专题图,通过多尺度的景观格局分析和统计分析,定量解析森林景观破碎化的时空演变特征及其与城市扩张格局间的关系。研究结果显示:1)1980—2018年,大湾区林地覆盖面积缩减1,274 km²,林地转变为建设用地的面积占林地丧失总面积的比例从1980—1990年的11%增长至2010—2018年的42%,表明城市扩张已成为林地丧失的主导因素;2)森林景观破碎化程度加剧,表现为林地斑块密度提高,平均斑块面积减小,但破碎类型与程度具有地域差异;3)城市扩张幅度与空间格局显著影响林地破碎化,其中,城市扩张幅度对林地破碎化的影响更为重要。基于森林景观破碎化与城市扩张的现状,落实城市增长边界划定、关键斑块-廊道识别与生态网络构建等措施,有助于保护与连通重要生态空间,保障和提升生...     

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。     

基于土地利用变化的喀斯特断陷盆地景观格局演变与生态安全评价

喀斯特地区生态重要性与脆弱性并存,研究喀斯特断陷盆地景观生态安全格局演变对当地土地利用高效管理和生态修复具有重要意义。以云南、四川、贵州三省交界处的喀斯特断陷盆地为研究对象,基于2000-2020年土地利用数据,通过构建土地利用转移矩阵、计算景观格局指数和景观生态安全指数,系统分析土地利用、景观格局与景观生态安全水平的时空演变特征。结果如下：（1）林地、草地、耕地是研究区主要土地利用类型,面积占比超过96%。土地利用变化主要发生在2005-2010年和2015-2020年,空间上表现出整体稳定而局部变化剧烈的特点,以退耕还林还草和林地向草地转换为主,耕地面积在过去20年共减少了386.62 km²。（2）景观多样性与均匀度上升,景观蔓延度下降。林地的最大斑块面积比例下降而草地上升,多数用地的斑块密度上升而集聚度下降,土地利用结构整体优化,但破碎化趋势明显,尤其是林地、耕地和草地。此外,建设用地呈连片化扩张。（3）景观生态安全水平明显提升,一般安全及以上安全区面积占比由2000年的62.35%上升到2020年的98.11%。在石漠化治理和生态保护的推动下,南部的生态安全水平大幅提高,推动空间格局从"北高南低"逐步转向"南北相对均衡"。景观生态安全水平的空间集聚性明显,高-高值集聚区主要在北部而低-低值集聚区主要在南部,需进一步推动北部生态保护以保障其生态屏障功能的发挥,并加强南部生态修复来提升其生态安全水平。此外,需持续推进石漠化治理并合理调控当地经济发展与生态保护间的关系,来维持生态安全水平的长期稳定。     

岷江上游干旱河谷景观变化及驱动力分析

基于遥感和地理信息系统,应用景观格局分析软件,研究了岷江上游干旱河谷1974-2000年的景观变化,并对其驱动因子进行了分析.结果表明,岷江上游干旱河谷的面积在不断扩大,灌木林地面积占景观面积的60%以上,为景观基质.在景观类型面积比例的变化中,耕地的变幅最大.干旱河谷的整体形状较简单,1974-1995年破碎化程度和异质性程度持续增加,1995-2000年表现为降低趋势,而斑块内部的连通性先降低后增加,具体表现为斑块密度、多样性指数先增大后减小,蔓延度指数先减小后增大,而边界密度和分维数持续减小.人口增长和国家政策是导致岷江上游干旱河谷景观变化的主要驱动力.     

基于模拟景观的城市森林景观格局指数选取

基于现实的沈阳城市森林景观,模拟了4个景观格局梯度,并选取了1个与之相应的现实景观格局梯度,分析了28个景观格局指数在各梯度对景观破碎化和景观斑块形状复杂性的反映,从而筛选出描述这两种景观格局特征的适宜景观格局指数.结果表明：斑块密度（PD）和平均斑块面积（AREA_MN）在城市森林景观破碎化方面表现出较规律的变化趋势,斑块密度随破碎化程度的增加而增加,平均斑块面积随破碎化程度的增加而减小;面积加权平均周长面积比（PARA_AM）在描述景观斑块形状复杂性方面与景观格局梯度相吻合,且随斑块形状复杂性的增加而增加,能够较为准确地描述景观斑块形状的复杂性.     

陕北黄土高原景观破碎化及其土壤裸露效应

破碎化是黄土高原典型的景观特征 ,深刻影响着区域的景观格局与功能。为深入探讨黄土高原景观破碎化的格局特征及其生态效应 ,选择陕北黄土高原为研究区 ,结合景观格局指数与主成分分析对破碎化程度进行量化 ,并针对研究区相应的景观格局特征、造成破碎化的景观类型及土壤裸露程度 ,进行组成、分布及动态分析。研究结果发现陕北黄土高原景观格局中的斑块密度特征对破碎化有较强的指示意义 ,其次则是景观的空间构型特征。草地和农地等与人为活动关系较为密切的景观类型是造成研究区景观破碎化的主要原因 ,且高破碎化区域的土壤裸露值明显高于低破碎化区域     

道路网络扩展对区域生态系统的影响——以景洪市纵向岭谷区为例

道路网络的存在和扩展影响着周边景观的生态格局和过程,进而影响区域生态安全,定量表达道路影响域生态系统变化对生态系统管理具有重要意义.选取景洪市为研究区,利用缓冲区分析、对比分析和情景分析,研究道路与生态系统格局变化的关系,进而揭示不同道路类型对区域生态安全的影响.结果表明：近20a研究区林地、灌丛有所减少,旱地和建设用地增加显著,而道路为显著的驱动因子.景观的多样性,均匀度,斑块密度和人工干扰指数也随着道路缓冲距离增加而降低.道路影响域内林地受道路影响最大,其次为草地,旱地或灌丛,而旱地的斑块数目受低等级道路影响最多,其他等级林地数目最多.情景分析表明,随着道路网络的扩展,生态系统分维数、斑块数目增加,平均斑块面积减少,显示破碎化程度加剧,而低等级道路对区域景观格局的变化贡献率最大.     

平潭海坛岛景观格局动态变化及其生态效应分析

以平潭海坛岛为研究区,基于1990 年landsat TM 和2010 年ALOS 遥感影像,在ArcGIS 和Fragstats 等软件平台支持下,运用马尔科夫转移矩阵和动态度模型,以及景观格局指数,对20 年来研究区景观格局时空动态变化及其生态效应进行了定量分析。研究结果表明:近20 年来景观格局动态变化显著。建设用地和居民地增长幅度最大,农用地和沙滩则降幅最显著。研究区景观格局主要景观类型为农用地和林地,景观类型转移主要表现为农用地与林地的相互转化,以及二者向城镇用地(居民地、建设用地和道路交通)转化。从类型水平上看,各类型斑块均趋于破碎化;在景观水平上,研究区景观格局向着多样化方向发展,景观的异质性增强,景观呈破碎化程度加深;从景观生态效应空间变化看,人为活动的影响沿着交通干线、城镇区在整个研究区蔓延扩展。     

海南热带雨林国家公园高速公路穿越段景观动态与生态风险评估

海南热带雨林国家公园被中线高速公路自东北-西南方向穿越,改变了局域景观分布格局,影响到生态系统完整性与原真性,可能存在潜在的生态风险。选取海南热带雨林国家公园高速公路穿越段两侧3 km作为研究区域,运用GIS技术、Fragstats和景观生态学理论定量评价2013年(高速公路未建)、2016年(高速公路在建)和2019年(高速公路竣工)三年的景观要素变化,解析景观变化趋势和可能带来的潜在生态风险。结果表明,2016年高速公路建成面积(含动土区域)为325.51 hm²,林地面积略有减少,但林地斑块密度增加;耕地面积虽略有增加,但耕地最大斑块指数下降,耕地景观优势度降低。2019年高速公路建成竣工后,由于路旁绿化,高速公路占地面积有所下降,林地面积和林地斑块密度增加,但林地和耕地斑块的内聚力指数下降,自然连通度略降低,破碎化程度加剧;高速公路穿越段中等生态风险区和较高生态风险区面积逐年增加。但隧道和高架桥路段在一定程度上维持了道路两侧的植被连通性,对局域生态系统没有明显影响。高速公路造成的生境隔离与破碎化可能累积产生远期的负面生态学效应。海南热带雨林国家公园高速公路...     

太行山中低山区河谷内农田斑块特征及其分布格局——以河北省阜平县胭脂河主流河谷为例

以景观生态学原理为指导,调查了位于太行山中低山区的河北省阜平县胭脂河主流河谷,对河谷内农田斑块的特征及其分布格局进行了分析.结果表明,农田斑块除河流源头外贯穿整个河谷,从上游向下游,人为活动的增加使农田的比重不断增加,导致自然景观减少,环境异质性降低,农田斑块破碎化程度减小.胭脂河河谷总面积为2297.09hm²,构成河谷景观主体的农田有117个斑块,面积为1027.78hm²,占河谷面积的44.74%.农田基本紧靠河岸分布,处在水分条件优越但易受洪水威胁的土地带上.农田在河流两侧是非对称分布,其中左岸农田面积587.58hm²,占57.17%.斑块的宽度呈增加的态势,但变化比较大,基本上以狭长的特征出现.     

Correlations between leaf structural traits and the densities of herbivorous insect guilds

The functional composition of herbivorous insect assemblages was correlated with aspects of new and mature leaf surface features, anatomy and morphology across 18 co‐occurring plant species. Multivariate analyses of insects and leaf traits revealed that the functional composition of the herbivore assemblage was more strongly correlated with leaf structural traits than with leaf constituents. Leaf traits were more strongly correlated with the functional composition of the herbivore assemblage than with its taxonomic composition. Densities of sessile phloem feeders, ­rostrum chewers, and all herbivores were significantly negatively correlated with specific leaf weight, lamina and cuticle thickness, vascular tissue depth and stomate length, and were significantly positively correlated with stomate density. External chewer densities were significantly negatively correlated with percent lignified vein area, and significantly positively correlated with leaf surface area and the distance between lignified tissues. Spine‐like leaves were associated with significantly lower densities of sessile phloem feeders, external chewers and all herbivores compared to kite leaves (kite leaves are comprised of unfortified leaf tissue supported by a framework of vascular tissue). The presence of a thickened leaf hypodermis was associated with significantly lower densities of external chewers and rostrum chewers, while midrib protection was associated with significantly lower densities of external chewers. Leaf structural traits may not be the proximal factors influencing herbivorous insects, as leaf structural traits are correlated with many other plant traits such as photosynthetic rate, relative growth rate and leaf life‐span. Nonetheless, these results indicate that certain leaf structural traits may potentially be used to predict the functional structure of herbivorous insect assemblages. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 77 , 43–65.     

Canopy Herbivory and Insect Herbivore Diversity in a Dry Forest–Savanna Transition in Brazil

This study aimed to compare canopy herbivore diversity and resultant insect damage to vegetation in two distinct and adjacent ecosystems, specifically a dry forest ecosystem and a cerrado (savanna) ecosystem that occur together in an abrupt transition zone in southeastern Brazil. In the dry forest, the canopy was reached using a single rope climbing technique, whereas the shorter canopy of the cerrado was assessed using a 7 m ladder. Insect specimens were collected by beating the foliage, and 20 representative leaves were collected to calculate the specific leaf mass (SLM) and leaf area loss through herbivory. Also, we collected ten soil samples from each habitat to determine soil nutrient content. We sampled 118 herbivorous insects from ten families, mostly in dry forest trees (96 individuals belonging to 31 species). A higher abundance of chewing and sap-sucking insects were observed in dry forest trees than in cerrado trees. The same pattern was observed for the richness of chewers, with a higher degree of diversity of chewers found in dry forest trees than in cerrado trees. Herbivorous insects were not affected by SLM regardless of guild and habitat. However, we observed a negative correlation between the herbivory rate and the specific leaf mass (SLM). The cerrado trees showed a higher SLM and lower herbivory rates than trees occurring in the dry forest. These results suggest that herbivory rates in the transition dry forest–cerrado may be driven by soil nutrient content, which is thought to influence leaf sclerophylly.
Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp .     

Correlations between leaf constituent levels and the densities of herbivorous insect guilds in an Australian forest

Abstract Significant correlations were found between herbivorous insect densities and leaf constituent levels across 18 species of understorey shrub in an Australian forest. In general, insect densities were positively correlated with nitrogen and water and negatively correlated with fibre and its constituents (cellulose and lignin), but not all insect guilds were significantly correlated with all leaf constituents. When mature leaf traits were considered, total herbivore density among plant species was most strongly correlated with levels of nitrogen and water. However, when insects were divided into functional guilds, only densities of sucking insects were significantly correlated with mature leaf nitrogen and water, whereas chewing insect densities were significantly correlated with mature leaf fibre and lignin. Low leaf nitrogen levels were recorded for all plants surveyed (among the lowest reported for woody angiosperms), and many plant species also had high levels of leaf fibre. These features are characteristic of Australian forests and have been linked to the generally nutrient‐poor soils of this continent. Levels of new leaf nitrogen (% fresh weight) were generally less than or equal to levels of mature leaf nitrogen (% fresh weight). Hence the new leaf preference of several herbivore guilds could not be explained by higher levels of leaf nitrogen. However, significant negative correlations were found between chewer densities and levels of leaf fibre, cellulose and lignin for new and mature leaves, suggesting that higher levels of fibre, cellulose and lignin in mature leaves may be contributing more strongly to the new leaf preference of chewers than leaf nitrogen levels. Despite the significant correlations between leaf constituent levels and the densities of individual guilds, multivariate analyses found no significant relationship between leaf constituent levels and the taxonomic or guild composition of herbivorous insect assemblages.     

Forest Fragmentation Drives the Loss of Insectivorous Birds and an Associated Increase in Herbivory

Insectivorous birds are known to play a decisive role for the natural control of herbivorous insects. Thus, they enhance the growth, reproduction, and survival of plant individuals and in the long‐term benefit plant regeneration. However, particularly in the tropics, forest fragmentation has been suggested to cause a loss of insectivorous birds. Yet, it is unclear whether this hampers the trophic control of herbivorous insects with potential consequences for plants. Therefore, we investigated the effect of increasing forest fragmentation on tritrophic interactions between insectivorous birds, herbivorous insects, and plants in a subtropical forest landscape, South Africa. We monitored the community composition of birds and estimated insectivorous bird abundances along a gradient of forest fragmentation. In the same sites, we installed bird exclosures on a common plant species (Englerophytum natalense) to assess effects of the trophic control of insectivorous birds on herbivorous insects and leaf area loss (LAL). Forest fragmentation strongly shaped the functional composition of bird communities, particularly through a loss of forest‐dependent insectivorous birds. Moreover, LAL was higher within bird exclosures than on control branches and increased with increasing forest fragmentation on the control branches. Altogether, forest fragmentation seems to hamper the trophic control of herbivorous insects by insectivorous birds through changes in the community composition. This, in turn, may interfere with tritrophic interactions and ecological processes. Thus, conservation efforts aiming at enhancing the natural control of herbivorous insects should focus on the maintenance of continuous indigenous forests that are well‐connected to smaller forest fragments on the landscape scale.     

Insect Herbivores and Leaf Damage along Successional and Vertical Gradients in a Tropical Dry Forest

The availability and quality of resources for herbivores in tropical dry forests (TDFs) vary in time and space, affecting herbivore guilds differently across spatial scales (both horizontally and vertically), with consequences to the distribution of leaf damage in these forests. We attempted to elucidate the distribution patterns of herbivorous insect guilds and leaf damage throughout the secondary succession and vertical stratification along the rainy season in a Brazilian TDF. With the advance of the succession, a greater richness and abundance of herbivorous insects were found, resulting in higher leaf damage in intermediate and late stages. This pattern, however, was not observed for the frequency of leaf miners. At a smaller spatial scale, the host tree height positively affected the richness and abundance of insects. The higher leaf damage was found in canopy, which also harbored a greater richness and abundance of chewing herbivores compared to the understory at both the beginning and the end of the rainy season. Although for sap‐sucking insects, this was only true at the beginning of the season. We detected a decrease in insect richness and abundance at the end of the rainy season, probably due to a synchronization of insect activity with the availability of young, highly nutritious plant tissues. These results are consistent with other studies that found a general trend of increasing richness and abundance of herbivorous insects and leaf damage throughout the secondary succession (early to late stages) and between vertical strata (understory to canopy), suggesting that forest complexity positively affects herbivores.     

京津冀城市群生态空间固碳服务功能及其与景观格局的关系特征

在全球气候变暖、城市群快速发展导致景观格局破坏与生态系统服务功能受损的背景下,研究城市群生态系统服务功能与景观格局的关系具有重要的意义。基于以上背景与前人研究,选取在中国经济社会发展中最具代表性的城市群京津冀城市群,通过遥感解译、ArcGIS 10.6制图分析及SPSS软件相关性分析等,从土地利用的角度研究其生态空间固碳服务功能及其与景观格局的关系特征,并提出相关探讨。结果表明：1)京津冀生态空间中耕地、林地、草地均为碳汇用地,2000—2018年期间用地面积排序为：耕地>林地>草地,用地面积减少量排序为：林地>耕地>草地。耕地为研究区东南半部的主导类型,林地作为区域西北半部的主导类型,草地分布呈与林地相间状态。2018年北京市内西北部大面积的林地转化为耕地。2)2000—2018年期间生态空间三种用地的年固碳量排序为：耕地>林地>草地,用地年固碳量增长量排序为耕地>林地>草地。从平均单位固碳量来说,四个时间点均表现为：林地>耕地>草地。单位固碳量区域分布差异明显且随时间变化量大。3)不同生态空间用地的固碳量与不同景观指数的相...     

Indirect effect of aquatic insect emergence on a terrestrial insect population through by birds predation

A manipulative field experiment was performed to determine the effect of birds, subsidized by aquatic insect emergence, on the insect herbivores in a riparian deciduous forest. Insectivorous birds were observed more frequently in the riparian forest than in upland forest away from the stream, utilizing both herbivorous insects feeding on the riparian vegetation and aquatic insects emerging from the stream as their prey. Field experiments revealed that the insect herbivore population in the riparian forest was more depressed by bird predation than that in the upland forest. This suggests that allochthonous prey input to the in situ prey population was responsible for a modification in the interaction between birds and herbivorous insects, resulting in a heterogeneous food web structure in the forest.     

上海临港新城河岸带昆虫群落特征

临港新城是上海大都市圈中一个快速城市化的滨海城区。为掌握临港新城河岸带在快速城市化下昆虫群落的特点,2009年10月—2010年9月对临港新城河岸带昆虫分不同生境及不同季节进行了调查,共获得昆虫7755头,隶属于13目、84科、199种。该区域河岸带昆虫优势类群为半翅目(Hemiptera)、双翅目(Diptera)和膜翅目(Hymenoptera)昆虫,分别占总数的37.7%、23.5%和16.5%;水生昆虫种类数及个体数分别占所调查昆虫的12.1%和11.2%;从Shannon多样性指数看,人工林昆虫多样性最高为1.73,其他生境依次为次生林(1.69)>绿地(1.48)>荒地(1.46)>农田(1.42);季节动态变化和生境类型对昆虫的数量、种类、丰富度和均匀度影响较大;该区域河岸带昆虫依食性可分为6类:植食性、捕食性、寄生性、腐食性、杂食性和访花昆虫,植食性昆虫种类和数量分别占62.8%和55.5%,其他食性的昆虫偏少,人类的干扰活动及河岸带景观植被对原有植被的破坏是主要原因。     

Forest loss increases insect herbivory levels in human-altered landscapes

Insect herbivory has been observed to be affected by habitat loss and fragmentation, although the mechanisms by which these anthropogenic disturbances affect this process are not well understood. To aid in clarifying this issue, we assessed the relation between forest cover and leaf damage caused by herbivorous insects on a representative tropical forest understory plant family, the Rubiaceae. We measured leaf area loss of Rubiaceae plants in 20 forest sites located in the Brazilian Atlantic forest, and also tested whether variation in forest cover, abundance of insectivorous birds (predators) and of Rubiaceae plants (resources) could explain the observed variation in leaf damage. Herbivory levels varied between 2.6 and 12.5 percent leaf area lost and increased with decreasing forest cover, whereas the other explanatory variables did not provide additional explanatory power. Therefore, forest loss appears to be the main driver of changes in local herbivory, and ecological processes such as top-down and bottom-up control may not account for the deforestation-related increase in herbivory levels. Other mechanisms, for example leaf quality and/or the influence of the adjoining land uses, have to be explored in future studies.     

Shifts in reciprocal river‐riparian arthropod fluxes along an urban‐rural landscape gradient

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