景观边界影响域研究进展

景观边界影响域研究是景观边界研究的重要组成部分,也是景观生态学国内外研究的一个热点问题.本文主要从景观边界影响域的定量判定方法、非生物因子边界影响域、生物因子边界影响域的研究以及边界影响域的影响因子等方面综述了国外近几十年边界影响域的研究进展.并在探讨国内景观边界影响域的研究现状基础上,对边界影响域的研究前景进行展望.     

Depth of edge influence of the agricultural-forest landscape boundary,Southwestern China

The landscape boundary is an important component of a landscape and often plays an indispensable role in regulating ecological flows. The primary objective of this study was to estimate how far the edge effects on agricultural-forest landscape boundaries can penetrate into the forest and agricultural field. This will serve as a basis for understanding the interaction between forest and agricultural fields in the mountainous area of southwestern China and provide scientific basis for the practice of the policy of “returning agricultural field to forest.” Based on field investigations, three types of boundaries with six sampling transects were selected. We investigated the soil moisture, soil nutrients and vegetation diversity along the transect gradient and explored the depth of edge influence (DEI) with moving split-window techniques for analyzing the data. DEI for soil moisture changed with the seasons, ranging from 6 m in the pepper field to 2 m in the forest during the dry season, and from 12 m in the pepper field to 2 m in the forest after heavy rain. DEI based on soil organic matter ranged from 1.5 to 10 m in the forest field, while it was not detected based on other soil nutrient factors. DEI based on vegetation diversity varied from 4 to 26 m and from 10 to 31 m in the forest and agricultural fields, respectively. These results provide the scientific basis for the policy “returning agricultural field to forest”. Based on these field observations, reducing human disturbance and revegetating with natural shrubs and meadows could be more effective for vegetation conservation in terms of soil moisture and soil nutrient content in the arid valley of the Minjiang River.     

岷江上游干旱河谷农林边界影响域的研究

对岷江上游农林边界的影响域进行研究,以提高该区管理农田和林地的水平．共调查3种类型农林边界10条样带,采用移动窗口法对植物多样性的数据进行分析,结果表明,当窗口宽度达到6～10时。SED曲线的变化趋向稳定,并且在曲线上有一或两个峰值出现．不同类型边界的影响域是不同的,但均在距边界50m内．各类型边界的影响域多在12～30m之间．6条林地样带只有M2和M6样带林地的影响域被确定,而4条农田样带的影响域均被确定．影响域的大小取决于边界两侧斑块类型和地形以及小气候等因子,但坡向对其影响不大;移动窗口法能有效地刻画边界动态,是一种分析边界简单而有力的工具．这些结果有利于进一步理解干旱河谷区农林间的相互作用．     

Edge influence detection using aerial LiDAR in Northeastern US deciduous forests

The northeastern United States is currently experiencing a decline in forested lands, primarily due to the expansion of human development. Of particular concern is the loss of “core areas” or the areas within forests that are not influenced by other land cover types. Core areas are of significant importance to native flora and fauna, since they generally are less vulnerable to invasion by exotics and are more resilient to the effects of climate change. However, the exact reduction of core area in the northeast is still unknown. Current methods of estimation are not particularly precise, since areas of edge influence are quite variable and situational. Therefore, the purpose of this study is to devise a new method for identifying edge influence areas using remote sensing techniques. Eight transects were sampled perpendicular to the edge of an abandoned golf course within Harvard Forest in Petersham, MA. Vegetation inventories as well as Photosynthetically Active Radiation (PAR) at different heights within the canopy were used to determine edge depth in the field. Small-footprint discrete aerial LiDAR datasets were comparatively used to identify edge depths. LiDAR returns were binned and transformed into canopy height profiles before the sum of squared differences was used to determine where edge influence diminished, creating a LiDAR derived edge depth. LiDAR estimated edge depths were not significantly different from the field identified edge depths, indicating it might be a low-cost method for estimating edge depths.     

Edge,area and anthropization effects on mangrove-dwelling ant communities

In mangroves the habitat fragmentation has contributed to area reduction and increased edge extension, as well as other anthropogenic consequences that can change abiotic conditions, interfere with ecosystem functioning and lead to the loss of biodiversity. These impacts may affect terrestrial and marine invertebrates living in this coastal system. This study investigated the effects of fragment characteristics (size and matrix type) and distance to edge on ant richness, occurrence of functional groups and of the most frequent species in mangroves in North-Eastern Brazil. Our research covered ten mangrove fragments. We used sardine and honey baits in twelve randomly selected points per area. Twenty-five species of ants were recorded, with Camponotus arboreus, Crematogaster erecta, Azteca sp. and Neoponera villosa being the most frequent. Only four functional groups were found, the most representative of which were the Arboreal Omnivores with Massive Recruitment and the Generalist Predators. No relationship was found between the response variables and the environmental characteristics. Mangroves ants are mostly arboreal; thus, the pattern of competition between ant species or even tree architecture elements may have stronger effects than those related to anthropization, loss of area and fragmentation in this environment. Furthermore, the harsh physical conditions in the mangrove serve as barriers for most exotic species and to some functional groups of ants. This study highlights the natural restrictive nesting and foraging conditions in mangrove areas as the powerful forces in ant community structuring, possibly even more than anthropization itself.     

全软成形环与缘对缘瓣膜成形术在心脏瓣膜关闭不全成形术中的疗效比较

目的:观察和比较全软成形环与缘对缘瓣膜成形术在心脏瓣膜关闭不全成形术中的疗效。方法:回顾性研究我院行心脏瓣膜关闭不全成形术患者80例,随机分为Ⅰ组与Ⅱ组,每组各40例。第Ⅰ组患者在行心脏瓣膜关闭不全成形术中使用全软成形环进行治疗,第Ⅱ组患者在手术过程进行缘对缘瓣膜成形术。比较治疗前后两组患者二尖瓣口、二尖瓣环面积和收缩期及舒张期二尖瓣环周径、左心室内径、心搏出量、射血速率、射血时间及临床有效率。结果:治疗后,两组二尖瓣形态、左心室内经、心搏出量、射血速率及射血时间均较治疗前有所改善(P0.05);且与第Ⅱ组相比,第Ⅰ组患者二尖瓣口面积、心搏出量及射血速率较大,二尖瓣环的面积、收缩期及舒张期二尖瓣环周径、左心室内径较小,射血时间明显缩短(P0.05)。第Ⅱ组治疗总有效率为95%,较第Ⅰ组(62.5%)显著升高,差异具有统计学意义(P0.05)。结论:与缘对缘瓣膜成形术相比,全软成形环在心脏瓣膜关闭不全成形术中的疗效更好,其机制可能与增大二尖瓣口面积、心搏出量及射血速率,减小二尖瓣环的面积、收缩期及舒张期二尖瓣环周径、左心室内径,缩短射血时间有关。     

岷江上游花椒地/林地边界土壤水分影响域的定量判定

在岷江上游干旱河谷区,选取典型的花椒地/林地边界,利用TDR仪测定干旱条件下、雨后和每月0～15 cm土层水分含量,并用移动窗口法判定土壤水分的边界影响域.结果表明,若用移动窗口法对土壤水分的边界影响域进行判定,当窗口宽度为8～12时,边界影响域较易判定.年内土壤水分随时间变化而变化.这种变化可分为土壤水分上升期、高峰期和消退期3个时期.干旱条件下土壤水分的边界影响域较小,其宽度约从花椒地6 m到林地2 m;雨后土壤水分的边界影响域有较大增加,其宽度约从花椒地12 m到林地2 m;年内土壤水分的边界影响域宽度约从花椒地10 m到林地2 m之间变化.不同季节土壤水分的边界影响域不同,并随着季节的变化呈动态变化.从生态学意义上讲,岷江上游地区目前进行的将花椒地退耕成林地、栽植树苗的措施是不可取的,该区退耕还林的最好方法应该是退耕,使其灌木林或草本植物自然生长.     

Response of ground-dwelling beetles across logging coupe edges into streamside reserves

Streamside reserves can provide important habitat reservation in forest landscapes subject to logging. Depending on the width of streamside reserves, edge effects have the potential to compromise their effectiveness for terrestrial conservation, yet edge effects into riparian environments have rarely been assessed. It would be unwise to assume that edge effects act in the same way at streamside reserves as at the non-riparian edges of logging coupes, as interactions with riparian influences on beetles along the stream-upslope gradient might create unique edge conditions. In this study, we assess edge effects on ground dwelling beetles at four sites, using transects of pitfall traps across logging coupe edges into streamside reserves that have only been affected by logging on one side of the stream. Edge effects were found to extend further into streamside reserves in this study than into upslope habitat at the same sites from a concurrent study. Edge effects were site specific and appeared to extend as far as the stream in most cases (23–65 m). Comparison of beetle assemblage composition with adjacent unlogged streams supported the conclusion that beetles within 10 m of streams in streamside reserves were still responding to edge effects. These results suggest that streamside reserves might not contain habitat comparable with riparian areas away from the influences of nearby clearfelling, and wider reserves are recommended to maintain core habitat not compromised by edge effects.     

Edge influence on plant litter biomass in forest and savanna in the Brazilian cerrado

Edge influence, characterized by differences in ecosystem characteristics between the edge and the interior of remnants in fragmented landscapes, affects a variety of organisms and ecosystem processes. An important feature that may be affected by edges is the amount of plant litter, which provides important habitat for a large variety of organisms and influences ecological processes such as fire dynamics. We studied edge influence on plant litter and fine woody debris in the cerrado of São Paulo state, south‐eastern Brazil. We collected, sorted, dried and weighed plant litter along 180 m‐long transects perpendicular to three savanna and eleven forest edges adjacent to different anthropogenic land uses, with four to five transect per edge. There tended to be less biomass of the finer portions of fine woody debris at both savanna and forest edges. Graminoid litter at savanna edges was greater than in the corresponding interior areas, whereas other litter portions were either unaffected by edges or did not show consistent patterns in either savanna or forest. Edge influence was usually restricted to the first 20 m from the edge, was not influenced by edge characteristics and exhibited no clear differences between savanna and forest areas. Several mechanisms may have led to the variable patterns observed including variation in the plant community, plant architecture, and invasive species. The edge‐related variation in plant litter may putatively lead to, for example, increased fire frequency and intensity at the savanna edges and altered trophic dynamics at forest edges; the mechanisms and consequences of this edge influence should be addressed in future studies.     

Structure and composition of edges next to regenerating clear‐cuts in mixed‐wood boreal forest

Abstract. We investigated the spatial and temporal pattern of edge influence on primary (forest structure) and secondary (understory structure and composition) responses at forest edges next to regenerating clear‐cuts in Populus‐dominated boreal forest in Alberta, Canada. We used before/after‐harvest comparisons to determine whether there were significant effects of edge creation in the first and second year after harvest. We also investigated 5‐ and 16‐yr‐old edges to determine whether their structure and composition were significantly different from interior forest. Distance of edge influence (20–60 m) was not extensive compared to findings from studies conducted in other forest types. In the first two years after harvest, there were significant primary responses to edge creation including increased tree mortality, snag breakage and amount of downed coarse woody debris; as well as secondary responses including prolific vegetative regeneration of Populus spp. and a decrease in total shrub cover. Significant edge effects were still detectable 5 and 16 yr after edge creation, despite the rapid regeneration of Populus‐ dominated forest in the adjacent clear‐cuts. These older edges showed evidence of past primary and secondary responses, including a more heterogeneous canopy, along with additional changes in under‐ story composition. At both younger and older edges the distance of edge influence was greater for secondary responses (up to 60 m) than for primary responses (10–20 m). We hypothesize that secondary responses to edge creation start later than primary responses and that the distance of edge influence is greater for secondary (vs. primary) responses.     

Edge influence on herbaceous plant species,diversity and soil properties in sparse oak forest fragments in Iran

伊朗稀疏橡木林片段对草本植物物种多样性和土壤特性的边缘影响 温带和热带森林中的森林边缘现象已经得到了很好的研究,但在稀疏的橡木林片段中的相关研究却较为缺乏。本文研究了稀疏橡木林片段对植物物种多样性和土壤特性的边缘影响。本研究沿着伊朗克尔曼沙赫省3个小型(<10 ha)和3个大型(>10 ha)橡木林片段的3个横断面收集了从边缘到内部的相 关数据,测量了0(森林边缘)、25、50、100和150 m处的草本植物(高度<0.5 m)和土壤特性。使用香农指数量化了物种多样性,使用稀疏标准化方法比较了两个大小不同片段中的物种丰富度,并应用了非度量多维测度排序研究了物种组成的变化。通过随机化测试估算了边缘影响的距离,并利用Tukey HSD事后检验法的广义线性混合模型评估了距边缘距离和片段大小对多样性和土壤特性的影响。研究结果表明,大小片段边缘具有较高的物种丰富度、多样性和均匀度,而大片段边缘的土壤氮和有机碳含量则较内部更低(边缘50 m范围内的变化最大)。大小片段的物种组成、土壤有机碳和氮总量都存在显 著差异。本研究关于这些稀疏森林对草本植物和土壤特性产生显著边缘影响的发现,对于边缘研究,尤其是边缘和草本植物的相关研究具有重大贡献。     

作物群体边际效应规律及其应用

对作物边际效应的研究表明,有利生态因子的作用大于不利生态因子的作用时,作物群体发生正边际效应,表现为边际优势;不利生态因子的作用大于有利生态因子的作用时,作物群体发生负边际效应,表现为边际劣势．在作物群体内部条件一致的情况下,边际效应的绝对值随边距递增而递减．     

Border and ecotone detection by vegetation composition along forest‐savanna transects in Ivory Coast

Abstract. Question: How do properties of different vegetation components vary along ecotones of semi‐deciduous forest islands, and can the depth of edge influence (DEI) of the components be detected using a novel combination of analyses? Location: Comoé National Park (CNP), NE Ivory Coast. Methods: Along eight transects at semi‐deciduous forest islands tree individuals > 20 cm DBH were mapped. At one transect, tree and shrub individuals down to 1 cm DBH were measured and cover of species was estimated. Split moving window dissimilarity analysis (SMWDA) and moving window regression analysis (MWRA) were combined to detect statistical significance of borders in multivariate vegetation data along continuous transects, to determine the width of associated ecotones, and, thus, the DEI towards the forest interior. Results: For trees > 20 cm DBH, a distinct boundary formation was detected, dominated by the semi‐fire resistant tree species Anogeissus leiocarpus. The median of DEI towards the forest interior was 55 m. Ecotone detection with all species present revealed an interlocked sequence of ecotones for grasses, herbs, woody climbers, shrubs and trees, with each of these ecotones being narrower than the overall ecotone. DEI ranged from 10 m for grasses up to 120 m for trees and shrubs. Conclusions: The coherent set of analyses applied proved to be an objective method for detecting borders and the width of associated ecotones. The patterns found may be explained by successional processes at the forest‐savanna border. The DEI measured for the forest islands in the nearly undisturbed semi‐natural system of the CNP is of relevance to concepts of core‐area analysis and the protection of forest interior species in semi‐deciduous forests in tropical West Africa.     

Edge effects on ground beetles at the woodlot–field interface are short‐range and asymmetrical

• 1 Boundaries between woodlots and agricultural habitats are numerous in temperate agricultural landscapes and influence ecological processes in both woodlots and agricultural habitats.
• 2 We aimed to determine how far the species assemblage of ground beetles in woodlot and open habitats was influenced by the presence of the woodlot–field boundary.
• 3 We studied the distribution of ground beetles on both sides of the boundaries of four woodlots along transects of pitfall traps (n = 140). The depth of edge influence (i.e. the distance from the boundary at which the presence of the boundary has no more significant influence) on the species assemblage of ground beetles in each woodlot and in each agricultural habitat was determined with nonlinear canonical analysis of principal coordinates, an ordination method that is followed by nonlinear regression of the principal coordinates on distance from the boundary.
• 4 The depth of edge influence on the species assemblages of ground beetles was asymmetrical relative to the boundary: it was generally higher and had higher variability in open habitats (14.4 ± 12.3 m) than in woodlots (4.9 ± 2.3 m). Species assemblages of ground beetles in edges were a mix between both adjacent species assemblages. Edge effects in woodlots were deeper in the woodlots exhibiting a deeper penetration of open habitat species. Symmetrically, edge effects in open habitat were deeper in the open habitats with a deeper diffusion of forest species into the open habitat.
• 5 Forest ground beetles were not threatened by edge effects. Rather, edge effects are likely to benefit agriculture, mostly through the dispersal of predatory forest species into agricultural fields.