Forest Patch Area Research Articles

Conservation–Protection of Forests for Wildlife in the Mississippi Alluvial Valley

The nearly ubiquitous bottomland hardwood forests that historically dominated the Mississippi Alluvial Valley have been greatly reduced in area. In addition, changes in hydrology and forest management have altered the structure and composition of the remaining forests. To ameliorate the detrimental impact of these changes on silvicolous wildlife, conservation plans have emphasized restoration and reforestation to increase the area of interior (core) forest habitat, while presuming negligible loss of extant forest in this ecoregion. We assessed the conservation–protection status of land within the Mississippi Alluvial Valley because without protection, existing forests are subject to conversion to other uses. We found that only 10% of total land area was currently protected, although 28% of extant forest was in the current conservation estate. For forest patches, we prioritized their need for additional conservation–protection based on benefits to forest bird conservation afforded by forest patch area, geographic location, and hydrologic condition. Based on these criteria, we found that 4712 forest patches warranted conservation–protection, but only 109 of these forest patches met our desired conservation threshold of >2000 ha of core forest that was >250 m from an edge. Overall, 35% of the area of forest patches warranting conservation–protection was protected within the conservation estate. Even so, for those forest patches identified as most in need of conservation–protection, less than 10% of their area was currently protected. The conservation–protection priorities described fill an unmet need for land trusts and other conservation partners pursuing strategic forest protection in support of established bird conservation objectives.

Ecological pattern of urban forest landscape of Ji'nan City, China

The ecological pattern research on urban forest landscape is the foundation and premise of urban forest system planning and urban ecological construction, as well as an important way of optimizing urban spatial structure, giving full play to urban forest ecological function and creating ecological and livable environment. Ecological pattern of urban forest landscape in built-up area of Ji'nan city was quantitatively analyzed and the corresponding optimization countermeasures were put forward through quantitative analysis and gradient analysis of the overall landscape ecological pattern by RS and GIS technology with 10 landscape indices at patch level and landscape level. The results showed that urban forest coverage rate in built-up areas was 15.8%. At the landscape level, the overall landscape ecological pattern of urban forest showed following patterns: relatively complete types of urban forest landscape patches, greater degree of landscape fragmentation, different area of various types of urban forest, large major patches, and highly connected same patch types. At the level of patch type, the ecological public welfare forest was dominated by large patches. The shape of scenic recreational forest was regular and dominated by large and medium patches. The shape of road forest and subsidiary forest was complex and dominated by small patches. The production and management forest was lacking. At the level of patch type, landscape recreational forest was the dominant type, ecological public welfare forest patch area was the largest, road forest and ancillary forest fragmentation was large. At the level of landscape, urban central forest landscape fragmentation was large, human interference was serious, and landscape shape was complex. Based on the analysis of the ecological pattern of urban forest landscape, we proposed the construction scheme of Ji'nan urban forest ecological network, which was "one ring, two networks, three four axes, and multi-point chessboard". Such scheme would help strengthen the connectivity of various types of urban forests and exert overall ecological benefits of large-scale ecosystems.

Forest fragmentation shapes the alpha–gamma relationship in plant diversity

AbstractQuestionsForest fragmentation affects biodiversity locally (α diversity) and beyond — at relatively larger scales (γ diversity) — by increasing dispersal and recruitment limitations. Yet, does an increase in fragmentation affect the relationship between α and γ diversity and what can we learn from it?LocationNorthern France.MethodsWe surveyed 116 forest patches across three fragmentation levels: none (continuous forest); intermediate (forest patches connected by hedgerows); and high (isolated forest patches). Plant species richness of both forest specialists and generalists was surveyed at five nested spatial resolutions across each forest patch: 1 m2; 10 m2; 100 m2; 1,000 m2; and total forest patch area. First, we ran log‐ratio models to quantify the α–γ relationship. We did that separately for all possible combinations of fragmentation level (none vs intermediate vs high) × spatial scale (e.g., α‐1 m2 vs γ‐10 m2) × species type (e.g., α‐specialists vs γ‐specialists). We then used linear mixed‐effects models to analyze the effect of fragmentation level, spatial scale, species type and all two‐way interaction terms on the slope coefficient extracted from all log‐ratio models.ResultsWe found an interaction effect between fragmentation level and species type, such that forest specialists shifted from a linear (i.e., proportional sampling) to a curvilinear plateau (i.e., community saturation) relationship at low and high fragmentation, respectively, while generalists shifted from a curvilinear to a linear pattern.ConclusionsThe impact of forest fragmentation on the α–γ relationship supports generalist species persistence over forest specialists, with contrasting mechanisms for these two guilds. As fragmentation increases, forest specialists shift from proportional sampling towards community saturation, thus reducing α diversity likely due to dispersal limitation. Contrariwise, generalists shift from community saturation towards proportional sampling, thus increasing α diversity likely due to an increase in the edge:core ratio. To ensure long‐term conservation of forest specialists, one single large forest patch should be preferred over several small ones.

Assessment on latitudinal tree species richness using environmental factors in the southeastern United States.

The southeastern region of the United States exhibits an unusual trend of decreasing tree species richness (TSR) from higher to lower latitudes over the Florida peninsula. This trend contradicts the widely marked latitudinal diversity gradient where species richness is highest in tropical zones and decreases towards extratropical regions. This study aims to assess the environmental factors that prompt this atypical inverse latitudinal gradient seen in TSR using the USDA Forest Service’s Forest Inventory and Analysis (FIA) database. Fifteen variables under four categories of forested area, groundwater, soil properties, and climate groups were examined to model TSR in the region. Generalized linear models (GLMs) with Poisson distributions first assessed individual variables to test explanatory power then the LASSO regularization method was utilized to extract two subsets of the most influential variables to predict TSR. Forest area and four climate variables (mean annual temperature, precipitation seasonality, mean temperature of coldest quarter, and mean precipitation of driest quarter) were the top five variables during the initial GLM assessment implying their potential individual influence in regulating TSR. Two subsets of LASSO models contained seven and three predictor variables, respectively. Frist subset includes seven predictors, presented in highest to low standardized coefficient, mean temperature of coldest quarter, forested area, precipitation seasonality, mean precipitation of driest quarter, water table depth, spodosol, and available water storage. The other subset further excluded four lowest influential variables from the first set, leaving the top three variables from the first subset. The first subset of the LASSO model predicted TSR with 63.4% explained deviance while the second subset reproduced 60.2% of deviance explained. With only three variables used, the second model outperformed the first model evaluated by the AIC value. We conclude that forest patch area, mean temperature of coldest quarter, and precipitation seasonality are the highly influential variables of TSR among environmental factors in the southeastern region of U.S., but evolutionary or historic cause should be further incorporated to fully understand tree species diversity pattern in this region.

Effects of habitat fragmentation and human disturbance on the population dynamics of the Yunnan snub-nosed monkey from 1994 to 2016.

In this study, we integrate data from field investigations, spatial analysis, genetic analysis, and Generalized Linear Models (GLMs) to evaluate the effects of habitat fragmentation on the population dynamics, genetic diversity, and range shifts in the endangered Yunnan snub-nosed monkey (Rhinopithecus bieti). The results indicate that from 1994 to 2016, R. bieti population size increased from less than 2,000 to approximately 3,000 individuals. A primary factor promoting population recovery was the establishment of protected nature reserves. We also found that subpopulation growth rates were uneven, with the groups in some areas, and the formation of new groups. Both the fragmentation index, defined as the ratio of the number of forest patches to the total area of forest patches (e.g., increased fragmentation), and increasing human population size had a negative effect on population growth in R. bieti. We recommend that government conservation plans prioritize the protection of particular R. bieti populations, such as the Baimei and Jisichang populations, which have uncommon haplotypes. In addition, effective conservation strategies need to include an expansion of migration corridors to enable individuals from larger populations such as Guyoulong (Guilong) to serve as a source population to increase the genetic diversity of smaller R. bieti subpopulations. We argue that policies designed to protect endangered primates should not focus solely on total population size but also need to determine the amount of genetic diversity present across different subpopulations and use this information as a measure of the effectiveness of current conservation policies and the basis for new conservation policies.

Body Size Influences Stingless Bee (Hymenoptera: Apidae) Communities Across a Range of Deforestation Levels in Rondônia, Brazil.

Developments in understanding bee responses to habitat loss indicate that body size is a trait with important consequences for conservation. Stingless bees (Hymenoptera, Apidae, Meliponini) are a diverse group of eusocial bees providing pollination services in tropical landscapes, exhibiting a large range in body size across species. We tested the effects of deforestation on the body sizes of stingless bee communities by using museum specimens and revisiting a previous effort that sampled stingless bee communities across varying levels of deforestation at 183 sites in Rondônia, Brazil, in 1996–1997. Body size measurements (intertegular distance) from 72 species collected were included as dependent variables in response to forest area, forest edge, and connectivity of forest patches at several spatial scales. We find that stingless bee body size is negatively related to forest cover: mean community body size was larger in areas with greater amounts of deforestation, and smaller in areas with less deforestation. Second, stingless bee species richness was positively associated with forest edge regardless of body size. Lastly, we find that as forest patch isolation increased, the stingless bee community body size also increased. These findings support hypotheses that small stingless bee species might be more negatively affected by deforestation, adding to the growing body of evidence that stingless bees require areas of intact forest in near proximity to other forest patches to conserve these diverse pollinator communities.

Population dynamics and geographical distribution of the gypsy moth, Lymantria dispar, in Japan

The gypsy moth, Lymantria dispar L. (Lepidoptera: Lymantriidae), is distributed throughout most of the northern hemisphere and known as one of the most significant insect pest both in its native and introduced regions. The aim of this study was to examine whether there are differences in the outbreak pattern of L. dispar, and these differences can be explained by different subspecies or divided populations across Japan for appropriate management of L. dispar. We reviewed the records of outbreaks of L. dispar in Japan using available literature and internet sources. We also examined phylogenetic relationships between L. dispar populations in Japan and other global populations to clarify current debated classification of the Japanese L. dispar. We then estimated the distribution of Japanese L. dispar with a species distribution model (Maxent). Phylogenetic mtDNA analysis revealed that Lymantria species consisted of four clusters: the first cluster contained three L. dispar subspecies from Europe and continental Asia (classified into L. dispar dispar), the populations of Honshu and western Hokkaido (L. dispar asiatica), and the central and eastern Hokkaido populations of L. dispar hokkaidoensis, while the second and third clusters comprised L. albescens and L. postalba, respectively. According to historical records, L. dispar outbreaks occur in approximately 11 year-cycles in Hokkaido, regardless of its classification at the subspecies level. Within northeastern Japan, L. dispar outbreaks occurred simultaneously from 2014 to 2015, whereas there were few reports of outbreaks in southwestern Japan. The distribution ranges of L. dispar were determined mainly by the maximum depth of snow cover (100–250 cm), forest patch area (0–0.6 km2), and elevation (600–1400 m); clearly divided at the species level but not at the subspecies or divided population level. On the other hand, the forest types are likely to contribute to the population dynamics and geographical distribution of L. dispar.

Invasive alien plant species, fragmentation and scale effects on urban forest community composition in Durban, South Africa

BackgroundUrban forests are under increased pressure from invasion by exotic (alien) species. The vegetation present in the matrix of urban sites is a rich source of alien invasive propagules, which increases the risk of alien invasion in forests within an urban space, leading to a decline in indigenous species. Therefore, determining the distribution patterns of native and exotic species as influenced by environmental factors can assist in quantifying the impact of exotic species at broad scales based on responses on a finer scale. Quantifying the effects of multiple environmental factors on the distribution patterns of both indigenous and alien species in the ecosystem may help in prescribing suitable management efforts.MethodsFifteen forest patches were sampled in the eThekwini (Durban) Municipality and data collected from 74 100-m2 plots with different degrees of invasion. Indigenous and alien species of trees, shrubs and climbers occurring in ten and more plots were considered for analysis and the CANOCO 5.1 package was used to run various constrained ordination analyses. Variation partitioning analysis was used to assess the impact of environmental variables at different spatial scales, namely the plot and patch scales.ResultsCanopy gaps are the major controlling factor for invasive alien plants (IAPs) occurrence at fine scale. At patch level, residential and industry areas outside the boundaries (buffer area) of forest patches have a high influence on the distribution of IAPs. Communities dominated by the invasive Chromolaena odorata (L.) R.M. King are most common on the lowland coastal forests while communities dominated by either Litsea glutinosa (Lour.) C.B.Rob. or Cardiospermum grandiflorum Sw. can prevail in both lowland coastal and scarp forests.ConclusionsCanopy gaps in lowland forests can facilitate the transition of native forests to novel communities containing a variety of alien plant species. Communities of shrub, climber and tree IAPs occur in lowland coastal forests while climber and tree IAPs dominate the high-elevation scarp forests. The resilience shown by some native species to the tree, shrub and climber IAPs by remaining when IAPs establish makes these species very suitable for restoration projects. Forest patches surrounded by a high incidence of residential and industrial areas in the buffer matrix are likely to have a high diversity of IAPs. Larger patch size and high connectivity to nearby native forests are key in reducing invasion by IAPs.

Impact of patch size on woody tree species richness and abundance in a tropical montane evergreen forest patches of south India

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region, south India. We sampled woody trees (≥ 1 cm dbh) from 21 forest patches in the upper Nilgiri hills (> 2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs (≥ 1 to < 10 cm dbh) increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees (≥ 10 to < 30, ≥ 30 to < 60 and ≥ 60 cm dbh, respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance. Our findings suggest that with increasing forest patch area, tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns. Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area.

Forest patch isolation drives local extinctions of Amazonian orchid bees in a 26 years old archipelago

Major hydroelectric dams are among key emergent agents of habitat loss and fragmentation in lowland tropical forests. Orchid bees (Apidae, Euglossini) are one of the most important groups of specialized pollinators of flowering plants in Neotropical forests. Here, we investigate how an entire assemblage of orchid bees responded to the effects of forest habitat loss, isolation and forest canopy degradation induced by a hydroelectric reservoir of Central Brazilian Amazonia. Built in 1986, the Balbina Dam resulted in a vast archipelagic landscape containing 3546 primary forest islands of varying sizes and isolation, surrounded by 3129km2 of freshwater. Using scent traps, we sampled 34 islands, 14 open-water matrix sites, and three mainland continuous forests, yielding 2870 male orchid bees representing 25 species. Local orchid bee species richness was affected by forest patch area but particularly by site isolation. Distance to forest edges, either within forest areas or into the open-water matrix, was the most important predictor of species richness and composition. Variation in matrix dispersal of individual species to increasingly isolated sites was a key determinant of community structure. Given the patterns of patch persistence and matrix movements of orchid bees in increasingly fragmented forest landscapes, we outline how forest bees respond to the landscape alteration induced by major hydroelectric dams. These results should be considered in environmental impact studies prior to the approval of new dams.

Gamebird responses to anthropogenic forest fragmentation and degradation in a southern Amazonian landscape.

Although large-bodied tropical forest birds are impacted by both habitat loss and fragmentation, their patterns of habitat occupancy will also depend on the degree of forest habitat disturbance, which may interact synergistically or additively with fragmentation effects. Here, we examine the effects of forest patch and landscape metrics, and levels of forest disturbance on the patterns of persistence of six gamebird taxa in the southern Brazilian Amazon. We use both interview data conducted with long-term residents and/or landowners from 129 remnant forest patches and 15 continuous forest sites and line-transect census data from a subset of 21 forest patches and two continuous forests. Forest patch area was the strongest predictor of species persistence, explaining as much as 46% of the overall variation in gamebird species richness. Logistic regression models showed that anthropogenic disturbance—including surface wildfires, selective logging and hunting pressure—had a variety of effects on species persistence. Most large-bodied gamebird species were sensitive to forest fragmentation, occupying primarily large, high-quality forest patches in higher abundances, and were typically absent from patches <100 ha. Our findings highlight the importance of large (>10,000 ha), relatively undisturbed forest patches to both maximize persistence and maintain baseline abundances of large neotropical forest birds.

Assessment of Land-Use/Land-Cover Change and Forest Fragmentation in the Garhwal Himalayan Region of India

The Garhwal Himalaya has experienced extensive deforestation and forest fragmentation, but data and documentation detailing this transformation of the Himalaya are limited. The aim of this study is to analyse the observed changes in land cover and forest fragmentation that occurred between 1976 and 2014 in the Garhwal Himalayan region in India. Three images from Landsat 2 Multispectral Scanner System (MSS), Landsat 5 Thematic Mapper (TM), and Landsat 8 Operational Land Imager (OLI) were used to extract the land cover maps. A cross-tabulation detection method in the geographic information system (GIS) module was used to detect land cover changes during the 1st period (1976–1998) and 2nd period (1998–2014). The landscape fragmentation tool LFT v2.0 was used to construct a forest fragmentation map and analyse the forest fragmentation pattern and change during the 1st period (1976–1998) and 2nd period (1998–2014). The overall annual rate of change in the forest cover was observed to be 0.22% and 0.27% in the 1st period (1976–1998) and 2nd period (1998–2014), respectively. The forest fragmentation analysis shows that a large core forest has decreased throughout the study period. The total area of forest patches also increased from 1976 to 2014, which are completely degraded forests. The results indicate that anthropogenic activities are the main causes of the loss of forest cover and forest fragmentation, but that natural factors also contributed. An increase in the area of scrub and barren land also contributed to the accumulation of wasteland or non-forest land in this region. Determining the trend and the rate of land cover conversion is necessary for development planners to establish a rational land use policy.

How well is current plant trait composition predicted by modern and historical forest spatial configuration?

There is increasing evidence to suggest that a delayed response of many forest species to habitat loss and fragmentation leads to the development of extinction debts and immigration credits in affected forest habitat. These time lags result in plant communities which are not well predicted by present day landscape structure, reducing the accuracy of biodiversity assessments and predictions for future change. Here, species richness data and mean values for five life history characteristics within deciduous broadleaved forest habitat across Great Britain were used to quantify the degree to which aspects of present day forest plant composition are best explained by modern or historical forest patch area. Ancient forest specialist richness, mean rarity and mean seed terminal velocity were not well predicted by modern patch area, implying the existence of a degree of lag in British forest patches. Mean seedbank persistence values were more closely related to modern patch area than historical, particularly in larger patches. The variation in response for different mean trait values suggests that species respond to landscape change at different rates depending upon their combinations of different trait states. Current forest understorey communities are therefore likely to consist of a mixture of declining species whose extinction debt is still to be paid, and faster colonising immigrant species. These results indicate that without management action, rare and threatened species of plant are likely to be lost in the future as a result of changes in forest spatial configuration that have already taken place. The lag seen here for rare specialist plants suggests however that there may still be scope to protect such species before they are lost from forest patches.

Impacts of land-use change on sacred forests at the landscape scale

Sacred forests often exist as isolated patches of natural forest even after conversion of the surrounding matrix to different forms of land-use. This study set out to: (1) evaluate land-cover changes and patch fragmentation in a landscape containing sacred and non-sacred forest patches over 15 years and (2) compare the effects at an individual patch level between sacred and non-sacred forests. Past changes in area and patch fragmentation of land cover classes and individual forest patches in the Gamo Highlands, Ethiopia, were assessed using maximum-likelihood classification of LANDSAT images. Large changes in land-cover occurred during 1995–2010, with 109.4% increase in area of farm and settlement and 36.6% decrease of forest area, with a decrease in number of forest patches by 16.1%, mean size by 26.8%, edge density by 29.1% and shape index by 13.3%. While all four individually studied non-sacred forests decreased in size over this period only four of the six individual sacred forests patches showed reduction in area. Forest patches with sacred status had greater protection by local communities than non-sacred forests in the Gamo Highlands. However, their small size and increasing edge density indicate high vulnerability, especially if an erosion of traditional cultural values reduces their protection.

Effects of patch size on liana diversity and distributions in the tropical montane evergreen forests of the Nilgiri Mountains, southern India

Abstract:We investigate the effect of patch size on liana diversity and distribution in 19 patches of montane evergreen forest in the Nilgiri hills, Western Ghats, southern India. Additionally, we examined how liana species richness and community assemblage in both edge (within 10 m of the forest edge) and interior regions of forest patches respond to patch size, in order to infer the impact of forest expansion or reduction on the liana communities. A total of 1276 woody liana individuals of 15 species were identified, belonging to 10 genera and nine families. Total species richness of lianas was significantly positively related to forest-patch area, both when analysed for the entire patch, in addition to both core and edge regions when examined separately. Species richness of larger lianas also showed a significant positive relationship with increasing forest patch area. Community assemblage varied with respect to forest edge, with shade-dependent species only occurring in interior patch regions, shade-averse species in edge regions, and shade-tolerant species occurring throughout. Disturbance also played a role in determining the response of liana diversity to patch size, with heavily disturbed patches showing no relationship between patch size and diversity, whereas positive relationships exist in low to moderately disturbed patches. The most significant result is the change in liana community composition between small and larger fragments. Many species present in smaller patches are also present in edge zones of larger fragments. This suggests that lianas are important structural components of montane forest ecosystems, and their compositional patterns are possibly driven by succession. Moreover, this study reveals the importance of edge effect and patch size in influencing liana species richness and compositional patterns.

Identifying deforestation attractors and patterns of fragmentation for seasonally dry tropical forest in central Veracruz, Mexico

Seasonally dry tropical forests (SDTF) are exposed to numerous threats stemming from human activity and are considered a high conservation priority globally. Nevertheless, planning the conservation, management, and restoration of forests requires a detailed regional understanding of current forest distribution, and patterns and attractors of deforestation. We explored SDTF cover in the state of Veracruz, Mexico, where little is known about this type of forest since it was erroneously considered to have been eliminated and thus has not be included in recent conservation planning in Mexico. A time-series of land use and land cover (LULC) maps, based on Landsat imagery from 1973 (MSS), 1990 (TM), and 2000 (ETM+), was used to analyze historical patterns of deforestation and fragmentation of SDTF in a priority watershed in central Veracruz. Stepwise logistic regression was used to identify the main attractors of forest loss. Maps based on higher resolution SPOT imagery (2007–2008) were used to determine the current extent of SDTF. Results from our LULC analysis revealed landscapes that were consistently dominated (>50%) by some combination of intensified land use including cattle pastures, rain-fed and irrigated agricultural lands, with closed SDTF cover fluctuating from 11.3 to 9.26% during the study period (1973–2007). Annualized rates of forest loss between Landsat images (1973 vs. 2000; −2.02%) and between Landsat and SPOT images (1973 vs. 2007; −0.59), were moderate to low, with historical records suggesting that most deforestation occurred more than a century ago before the Mexican revolution. Nevertheless, rates of forest loss varied considerable between different time periods, with slight reforestation initially (1.55%; 1973–1990), followed by a marked decline (−8.08%; 1990–2000), and finally a noticeable increases in forest cover (4.92%; 2000–2007) that corresponds with changes in public policy and trends in population migration. The number of forest patches tripled between 1973 and 2000 and the mean forest patch area decreased almost 80% over the same time period. Logistic regression analysis (1973–2000) indicated that the main attractors of closed forest transformation were proximity to gentle slopes, cattle pastures, and the hydraulic infrastructure needed for crop irrigation. Although SDTF is highly fragmented and perturbed, important remnants of this diverse native forest still persists in the region. Our findings are discussed in the context of future conservation and restoration efforts.

Landscape connectivity dynamics based on network analysis in the Xishuangbanna Nature Reserve, China

Lack of landscape connectivity and habitat loss is major threats to biodiversity and ecosystem integrity in nature reserves aimed at conservation. In this study, we used structural pattern and functional connectivity metrics to analyze the spatial patterns and landscape connectivity of habitat patches for the Shangyong sub-reserve of the Xishuangbanna Nature Reserve from 1970, 1990, and 2000. On the basis of vegetation and land cover data, we applied the equivalent connected area ECA(PC) indicator to analyze the changes in forest connectivity. Four distance thresholds (2, 4, 8, 12 km) were considered to compare the patch importance of connectivity by dECA values. The results showed the declining trends of landscape connectivity measured by ECA(PC) index from 1970 to 2000. The importance of connectivity in each forest patch varied with the increment of dispersal distances at the patch level, and some important habitat patches, which exhibit a potential to enhance landscape connectivity, should be given more attention. The least-cost pathways based on network structure were displayed under four dispersal distances in three periods. The results showed that the number of paths among the fragments of forest patches exhibited radical increases for larger dispersal distances. Further correlation analyses of AWF, ECA (IIC), and ECA (PC) showed the weakest and least-frequent correlations with the structural pattern indices, while H presented more significant correlations with the PD fragmentation metric. Furthermore, Kendall's rank correlations between the forest patch area and functional connectivity indicators showed that dECA (PC) and dAWF indicators should provided the area-based prioritization of habitat patches. Moreover, the low-rank correlations showed that dF and dLCP can be considered as effective and appropriate indicators for the evaluation of habitat features and network patterns.

道路对林地景观连接度的影响研究——以巩义市为例

基于景观连接度原理，借用景观连接度指数，在地理信息系统支持下，探讨了巩义市山区林地景观在不同距离阈值下连接度的变化，定量分析了道路对林地景观连接度的影响。结果显示，随着景观距离阈值的增大，无论是否有道路，林地景观整体可能连通性指数值都表现为逐渐增大；对林地景观连接度起“非常高”和“高”作用的林地斑块数量都比较少，但占林地总面积比例较大，面积大的林地斑块在提高景观连接度中起的作用较大；道路的分割使得林地斑块重要值降低，就单一斑块而言，随着景观距离阈值的增大，分割成的小斑块的重要值降低程度在逐渐减小。;Landscape connectivity, defined as the degree to which the landscape facilitates or impedes the movement of organisms or ecological processes among patches, has been widely recognized as one of the key objectives in studies of forest landscape management, ecological conservation and construction. The dispersal ability of organisms across changing landscapes is critical for long-term biodiversity conservation, and successful dispersal of organisms always depends on the landscape connectivity. The landscape fragmentation caused by roads has significant effects on the landscape pattern and ecological processes, such as the migration of species and biodiversity maintenance in different ecosystems of landscape. This paper aims to analyse the road impact on forest landscape connectivity in mountain area of Gongyi City, Henan Province, China. The landscape connectivity is evaluated based on a graph-theory framework, in which a graph represents a landscape as a set of nodes (habitat patches) connected to some degree by edges that join pairs of nodes functionally. Both the graph structure and the habitat availability metrics provide significant improvements for analyzing landscape connectivity and decision making in conservation planning of different ecosystems or landscapes. The geographic data sets for the study area, such as DEM, landuse, soil, vegetation and hydrology, were collected and managed in GIS. Two connectivity indicators, the probability index of connectivity (<em>PC</em>) and the importance value (Percentage of the variation in <em>PC</em>, <em>dPC</em><em>_k</em>), were calculated. Considering the dispersal distances for different organisms, we examined the variation of landscape connectivity of the woodland in the low and middle mountainous areas according to five distance thresholds: 0.5 km, 1 km, 2.5 km, 5 km, and 10 km. The importance values of the woodland patches were calculated in the scenarios with roads and without roads in different dispersal distances. In addition, the impact of roads on the landscape connectivity of five selected woodland patches was elucidated in detail. The results shows that: (1) the woodland landscape <em>PC</em> values tend to increase with the distance thresholds from 0.5 km to 10 km, in both scenarios of with roads or without roads; (2) there are few patches with larger area, and in the very high and high categories of contribution to woodland landscape connectivity; (3) the <em>dPC</em><em>_k</em> values of woodland landscape patches gradually decrease with the segmentation of roads, especially for some small patches. We conclude that the roads have important effects on the forest connectivity in the study area. The landscape indexes (such as distance threshold, node position of forest patch and forest area) and the topographical factors (elevation and slope) should be comprehensively considered when analyzing the relationships between roads and forest connectivity. Moreover, the case study also proves that the analysis of landscape connectivity could and should be used as a criterion for selecting important patches in woodland restoration planning. The analytical methods used in this paper are relatively easy to implement, and thus have application potentials in ecological restoration management and landscape planning.

Quantifying Landscape-Scale Patterns of Temperate Forests over Time by Means of Neutral Simulation Models

Several studies attempt to describe changes in the spatial patterns of forests over time, resorting to the comparison of landscape pattern indices (LPI), but new methods for quantifying landscape differences in a statistical context are necessary. In this paper, we quantified and assessed the statistical significance of the forests pattern changes, which have occurred since the end of WWII in Central Italy (Isernia). To do this; based on the proportion of forest cover (pi) and contagion (H) of three land cover maps (1954–1981–2006); we generated 100 forest maps with predictable results through the midpoint displacement algorithm. Then, for both observed and simulated maps, we computed a set of LPI (number of patches, cohesion, largest forest patch index and area weighted mean shape index) and we derived their empirical distributions; finally, we compared the empirical distributions using the non-parametric Kruskal-Wallis test. Our results show significant changes in the spatial pattern of forests and underline the process of natural forest re-growth, which, in the area, is constrained by “remnants” of traditional activities. The adopted approach could be extended to a large ensemble of landscapes and spatial scales and could become a standard procedure when comparing patterns in time.

Large Forest Patches Promote Breeding Success of a Terrestrial Mammal in Urban Landscapes

Despite a marked increase in the focus toward biodiversity conservation in fragmented landscapes, studies that confirm species breeding success are scarce and limited. In this paper, we asked whether local (area of forest patches) and landscape (amount of suitable habitat surrounding of focal patches) factors affect the breeding success of raccoon dogs (Nyctereutes procyonoides) in Tokyo, Central Japan. The breeding success of raccoon dogs is easy to judge as adults travel with pups during the breeding season. We selected 21 forest patches (3.3–797.8 ha) as study sites. In each forest patch, we used infra-red-triggered cameras for a total of 60 camera days per site. We inspected each photo to determine whether it was of an adult or a pup. Although we found adult raccoon dogs in all 21 forest patches, pups were found only in 13 patches. To estimate probability of occurrence and detection for raccoon in 21 forest fragments, we used single season site occupancy models in PRESENCE program. Model selection based on AIC and model averaging showed that the occupancy probability of pups was positively affected by patch area. This result suggests that large forests improve breeding success of raccoon dogs. A major reason for the low habitat value of small, isolated patches may be the low availability of food sources and the high risk of being killed on the roads in such areas. Understanding the effects of local and landscape parameters on species breeding success may help us to devise and implement effective long-term conservation and management plans.