Forest Landscape Structure Research Articles

Principle, structure and application progress of the forest landscape model FireBGCv2.

Forest landscape model can quantitatively simulate the spatiotemporal variations in forest structure and function at the landscape scale based on traditional field survey data and mathematical models, providing a reference for the formulation of scientific forest management strategies. FireBGCv2 is one of the representative models currently used in the research area of forest landscape changes. It can simulate ecological processes at various scales, including trees scale (tree growth, establishment, and mortality), stand scale (carbon and nitrogen pools, fuel treatment, decomposition), site scale (resource competition and species phenology), and landscape scale (seed dispersal and wildfire disturbances), and the effects of those processes on forest landscape structure and function. The advantage of this model lies in its ability to simulate multiple ecological processes while considering the diversity and complexity of ecosystems. However, it also has drawbacks, such as high computational demands and complexity of use. We summarized the basic principles and structure of FireBGCv2 and introduced its application progress in forest landscape research and management. Currently, the application of the FireBGCv2 model, both domestically and internationally, mainly focused on exploring the interactions between fire, climate, and vegetation, quantifying the spatial and temporal dynamics of fires, and describing potential fire dynamics under future climate scenarios and land management strategies. With the in-depth development of forest landscape model theories and applications, the future prospects of FireBGCv2 include improving and updating the model's algorithms, adding new functional modules to explore fire management issues, and meeting the needs of different users.

Diversity, Stability, and the Forecast Challenge in Forest Lepidopteran Predictive Ecology: Are Multi-Scale Plant–Insect Interactions the Key to Increased Forecast Precision?

I report on long-term patterns of outbreak cycling in four study systems across Canada and illustrate how forecasting in these systems is highly imprecise because of complexity in the cycling and a lack of spatial synchrony amongst sample locations. I describe how a range of bottom-up effects could be generating complexity in these otherwise periodic systems. (1) The spruce budworm in Québec exhibits aperiodic and asynchronous behavior at fast time-scales, and a slow modulation of cycle peak intensity that varies regionally. (2) The forest tent caterpillar across Canada exhibits eruptive spiking behavior that is aperiodic locally, and asynchronous amongst regions, yet aggregates to produce a pattern of periodic outbreaks. In Québec, forest tent caterpillar cycles differ in the aspen-dominated northwest versus the maple-dominated southeast, with opposing patterns of cycle intensity between the two regions. (3) In Alberta, forest tent caterpillar outbreak cycles resist synchronization across a forest landscape gradient, even at very fine spatial scales, resulting in a complex pattern of cycling that defies simple forecasting techniques. (4) In the Border Lakes region of Ontario and Minnesota, where the two insect species coexist in a mixedwood landscape of hardwood and conifers, outbreak cycle intensity in each species varies spatially and temporally in response to host forest landscape structure. Much attention has been given to the effect of top-down agents in driving synchronizable population cycles. However, foliage loss, tree death, and forest succession at stem, stand, and landscape scales affect larval and adult dispersal success, and may serve to override regulatory processes that cause otherwise top-down-driven periodic, synchronized, and predictable population oscillations to become aperiodic, asynchronous, and unpredictable. Incorporating bottom-up effects at multiple spatial and temporal scales may be the key to making significant improvements in forest insect outbreak forecasting.

Unveiling the threshold in forest patch shapes to soil retention ecosystem services

Soil erosion is a critical process that leads to landscape degradation, compromising soil fertility and ecosystem functions. Forest ecosystems, with their intricate characteristics, play a pivotal role in mitigating soil erosion and providing soil retention ecosystem services (SRES). This study explores the impact of forest patch thresholds and critical points on soil erosion rates, focusing on 401 catchments in Poland using generalised additive models to identify thresholds and critical points in forest patches.Landscape metrics were applied to measure landscape structure, including shape, fractal dimension, contiguity, related circumscribing circles, and perimeter-area ratio indexes. These metrics, along with slope, rainfall, organic carbon content, water content, and clay ratio variables, were considered dependent variables in the models. The developed models have demonstrated reliable performance in estimating soil erosion rates, with a significant deviation explained from 80.5 to 81.1 for coniferous forest patches, 79.1 to 80.1 for broad-leave forest patches, and 80.9 to 81.4 for mixed forest patches at p < 0.05.In broad-leaved forests, three thresholds are identified in the shape index, which influence soil erosion rates in a complex manner. For coniferous forests, thresholds in the perimeter area ratio, related circumscribing circles, and contiguity indexes exhibit nonlinear relationships with soil erosion rates. Mixed forests show two thresholds in the related circumscribing circle and one in the fractal dimension index, affecting soil erosion rates differently.This research contributes significantly to understanding the interplay between forest patch shapes and soil erosion rates, providing decision support for land use planning. The identified thresholds and critical points offer valuable tools to enhance sustainable landscape functionality, emphasizing the importance of considering forest landscape structure in preserving soil retention ecosystem services.

Lower wood stiffness in old-growth than in post-cut and post-fire stands indicates forest structure is a key driver of wood properties in black spruce

Forest fires and logging drive the structure of boreal forest landscapes. According to recent studies, stand origin is a key driver of the variation in wood properties in black spruce (Picea mariana (Mill.) BSP.), although the underlying mechanisms remain to be elucidated. By comparing post-cut, post-fire and old-growth forests, this study aimed to better distinguish the effects of stand structure from those of the seed or layer origin of the trees on wood properties. We conducted comparative analyses based on ecological characteristics of the sites and static bending tests of small, defect-free wood specimens. Black spruce stands with a regular structure established after logging or fire exhibited higher stiffness at a given cambial age than old-growth forests with irregular structures, as well as lower wood density in the first 40 rings near the pith. However, the bending strength was comparable in all three types of forests studied. Differences in wood stiffness among stand types appeared to be driven more by stand structure than by the seed or layer origin of the stems.

The Application of Geographic Information System in Urban Forest Ecological Compensation and Sustainable Development Evaluation

Urban forests can alleviate the urban heat island effect, improve air quality, and improve residents’ mental health. By studying urban forests, these resources can be better used and managed to create more livable urban environments. Therefore, the urban forest in the Taishan region is taken as the research object, and the ecological compensation and sustainable development of urban forest in Tai’an City are deeply analyzed by GIS. It divided the area into forest land, water bodies, wetlands, grasslands, and shrubs as the basic ecosystem types. And through secondary interpretation and combination, a complete urban forest information database was established. To evaluate the comprehensive benefits of urban forests, the analytic hierarchy process was utilized to establish a corresponding evaluation index system. Based on the assessment outcomes of the comprehensive benefits of urban forests in the area, a standard accounting method for urban forest ecological compensation was proposed. The results showed that each index of the comprehensive benefits of urban forests and the random consistency ratio were both less than 0.1. This indicated that the matrix calculation results of various indicators of urban forest comprehensive benefits had good consistency. At the target level, the comprehensive evaluation score of urban forests in the study area was 7.69. At the factor level, the weight value of the urban forest landscape structure was 0.675, and the comprehensive score was 7.62. The weight value of urban forest comprehensive benefits was 0.325, and the comprehensive score was 7.82. The quantitative weight value of urban forest greening in the study area was 0.6138, with a comprehensive score of 7.57. Based on the analysis of the issues in urban forests and ecological compensation in the research area of Tai’an City, corresponding ecological compensation strategies have been proposed. It is of great value to study the urban forest of Tai’an city, which can help to formulate more effective urban planning and sustainable development strategies. The research results can also provide a valuable reference and inspiration for the improvement of urban forest ecological environment and biodiversity protection in other areas.

Current status of the remaining Mexican cloud forests: landscape findings and conservation initiatives.

Tropical montane cloud forests are known for their unique biodiversity and their critical role in sustaining ecosystem services; however, approximately 50% of their original cover in Mexico was estimated to have been lost by 1998. The Mexican ecoregion that supports these ecosystems experienced one of the highest rates of deforestation between 2001 and 2021. Thus, a more recent evaluation of Mexico's cloud forests is required. There is limited data on the landscape structure of cloud forests in Mexico, despite the possible application of landscape factors in conservation planning. Here, we estimated the average total area, number of patches, effective mesh size, total edge, and the shape of mixed forests that was present in 2020 within polygons of cloud forests defined in 1999 by Mexico's National Commission for the Use and Knowledge of Biodiversity (CONABIO for its acronym in Spanish). We estimated land cover using data from the North American Land Change Monitoring System, which classifies cloud forests as mixed forests. We found that eight out of the 109 polygons have no mixed forests and that an average of 49% of the 1,768,914 ha of cloud forests polygons are now covered by mixed forests distributed across 13 states. Additionally, within the remaining 101 polygons that do contain this type of vegetation, mixed forest is distributed on average across 140 patches (range = 1-1,473); 80% of these forests have very low effective mesh size values; 90% of them have low total edge values (<2,000 km); and their shapes tend to be uniformly distributed. Furthermore, most of cloud forest polygons are located outside of federal protected areas. Overall, our results suggest that the remaining Mexican cloud forests are extremely vulnerable and fragmented and that their extent has steadily declined since 1999. To ensure the survival of Mexican cloud forests, it will be crucial to prioritize high-diversity areas, strengthen protection in critical zones, establish ecological corridors, encourage sustainable practices, and actively engage local communities. This study highlights the complex issues and inherent heterogeneity that characterize cloud forest ecosystems in Mexico and provides crucial insights for conservation.

Confronting the cycle synchronisation paradigm of defoliator outbreaks in space and time—Evidence from two systems in a mixed‐species forest landscape

Abstract Defoliators cause extensive damage in boreal and temperate forests of the world. Considerable effort has been invested to understand their individual population dynamics, and despite ample theorising, there is little empirical evidence on factors causing spatial synchrony of pest eruptions at landscape scales. We report on the landscape‐level effect of forest configuration and composition on the intensity of outbreaks of spruce budworm and forest tent caterpillar in a mixedwood boreal forest in northern Minnesota (USA) and adjacent Ontario (Canada), and how this is related to the degree of spatial synchrony in each species' outbreak cycling. Using a large spatiotemporal tree‐ring reconstruction of outbreak impacts across these two systems, we evaluate two contrasting theories governing defoliator outbreaks: harmonic oscillation (a.k.a. ‘clockwork’) and relaxation oscillation (a.k.a. ‘catastrophe’), each with consequences linked to top‐down versus bottom‐up influences on outbreak behaviour in time and space. We find synchrony varies temporally, among outbreak cycles and in direct proportion to cycle peak intensity; however, cycle peak intensities are distributed bimodally in time, and so, therefore, are synchrony coefficients. Spatially, the area where each pest species currently cycles with the greatest peak intensity and synchrony is where their preferred host trees are currently found in greatest proportion. Despite overall synchrony in cycling, we found, in both systems, a persistent negative spatial correlation among successive eruptive pulses of defoliation. Many of these eruptions failed to spread spatially and to coalesce with other spot eruptions to form extensive area‐wide outbreaks. Eruptions often fail to spread at the hardwood‐conifer interface, resulting in outbreak pulses that systematically bounce back and forth between landscape types, particularly when systems were cycling at low amplitude. These over‐dispersed spatial patterns of pulse impact are consistent with a contagious theory of eruption and outbreak spread. They could be considered consistent with harmonic oscillation theory only for populations cycling at different frequencies, with cycling frequency determined by host forest landscape structure. Synthesis. We find that defoliator outbreak dynamics across systems include spatiotemporal signatures of each theoretical paradigm—suggesting a hybrid approach will better characterise outbreak behaviour. Host concentration influences which paradigm dominates the spatial dynamics in any given forest landscape context. Because of the synchronising effect of host concentration on forest insect spatial dynamics, mixedwoods appear to be less prone to intense, synchronised defoliator attack than forests of pure hardwood or pure conifer.

Landscape Structure and Fragmentation: Key Factors in the Characterisation of Urban and Peri-Urban Forests in Slovenia

Urban and peri-urban forests are strongly influenced by urbanisation and infrastructure-driven development. The main objective of the study is to evaluate and assess key factors characterising of urban and peri-urban forests in Slovenian regions with large differences in landscape fragmentation, from the Pannonian Plain to the Alps and the Mediterranean Sea. To assess landscape fragmentation and potential urban and peri-urban forests (UPFs), we used a spatial model of landscape structure and spatial characteristics of forests’ fragmentation and connectivity. The basis for estimating landscape structure and spatial characteristics of UPFs was tested for the 69 settlements with city status and for 150 smaller, rural settlements, which are the centres of individual municipalities. Of the 219 Slovenian settlements analysed, forest core areas within walking distance were estimated for 98% of the settlements. The proportion of the walking distance area with forest cover and 100 m or more from the forest edge is no more than one tenth of this area for 45% of Slovenian towns and for 42% of smaller settlements. By assessing the gradients of landscape ecological variables and accessibility of UPFs, it is possible to compare UPFs in different regions and take them into account when preparing guidelines for spatial planning based on landscape structure principles at the local level. Large differences in the landscape and UPF fragmentation within cities and settlements highlight the importance of spatial planning that adapts to the individuality of the landscape and each UPF.

Not all roads are barriers: Large mammals use logging roads in a timber concession of south-eastern Cameroon

In the literature, roads are often considered to be barriers for large vertebrates. In central Africa, the creation of roads and skid trails by logging operations leads to changes in the structure of forest landscapes that could influence wildlife movements. To assess the use of logging roads by six emblematic species of the central African forests, we conducted a camera trap (CT) survey on three types of tracks (secondary roads, skid trails, and elephant paths as control) in a logging concession of south-eastern Cameroon. The relative abundance indices (RAI) of each species derived from the CT data were used in a mixed linear model to test the effects of four factors (type of track; time: day vs. night; gregariousness: alone vs. group; and time after logging: less than one year vs. between one and two years). The results showed no preference for any type of track for gorillas (Gorilla gorilla) and chimpanzees (Pan troglodytes). In contrast, significantly higher RAI on secondary roads were observed for buffalos (Syncerus caffer), forest elephants (Loxodonta cyclotis), and bongos (Tragelaphus eurycerus). For the last two, the difference was only significant if they were detected in the most recently logged areas, at night (for elephants), or alone (for bongos). We could not test for leopard (Panthera pardus) as we captured only two events. Although none of the species appear to avoid roads and skid trails, nor do they perceive them as a barrier, further studies should be conducted to increase sampling efforts over time and space to consider seasonality, vegetation growth after logging, geographical variability, and other anthropogenic influence. However, these first results reveal the importance of closing roads after logging to limit encounters between wildlife and humans and highlight the relevance of characterizing roads (type of road, width, surfacing, and canopy structure over the road) when studying their impact on wildlife.

Natural Forests or Cultural Forests? Forest Changes within Italian Protected Areas in the Last 85 Years

The cultural dimension of many forests is not adequately considered by current forest definitions, policies, inventories, and management. Moreover, the concept of “protected area” as a synonym of “natural area” ignores that many forests today included in protected areas (PAs) have been managed and exploited for centuries. The abandonment of rural areas that occurred in the last 60 years in EU countries caused the expansion of forests, with the risk of a homogenization of forest typologies, the loss of cultural features, and the loss of biodiversity at the landscape scale. The aim of this study is to investigate the origin and evolution of forests within Italian PAs in the last 85 years through GIS-based spatial analyses. In 1936, only a minority of the surface included in current PAs was covered by forests, ranging from 32% in Natura 2000 sites to 35% in regional PAs. Forest surface in Italian PAs increased in the last 85 years (from +33.1% in regional PAs to +45.2% in national PAs), mainly due to secondary successions, with a growth rate in Natura 2000 sites equal to 8709 ha/year. In regional PAs, 40.1% of the current forest cover originated after 1936, and this percentage increases to 43% in Natura 2000 sites and to 44.7% in national PAs. The altitudinal range of 500–1000 m a.s.l. is the one most affected by forest spread. In addition, most of the forests in 1936 were regularly managed as coppice: 44% in national PAs, 56% in Natura 2000 sites, and 62% in regional PAs. The study confirms that most of the forest surface included in Italian PAs has a clear cultural origin and is the consequence of the abandonment of pastures and/or cultivations that occurred in the last 85 years. PA management should take into consideration that open areas are shrinking and that the diversity of habitats and forest communities is strongly linked to the persistence of traditional human activities. The current forest characteristics (species composition, vertical and horizontal structure) are also the result of past management, and only active management of forest resources can counteract the homogenization of forest communities and landscape structure.

基于MSPA分析的福建省生态网络构建

PDF HTML阅读 XML下载 导出引用 引用提醒 基于MSPA分析的福建省生态网络构建 DOI: 10.5846/stxb202107101863 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31971639）；福建省自然科学基金项目（2019J01406） Construction of ecological network in Fujian Province based on Morphological Spatial Pattern Analysis Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:快速城镇化进程导致森林景观破碎化、连通性下降，严重威胁区域可持续发展、生物多样性保护和生态服务能力的维持。生态网络构建是提高景观连接度，维持物种扩散过程，保护生物多样性的有效手段。以福建省为例，借助形态学空间格局分析（MSPA）探讨2000、2010和2020年的森林景观结构动态变化，并在利用组分数（NC）与整体连通性指数（IIC）确定适宜距离阈值的基础上，根据可能连通性指数（PC）筛选生态源地；从人-地关系角度选择路网分布、建设用地分布、土地覆盖类型、坡度四种评价因子构建阻力面，采用最小阻力模型（MCR）提取生态廊道形成初步生态网络，进一步计算PC指数对生态廊道进行重要性分级；最后基于图论法，利用闭合度α、线点率β、网络连接度γ对所构建的生态网络进行定量评价。结果表明：（1）近20年来福建省森林景观结构较为稳定，其中核心区占比高达76.27%，但仍存在一定程度的破碎化趋势；（2）根据NC与IIC的计算结果，以500m为合适的距离阈值计算了PC，据此识别出15处生态源地，多位于闽西及闽北地区；（3）采用MCR模型提取了105条生态廊道，其中重要生态廊道27条，分布均匀且连通四方；（4）生态廊道穿过的土地利用类型中受人类干扰小的林草地占比超过85%，耕地占比12.33%，受人类干扰强烈的建设用地及未利用土地占比不足1%；（5）识别出生态节点62个，生态网络结构指数α=0.37，β=1.69，γ=0.58，表明网络结构较为合理，连通性较好。研究结果可从整体角度出发指导福建省生态安全格局构建，以期为土地资源有限背景下，省域尺度复合种群保护工作提供科学依据。 Abstract:The rapid urbanization process has led to the fragmentation and the declining in the connectivity of forest landscapes, which seriously threatened the sustainable development of regions, including the maintenance of biodiversity and ecological service. The construction of ecological network is an effective means to improve the connectivity of landscape, maintain the spread of species, and thus protect biodiversity. Taking Fujian Province as a case, the Morphological Spatial Pattern Analysis (MSPA) was employed to explore the dynamic changes of forest landscape structure in 2000, 2010 and 2020. Then, the appropriate distance threshold of patch connectivity was determined according to the number of components (NC) and the integral index of connectivity (IIC). On this basis, the probability connectivity index (PC) was calculated to identify the ecological sources. Then, from the perspective of human-land relationship, the factors including the distance from road network, distance from construction land, land cover type, and slope, were selected to construct the comprehensive resistance surface, which reflects the degree of obstruction for the species travelling between the ecological sources (i.e., core forest patches). To this end, the minimum cumulative resistance (MCR) model was adopted to extract the preliminary ecological corridors, which was ranked and filtered subsequently by the PC values. Finally, based on the graph theory method, the quantitative evaluation of the ecological network α, β, and γ index were carried out. The results show that:(1) the forest landscape structure in Fujian Province has been relatively stable in the past 20 years, of which the core area accounted for 76.27% of the total landscape area, but it still tended to fragmentation to a certain degree; (2) According to the results of NC and IIC, the PC value was calculated with a distance threshold of 500 meters, and 15 ecological sources were identified, which were mostly in the western and northern regions of Fujian; (3) 105 ecological corridors were extracted by MCR model, of which 27 were important corridors, which were evenly distributed and extended in all directions across the study area; (4) The ecological corridors and land use were superimposed to obtain the proportion of the corridors passing through each landscape type, of which the forests and grasslands less disturbed by humans accounted for more than 85%, the cultivated land accounted for 12%, while the construction land and unused land strongly disturbed by humans accounted for less than 1%; (5) Totally, 62 ecological nodes were identified, and the ecological network structure index α, β and γ were 0.37, 1.69 and 0.58, respectively, indicating that the reasonability of the network structure and the goodness in the network connectivity. The results can shed a light on the construction of the ecological security pattern in Fujian Province from a holistic perspective, and provide a scientific basis for biodiversity conservation at the provincial scale with the limited land resources. 参考文献 相似文献 引证文献

Expanding wildland-urban interface alters forest structure and landscape context in the northern United States

The wildland-urban interface (WUI), where housing intermingles with wildland vegetation, is the fastest-growing land use type in the United States. Given the ecological and social benefits of forest ecosystems, there is a growing need to more fully understand how such development alters the landscape context and structure of these WUI forests. In a space-for-time analysis we utilized land cover data, forest inventory plots, and housing density data over time to examine differences in forest characteristics of the northern US across three WUI change classes: (a) forest that has been in WUI housing density levels since at least 1990 (old-WUI), (b) forest where development crossed the WUI housing density threshold after 1990 (new-WUI), and (c) forest with little to no housing development (non-WUI). Of the 184 million acres of forest in the study area, 34 million acres (19%) were in old-WUI, 12 million acres (7%) were new-WUI, and 136 million acres (74%) were non-WUI. In general, as areas transitioned from non-WUI to newer WUI to older more established WUI, the forest was associated with decreased spatial integrity, increased forest-developed edges, and lower proportions of forest in the surrounding landscape. Forest in the WUI had greater carbon storage, with greater aboveground biomass, relative stand density, and more live trees per hectare than non-WUI forest, suggesting greater capacity to sequester carbon compared to non-WUI forest. At the same time, WUI forest also had significantly reduced structural diversity compared to non-WUI forest, with fewer saplings, seedlings, and dead trees per hectare. Forest that more recently crossed the WUI housing density threshold appeared to be on a trajectory towards that of old-WUI forest. These differences in forest structure across the northern US suggest reduced capacity for forest regeneration in the WUI and the potential for changes in other ecological functions.

Enfoque de paisaje para apoyar el manejo forestal sostenible en la región Mixteca Alta, Oaxaca, México

Forest landscape structure comprises a mosaic of natural and human-modified units, which when well depicted, may help to plan and implement forest management policies, which commonly assume territorial homogeneity. Usually, forest policies lack the use of spatial tools that can help scale up conservation program in heterogeneous forested landscapes. This paper applied a conceptual-methodological framework as baseline to guide regional strategies and scale-up community collective action based on local forestry ejidos and communities. The study case was conducted in the Mixteca Alta, a forestry region in Oaxaca, Mexico, where common property prevails. Zoning was made based on biophysical, social, and forest management criteria. A total of 97 communities were surveyed and the region was disaggregated into five zones based on precipitation, watersheds, community forest management experience and level of regional collective action. Each zone was recognized as having different forestry potentials and intervention needs, ranging from restoration to timber and non-timber product management. This zoning proved the potential to guide forest projects and promote joint regional forest development. The potential use of landscape zoning was discussed in the light of the current need for scale-up forest policies.

GEF Innovative Forest Management Plan—Taking Grassland Forest Farm in Fengning County as an Example

Currently, China’s forest ecosystem focus is shifting from a single management objective to multiple management objectives, aiming to improve forest quality and maximize the benefits of ecosystem services. Many difficulties and problems are encountered in the long-term development of most northern state-owned forest farms—for example, the fragmentation and degradation of forest landscapes caused by poor forest management and extensive land use—resulting in an ecosystem that is unable to provide optimal services. This research was conducted on the Fengning Grassland Forest Farm, which is based on the GEF project of state-owned forest farms. We applied lessons from international advanced concepts, such as landscape restoration, and combinecombined all types of existing data and supplementary survey data on forest farms. In addition, we used multivariate statistical analysis and geostatistical analysis methods to optimize spatial layout and forest landscape structure. Strategies of landscape restoration and optimization, forest quality improvement, and grassland ecological restoration were proposed. A forest growth model was established to predict the annual growth of forests, calculate sustainable levels of annual cutting, calculate biomass and carbon sequestration in the management period, and evaluate the value of the ecological service functions of forest ecosystems in forest farms. Finally, a set of forest management methods was developed to effectively improve the sustainable management level of state-owned forest farms and enhance the service function of forest ecosystems.

西双版纳地区森林变化碳效应与生态效益评估

减少发展中国家因森林砍伐与森林退化导致的碳排放和保持碳储量（REDD+），不仅能减少因森林砍伐和森林退化造成的碳排放，而且还可以带来其它生态效益，如减缓森林破碎化、保护生物多样性和增强水土保持功能等。以中国的西双版纳地区为研究区域，以毁林最严重的1976-2007年为REDD+基线，基于卫星影像，并结合植被指数，提取了研究区的土地利用变化信息。基于IPCC温室气体清单方法，计算了研究区的森林碳储量变化。在此基础上，对REDD+的碳汇效益和生态效益进行了系统综合评估。结果显示：（1）1976-2007年间天然林碳储量从占总碳储量的78.24%减少至50.52%，这是造成西双版纳地区碳储量减少的主要原因。（2）1976-2007年，天然林的斑块数量和平均最近邻距离分别增加了120.00%和25.21%，平均斑块面积下降了71.98%，说明天然林的破碎化程度加剧。从研究区整体景观格局来看，斑块数量、Shannon多样性指数和Shannon均一性指数分别增加了8.16%、51.39%和34.07%；与此同时，平均斑块面积和景观内聚力指数分别下降了26.26%和2.13%，表明研究区整体景观格局朝破碎化方向发展，这和碳排放的增加相一致。（3）该区的土壤侵蚀程度逐年加剧，并与碳储量的减少密切相关。分析表明，土壤侵蚀剧烈的区域，其平均碳排放也相对较高。1999年到2007年间，剧烈侵蚀区域的平均碳排放是轻度侵蚀区域的6倍多。这些结果说明：如果REDD+政策得以实施，不仅能减少因毁林和森林退化导致的碳排放，而且能带来高的生态效益。从这个角度出发，REDD+的本质可以认为是以"增汇"或"减排"为主导功能，同时提升生态效益的一种管理方式。;The REDD+ partnership works to promote the reduction of greenhouse gas (GHG) emissions by reducing emissions from deforestation and forest degradation in the developing countries through positive incentives and conversation of forest carbon stocks. It is regarded as an essential component of the post-2012 climate regime to stabilize GHG emissions and engage the developing countries in worldwide mitigation endeavors. If cost-efficient carbon benefits can be achieved through REDD+, increases in atmospheric CO₂ concentrations could be slowed, effectively buying much needed time for countries to move to lower emissions technologies. We chose tropical forests in Xishuangbanna of China as our study area and took the most severe deforestation from 1976 to 2007 as the baseline of REDD+. Land use information was obtained through the combination of Landsat TM images and Normalized Difference Vegetation Index masks. Forest carbon storage change in the study area was firstly calculated based on IPCC methodology. Secondly ecosystem-based benefits from REDD+ were assessed systematically. Our results showed that from 1976 to 2007, the natural forest carbon storage decreased from 78.24% to 50.52% of total carbon storage, which was the main reason for the reduction of carbon storage in Xishuangbanna. At the meantime, significant degradation of ecosystem services emerged. This was demonstrated by two important indicators:forest fragmentation and soil erosion. For example, from 1976 to 2007 the percentage change in the carbon stocks was 1.4%, accompanying with increasing 8.16% in number of patches, 51.39% in Shannon's diversity index and 34.07% in shannon's evenness index. Meanwhile, mean path area and patch cohesion index decreased by 26.26% and 2.13%, respectively. It suggested that the forest ecosystem was changing in both carbon storage and forest landscape structure. The number of patches and average nearest neighbor distance of natural forest increased by 120.00% and 25.21%, respectively, and the average patch area decreased by 71.98%, indicating the degree of exacerbated fragmentation in natural forest. In this sense, carbon emission and forest fragmentation were well integrated. Furthermore, we investigated relationship between carbon emission and soil erosion and high correlation was found. For example, carbon emissions which accounted for 45% of the total located in the high erosion area, which is 18% of the whole study area. As a result, when forests that would have been lost or degraded are retained or restored through REDD+, they deliver ‘multiple benefits’ in addition to protecting or enhancing carbon stocks. These ecosystem-based benefits may include conservation of forest biodiversity, water regulation, soil conservation, timber, forest foods and other non-timber forest products, most of which have been demonstrated or proved in this study. By securing benefits beyond carbon, REDD+ has the potential to encourage countries to realize a broader range of values.

Effects of stand edges on the structure, functioning, and diversity of a temperate mountain forest landscape

AbstractHuman land use is fragmenting forests around the globe, increasing the edge density in forest landscapes. More frequent natural disturbances also increase the presence of edges in forest ecosystems. Studying a mountain landscape in the Eastern Alps, we contrasted 661 plots situated at varying distances from a stand edge with 615 plots sampled in forest interiors. Our objectives were (1) to analyze the strength of edge effects on forest structure, functioning, and diversity; (2) to determine the penetration depth of edge effects into the forest interior; and (3) to quantify the difference between permanent edges (i.e., to a different land cover type) and transient edges (as created e.g., by natural disturbances). Edges affected forest biomass accumulation negatively (basal area, litter depth, live tree carbon), but had positive effects on diversity (variation in tree diameter, effective plant species number, plant species richness, number of red‐listed plant species). Biodiversity indicators responded most strongly to the presence of edges. The maximum distance of a significant edge effect was &lt;50 m across all indicators. Effects on forest structure and functioning were generally stronger at transient edges compared to permanent edges. Our findings highlight that both permanent and transient edges have a considerable influence on forest ecosystems and should be considered more explicitly in the analysis and management of forest landscapes.

Forest connectivity percolation thresholds for fire spread under different weather conditions

How fuel influences fire spread at different spatial scales has been broadly studied but it is still under research. Although prior research has generally explored fuel effects at the stand scale, there is increasing recognition that forest structure and composition at the landscape scale can regulate fire size when weather conditions allow fire to have enough initial capacity to spread. Simulation models have usually been adopted to test forest landscape structure’s effect on fire activity, but we still lack empirical evidence of these effects on a broad scale and using multiple fires. In this study, we use the graph theory and the percolation theory to test the relationship between forest functional connectivity and fire size in a Mediterranean region (Catalonia, NE Spain, ~32000 km2) and under different weather conditions. Using a total sample of 554 fires that occurred between 1987 and 2019, we relate fire size with forest connectivity inside the fire perimeter, which we describe with different interpretations of forest-land cover maps and at different fire dispersal distances (10-, 100- and 2000- meters spotting capacity). Previously, fires were classified according to the weather and drought conditions in which they occurred (windy, arid or regular days, and dry or non-dry conditions) with the hypothesis that the capacity of fire to “read” the forest landscape differs according to weather variables. We found that a forest percolation threshold existed for most types of fires: forest connectivity had a positive influence on fire size until a threshold at which the landscape becomes continuous and other processes to control fire cease to have effect. This percolation threshold is about 0.40 for fires occurring under arid conditions. Under regular weather conditions, the threshold is non-existent and forest connectivity always exerts a positive effect on fire size. Notably, forest connectivity has no influence on fire size on windy- and dry-weather days. All these results are of paramount relevance for forest and landscape management aimed at reducing wildfire risk, since for fires driven by extreme weather conditions (more prone to happen in the future), landscape offers less opportunities to stop them. Researchers and managers need to identify the probability of experiencing each of the different weather types in a climate change context to boost the management of forests and landscapes in a cost-effective way.

Spatiotemporal Patterns of Ant Metacommunity in a Montane Forest Archipelago.

Naturally fragmented landscapes are adequate systems for evaluating patterns and mechanisms that determine species distribution without confounding effects of anthropogenic fragmentation and habitat loss. We aimed to evaluate an ant metacommunity's spatiotemporal patterns in montane forest islands amid a grassland-dominated matrix. We assessed these patterns by deconstructing the ant metacommunity into forest-dependent and habitat generalist species. We sampled twice a year (summer and winter) over 2 years (2014 and 2015), using soil and arboreal pitfall traps, in fourteen forest islands (varying in size, shape, and connectivity) in the Espinhaço Range Biosphere Reserve, Brazil. We evaluated the relationship between ant species richness, composition (β-diversity), and predictor variables of forest island structure (canopy cover and understory density) and landscape structure (forest amount, number of forest islands, and shape). We sampled 99 ant species, 66.7% of which were classified as forest-dependent and 33.3% as habitat generalist species. We found that ant β-diversity was higher in space than in time, and that species composition variation in time (temporal β-diversity) differed between ant species groups. Both ant groups responded differently to forest island and landscape structure characteristics. Landscape structure seems to act as a spatial filter and the forest islands' local characteristics as an environmental filter, which jointly determine the local and regional diversity. We demonstrate the importance that forest archipelagos pose to ant metacommunity's structure and dynamics in montane tropical regions. Mountaintop conservation and management strategies must consider the forest island archipelago to maintain the biodiversity and the functioning of these systems.

Forest landscape structure influences the cyclic‐eruptive spatial dynamics of forest tent caterpillar outbreaks

AbstractA fundamental question in forest insect ecology is the role of forest landscape structure, particularly the amount and spatial configuration of host tree species, in shaping the dynamics of recurring forest insect outbreaks. For forest tent caterpillar (FTC), independent studies do not converge on a singular conclusion, although all indicate that forest structure influences outbreak dynamics. These studies also vary in how they treat climate as a covariate. We evaluated the relative importance of host forest landscape composition and configuration, as well as climate, for their influence on FTC outbreak cycling in the twentieth century. We predicted that FTC outbreaks would exhibit greater synchrony and intensity within areas associated with higher abundance of host trees. We reconstructed FTC outbreaks from 1928 to 2006 using tree‐ring analysis within a well‐structured experimental landscape located in northwestern Ontario and northern Minnesota. Time‐series clustering and spatial nonparametric covariance were used to determine whether similarities in time series and patterns in spatial synchrony corresponded with land management history. Using constrained ordination, we compared statistical properties of outbreak time series to landscape variables representing host abundance, forest configuration, and climate. We found no evidence of climatic effects at the scale of this study, but a significant albeit small influence of landscape structure on outbreak dynamics. Outbreaks were more synchronous and more cyclic within managed zones containing a greater relative abundance of aspen and other hardwood host tree species, compared with the more conifer‐dominated Wilderness area. Yet, we also observed asynchronous outbreak dynamics across the study area, such that correlations with slower‐changing forest landscape variables varied starkly among outbreak pulses. Consequently, the strength of relationship between landscape variables and FTC outbreak patterns varied strongly through time—a result that may explain why short‐term studies yield conclusions that are at odds with one another. Our results speak to the importance of long time series, contrasting landscape structure, use of multivariate methods, and controlling for climatic variation when investigating the effects of forest landscape structure on the cyclic‐eruptive spatial dynamics for forest defoliators.

Spatially-Explicit Prediction of Wildfire Burn Probability Using Remotely-Sensed and Ancillary Data

Wildfire is a critical process shaping the structure and composition of forest landscapes of western Canada. Spatially-explicit forest disturbance history and forest structure estimated using remotely-sensed data enables the characterization of burn probability, defined as the susceptibility of landscapes to fire hazard over time. In this research, we leveraged the Landsat archive to determine the capacity of land cover, forest structure, and forest disturbance information, together with ancillary data, to estimate burn probability. We analyzed the interactions between a number of contributing factors and identified landscapes with high probability to burn across forested ecosystems of Saskatchewan, Canada. Overall, we found that forests composed of coniferous species, with shorter trees (<3 m), low canopy height variability, an open stand structure (<10% canopy cover), and low timber volumes (<50 m3/ha), had higher burn probabilities. A 2015 burn probability map indicated that forests that did burn in 2015 (determined using independently mapped wildfires) had a median predicted burn probability of 81%, while the median burn probability for unburned forest area was 19%. This paper demonstrates the potential to generate detailed and spatially-explicit burn probability maps from time series remote sensing data to inform wildland fire risk modeling, management, and mitigation.