Forest Spatial Structure Research Articles

Forest ecosystems functionality evaluation by multiscale and multitemporal analysis of ecological network

The aim of this study was to model the relationships between forest spatial structure and potential forest vulnerability, resilience and resistance (FVRR) in Molise (Italy) on the basis of a multitemporal and multiresolution raster dataset. The FVRR index of forest ecosystems was quantified and mapped by two different approaches, such as a ‘species-specific’ and a ‘species-unspecific’ approach, modelling the proximity to a potential ecological optimum by fuzzy functions. The temporal trends between the summing up of index values of each model are similar. The ‘species-unspecific’ approach seems to be not scale dependent when applied for monitoring temporal trends, since trends of the index of low and high resolution datasets are nearly the same.

天目山近自然毛竹林空间结构与胸径的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 天目山近自然毛竹林空间结构与胸径的关系 DOI: 10.5846/stxb201308252154 作者: 作者单位: 浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,天目山国家级自然保护区管理局 临安 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(31170595); 国家"十二五"科技支撑计划(2012BAD22B0503); 浙江省重点科技创新团队(2010R50030); 教育部留学回国人员科研启动金项目(20101561); 国家林业局造林司委托项目(SFA2130218-2) The relationship between spatial structure and DBH of close-to-nature Phyllostachys edulis stands in Tianmu Mountain Author: Affiliation: School of Environment and Resource,Zhejiang A F University,School of Environment and Resource,Zhejiang A F University,School of Environment and Resource,Zhejiang A F University,School of Environment and Resource,Zhejiang A F University,Management Office,National Nature Reserve of Tianmu Mountain,Linan 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:以浙江省天目山国家级自然保护区内的近自然毛竹林为研究对象,设置1块100m×100m的固定标准地,采用相邻网格调查法划分为100个调查单元,通过全站仪精确定位毛竹基部的三维坐标(X, Y, Z),利用角尺度、大小比数和年龄隔离度3个林分空间结构指数,并按毛竹胸径大小划分为Ⅰ(DBH < 7cm) 、Ⅱ(7cm ≤ DBH<13cm)、Ⅲ(DBH ≥ 13cm)3个径级,分析近自然毛竹林空间结构与胸径的关系。结果表明:毛竹林直径结构呈右偏近似正态分布,与乔木同龄林直径结构较接近;Ⅰ、Ⅱ、Ⅲ径级毛竹以及全林分的空间分布格局分别为聚集、随机、随机和随机,毛竹林角尺度随径阶的增加有减小的趋势,且服从幂函数关系,决定系数R2=0.7793,各径阶角尺度无显著性差异(P > 0.05);毛竹林整体处于中庸状态,胸径大小分化不明显,各径级毛竹优势度排序为Ⅲ > Ⅱ > Ⅰ,毛竹林大小比数随径阶的增加而减小,与胸径呈线性关系,决定系数R2=0.9233,各径阶大小比数差异极显著(P < 0.01);毛竹林的平均年龄隔离度为0.8178,属强度至极强度异龄,各径级毛竹年龄隔离程度大小排序为Ⅲ > Ⅱ > Ⅰ,毛竹林年龄隔离度随径阶的增大呈现逐渐递增的趋势,且服从幂函数关系,决定系数R2=0.6774,各径阶年龄隔离度差异极显著(P < 0.01)。 Abstract:Tree diameter structure is an important and basic role in forest structure. For the reason that the diameter at breast height (DBH) can be easily and accurately measured. Because it has a close relationship with variables such as stand density, tree age, tree height, canopy, biodiversity and so on, diameter structure is often used as a direct-response stand structure characteristic. DBH belongs to a set of non-spatial forest structure factors, and is frequently used to analyze the relationship between stand structure and growth, e.g. Recently, studies of forest spatial structure have expanded, partly due to the fact that the DBH is an important factor in explaining the growth of trees, and in many cases because the diameter structure has been used to analyze the relationship between spatial structure and DBH. Similarly, DBH is also an important factor in reflecting the growth of moso bamboo (Phyllpstachys edulis) forests. The DBH of moso bamboo can directly influence leaf area and root area volume, which affects the growth of moso bamboo. Others have performed a number of research studies on the relationship between DBH and other bamboo forest structure factors, such as bamboo height, age composition, canopy structure, and so on. However, these factors are generally measures of non-spatial structure. Recently, research suggests that a distance-dependent spatial index can accurately describe the moso bamboo stand structure, and therefore it is important to analyze and control the relationship between moso bamboo stand structure and function. Previous studies rarely reported the relationship between moso bamboo stand spatial structure and diameter. Therefore, three spatial structure parameters, uniform angle index, neighborhood comparison and age mingling degree were used to analyze the relationship between moso bamboo spatial structure and diameter, and thus provide a theoretical basis for sustainable moso bamboo forest management. The study was established in a close-to nature moso bamboo stand in Tianmu Mountain National Nature Reserve, Zhejiang province. The study design involved a fixed plot of 1hm2 (100 m×100 m), which was divided into 100 units by adjacent grid inventory. Each moso bamboo was located in terms of x-, y-, and z-coordinates using a Total Station. Three spatial structure parameters, including neighborhood comparison, uniform angle index, age mingling degree were evaluated. The DBH was recorded into one of three classes: Ⅰclass (DBH < 7 cm), Ⅱ class (7 cm ≤ DBH < 13 cm), Ⅲ class (DBH ≥ 13 cm). These classes were used to analyzed the relationship between spatial structure and DBH of the close-to-nature moso bamboo stand. The results showed that the frequency distribution of DBH had a right-skewed normal distribution, which is the similar to even-aged arbor stands. The spatial pattern of class Ⅱand class Ⅲ was of random distribution, similar to the distribution of the whole stand, but the pattern of class Ⅰshowed an aggregation distribution pattern. The uniform angle indexes decreased with increasing diameter classes, and results showed that the uniform index had a powerful relationship with DBH, with the determination coefficient between DBH and uniform index being 0.7793. The uniform angle of different diameter classes showed no obvious significant difference (P > 0.05). The neighborhood comparison showed that for stands in an intermediate status, the DBH differentiation was not significant. The neighborhood comparison values showed that the ranking of the dominant degree was: Ⅲ > Ⅱ > Ⅰ. And the neighborhood comparisons decreased with increasing diameter classes, as well as had a significantly linear correlation with DBH (the determination coefficient was 0.9233). The neighborhood comparison of different diameter classes showed significant differences (P < 0.01). The average age mingling of the stand was 0.8178, suggesting the age mingling intensity was intensive. The age mingling values showed the ranking of age segregation was: Ⅲ > Ⅱ > Ⅰ. And age mingling increased with increasing diameter classes, as well as had a strong relationship with DBH, where the determination coefficient was 0.6774. The age mingling of different diameter classes was also significanly different (P < 0.01). 参考文献 相似文献 引证文献

Comparing the influence of large- and small-scale disturbances on forest heterogeneity: A simulation study for mangroves

Disturbances play a crucial role in various forest ecosystems and represent major shaping forces in forest succession and spatio-temporal processes. In this study, we simulated different disturbance regimes using the individual-based mangrove forest model KiWi. Frequent small-scaled gaps caused by lightning strikes and rare medium-sized patches caused by hurricanes were produced with varying size, severity and frequency. Additionally, a mixed regime including both lightning strikes and hurricanes was simulated. All three scenarios produced the same tree mortality rate over the simulation periods. We analyzed the temporal and spatial variations in these disturbances, taking into account their homogenizing or heterogenizing effects on the forest structure of a simulated area of 25ha. All disturbance regimes produced significantly more homogenizing effects on the spatial forest structure than an undisturbed scenario. The hurricane regime produced a temporal heterogenization of the forest structure, while the small-scaled frequent lightning strike gaps were not able to contribute to additional heterogeneity. This shows that the explicit implementation of the disturbances generates different forest structures. The simulation results were integrated into an existing conceptual model for mangrove forest dynamics.

Incorporating the mechanisms underlying inter-tree competition into a random point process model to improve spatial tree pattern analysis in forestry

The spatial structure of complex forest stands results from competitive interactions among trees which is one of the most important ecological processes influencing forest development. The aim of the study is to incorporate in a new class of random point process models a coherent representation of the competition process driving forest stand dynamics to establish a direct link between pattern and ecological processes. The resulting area-saturation model was defined by a set statistic characterised by overlapping discs representing tree interactions. Unlike previous approaches, this new spatial model has the advantage of allowing a straightforward interpretation of its parameters in terms of inter-tree competition. A 60m×60m plot of even-aged Scots pines was used to illustrate the potential of this approach in modelling the spatial structure of a plant community. The social status of each tree was taken into account, leading to a multivariate point pattern exhibiting various spatial properties (regularity, clustering and randomness) at different scales. We considered a hierarchical structure of interactions to account for the fact that competition for light is size-asymmetric. According to the analysis, the generalised area-saturation model has the required flexibility to capture complex spatial tree patterns.

Comparison of stand spatial structure in different plantations and natural forests in rocky mountain area of northern china

China is the global leader in afforestation efforts to restore degraded forest ecosystems. However, it is diffi cult for these efforts to completely substitute for natural forests. In order to reveal the differences between plantations and natural forests, we compared stand spatial structure of plantations, mixed plantations, and natural forests by using the mingling degree (M i ), uniform angle index (W i ), and neighborhood comparison ( U i ) in the Mulan-Weichang Forestry Administrative region of the rocky mountain area, northern China. The results indicated that natural forests were characterized by varying species composition, individual tree distribution, and competitive relationships, which were more complex than monoculture plantations. Forest management is benefi cial to stand spatial structure improvement, resulting in mixed plantations that are closer to natural forests. On this basis, China’s forest policy should shift focus from afforestation for area expansion to forest management for ecological improvement.

Wildland fires and moist deciduous forests of Chhattisgarh, India: divergent component assessment

We studied moist deciduous forests of Chhattisgarh, India (1) to assess the effect of four levels of historic wildland fire frequency (high, medium, low, and no-fire) on regeneration of seedlings in fire affected areas during pre and post-fire seasons, (2) to evaluate vegetation structure and diversity by layer in the four fire frequency zones, (3) to evaluate the impact of fire frequency on the structure of economically important tree species of the region, and (4) to quantify fuel loads by fire frequency level. We classified fire-affected areas into high, medium, low, and no-fire frequency classes based on government records. Tree species were unevenly distributed across fire frequency categories. Shrub density was maximum in zones of high fire frequency and minimum in low-frequency and no-fire zones. Lower tree density after fires indicated that regeneration of seedlings was reduced by fire. The population structure in the high-frequency zone was comprised of seedlings of size class (A) and saplings of size class (B), represented by Diospyros melanoxylon, Dalbergia sissoo, Shorea robusta and Tectona grandis. Younger and older trees were more abundant for Tectona grandis and Dalbargia sissoo after fire, whereas intermediate-aged trees were more abundant prefire, indicating that the latter age-class was thinned by the catastrophic effect of fire. The major contributing components of fuel load included duff litter and small woody branches and twigs on the forest floor. Total fuel load on the forest floor ranged from 2.2 to 3.38 Mg/ha. The net change in fuel load was positive in high- and medium-frequency fire zones and negative under low- and no-fire zones. Repeated fires, however, slowly reduced stand stability. An ecological approach is needed for fire management to restore the no-fire spatial and temporal structure of moist deciduous forests, their species composition and fuel loads. The management approach should incorporate participatory forest management. Use of controlled fire, fire lines and mapping of fire prone areas are fundamental principles of fire hazard reduction in these areas.

Мелиоративная роль дубрав Центральной лесостепи

Arena and ravine oak forests make up a single, suitable for each stage of development of forest steppe spatial structure of forests. According to the domestic foresters role of oak forests in the forest is much more important than their productivity. Forest cover of the region must correspond to its network of gullies and ravines. Current state of gullies and gully systems, direction climatic changes indicate the formation of favorable conditions for their natural overgrowth with trees and shrubs, which leads to stabilization of forest-steppe landscapes.

Relationships between stand spatial structure characteristics and influencing factors of broad-leaved Korean pine (Pinus koraiensis) forest in Liangshui Nature Reserve, northeast China

The relationships between stand spatial structure and influencing factors of broad-leaved Korean pine forest in Liangshui Nature Reserve of northeast China,was studied with the method of canonical correspondence analysis( CCA). The data were collected form the forest resource inventory of the study area in 2009,which contain 60 plots. However,only 28 plots of typical broad-leaved Korean pine were selected in this paper, including five stand spatial structure parameters and eighteen influencing factors. The results showed that the broad-leaved Korean pine forest of the study area had a reasonable stand spatial structure overall,e. g.,the horizontal distribution pattern of stands was mainly random distribution,the states of tree growth were at the doctrine of mean as a whole,and the mixed degree of species were also high. The relationships between stand spatial structure and influencing factors could be reflected by the CCA. The first CCA axis accounted for the stand age,slope,hardwood ratio and aspect,and the second CCA axis showed variation due to aspect,soil organic matter and mean diameter at breast height. On the whole,the combination of these six factors largely determined the stand spatial structure characteristics. Furthermore,the influencing factors were quantitatively assessed. The stand spatial structure of broad-leaved Korean pine forest explained by stand,terrain and soil factors reached 59. 20%. Within that,pure terrain factors accounted for up to 30. 68% of the variation,stand factors for 19. 01%, and soil factors for 8. 21%. Other undermined factors accounted for an additional 40. 80% of the variation.

近自然毛竹林空间结构动态变化研究

PDF HTML阅读 XML下载 导出引用 引用提醒 近自然毛竹林空间结构动态变化 DOI: 10.5846/stxb201307081859 作者: 作者单位: 浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,浙江农林大学环境与资源学院 临安,天目山国家级自然保护区管理局 临安 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（31170595）；国家十二五科技支撑计划（2012BAD22B0503）；浙江省重点科技创新团队（2010R50030）；教育部留学回国人员科研启动金项目（20101561） Dynamic analysis of spatial structure in a close-to-nature Phyllostachys edulis stands Author: Affiliation: 浙江农林大学,浙江农林大学,,, 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:2009年7月在浙江省天目山国家级自然保护区，建立了1块100 m×100 m的近自然毛竹林固定标准地，采用相邻网格法进行每竹调查，利用全站仪测量毛竹的三维坐标（X，Y，Z），结合2010-2012年的3次毛竹复查数据，利用角尺度、大小比数和年龄隔离度3个结构指数，分析毛竹林空间结构的动态特征。结果表明：天目山近自然毛竹林大小年现象明显，平均胸径逐年增加；空间分布格局特征表现为2009、2012年毛竹林呈随机分布，2010、2011年毛竹林呈聚集分布；各年份毛竹林角尺度均服从左偏近似正态分布，且各年份的角尺度无显著性差异（P > 0.05）；各年份毛竹林的平均大小比数均接近0.5，林分处于中庸状态；各年份毛竹林大小比数分布频率出现均衡分布特征，林分较稳定，且各年份间的大小比数无显著性差异；各年份毛竹林的年龄多样性及年龄隔离程度均较高；年龄隔离度逐年增加，毛竹小年向大年过渡期毛竹林年龄隔离度有显著性差异（P < 0.05），大年向小年的过渡期则无显著性差异。 Abstract:Moso bamboo (Phyllostachys edulis) forests are one of the most economic forests in China, and they possess a lot of advantages over other forest types, such as rapid growth, wide distribution, and high production. Traditional moso bamboo stand management involves a predatory management approach which focuses on economic benefits, blind pursuit the production of bamboo and bamboo shoots, and a lack of emphasis regarding the relationship between structure and function. Due to these reasons, this management leads to a series of problems such as soil degradation, increases in plant diseases and insect problems, the inability to withstand natural disasters, and environmental degradation. Thus, this suggests that the relationship between stand structure and function is a key factor to the sustainable management of these bamboo forests. Traditional descriptions of moso bamboo stand structure have focused on stand-level collective attributes such as density, species composition, and basal area. However, given a general lack of spatial information, non-spatial attributes are difficult to use for accurately estimating whole stand characteristics. The spatial structure of a forest can reflect environmental processes, such as competition, regeneration, spatial distribution, and mortality. These factors can affect the stability,the development, and the management of a stand. Therefore, forest spatial structure approach would involve spatial pattern, mingling, and competition. Information regarding bamboo forest spatial structure is necessary for stand structure optimization. Many static spatial studies have been conducted in bamboo forests, including mingling, spatial pattern, and competition, and so on. Compared with other types of forests, bamboo grows faster, and this provides the possibility to study the dynamic change rule of stand spatial structure. Previous studies had not yet shown the dynamic change of moso bamboo stand spatial structure. Therefore, three spatial structure parameters, uniform angle index, neighborhood comparison, and age mingling degree were used to analyze the moso bamboo stand spatial structure dynamics (change) from 2009 to 2012, and thus provide theoretical basis for sustainable moso bamboo forest management.In July of 2009, one 100 m×100 m standard plot was established in a close-to-nature Phyllostachys edulis stand in Tianmu Mountain National Nature Reserve, Zhejiang Province. The plot was divided into 100 units by adjacent grid inventory, and has been annually surveyed four times. Results showed that the moso bamboo stand has a clear on-year and off-year cycle, and the average diameter at breast height (dbh) increased gradually over year. The spatial pattern of the stand presents a random distribution in 2009 and 2012, but the 2010 and 2011 years showed an aggregation distribution pattern. The frequency distribution of uniform angle index of each year was described by a left-skewed normal distribution trend, and had no significant difference during these years (P > 0.05). The average neighborhood comparison values of each year were close to 0.5, suggesting that the stand has kept an intermediate status. The frequency distribution of neighborhood comparison of each year appeared to have a balanced trend, suggesting that the stand was in a stable state. However, the neighborhood comparison showed no significant difference of each year. The stand showed high age diversity and age isolation levels, and the age mingling value increased as the years increased. The age mingling in the transition period from on-year to off-year was significantly different (P < 0.05), but in the transition from off-year to on-year there was no significant difference. 参考文献 相似文献 引证文献

Assessing fire effects on forest spatial structure using a fusion of Landsat and airborne LiDAR data in Yosemite National Park

Mosaics of tree clumps and openings are characteristic of forests dominated by frequent, low- and moderate-severity fires. When restoring these fire-suppressed forests, managers often try to reproduce these structures to increase ecosystem resilience. We examined unburned and burned forest structures for 1937 0.81ha sample areas in Yosemite National Park, USA. We estimated severity for fires from 1984 to 2010 using the Landsat-derived Relativized differenced Normalized Burn Ratio (RdNBR) and measured openings and canopy clumps in five height strata using airborne LiDAR data. Because our study area lacked concurrent field data, we identified methods to allow structural analysis using LiDAR data alone. We found three spatial structures, canopy-gap, clump-open, and open, that differed in spatial arrangement and proportion of canopy and openings. As fire severity increased, the total area in canopy decreased while the number of clumps increased, creating a patchwork of openings and multistory tree clumps. The presence of openings >0.3ha, an approximate minimum gap size needed to favor shade-intolerant pine regeneration, increased rapidly with loss of canopy area. The range and variation of structures for a given fire severity were specific to each forest type. Low- to moderate-severity fires best replicated the historic clump-opening patterns that were common in forests with frequent fire regimes. Our results suggest that managers consider the following goals for their forest restoration: 1) reduce total canopy cover by breaking up large contiguous areas into variable-sized tree clumps and scattered large individual trees; 2) create a range of opening sizes and shapes, including ~50% of the open area in gaps >0.3ha; 3) create multistory clumps in addition to single story clumps; 4) retain historic densities of large trees; and 5) vary treatments to include canopy-gap, clump-open, and open mosaics across project areas to mimic the range of patterns found for each forest type in our study.

Spatial forest structure reconstruction as a strategy for mitigating edge-bias in circular monitoring plots

Forest ecosystem monitoring is an important task of forest science worldwide and its outcomes have important consequences both for national forest policies and local decision making. Often forest monitoring is implemented using circular plots of limited size. Edge effects can seriously bias the results of spatially explicit analyses of circular plot data and little research has been carried out on how to mitigate this problem. In this study, we have compared the method of spatial forest structure reconstruction to traditional plus-sampling, to the reflection method and to a situation where no edge-bias mitigation method is used at all. Reconstruction is a non-parametric modelling method based on simulated annealing. In the context of this study, the arithmetic means of structural summary characteristics are used to extrapolate spatial patterns previously measured in the core area of the monitoring plots to the margins outside. The computer experiments were based on 706 circular monitoring plots of the Estonian long-term monitoring network maintained by the Estonian University of Life Sciences, Tartu. The results clearly indicate the superiority of the reconstruction method and suggest that this approach has great potential for future spatially-explicit data analyses and modelling involving circular monitoring plots. Further improvements can be expected from using density functions and histograms of structural summary characteristics instead of arithmetic means.

FUTURES: Multilevel Simulations of Emerging Urban–Rural Landscape Structure Using a Stochastic Patch-Growing Algorithm

We present a multilevel modeling framework for simulating the emergence of landscape spatial structure in urbanizing regions using a combination of field-based and object-based representations of land change. The FUTure Urban-Regional Environment Simulation (FUTURES) produces regional projections of landscape patterns using coupled submodels that integrate nonstationary drivers of land change: per capita demand, site suitability, and the spatial structure of conversion events. Patches of land change events are simulated as discrete spatial objects using a stochastic region-growing algorithm that aggregates cell-level transitions based on empirical estimation of parameters that control the size, shape, and dispersion of patch growth. At each time step, newly constructed patches reciprocally influence further growth, which agglomerates over time to produce patterns of urban form and landscape fragmentation. Multilevel structure in each submodel allows drivers of land change to vary in space (e.g., by jurisdiction), rather than assuming spatial stationarity across a heterogeneous region. We applied FUTURES to simulate land development dynamics in the rapidly expanding metropolitan region of Charlotte, North Carolina, between 1996 and 2030, and evaluated spatial variation in model outcomes along an urban–rural continuum, including assessments of cell- and patch-based correctness and error. Simulation experiments reveal that changes in per capita land consumption and parameters controlling the distribution of development affect the emergent spatial structure of forests and farmlands with unique and sometimes counterintuitive outcomes.

Historical analysis of landscape change in the eastern boreal mixedwood: A case study in the context of cohort-based management

Maintenance of forest spatial structure through forest management is increasingly recognized as an important landscape-level aspect to maintaining biodiversity. In this study, we use forest inventory maps dating from 1965, 1972, 1983, and 1994 to describe the recent historical spatial structure at the Lake Duparquet Research and Teaching Forest (LDRTF) in northwestern Quebec, Canada. Mapped forest stands were classified according to a conceptual cohort model of stand development based on species composition and other stand attributes. Contiguous forest stands of the same cohort class were agglomerated to form relatively uniform patches containing a single cohort class. Landscape spatial structure was defined using four landscape characterization indices: proportion of the landscape, mean patch size, mean distance to nearest neighbour and mean patch shape index. Cohort 1 patches occurred as both small and large units that had complex shapes while Cohort 2 patches occurred as small dispersed units that had simple shapes. Cohort 3 patches dominated the landscape matrix and formed both small and large units that were generally agglomerated in the same vicinity. Our cohort classification of mapped stand polygons was validated by comparing the proportion of land occupied by each cohort in two natural fires (1923 and 1760) that have shaped this area. Theoretical local targets for maintaining cohort structure in the landscape were then formulated based on these historical landscape characteristics.

洞庭湖森林生态系统空间结构均质性评价

The spatial structure rationality evaluation and ideal spatial structure of forest ecosystem is an important and difficult problem in forest management at home and abroad.In order to reveal the reasons why the community structure is simple and the stability of ecosystem is poor,and to take the regulation mechanism of structure in Dongting Lake forest,the research is targeted at East,South,West Dongting Lake area including Junshan Island,Longshan,Longhu forest farm on Chishan Island,Minglang mountain,Changde forest farm,Hefu Forest farm and natural secondary forest of Taoyuan County.Utilizing the ecosystem internal balance and homogenizing principle of the ecology,in the forest ecological system(plaque) scale,it analyses the spatial structure of mixed,competed and spatial distribution pattern.And then the heterogeneity goal of optimized stand spatial structure is proposed,which has multiple sub-goals in mixed,competed and spatial distribution pattern.Meanwhile the heterogeneity index of single tree and stand spatial structure is also defined,and the evaluation index,evaluation method and evaluation standard of stand spatial structure heterogeneity is determined.By applying the proposed evaluation method to the Dongting Lake area secondary forest heterogeneity evaluation,the results show that: in the fifteen Dongting Lake wetlands under investigation,the forest stand average homogeneity evaluation index is 0.2517.There are 12 stands in the grade 1 and grade 2 which is accounted for 80%,and only 3 stands in the 3 grade accounted for only 20% in the five grades of homogeneity index.However,it lacks of the grade 4 and grade 5 ideal stand spatial structure in Dongting Lake survey.The evaluation results show that only part of stand spatial structure factors in Dongting Lake Forest meet the standard values.Although there is a certain degree of mixed size between dominant tree species and pioneer species,and there are more obvious differentiation between even-aged and uneven-aged forest stands,it yet shows that: the whole stand appears monolayer,and tree species has little isolation;trees′ distribution pattern appears randomized into uniform distribution status;competition is more obvious between individual trees,and it has low diversity and weak illumination.It illustrates that the Dongting Lake stands as a whole have unconspicuous advantage on spatial structure,growth environment and species dominance and other aspects.Many irrational factors exist in forest structural characteristics including space information,and there is far from ideal spatial structure.According to the different altitudes,forest spatial structure homogeneity characteristics gradually grow from the lake to the hilly land in Dongting Lake wetland.This conclusion reflects the real situation of forest resources in Dongting Lake area,and it has a close relationship with the long-term natural and man-made interference,protection and restoration of fatigue. The proposed forest ecological system space optimization objectives and heterogeneity index prolongate the sustainable forest management.The heterogeneity evaluation method breaks through the traditional analysis method of forest spatial structure.The heterogeneity index comprehensively and realistically describes the characteristics of spatial structure,and also quantifies the goal structure of forest spatial neighborhood relation and optimized spatial structure.The method has both forestry and ecological significance on optimizing and adjusting the existing forest spatial structure of Dongting Lake,on transforming large single plantation which mainly consists poplar and willow,and on restoring the functions of Dongting Lake ecological system,such as nourishing and cherishing water,conserving soil and water,reinforcing dam and so on.At the same time,the proposed method in this paper has provided a new way to establish and express ideal spatial structure for other regional forest management.

Forest dynamics during the transition from the Oldest Dryas to the Bølling–Allerød at Gerzensee—a simulation study

The aim of this study was to explore potential causes and mechanisms for the sequence and temporal pattern of tree taxa, specifically for the shift from shrub-tundra to birch–juniper woodland during and after the transition from the Oldest Dryas to the Bølling–Allerød in the region surrounding the lake Gerzensee in southern Central Europe. We tested the influence of climate, forest dynamics, community dynamics compared to other causes for delays.For this aim temperature reconstructed from a δ18O-record was used as input driving the multi-species forest-landscape model TreeMig. In a stepwise scenario analysis, population dynamics along with pollen production and transport were simulated and compared with pollen-influx data, according to scenarios of different δ18O/temperature sensitivities, different precipitation levels, with/without inter-specific competition, and with/without prescribed arrival of species. In the best-fitting scenarios, the effects on competitive relationships, pollen production, spatial forest structure, albedo, and surface roughness were examined in more detail.The appearance of most taxa in the data could only be explained by the coldest temperature scenario with a sensitivity of 0.3‰/°C, corresponding to an anomaly of −15°C. Once the taxa were present, their temporal pattern was shaped by competition. The later arrival of Pinus could not be explained even by the coldest temperatures, and its timing had to be prescribed by first observations in the pollen record. After the arrival into the simulation area, the expansion of Pinus was further influenced by competitors and minor climate oscillations. The rapid change in the simulated species composition went along with a drastic change in forest structure, leaf area, albedo, and surface roughness. Pollen increased only shortly after biomass.Based on our simulations, two alternative potential scenarios for the pollen pattern can be given: either very cold climate suppressed most species in the Oldest Dryas, or they were delayed by soil formation or migration. One taxon, Pinus, was delayed by migration and then additionally hindered by competition. Community dynamics affected the pattern in two ways: potentially by facilitation, i.e. by nitrogen-fixing pioneer species at the onset, whereas the later pattern was clearly shaped by competition. The simulated structural changes illustrate how vegetation on a larger scale could feed back to the climate system.For a better understanding, a more integrated simulation approach covering also the immigration from refugia would be necessary, for this combines climate-driven population dynamics, migration, individual pollen production and transport, soil dynamics, and physiology of individual pollen production.

The bivariate distribution characteristics of spatial structure in natural Korean pine broad‐leaved forest

AbstractAimsSpatial structure is important in describing forest stand structure and change. We present a new method for the quantitative analysis of forest spatial structure based on the relationship of nearest neighbour tree groups.LocationSix hundred m a.s.l., Dongdapo Natural Reserve, Jiaohe, Jilin Province, ChinaMethodsSix plots in three common stand types of natural Korean pine broad‐leaved forest in northeast China were used to validate the method. Each plot measured 100 × 100 m, and all trees with DBH ≥5 cm were marked and located using a Total Station. We calculated bivariate distribution of the structural parameters, uniform angle index, mingling and dominance using Winkelmass and Excel software.ResultsMost trees in the forest were highly mixed by species and randomly distributed. Individuals with high DBH values were typically surrounded by other species; trees within stochastic distribution patterns were usually surrounded by different species; and medium‐sized trees were randomly distributed.ConclusionsThe bivariate distribution of structural parameters can provide more direct and useful information about the heterogeneity of spatial structure than can univariate distributions or other conventional stand descriptors. This could be helpful for selective thinning in continuous cover forest management and in modelling and restoring forests.

Tracking Analysis of Forest Spatial Structure Change after Different Selective Cutting Intensities in a Natural Forest

Based on long-term tracking retest data and three structure parameters(mingling intensity,neighborhood comparison and uniform angle index),we investigated the effects of four different selective cutting intensities(low intensity of 13.0% in volume,medium intensity of 29.1%,high intensity of 45.8%,and over-high intensity of 67.1%) on forest spatial structure change in a natural forest.After low and medium selective cutting forest,plot average mingling and neighborhood comparison increased while high and over-high selective cutting decreased.Selective cutting did not change the forest spatial distribution pattern.However,the variety of forest plot showed aggregated distribution,and medium selective cutting in random distribution state forest number increased considerably.After low and medium selective cutting,forest spatial structure was optimized in general.

基于相邻木排列关系的混交度研究

Mingling,its concept was put forward by Gadow in 1992,is an important indicator to reflect species mutual segregation in a forest community,and is a significant forest spatial structure index.Currently,many mingling indices have been proposed.A simple mingling index Mg proposed by Gadow only involves the difference between objective trees and their nearest neighbor trees,and cannot accurately reflect the response of tree species to spatial segregation,which was noticed by Tang Mengping(2004) and Hui Gangying(2008).They put forward tree species diversity mingling Mv(further considering the number of nearest tree species) and tree species spatial status Ms(further considering the number of tree species in spatial structure unit),respectively.However,Mv and Ms cannot distinguish the difference between two of the same species on four of the nearest tree species and three of the same species on four of the nearest tree species.Actually,two of the same species on four of the nearest tree species are different in sequence and interleaving arrangement,but they are the same in the analysis of Mv and Ms.Virtually,neighborhood spatial permutation is a significant factor in describing tree species spatial segregation,which was ignored by Mv and Ms.Therefore,a new mingling index,Mp based on neighborhood spatial permutation has been put forward in this paper. 1+4 structure,which was the abbreviation of optimum spatial structure unit proposed by Hui Gangying(2003),composed by one objective tree and four of its nearest trees,and has 17 spatial structure units that are different in tree species spatial permutation.Mp was compared with Mg,Mv and Ms through 17 spatial structure units and evergreen broad-leaved data from Tianmu Mountain,a national nature reserve in Zhejiang province.Data were collected in a 1hm2(100m×100m) permanent plot that had been established in 2005.The results show that Mp has the strongest distinction among them,Mv and Ms are the second,Mg is the worst.The ranking of the different mingling values was: MgMpMs,MgMv.Ms and Mp are both able to adequately analyze the simple mixed stand.Mp is the best mingling index among them to analyze the complex mixed stand.Here,there is a high value of mingling,if Mg is used.Sometimes,Mv is unable to analyze the tree species spatial segregation.Spatial structure units which have two of the same species on four of the nearest tree species are different in sequence and interleaving arrangement,and the number of sequence arrangement is significantly more than that of interleaving,and thus there is a moderate mingling level on evergreen broad-leaved in Tianmu Mountain.Mp is based on neighborhood spatial permutation and can distinguish tree species spatial segregation accurately,and has higher distinction degree accuracy than that of traditional mingling.This better reflects the actual mixed situation of forest,and is an effective indicator to reflect species mutual segregation in a forest community.1+4 structure has 17 different spatial structure units,however,what needs further study is the number of spatial structure units in the 1+n structure,and how to determine the deduction relation.Further,the number of units may obey certain mathematic distributions in natural mixed forests,and the mathematic distribution function may be a significant reference to measure the near-natural degree of cultivation in mixed forests.These issues need further study.

Two-dimensional wavelet analysis of spruce budworm host basal area in the Border Lakes landscape

Increases in the extent and severity of spruce budworm (Choristoneura fumiferana Clem.) outbreaks over the last century are thought to be the result of changes in forest structure due to forest management. A corollary of this hypothesis is that manipulations of forest structure and composition can be used to reduce future forest vulnerability. However, to what extent historical forest management has influenced current spatial patterns of spruce budworm host species is unknown. To identify landscape-scale spatial legacies of forest management in patterns of spruce budworm host species (i.e., Abies balsamea and Picea spp.), we analyzed remotely sensed forest data from the Border Lakes landscape of northern Minnesota and northwestern Ontario. Our study area contains three regions with different management histories: (1) fine-scale logging patterns in Minnesota, (2) coarse-scale logging patterns in Ontario, and (3) very limited logging history in the Boundary Waters Canoe Area and adjacent Quetico Provincial Park. We analyzed forest basal-area data using wavelets and null models to identify: (1) at which scales forest basal area is structured, (2) where those scales of pattern are significantly present, and (3) whether regions of local significance correspond to regional boundaries that separate the study area. Results indicate that spatial patterns in host basal area are created by nonstationary processes and that these processes are further constrained by lakes and wetlands. Wavelet analysis combined with significance testing revealed a bimodal distribution of scale-specific wavelet variance and separate zones of host species basal area that partially correspond with regional boundaries, particularly between Minnesota and the Wilderness region. This research represents one of the first comparisons of forest spatial structure in this region across an international border and presents a novel method of two-dimensional wavelet analysis that can be used to identify significant scale-specific structure in spatial data.

Genetic differences within natural and planted stands of Quercus petraea

Abstract Five sessile oak [Quercus petraea (Matt.) Liebl.] stands from the Czech Republic were studied to learn about the impact of different types of forest management regimes on the genetic differences among tree populations and on population structures. One population had not been markedly affected by human activity, two populations represented unplanted stands that were extensively managed for a long period of time using the coppice system, and two populations were planted stands. Approximately 100 trees from each stand were mapped and subsequently genotyped using 10 nuclear microsatellite loci. We determined the spatial genetic structure of each population and the genetic differentiation among the populations. We found that: (i) the populations were genetically differentiated, but the differences between the unplanted and planted stands were not markedly significant; (ii) the genetic differentiation among the populations depended on the geographical distribution of the populations; (iii) within unplanted stands, a strong spatial genetic structure was seen; and (iv) within planted stands, no spatial genetic structure was observed. Our findings implies that the analysis of spatial genetic structure of the sessile oak forest stand can help reveal and determine its origin.