Unveiling the adaptation strategies of woody plants in remnant forest patches to spatiotemporal urban expansion through leaf trait networks

Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion on the networks of leaf traits in woody plants within remnant forest patches,thereby enhancing our understanding of plant adaptive strategies and contributing to the conservation of urban biodiversity.Methods:Our study examined woody plants within 120 sample plots across 15 remnant forest patches in Guiyang,China.We constructed leaf trait networks (LTNs) based on 26 anatomical,structural,and compositional leaf traits and assessed the effects of the spatiotemporal dynamics of urban expansion on these LTNs.Results and conclusions:Our results indicate that shrubs within these patches have greater average path lengths and diameters than trees.With increasing urban expansion intensity,we observed a rise in the edge density of the LTN-shrubs.Additionally,modularity within the networks of shrubs decreased as road density and urban expansion intensity increased,and increases in the average path length and average clustering coefficient for shrubs were observed with a rise in the composite terrain complexity index.Notably,patches subjected to‘leapfrog’expansion exhibited greater average patch length and diameter than those experiencing edge growth.Stomatal traits were found to have high degree centrality within these networks,signifying their substantial contribution to multiple functions.In urban remnant forests,shrubs bolster their resilience to variable environmental pressures by augmenting the complexity of their leaf trait networks.

Divergent responses of Picea crassifolia Kom.in different forest patches to climate change in the northeastern Tibetan Plateau

Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and terrain,some tree species may form different forest patches at the edges of their distribution areas.However,how forest patches of various sizes respond to climate change is unclear.In this study,we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom.in the northeast Tibetan Plateau.And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020.We simultaneously measured the contents of nonstructural carbohydrates(NSC),total nitrogen and total phosphorus of tree needles.Our results showed that the growth of trees in small-and medium-size forest patches(0.8–18.6 ha)has increased significantly.The early growing season(May–July)minimum temperature was the most important climate factor driving the growth of small-and medium-sized patch trees.The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches(362.8 ha).The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature,maximum temperature,precipitation,actual evapotranspiration,and palmer drought severity index was stronger.The higher NSC content,stronger photosynthesis,and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches.In extreme drought years,as the forest patch area increased,the overall trend of tree growth resistance showed a unimodal pattern,with the highest at a forest patch area of 7.1 ha,while the overall trend of tree growth recovery was opposite.Therefore,we should strengthen the management of trees in large forest patches to cope with climate change.

Aboveground Woody Biomass, Carbon Stocks Potential in Selected Tropical Forest Patches of Tripura, Northeast India

To estimate woody plant biomass stocks in different patches of forest ecosystems, total 20, 500 × 10 m (0.5 ha) sized line transects were laid in a protected area of Tripura, Northeast India. Overall, 9160 individuals were measured at ≥10 cm diameter at breast height (dbh) in 10 ha sampled area. Estimation of biomass suggested that highest coefficient for allometric relationships between density and biomass in 10 dbh classes was observed in bamboo brakes (R2 = 0.90) than lowest for semi evergreen patch (R2 = 0.48). The stock of carbon (C) was differ significantly along the forest patches (F = 7.01, df = 3.19;p < 0.01). Most of biomass stock (69.38%) was accumulated in lower dbh class (<30 cm) and only 23% of biomass was estimated at higher dbh classes (> 70 cm). Range of biomass stock (37.85 - 85.58 Mg ha-1) was low, compared to other tropical forest ecosystems in India, which implies that the proper management is required to monitor regional ecosystem C pool.

Flora, Structure and Carbon Sequestration of Vegetation in the Southeast of the Mono Biosphere Reserve in Togo Amidst Environmental Challenges

In most Sub-Saharan African countries such as Togo, people’s heavy dependence on ecosystem services is a major factor in accelerating the degradation of natural resources, which are already suffering as a result of climatic factors. This study was initiated to contribute to the sustainable and rational management of forest resources in the south-east of the Mono Biosphere Reserve in Togo. It specifically aims to identify and characterize the flora of the residual forest ecosystems within the reserve through their specific diversity, demographic structure, and carbon sequestration potential. The study was carried out in the forest ecosystems of Avévé. The methodology used was based on the analysis of phytosociological, forestry, ecological, and regeneration inventory data. Overall, the study revealed that the RBMT still has floristically viable habitats, despite the anthropogenic pressures it is subject to revealed a floristic diversity of 160 plant species divided into 52 families and 135 genera. The most represented families are Rubiaceae (29.09%), followed by Fabaceae (27.94%). The most represented species are Mitragyna inermis (Willd.) Kuntze (24.38%), Lecaniodiscus cupanioides Planch. Ex Benth (X) and Lonchocarpus sericeus (Poir.) Kunth (10.93%). The high presence of Mitragyna inermis observed in all the ecological groups identified makes it the characteristic species of the flooded marshy areas of southeast Togo and contributes to the resilience of the ecosystems and populations in the study area. The Shannon index for the formation groups varies between (3.03 and 5.16) bits. Pielou’s equitability varies between (0.43 and 0.63) bits. The overall average density is estimated at 210 stems/ha, with an average diameter of 25.57 ± 21.77 m and an average height of 7.93 ± 3.83 m. The adjustment of the diameter classes of the plant groups to the Weibull distribution gave an “inverted J” shape with coefficient values of less than 1 overall, reflecting the existence of multispecific or uneven-aged stands. Assessment of the horizontal and vertical structure shows a predominance of the shrub layer in all the groups identified. The carbon sequestration potential is 41.89 T/Ha. Despite ongoing anthropogenic pressures, the Mono Biosphere Reserve abounds in a relatively rich diversity of flora, the preservation of which is essential for the survival of biodiversity and even for the riparian population. The data provided by this study would form the basis for sustainable management planning of the forest islands in the biosphere reserve.

景观斑块对重大森林火灾的影响研究进展

重大森林火灾所占比例小,但影响大。森林景观中的斑块对重大森林火灾的影响非常明显。景观斑块作为景观格局的基本组成单元,对森林火灾的影响是景观生态学的研究热点。尽管重大森林火灾发生频率较小,但是如果不能及时控制,火将会在各森林景观斑块中蔓延和发展,造成更大损失。本文简要概述了景观斑块和重大森林火灾的主要研究内容,阐述了二者之间的相互关系,并从景观斑块对重大森林火灾的促进和抑制作用入手,揭示景观斑块对重大森林火灾的影响,研究结果为重大森林火灾的预防和扑救提供了理论参考。

Influencing Factors of Seed Long-distance Dispersal on a Fragmented Forest Landscape on Changbai Mountains,China

Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.

林内色彩斑块分布格局对秋季生态景观林美景度的影响--以塞罕坝机械林场为例

色彩是林内最强烈的视觉语言,秋季林内色彩差异尤为明显,研究色彩斑块布局对人工景观林质量提升有重要意义。为了探究色彩对生态景观林秋季景观质量的影响特征,以塞罕坝机械林场白桦纯林、2个密度的落叶松纯林、白桦-落叶松混交林为研究对象,选取了36张景观照片,采用ArcGis 10.3软件对照片进行矢量化处理,采用FRAGSTATS 4.2软件提取矢量化后照片的格局指数,采用美景度评价法(SBE)对照片中景观进行质量评价,美景度计算用的是标准化处理后的数据,故对照照片为随机1张照片。通过比较秋季4个林分色彩斑块形状指数(LSI)、香农多样性指数(SHDI)、香农均匀度指数(SHEI)和分离度指数(SPL)的变化特征,明确林内色彩斑块景观指数对生态景观林美景度的影响,分析不同林分景观质量的差异性,进而为生态景观林经营与评价提供依据。主要研究结果如下:(1)白桦纯林斑块多样性指数最高,美景度与斑块多样性指数呈显著负相关(相关系数为-0.847),导致白桦纯林美景度最低,且与其他3个林分类型差异显著;低密度落叶松纯林美景度最高,人们对落叶松纯林喜好程度较高。(2)美景度与色彩斑块LSI值存在正相关性,相关系数为0.620,与SPL、SHDI和SHEI存在不同程度的负相关性,其中与SHDI值相关系数达到了-0.847。斑块形状指数、多样性指数与均匀度指数对秋季林内景观质量影响较大。总之,林内色彩斑块简洁,零散的分布格局更易被游人接受,而色彩多样且集中连片、通透性较差降低了森林的可达性,影响林内景观质量。

基于GIS的永泰县森林景观格局特征研究

基于永泰县森林资源二类调查数据,利用GIS技术和景观生态学原理与方法,从斑块类型水平和景观水平选取景观指数分析研究永泰县森林景观格局特征。结果表明:①研究区林地景观面积为184433.02 hm^(2),占总面积的82.72%,其中乔木林地在林地景观类型中占明显优势,占林地景观面积的84.27%。②乔木景观平均斑块面积最大,破碎度最小;竹林地和宜林地的平均斑块面积最小,破碎度最大;乔木林地和竹林地斑块形状复杂,迹地的斑块形状简单;各类林地景观的聚集度高,均在90%以上。③研究区多由大的景观斑块构成,林地景观破碎程度较高,多样性较高,但林地景观分布不均匀。

浙江安吉山区森林景观空间格局动态分析

森林景观空间结构分析 ,是认识森林景观结构、功能动态的重要途径 .运用景观生态学原理 ,借助地理信息系统技术 ,选取斑块面积、斑块分维数、斑块面积变异系数及标准差、景观多样性、景观优势度等指标 ,分析了安吉山区森林景观的空间分布格局特征 .从 1 985年至 1 999年显示森林斑块面积变异系数及标准差从 1 .487、 2 .373到 1 .70 0、 3.844,呈明显增大趋势 ;森林景观形状指数从 83.69到 91 .5 ,呈增大趋势 ;景观优势度从 0 .868到 0 .80 7,呈减弱趋势 ;森林景观破碎度从 9.1 5 %到 8.32 % ,呈降低趋势 .反映出由于生态公益林面积的逐年增加 ,林种结构比例的适度调整 。

山地次生林破碎化对喜鹊繁殖功效的影响

于 1999～ 2 0 0 0年春夏两季 ,在左家自然保护区及土门岭地区研究了破碎化山地次生林斑块面积对喜鹊 (Picapica)繁殖功效的影响。运用GPS定位系统确定了 12块大 (>2 0hm2 ,n =4 )、中 (10～ 2 0hm2 ,n =3)、小 (<10hm2 ,n =5 ) 3种类型的含喜鹊巢的次生林斑块及 2块毗邻的含喜鹊巢的连续分布次生林 (>2 0 0hm2 )对照样地 (每块面积 2 0hm2 )。观测了各斑块及对照样地中喜鹊产第 1枚卵的时间、窝卵数、平均卵重、出雏量及雏鸟出飞量等生态指标。结果表明 ,①斑块面积对喜鹊的繁殖功效存在着显著的影响 ;②喜鹊在对照样地和大面积斑块中的平均产卵时间早于小斑块中的 11 6 2d ;③对照样地和大面积斑块内的窝卵数略高于中、小面积斑块内 ,但差异不显著 ;④各斑块及对照样地中的平均卵重无显著差异 ,小面积斑块中的出雏率和雏鸟出飞率均最低 (5 1 17%和 4 2 88% ) ,大面积斑块中的出雏率最高 (72 12 % ) ,对照样地略次之 (71 93% ) ,对照样地中的雏鸟出飞率最高 (6 5 4 5 % ) ,大面积斑块次之 (6 2 71% ) ;⑤喜鹊在小面积次生林斑块中繁殖功效较低的主要原因是巢损失率较高。

广州市帽峰山森林景观斑块特征分析

以SPOT卫星影像数据为主要信息源,结合地形图及数字高程模型,采用景观土地属性分类的植被分类途径,将景观分类结果利用地理信息系统软件ARCVIEW进行分析处理,并提取斑块特征信息.结果表明:(1)广州市帽峰山森林景观共有11个斑块类型;(2)各类型拥有的面积、周长及斑块数极不均衡;(3)阔叶混交林、针阔混交林类型是帽峰山森林景观的主导景观类型;(4)经济果林、竹林类型斑块小而密集,呈散布型分布,其形状指数、密度指数均较大,景观的破碎化程度较高,而阔叶混交林、针阔混交林却较小,类型保持完整,景观破碎化程度低.

次生林斑块的边缘效应对鸟类分布格局的影响

2005~2006年鸟类的繁殖季节,在吉林省左家自然保护区确定了11块次生林斑块,对次生林斑块的边缘效应对鸟类分布格局的影响进行了研究.结果表明：11块样地面积在10.9~51.2 hm2之间,平均面积为24.8 hm2;鸟类主要分布在0~50和50~100 m两个距离梯度;不同梯度中鸟类的分布在年际间未发生较大波动（P〉0.05）,不同距离梯度的鸟类分布差异很大,达到极显著水平（P=0.00）;0~150 m为鸟类的主要分布区域,边缘距离为150 m,次生林斑块中边缘效应存在.

海南霸王岭热带山地雨林森林循环与树种多样性动态

通过对海南岛霸王岭热带山地雨林的调查 ,研究了热带山地雨林树种多样性特征随森林循环的动态变化规律。结果表明 :( 1 )热带山地雨林森林循环不同阶段斑块在森林景观中所占的面积比例分别是 :林隙阶段 ( G)占 38.5 0 % ,建立阶段 ( B)占 2 8.5 0 % ,成熟阶段 ( M)占 2 7.0 0 % ,衰退阶段 ( D)占 6 .0 0 %。 ( 2 )热带山地雨林中乔木树种的密度随森林循环的变化趋势是由 G→B→M呈现出逐渐增加的趋势 ,以成熟阶段达到最大 ,而到衰退阶段又趋于下降。灌木树种则表现出 G阶段斑块的密度最大 ,B阶段的最小 ,从 B到 M有所增加 ,到 D又稍有下降。 ( 3)热带山地雨林中不同高度级和不同径级的树木的密度在森林循环的不同阶段表现出不同的增减趋势 ,其随森林循环过程呈现出的动态变化可能与不同阶段斑块内的空间、环境及物种生物学特性有关。 ( 4 )热带山地雨林中树木的平均胸径、平均高、平均胸高断面积、平均单株材积随森林循环过程呈现出不断增加的趋势 ,其中平均胸径和平均高随森林循环的变化较为平缓 ,而平均胸高断面积和平均单株材积之变化较为陡急。 ( 5 )热带山地雨林森林循环不同阶段的物种多样性指数不同 ,其中 G和 B阶段的物种丰富度和多样性指数值较接近 ,M阶段的物种丰富度达到最大 ,D阶段则最小。

侧柏风景林美景度的林内色彩斑块非线性模型研究

利用景观生态学的景观空间格局分析原理,以照片的色彩斑块结构为基础,开展风景林林内景观质量评价研究。分析美景度等级和14个斑块指数的关系,利用简相关法筛选出对美景度影响大的SPLIT、SHDI、DIV、SIEI、ACOV和LPI 6个指数,研究表明:随着美景度等级的降低,DIV、SIEI、ACOV和LPI呈曲线变化趋势;SPLIT、SHDI呈线性增大的变化趋势。依据6个指标,利用聚类方法将侧柏人工林分为4种类型。以指数为自变量分别构建了线性和非线性美景度模型。对比结果表明:非线性模型拟合精度高于线性模型,所以选用二次多项式逐步回归模型从总体上较好地反映出景观指数与美景度间的关系。

破碎化次生林斑块面积及斑块隔离对大山雀繁殖成功的影响

研究了破碎化山地次生林中斑块面积及斑块隔离度对大山雀 (Parusmajor)繁殖成功的影响 .运用GPS定位系统确定了 18块大、中、小 3种类型的斑块及对照样点 .观测了大山雀产第一枚卵时间、窝卵数、平均卵重、出雏量及雏鸟出飞量等生态指标 .结果表明 ,斑块隔离度对大山雀繁殖成功没有影响 ;1999～ 2 0 0 0年两年中 ,大山雀在连续分布次生林中的产卵时间平均早于各斑块中的产卵时间 7.2d ,各斑块间的产卵时间差异较小 ;连续分布次生林和较大面积斑块内的大山雀窝卵数略高于中、小面积斑块内的窝卵数 ;连续分布次生林中的平均卵重最大 ;斑块面积对出雏量及雏鸟出飞量没有影响 ;中、小面积斑块内的巢损失率较高 ,最主要的原因是巢址竞争较激烈 .

游憩型城镇景观林林内景观斑块类型特征研究

以林内景观斑块结构为基础,对北京市各类公园游憩型景观林景观斑块特征进行了分析。北京市各类公园游憩型景观林可分为中密度锻炼型景观林、中密度休闲型景观林、中高密度锻炼型景观林、高密度休闲型景观林、低密度综合景观林等5类。而具有低林分密度、高草本覆盖、适量灌木覆盖、丰富的色彩数量、乔草或乔灌草结构的林内景观更符合大众审美。在16个景观斑块要素中,景观密度越大,色彩斑块的SHDI越低,草本覆盖率越高PLADJ和AI越高、而NP、PD、景观斑块形状指数LSI越低。景观指数变化对林内景观美景度影响程度依次为SPLIT>CONTAG>PAF>SIEI>SHDI。随着美景度等级降低,CONTAG呈现线性递减趋势,而PAF、SPLIT、SHDI和SIEI呈现非线性变化趋势。高密度和整齐划一式的林木排列以及简单的林下植被在一定程度上简化了林内景观要素的复杂性,并不利于提高林内景观质量,适当增加树种丰富度,通过提高垂直层次数量和多样化的林下植被,使用提高林下植被近自然程度、采取规则式和非规则式树木排列方式相结合的多样化水平空间配置,将有益于提高林下植被斑块色彩多样性,并可有效地提高林内景观质量。

森林景观恢复过程中景观要素斑块规模的动态分析

以 1 959年以来的 4期航片为基础资料 ,通过对研究地区各类景观要素的斑块平均规模和粒级结构及其动态变化过程进行分析 ,揭示了研究地区森林景观恢复演替过程中景观要素斑块规模的动态特点 ,阐明了植被演替和干扰格局控制下森林景观要素斑块恢复演替的过程和规律。研究地区森林景观自 50年代以来在整体上始终属于细粒结构景观 ,但景观要素斑块规模和粒级结构发生了显著变化 ,在三个不同时期表现出不同的变化特点 ,而且不同景观要素的斑块规模和粒级结构变化过程也很不相同。

森林景观斑块密度及边缘密度动态研究——以关帝山林区为例

Based on the air photos of four stages since 1959 in Guandishan forest region,and assisted by other forest survey information,four stages of landscape element patch digital maps were generated in ARC INFO.By analyzing the patch density and edge density of landscape,dynamic laws of landscape heterogeneity and patch characters were comprehensively explored in this paper.The results showed that patch density and edge density both could be used to study landscape heterogeneity and its dynamic character.The outline of patch transformation and patch character changes during forest restoration in the study area were expounded in the paper.Some principl proposals were also provided in the end for the planning of forest restoration in similar area.

基于树冠覆盖视角的乡村人居生态林现状评价与用地潜力分析

林木树冠覆盖是欧美国家城乡森林生态系统评价的最常用评价指标,与我国的林木绿化率、绿地率等指标相比,其具有不分用地权属、导向性明显、更注重绿地质量等突出优点,在我国目前全面推进新农村建设的新形势下,利用该指标对农村人居林生态现状与生态发展潜力进行评估,对于指导今后的农村生态环境保护与建设具有非常重要的理论与现实意义。本文以该指标为核心,选择山东省安丘市凌河镇2009年7—8月25 cm分辨率的航空影像数据,对其乡村人居生态林的结构特征、林木树冠覆盖现状以及潜在树冠覆盖分布等进行了分析。研究结果表明,研究区现实林木树冠覆盖面积为1 088.15 hm2,全镇的树冠覆盖率为17.12%,99%以上为乔木冠层覆盖面积。从林木树冠覆盖的斑块粒级结构来看,树冠覆盖斑块在面积上以巨型斑块为主,但在数量上则以中小型斑块为主。不同行政村的树冠覆盖率评价结果显示,全镇66个行政村中仅有24个行政村树冠覆盖率高于镇域平均水平17.12%。全镇林木树冠覆盖以中等覆盖度等级为主,隶属此等级的行政村占行政村总数的36.36%;其次为极低和低等覆盖度等级,行政村所占百分比分别为21.21%、18.18%;高等树冠覆盖度等级所占比例最少,仅为7.58%。不同树种树冠覆盖面积的比例差异较大,占有比例较高的树种主要有杨树、泡桐、刺槐、苹果、柿树等,其中,杨树的树冠覆盖比例最高,达11.97%,小檗最少,不足0.01%。从未来可绿化的树冠覆盖潜力看,研究区理论潜在树冠覆盖面积共计190.51 hm2,占研究区总土地面积的2.91%,包括滩涂地、裸土地、荒草地及其他未利用地等4类用地类型;理论上全镇未来能达到的最大林木树冠覆盖率为20.12%;扣除保障景观多样性的"10%急需律"后的实际潜力结果表明,实际可利用的林木潜在树冠覆盖率仅2.7%,其中以滩涂地覆盖斑块可增加的面积最多,为59.46 hm2。总体而言,研究区的林木树冠覆盖具有数量偏低、斑块破碎化程度高、类型单一等特点,今后的生态建设应该保护与建设并举,重点加强水系林网、道路林网和农田林网建设。

神农架地区常绿落叶阔叶混交林树种更新研究

在神农架山区山体的中部 ,选取代表性的常绿落叶阔叶混交林样地 ,总面积为 2 .4hm2。在样地中对出现的林窗斑块以及相邻的对照的非林窗样方进行群落学调查。记录乔木树种的种类、胸径和高度以及它的幼苗和幼树的高度、数量。按照树种在林窗内外重要值的位序差值将群落出现的乔木层树种划分为 4类生态种组 ,其中 ,对林窗强烈正更新反应的树种有 6种 ,强烈负更新反应的树种 9种 ,中等更新反应的 9种 ,不明显更新反应的 1 0种。林窗内外乔木树种生态种组的组成明显不同。不同生态种组树种的幼苗在林窗与非林窗斑块中的更新表现出显著的差别。对神农架地区常绿落叶阔叶混交林树种更新的反应和过程的研究结果支持了林窗