Spatial pattern of seedlings 1 year after fire in a Mediterranean pine forest

Summary The spatial distribution of seedlings of the dominant perennial plant species (Pinus halepensis, Cistus salviifolius, Rhus coriaria) and may annual species was studied after a wild fire in an eastern Mediterranean pine forest. The spatial distribution of all seedlings is affected by the location of the old burned pine trees. Seedling density of Pinus and Cistus is higher at a distance from the burned pine canopy and lower near the burned pine trunk. It is also higher beneath small burned pine trees than under big ones. Rhus seedling density is higher under big burned pine trees and also near the burned trunks. Seedlings of Pinus, Cistus and Rhus growing under the burned canopy of big pine trees tend to be taller than seedlings under small ones or outside the burned canopy. Most annual species germinate and establish themselves outside the burned canopies, and only a few annual species are found beneath them. It is suggested that variation in the heat of the fire, in the amount of ash between burned pine trees of different sizes, and in the distance from the burned canopy are responsible for the observed pattern of seedling distribution. The possible ecological significance of the spatial pattern of seedlings distribution and their differential growth rate are discussed.     

青藏高原东缘林线杜鹃-岷江冷杉原始林的空间格局

为深入理解高山林线原始林中优势树种的空间结构特征和种间关系,以青藏高原东缘林线杜鹃-岷江冷杉原始林1 hm²样地调查数据为基础,采用成对相关函数g(r)函数,分析了优势种岷江冷杉(Abies faxoniana)和凝毛杜鹃(Rhododendron agglutinatum)各径级的空间分布格局和各径级间的空间关联性。结果表明:岷江冷杉和凝毛杜鹃径级分布连续,呈倒"J"型,均为进展种群。小尺度上,对于岷江冷杉活立木(小树+中树+大树)、小树、中树为显著聚集分布,大树为均匀分布,死树则为随机分布;凝毛杜鹃活立木(小树+中树+大树)、小树、中树、大树、死树均为显著聚集分布。小尺度上随径级增大岷江冷杉的分布格局从聚集分布趋于均匀分布。岷江冷杉大树与其小树的空间关联验证了Janzen-Connell假说中的距离制约效应。通过验证接受了随机死亡假说,发现种内的密度制约效应不明显。两个树种的枯立木对凝毛杜鹃小树均表现为排斥关系,而对岷江冷杉小树表现为相互独立的关系。两个优势种总体表现为相互独立,但种间不同径级间的空间关联性各异。     

西藏色季拉山急尖长苞冷杉原始林粗木质残体空间格局分析

粗木质残体（Coarse woody debris,CWD）的空间格局反映了森林群落的死亡格局和干扰格局,在一定程度上体现了群落内林木的死亡过程。采用相邻网格法对色季拉山急尖长苞冷杉（Abies georgei var.smithii）原始林1 hm²固定样地内CWD进行调查,从CWD类型、腐烂等级、径级3个方面对CWD空间分布格局进行分析。结果表明：样地内CWD总密度为582株/hm²,倒木占55.33%,是CWD的主要输入形式。CWD密度在腐烂等级上的分布可用多项式拟合（R²=0.9973）,在径级上的分布可用指数衰减模型拟合（R²=0.9746）,且在不同类型、腐烂等级及径级上的分布差异较大。在50 m尺度内,CWD整体表现为小尺度的集群分布和中、大尺度的随机分布。在3种CWD分类中,仅有大枯枝、Ⅰ级腐烂、径级ⅠCWD在小尺度或中尺度表现为较强的集群分布,其余则均以随机分布为主,只是在个别尺度达到或接近集群分布。不同类型CWD间整体关联不显著,只有枯立木与大枯枝在0-21 m尺度内达到显著负关联。CWD空间分布格局是急尖长苞冷杉原始林的重要结构特征,在很大程度上决定着林下植物群落及林型自然更新格局。     

庐山香果树毛竹混交林空间格局研究

为了解庐山毛竹入侵对香果树的影响,采用Ripley’sK(t)函数分析香果树毛竹混交林群落空间分布格局和种间关联关系。结果表明:香果树幼树在较小的尺度上呈聚集分布,较大尺度上随机分布直至均匀分布;香果树成年树在较小的尺度上呈随机分布,较大尺度上聚集分布;毛竹在所有的研究尺度上为显著聚集分布,且随着尺度的增大,聚集强度增加。毛竹与香果树幼树在较小的尺度上没有明显关联性,在较大的尺度上呈显著负相关;毛竹与香果树成年树在一系列尺度上均表现为显著负相关。根据空间关联性分析结果,应从幼龄起对生长有香果树的森林群落进行必要的管理,伐除毛竹及一些影响较大的其它乔木树种,挖除地下竹鞭,为香果树提供良好的生长环境,进而恢复其种群的天然合理配置。否则,香果树这一珍贵的植物资源在庐山将有灭绝的危险。     

The spatial pattern and canopy-understory association of trees in a cool temperate,mixed forest in western Japan

The spatial distribution pattern of trees and the association between canopy and understory individuals were examined with reference to the distribution of tree crowns in a cool temperate, mixed forest in Ohdaigahara, western Japan. Line transect and contact sampling methods were used to examine the pattern over various spatial scales. These methods are useful to detect patterns over a large study area. The dominance ofChamaecyparis obtusa on steep slopes forming large patches suggested that the distribution of this species is a consequence of landslides. UnderstoryFagus crenata showed a clumped distribution, and the relative coverage of this species was larger in canopy gaps than under a closed canopy. Understory individuals ofAbies homolepis showed a positive association with canopy trees ofF. crenata but a negative association with conspecific canopy individuals. These patterns suggested thatF. crenata regenerates in canopy gaps and is replaced byA. homolepis. The dynamics of these two species are consistent with the process of gap dynamics. The effects of both small- and large-scale disturbance must be evaluated to understand the mechanisms of patch formation and the coexistence of forest tree species.     

杭州午潮山天然次生林木本幼苗组成及其时空分布格局

木本植物幼苗是森林生态系统的重要的组成部分,其定居、存活、生长的生态学过程对于森林植被的更新具有潜在指示和筛选作用。为探究浙江杭州午潮山亚热带常绿阔叶次生林群落更新和演替机制,基于样方法对150 m²样地内天然更新幼苗的物种组成、数量特征和基径结构进行统计,在此基础上采用最近邻分析和Ripley''s K函数的点格局方法,分析其中主要优势树种的更新动态及其时空分布格局。结果表明:(1)样地内乔木幼苗树种组成丰富,共调查到幼苗811株,隶属12科20属27种,其中樟科Lauraceae、壳斗科Fagaceae、山茶科Theaceae和山矾科Symplocaceae为主要优势科。(2)红楠Machilus thunbergii、薄叶润楠M. leptophylla、毛柄连蕊茶Camellia fraterna和刨花润楠M. spauhoi在所有调查物种重要值排序前4,因而被确定为优势林下植物,绘制的基径结构小提琴图(violin plot)进一步显示它们的种群分属快速增长型、稳定增长型、缓慢增长型和稳定型。(3)红楠、薄叶润楠和刨花润楠在小径级和小尺度上多呈聚集分布,随生长发育和空间尺度的增加,聚集强度呈现先增高后降低趋势,最终向离散分布或随机分布转变,可视为群落演替的早期树种;同时,三者在聚集强度上有所差异,排序为红楠＞薄叶润楠＞刨花润楠。毛柄连蕊茶Camellia fraterna种群密度较低,在小径级和小尺度上呈随机分布,随生长发育和空间尺度的增加,聚集强度呈波动趋势,最终向离散分布转变,可视为演替的中期树种。本研究在小尺度上初步揭了午潮山木本幼苗种群的演替过程中的种群结构和分布格局,可以为亚热带森林管理与植被恢复提供理论依据。     

尺度变化对关帝山庞泉沟云杉次生林空间分布格局的影响

林分空间格局研究对认识和理解森林群落结构的生态学过程具有重要作用。适宜的样地尺度不仅可以有效降低工作和时间成本,也可以提高林分属性的精确估计。同时,抽样尺度的适宜程度对科学评价林分空间结构调整也具有重要的现实意义。以关帝山庞泉沟4 hm²云杉次生林固定监测样地为研究对象,运用样地划分法和空间点格局的K2函数,评估了林分主要树种空间格局随样地面积变化的规律。结果表明:通过重要值排序,选取云杉(青杄+白杄)、华北落叶松、桦树(白桦+红桦)+其它阔叶树(花楸+辽东栎+山杨+山楂)作为主要树种(组)。随着样地尺度的减小(从4 hm²到0.25 hm²),空间分布格局主要表现为较小尺度(≤ 4 m)的聚集分布过度为随机分布与均匀分布,以及聚集和随机分布交替出现。所有树种的次级样地与参考样地的一致性指数差异显著,云杉和华北落叶松组合1 hm²样地一致性指数最高,而桦树和其它阔叶树完整1 hm²样地一致性指数最高;此外,云杉、华北落叶松和桦树0.25 hm²样地与组合1 hm²样地空间格局一致性指数组间差异显著。研究认为1 hm²样地尺度可以作为该地区云杉次生林空间分布格局的最小尺度。研究为探索云杉次生林空间格局的变化规律及样地抽样尺度的选取方面,提供了一定的理论基础和技术依据。     

贵州特有植物红花瘤果茶种群空间格局及数量动态研究

红花瘤果茶(Camellia rubituberculata)为地理分布狭窄的贵州特有植物,颇具经济价值。为查清其分布特征和评估其濒危状况,该文在红花瘤果茶的集中分布区设置三个典型样地进行调查,采用空间点格局及多元点格局分析法分析种群空间分布格局,利用种群动态量化指数分析预测种群数量动态规律。结果表明:(1)兴仁县新寨村大皮坡1号样地幼龄树的小尺度呈集群分布、大尺度呈随机分布,中龄树和老龄树均呈随机分布; 兴仁县新寨村槽子土2号样地的幼龄树均呈集群分布,中龄树和老龄树均呈随机分布; 晴隆县紫马乡龙头村上捧碧林区3号样地幼龄树、中龄树和老龄树均呈随机分布。(2)不同发育阶段的空间关联主要表现为1号样地幼龄树和中龄树均为负相关,幼龄树和老龄树在中小尺度上为负相关,在大尺度上为无相关,中龄树和老龄树均为无相关。2号样地幼龄树和中龄树在小尺度上为负相关,中大尺度上为无相关; 幼龄树和老龄树在中小尺度上为负相关,中大尺度上为无相关; 中龄树和老龄树均为无相关。3号样地的幼龄树和中龄树均为正相关; 幼龄树与老龄树在小尺度上为负相关,中尺度上为无相关,大尺度上为正相关; 中龄树和老龄树均为无相关。(3)种群数量动态分析表明3个样地中幼苗补充充裕,种群结构为增长型,但易受外界环境干扰、生态脆弱。(4)红花瘤果茶的生境异质性及其种内种间关系相互作用的结果是影响种群数量扩大和物种散布的主要因素。     

Establishment and growth pattern of <Emphasis Type="Italic">Pinus pumila</Emphasis> under a forest canopy in central Kamchatka

We investigated the spatial distribution and growth of the Siberian dwarf pine (Pinus pumila) in a valley–foothill larch–birch (Larix cajanderi–Betula platyphylla as canopy trees) mixed forest of fire origin located in central Kamchatka with the aim of elucidating the ecological features of P. pumila when it is an undergrowth species in a forest. The spatial distribution of all individuals of all tree species was clumped, and the spatial distribution of the two canopy tree species did not repulsively affect that of P. pumila (i.e., its establishment site). These results suggest that the regeneration of P. pumila does not depend on canopy gaps. However, the analysis using a growth model indicated that the canopy trees negatively affected the growth of P. pumila and that the negative effect of L. cajanderi on P. pumila growth was stronger than that of B. platyphylla. The direction of the crown extension of P. pumila was weakly related to the open-space direction. Our results suggest that, although the spatial pattern of establishment of P. pumila is not repulsed by the distribution of canopy trees, the crown can spread horizontally toward the more sparsely populated areas of the canopy trees where they may have higher growth rates.     

桥山林区麻栎种群不同发育阶段空间格局及关联性

为探究麻栎种群不同发育阶段的空间分布特征及关联性,以黄土高原南部桥山林区麻栎天然次生林为研究对象,用L(r)函数对麻栎种群不同发育阶段空间分布特征及关联性进行分析。结果表明:(1)样地内麻栎种群各发育阶段数量结构均为不规则倒"J"型,种群结构稳定,能实现持续更新。(2)麻栎种群总体的空间分布特征受生境异质性影响较大,纯林样地中,种群在0—10 m尺度上表现为高强度聚集分布,5—35 m尺度表现为低强度聚集;混交林样地中,0—5 m尺度上表现为高强度聚集分布,5—35 m尺度上则表现为低强度聚集分布。(3)随着种群的发育及尺度的增大,麻栎种群空间聚集强度减弱,纯林样地内,麻栎幼苗在0—6 m的小尺度表现为聚集分布,6—12 m尺度上表现为随机分布;幼树在各尺度上均表现为聚集分布;中龄树与成龄树在各尺度上均表现为随机分布。混交林样地中,仅幼苗在0—6 m尺度上表现为聚集分布,其余各阶段在各尺度下均趋于随机分布。(4)种群不同发育阶段不同尺度空间关联性不同,纯林样地中,幼苗与幼树在1—2 m小尺度上呈负相关,幼树与中龄树在8 m尺度呈正相关,其余各生长阶段之间在任意尺度上均无关联性;混交林样地中,幼树与中龄树在2—12 m尺度上表现为正相关,其余各生长阶段之间在各尺度上均无关联。在未来的森林经营中,应对不同发育阶段、不同生境的种群进行不同抚育措施,促进种群良性发育。     

Spatial structure and genetic diversity of three tropical tree species with different habitat preferences within a natural forest

Analyses of the spatial distribution pattern, spatial genetic structure and genetic diversity were carried out using a 33-ha plot in a hill dipterocarp forest for three dipterocarps with different habitat preferences, i.e. Shorea curtisii on the ridges, Shorea leprosula in the valleys and Shorea macroptera both on the ridges and in the valleys. The significant spatial aggregation in small-diameter trees of all the three species was explained by limited seed dispersal. At the large-diameter trees, only S. macroptera showed random distribution and this might further prove that S. macroptera is habitat generalist, whilst S. curtisii and S. leprosula are habitat specific. The levels of genetic diversity estimated based on five microsatellite loci were high and comparable in all the three studied species. As the three studied species reproduced mainly through outcrossing, the observed high levels of genetic diversity might support the fact that the plant mating system can be used as guideline to infer the levels of genetic diversity, regardless of whether the species is habitat specific or habitat generalist. The lack of spatial genetic structure but significant aggregation in the small-diameter trees of all the three species might indicate limited seed dispersal but extensive pollen flow. Hence, if seed dispersal is restricted but pollen flow is extensive, significant spatial aggregation but no spatial genetic structure will be observed at the small-diameter trees, regardless of whether the species is habitat specific or habitat generalist. The inferred extensive pollen flow might indicate that energetic pollinators are involved in the pollination of Shorea species in the hill dipterocarp forests.     

吉林蛟河不同演替阶段针阔混交林木本植物幼苗空间分布与年际动态

幼苗的空间分布对群落更新具有重要意义。于2011年夏季在蛟河地区3个不同演替阶段针阔混交林样地内共设置了451个种子雨-幼苗观测样站,并于2012—2014年对幼苗样方内胸径1 cm的木本植物幼苗进行了连续3a的调查。对木本植物幼苗的数量分布以及水曲柳(Fraxinus mandshurica)、五角枫(Acer mono)、杉松(Abies holophylla)和东北枫(Acer mandshuricum)4个主要树种幼苗与大树的空间关系及其年际变化进行了分析,并用Syrjala检验分析了样站尺度上幼苗密度、丰富度空间分布在年际间的差异。结果显示:(1)木本植物幼苗的数量分布在不同群落和年际之间都表现出明显的差异,样站尺度上3个样地内的幼苗密度存在着较大的空间变异性,而幼苗丰富度的空间异质性较低。表明幼苗分布的空间异质性对幼苗密度有着重要影响。(2)样站尺度上幼苗数量和物种数的空间分布在不同年份之间是存在差异的。在一定程度上证实了种子产量、扩散方式和群落组成对幼苗空间分布的影响。(3))从死亡幼苗与大树空间关系来看,4个主要树种的死亡幼苗与成树表现出相似的分布格局,这既表明成体植株的空间分布特征也能够影响幼苗的空间分布格局,也从侧面说明了负密度制约效应对幼苗空间分布的影响。     

荒漠草原不同土壤条件下猪毛蒿幼苗种群的点格局分析

采用摄影定位法测定了宁夏荒漠草原3种不同土壤条件下猪毛蒿（Artemisia scoparia）幼苗种群的空间格局,并应用完全空间随机模型、泊松聚块模型和嵌套双聚块模型对其分布格局进行了分析。结果表明：（1）在灰钙土生境下,猪毛蒿幼苗种群在小尺度上（0-2.85m）表现为聚集分布,随着尺度的增大先呈现为随机分布（2.85-3.75 m）,然后又呈现为均匀分布（3.75-5m）;在风沙土生境下,猪毛蒿幼苗种群在0-1.85 m之间表现为聚集分布,在1.85-2.35 m之间表现为随机分布,当尺度大于2.35 m时表现为均匀分布;而基岩风化残积土上的猪毛蒿幼苗种群在整个尺度上均呈现随机分布。（2）猪毛蒿种群幼苗在基岩风化残积土上符合泊松聚块模型,即猪毛蒿种群空间格局的聚块中不存在较高密度的小聚块;而在风沙土和灰钙土上则符合嵌套双聚块模型,即在大聚块中分布较高密度的小聚块。猪毛蒿幼苗种群空间格局的形成与土壤异质性存在着密切的联系,种群在空间中分布格局的形成机制可以通过种群空间格局的分析加以解释。     

择伐对思茅松自然种群结构和空间分布格局的影响

思茅松是云南省重要的材脂兼用树种,而择伐是思茅松天然林管理的有效手段,也是获取木材的重要途径。基于对云南省景谷县思茅松天然林的样地调查数据,采用种群径级结构代替年龄结构、Ripley的L函数点格局等方法,对思茅松天然林在不同强度择伐10a后的种群结构和空间分布格局及其不同发育阶段在不同尺度下的相互关系进行了系统研究和分析。结果表明:择伐10a后3种类型的思茅松自然种群的胸径、树高之间呈显著的正相关且可用幂指数模拟预测模型。未择伐的思茅松种群呈衰退型,轻度择伐(12.9%)后种群呈稳定型,中度择伐(29.3%)后的种群属增长型,适当的中度择伐有利于自然种群的更新;未择伐与中度择伐后的思茅松种群分布格局整体呈随机型,但后者较前者更趋向于均匀分布,轻度择伐后的思茅松种群分布格局随着尺度的增加由随机转向聚集分布。择伐对不同径级思茅松天然林种群空间分布格局有重要影响,未择伐的思茅松自然种群随着发育阶段的发展,多数尺度上由随机分布逐渐转变为聚集分布,至大树则又以随机分布为主;轻度择伐和中度择伐的思茅松自然种群则随着发育阶段的发展而由完全的随机分布逐渐转变为聚集分布,中度择伐的聚集分布则更为明显。思茅松不同发育阶段间在所有尺度上基本都呈显著正相关,表明思茅松种群种内竞争弱,有利于种群的维持。     

Spatial distribution of Eurya japonica in an old-growth evergreen broad-leaved forest,SW Japan

Abstract. The spatial distribution of Eurya japonica, an evergreen understorey species, was studied on a 4-ha permanent plot in an old-growth, temperate, evergreen broad-leaved forest in southwestern Japan. The pattern of spatial dispersion varied with size class, the environmental heterogeneity produced by tree-fall gaps and microtopography and the scale of observation. Seedlings (0.05 to < 0.5 m high) had the most clumped distributions, followed by saplings (0.5 to 1.3 m high) and adults (> 1.3 m). Individuals were more clumped at the smallest grid size, 1.56m × 1.56 m, and became less clumped as grid size increased for all size classes. On grids of less than 6.25 m × 6.25 m, no spatial correlations were found between seedlings and larger size classes; positive spatial correlations were found between saplings and adults at this scale. Abundant seedlings appeared in tree-fall gaps formed by uprooted trees, but seedlings were frequent on ridge tops and upper slopes. Saplings and adults also occurred on upper slopes, but their spatial distribution had little relation to current tree-fall gaps. The spatial distribution of E. japonica individuals was largely attributed to the distribution of tree-fall gaps and the differential responses to microtopographic variation by individuals at different size classes.     

藏东南急尖长苞冷杉群落空间点格局分析及其时空动态

为探究藏东南色季拉山急尖长苞冷杉（Abies georgei var.smithii）群落的空间分布格局及其时空动态,在急尖长苞冷杉纯林中设置1个1 hm²的固定样地,记录样地内所有高度>2 m的急尖长苞冷杉的年龄、胸径、冠幅和坐标等指标。根据径级分布分析种群的径级结构,采用点格局分析方法对种群的空间格局进行分析。结果显示：（1）急尖长苞冷杉的径级分布为倒"J"型,结构稳定,自然更新良好。（2）成树在各个时期和不同尺度上都呈随机分布;幼树在1891年之后的各个时期在小尺度（2 m）上呈聚集分布,1981-2012年在1-41 m尺度上陆续出现聚集分布;幼苗在1861-1920年在小尺度（1-2 m）上呈聚集分布,1951-1980年出现聚集分布的尺度范围最大（1-35 m、41 m和48 m）。（3）在不同时期中,不同年龄组树木之间几乎都呈正关联或无关联;成树和幼树随时间推移从无关联到在各个尺度上陆续出现正关联的变化;成树和幼苗随时间呈无关联、中大尺度（32-35 m、44 m和49 m）正关联和无关联的变化;幼苗和幼树呈现从无关联转变为小尺度（8 m）正关联和小、中尺度（1-30 m）正关联的变化。研究结果表明：成树在小尺度上对幼龄树存在一定的抑制,但在较大尺度是促进的。1951-1980年样地中的幼苗数量大量增加,随后30年幼树的数量因幼苗长大也有增加,这在一定程度上增大了竞争。但总体来看急尖长苞冷杉群落在演替过程中具有种内促进作用。     

沙地樟子松天然林南缘分布区林木竞争、空间格局及其更新特征

以呼伦贝尔沙地樟子松地理分布南缘天然林为研究对象,采用Hegyi竞争指数与点格局等分析方法,研究了沙地樟子松天然林的种群结构、种内竞争、空间格局及幼树更新等特征。结果表明:1)所调查区域天然沙地樟子松纯林处于中幼龄阶段,属增长型种群;2)其竞争指数与对象木胸径服从幂函数关系CI=242.24D~(-1.12)(R~2=0.91);3)幼树在小尺度上呈聚集分布,中树与大树在中大尺度上呈随机分布;幼树与中树在小尺度上呈正相关性,中树与大树在小尺度呈负相关性;4)竞争指数与更新幼树和存活更新幼树的密度均呈显著正相关性。在林分管理中需要充分考虑林木竞争、空间格局以及种群更新的关系,本研究可为沙地樟子松天然林的经营管理与保护提供重要的科学依据。     

Variation of plant diversity in a temperate unmanaged forest in northern Spain: behind the environmental and spatial explanation

The persistence of seedlings in the forest understorey is of major importance for the maintenance and regeneration of canopy trees in several forested ecosystems. In the present study, we examine the small-scale spatial pattern of a mixed beech and oak seedling–sapling bank in two areas of an unmanaged temperate deciduous forest with different environmental conditions. We used environmental, biotic and spatial variables to establish the main factors that explain the spatial pattern of these seedling–sapling banks at different scales. The stand structure in both areas was similar, but while in plot A beech dominated the canopy, plot B was dominated by oaks. In both areas, established beech individuals showed a clear reverse J-shaped distribution, whereas established oaks showed a unimodal distribution with only a few young individuals. Seedlings of beech and oak were distributed in aggregates, whereas beech saplings had a random distribution. At broader scales, the abundance of seedlings and saplings is affected by the environment as well as by inter-species competition, while at finer scales the spatial pattern is mainly influenced by stochastic processes, probably related to seed predation and establishment. The structure of the seedling–sapling bank indicates an advantage of beech over oak as far as regeneration is concerned. Beech seedlings and saplings tolerate the stress induced by the canopy and the understorey and persist for many years, while oak seedlings decline in a few years. Therefore, if current conditions persist, after canopy opening beech seedlings and saplings can grow rapidly into the canopy and the stands will move towards beech dominance.     

川西米亚罗亚高山暗针叶林岷江冷杉和糙皮桦空间格局及其关联性分析

基于2019年9月完成的川西米亚罗亚高山暗针叶林9.6 hm~2动态样地的调查数据,分析了主要优势种岷江冷杉(Abies fargesii var.faxoniana)与糙皮桦(Betula utilis)的径级结构,并运用O-ring统计中的成对相关函数g(r)和g₁₂(r),研究了两个优势种的空间格局及其种内、种间的关联性。结果表明：岷江冷杉与糙皮桦径级分布连续,均呈倒“J”型。岷江冷杉与糙皮桦的不同径级个体主要呈现由聚集分布向随机分布发展的趋势。岷江冷杉的小树对幼树、中树对幼树、中树对小树以及大树对中树的种内相关性在所有空间尺度上均为显著正相关(P<0.05),而相同径级糙皮桦的种内相关性则表现为由显著正相关(P<0.05)逐渐向无显著相关(P>0.05)变化。随着空间尺度的增大,岷江冷杉的大树对幼树、大树和小树由无显著相关(P>0.05)逐渐向显著正相关(P<0.05)变化,糙皮桦的大树对幼树由显著负相关(P<0.05)逐渐向无显著相关(P>0.05)变化。岷江冷杉大树对糙皮桦所有径级个体的种间相关性主要呈现由为显...     

庐山森林景观空间分布格局及多尺度特征

森林景观是区域整体景观的重要组成部分,研究其空间分布格局对于优化区域景观整体结构和发挥生态经济效益具有重要意义。基于庐山2010年植被斑块数据,将森林景观划分为常绿阔叶林、落叶阔叶林、松类、杉类和竹类等5类景观,从森林景观的不同发育阶段和林分类型角度出发,运用点格局分析法分析5类森林景观空间分布格局特征。最邻近距离分析表明:5类森林景观空间分布类型均服从集聚分布但聚集强弱有变化;不同发育阶段的森林景观空间分布类型以集聚分布为主,随机分布为辅,尤其幼龄林比较显著,中龄林和老龄林次之;5类森林景观的天然林均服从集聚分布,人工林大多趋于随机分布,只有松类和杉类呈显著集聚分布。Ripley's K函数揭示了不同发育阶段和林分类型的森林景观的多尺度集聚特征,即在小尺度范围内服从随机分布,随着空间距离的增大,以空间特征尺度为分界线,空间聚集强度先逐渐增强,随后不断减弱。总体来看,庐山森林景观的发育阶段主要处于幼年时期,原始植被遭到人类大肆破坏,幼龄林大片分布,属于典型的恢复性植被,未来要重点保护好天然林,减少人为干扰,实现森林景观适度集聚。研究庐山森林景观的空间分布和多尺度特征可以为生态环境保护和实现森林可持续经营提供理论指导。