格氏栲天然林与人工林细根生物量、季节动态及净生产力

通过对福建三明格氏栲天然林及在其采伐迹地上营造的33年生格氏栲人工林和杉木人工林细根分布、季节动态与净生产力进行的为期3a(1999～2001)的研究,结果表明,格氏栲天然林、格氏栲和杉木人工林活细根生物量分别为4.944t/hm2、3.198t/hm2和1.485t/hm2,死细根生物量分别为3.563t/hm2、2.749t/hm2和1.287t/hm2;死细根生物量占总细根生物量的比例分别为41.9%、46.2%和46.4%;<0.5mm细根生物量占总细根生物量的比例分别为31.2%、29.4%和69.9%。3种林分活细根生物量和死细根生物量季节间差异显著(P<0.05),但年份间差异则不显著(P>0.05);活细根生物量最大值均出现在3月份,最小值一般出现在5～7月份或11～翌年1月份间。0～10cm表土层格氏栲天然林活细根生物量高达295.65g/m2,分别是格氏栲人工林和杉木人工林的2.4倍和8.1倍;该层格氏栲天然林活细根生物量占全部活细根生物量的59.8%,均高于格氏栲人工林(39.07%)和杉木人工林(24.51%)。格氏栲天然林、格氏栲人工林和杉木人工林细根分解1a后的干重损失率分别为68.34%～80.13%、63.51%～77.95%和47.69%～60.78%;年均分解量分别为8.747、5.143和2.503t/hm2;死亡量分别为8.632、5.148和2.492t/hm2;年均净生产量分别为8.797、5.425和2.513t/hm2,年周转速率分别为1.78、1     

中亚热带杉木人工林细根生物量空间变异与取样数量估算

林木细根生物量具有一定的空间异质性,因此采用合理的细根取样策略对精确估算细根生物量十分重要。通过在福建省三明杉木人工林林内采用土钻法随机选取100个取样点,分析不同细根类型(杉木、林下植被、总细根)生物量的空间变异特征,并对细根生物量所需的取样数量进行估计。结果表明:不同细根类型单位面积生物量随径级(0—1、1—2 mm)及土层深度的增加变异增大,所需的取样数量也相应增加。Shapiro-Wilk检验表明,仅0—2 mm杉木细根和总细根单位面积生物量符合正态分布,其余各个细根类型不同径级不同土层单位面积生物量均不符合正态分布,均呈明显的右偏分布。蒙特卡罗统计模拟分析表明:在置信水平为95%、精度为80%的条件下,直径为0—1 mm、1—2 mm和0—2 mm的细根,杉木采集95、96、32个样品可以满足测定单位面积生物量的需要,林下植被分别采集98、98、63个样品可以满足测定单位面积生物量的需要,而总细根分别采集93、93、18个样品可以满足测定单位面积生物量的需要。     

格氏栲天然林与人工林枯枝落叶层碳库及养分库

通过对福建三明格氏栲天然林及在其采伐迹地上营造的 33年生格氏栲人工林和杉木人工林枯枝落叶层现存量与季节动态、C库及养分库的研究表明 ,格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层现存量分别为 8.99t· hm- 2 、7.5 6t· hm- 2 和 4 .81t· hm- 2 ;枯枝落叶层中叶占现存量的比例分别为 6 4 .96 %、6 1.38%和 38.0 5 % ,枝占比例分别为 31.5 9%、37.83%和 4 2 .6 2 %。格氏栲天然林与人工林枯枝落叶层现存量最大值均出现在春季 ,而杉木人工林枯枝落叶层现存量最大值出现在夏季。格氏栲天然林枯枝落叶层 C贮量为 4 .0 2 t· hm- 2 ,分别是格氏栲人工林和杉木人工林的 1.2 2倍和 1.77倍 ;格氏栲天然林和人工林枯枝落叶层 C库与杉木人工林的差异均达到显著水平 (P<0 .0 5 )。格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层养分贮量分别为 138.4 2 kg· hm- 2 、113.5 6 kg· hm- 2 和 72 .39kg· hm- 2 ;除 Mg外 ,格氏栲天然林枯枝落叶层中各种养分贮量均最高。与人工林相比 ,天然林枯枝落叶层现存量、C和养分贮量均最大。枯枝落叶层对林地长期生产力维持具有重要作用。     

不同连栽代数杉木人工林细根生长、分布与营养物质分泌特征

用土钻法研究了不同连栽代数杉木细根生长与分布,结果表明,杉木连栽1代后,细根生物量明显减少,第1代杉木活细根生物量的范围为646．4－799．7g.m-2,而第2代则为284．4－536．9g.m-2,在一定距离范围内,离树体的距离越远,细根分布越少,杉木连栽后,主要减少了表层土壤（0－10cm)细根的生长,根系分泌物的分析表明,杉木连栽1代后,根系阳离子NH4＋,Na ,K ,Ca2 ,Mg2 的分泌量没有变化,而阴离子NO3-,Cl-,SO4 2-,HPO4^2-,的量都减少,但只有Cl-和HPO4^2-差异显著（P＜0．05）,第2代杉木根系分泌物中的HPO4^2-量仅为第1代的1／65,根－土界面磷交换过程的阐明有利于说明第2代杉木根系HPO4^2-分泌量减少的原因,杉木连栽后,表层土壤细根生长的减少和根系分泌行为的改变可能是生产力下降的重要原因。     

格氏栲和杉木人工林地下碳分配

通过对福建三明36年生的格氏栲人工林和杉木人工林林木地下C分配(TBCA)进行研究,结果表明,由分室累加法直接测定的格氏栲和杉木人工林的TBCA分别为8.426和4.040 t C.hm-2.-a 1。在格氏栲和杉木人工林TBCA组成中,根系净生产量和根系呼吸各约占50%;在根系年净生产量中,细根年净生产量和粗根年净生产量各约占75%和25%。而格氏栲和杉木人工林的细根年C归还量则均约占各自TBCA的1/3(分别为33%和36%)。在假设地下C库处于稳定状态时,由C平衡法计算的格氏栲和杉木人工林的TBCA(分别为6.039t C.hm-2.-a 1和2.987 t C.hm-2.-a 1)低于分室累加法,这与两种人工林地下C库尚未达到稳定状态有关。利用R a ich and N ade lhoffer全球模式方程推算的格氏栲和杉木人工林的TBCA(分别为9.771t C.hm-2.a-1和5.344 t C.hm-2.-a 1)则高于分室累加法,这与全球模式方程只是一种全球尺度规律有关。     

阔叶和杉木人工林对土壤碳氮库的影响比较

通过比较我国亚热带地区19年生阔叶人工林和杉木人工林土壤碳氮储量,探讨树种对土壤碳氮库的影响.结果表明：阔叶人工林0～40 cm土层碳储量平均为99.41 Mg·hm^-2,比杉木人工林增加33.1%;土壤氮储量为6.18 Mg·hm^-2,比杉木人工林增加22.6%.阔叶人工林林地枯枝落叶层现存量、碳和氮储量分别是杉木人工林的1.60、1.49和1.52倍,两个树种的枯落叶生物量、碳和氮储量均有显著差异.枯枝落叶层碳氮比值与土壤碳、氮储量之间呈显著负相关.阔叶人工林细根生物量(0～80 cm)是杉木林的1.28倍,其中0～10 cm土壤层细根生物量占48.2%;阔叶人工林细根碳、氮储量均高于杉木人工林.在0～10 cm土层,细根碳储量与土壤碳储量具有显著正相关关系.阔叶树种比杉木的土壤有机碳储存能力更大.     

格氏栲天然林与人工林土壤非保护性有机C含量及分配

通过对福建三明格氏栲天然林及在其采伐迹地上营造的 33年生格氏栲人工林和杉木人工林土壤非保护性有机 C含量及分配的研究 ,结果表明 ,格氏栲天然林 0～ 10 0 cm土层内土壤有机 C贮量分别是格氏栲人工林和杉木人工林的 1.17倍和1.35倍 ,轻组有机 C贮量分别是后两者的 1.6 4倍和 2 .16倍 ,而颗粒有机 C贮量则分别是后两者的 1.6 0倍和 3.4 3倍 ,其土壤轻组有机 C和颗粒有机 C的分配比例亦显著高于后两者。不同林分间差异均以 0～ 10 cm土层为最大 ,该层格氏栲天然林土壤有机 C含量分别是格氏栲和杉木人工林的 1.5 2倍和 1.6 3倍 ,轻组有机 C含量分别是后两者的 1.70倍和 2 .14倍 ,而颗粒有机C含量则分别是后两者的 2 .18倍和 4 .85倍。这种差异与经营人工林时进行皆伐、炼山、整地等对林地干扰强度较大、幼林郁闭前产生水土流失及凋落物、枯死细根归还量减少等有关。土壤轻组有机 C和颗粒有机 C可作为土壤有机 C库变化的较为敏感指标 ,同时亦可指示土壤肥力演变。     

林分密度对思茅松人工林根系生物量空间分布的影响

以云南省普洱市思茅松人工林中14a龄林为研究对象,对5种造林密度(1m×1m、1.5m×1.5m、2m×1m、2m×2m、2m×3m)的思茅松人工林的林分特征及其根系生物量空间分布进行调查分析,以明确林分密度对思茅松人工林细根生物量空间分布的影响,为思茅松人工林经营管理提供理论依据。结果表明:(1)树高和胸径随着林分密度的减少呈增大趋势,而生物量呈减少趋势。(2)14a思茅松人工林的细根生物量随林分密度的增大而减少,单株细根生物量随林分密度的减小而增大,但粗根与死根生物量在5个林分密度之间无显著差异。(3)细根生物量主要分布在土壤上层,其中40.21%~54.73%的细根集中在0~10cm土壤深度,不同林分密度的细根生物量随土层深度的增加而减少的趋势较为明显,随着林分密度的减小,土壤上层的细根生物量比例呈先增加后减少的趋势。(4)林分密度和土壤深度对细根生物量有显著影响,而且乔木个体大小差异与细根生物量具有极显著的负相关关系,而单株细根生物量与林分密度、乔木个体大小差异、地下生物量及胸高断面积之间呈显著或极显著的负相关关系,而与树高和胸径之间呈显著正相关关系。     

增温下土壤资源异质分布对杉木幼苗生长的影响

在福建三明森林生态系统与全球变化研究站陈大观测点开展大气温度控制、土壤温度控制和土壤资源分布3因子试验,探讨土壤资源异质分布和增温对杉木幼苗地下和地上生长的影响,以及增温是否能改变杉木幼苗细根对土壤资源异质分布的识别度,以明确杉木人工林在全球变暖背景下对土壤资源异质分布的响应.结果表明:杉木对土壤资源异质分布的识别度主要体现在吸收根(0~1 mm径级)上,而1~2 mm径级细根则不具有识别度.除了单独大气增温处理对杉木1~2 mm径级细根的避贫系数具有显著影响外,不同增温处理均未对杉木幼树细根的贫富比、趋富系数和避贫系数产生显著影响.与土壤资源均质分布相比,土壤资源异质分布增加了0~1 mm径级细根生物量,降低了树高.与无大气增温相比,大气增温降低了0~1和0~2 mm径级细根生物量,增加了树高.与无土壤增温相比,土壤增温降低了1~2 mm径级细根生物量,但增加了树高和侧枝长度.大气增温控制、土壤增温控制和土壤资源异质分布对杉木地下、地上生长都无显著交互作用.杉木幼苗吸收根本身对土壤资源异质分布具有识别度,但增温并不会改变杉木幼苗细根对土壤资源异质分布的识别度.     

间伐对杉木不同根序细根形态、生物量和氮含量的影响

以25年生的杉木人工林为对象,研究了间伐对杉木1～5级根的生物量、形态和氮含量的影响.结果表明: 随着根序的增加,杉木细根的生物量、直径和组织密度(RTD)显著增加,而比根长(SRL)、根长密度(RLD)和根数(RN)显著降低.间伐显著提高了1～2级根的生物量、RLD和RN,以及1级和3～5级根的RTD,而对细根的SRL和氮含量无影响;1级和3～4级根的直径显著减小;表层(0～10 cm)土壤中的2级根直径明显小于亚表层(10～20 cm)土壤,而1～3级根的RLD和1～2级根的RN和氮含量均大于亚表层土壤.
间伐和土层的相互作用仅使1～2级根的直径减小.杉木细根的变化主要与间伐后的植被生长及更新密切相关.
     

The relation between fine root density and proximity of stems in closed Douglas-fir plantations on homogenous sandy soils: implications for sampling design

Studies have been carried out in two fully stocked, fast growing Douglas-fir plantations of the Dutch ACIFORN project in three consecutive years, to obtain information on fine root densities (Olsthoorn 1991). For the present paper, data collected in early summer 1987 were used to study the relation of fine root density and proximity to the nearest tree or the dominant tree. A large number of samples (37 in one site and 55 in another) was collected in a small plot (10 × 11 m). Two distances were measured at each sampling point: the distance to the nearest tree and the distance to the tree with a dominant crown above that point. There was large variability in fine root density in the samples. Tests with different regression models showed a distinct rooting pattern for one of the two locations. It is concluded that systematic errors in the assessment of fine root density can arise when sampling points are chosen at a constant distance from trees. For Douglas-fir, this systematic error could have been an overestimation of the fine root density by up to 10%. These systematic errors can be avoided easily, using a stratified random design or a random sampling design. When trees are spaced irregularly, a grid sampling design is also appropriate. This revised version was published online in June 2006 with corrections to the Cover Date.     

Response of fine roots to an experimental gap in a boreal Picea abies forest

We examined the initial response of the quantity and distribution of fine roots to the creation of an experimental canopy gap with a diameter of 50 m in a mature managed Norway spruce forest. Under the canopy, the fine root length densities of trees, shrubs, and grasses and herbs were 3207, 707 and 2738 m m^–2, respectively. The fine root biomass of trees, shrubs, and grasses and herbs were 182, 47 and 52 g m^–2, respectively. Two growing seasons after gap creation hardly any fine tree roots were found in the middle part of the gap. The living tree roots in the gap edge zone were mainly located within a 5-m distance from the standing edge trees. The indices developed here to show the influence of trees on fine root lenght density clearly revealed the effect of the vicinity of living trees on fine root lenght density. The root densities of grasses, herbs and dwarf shrubs did not show a clear response to gap creation despite the increase of their foliage. Our results suggest that in boreal spruce forests a gap disturbance creates a distinct tree root gap and that the gap edge trees do not extend their root systems rapidly into the formed root gap.     

Unusual Fine Root Distributions of Two Deciduous Tree Species in Southern France: What Consequences for Modelling of Tree Root Dynamics?

The spatial distribution of fine roots of two deciduous tree species was investigated in contrasting growing conditions in southern France. Hybrid walnut trees (Juglans regia×nigra cv. NG23) and hybrid poplars (Populus euramericana cv. I214) were both cultivated with or without annual winter intercrops for 10 years on deep alluvial soils. Soil samples for measuring the fine root distribution of both trees and crops were obtained by soil coring down to 3-m depth at several distances and orientations from the tree trunk. The distribution of live fine roots from walnut and poplar trees was patchy and sometimes unexpected. In the tree-only stands, fine root profiles followed the expected pattern, as fine root density decreased with increasing depth and distance from the tree trunk. However, many fine root profiles under intercropped trees were uniform with depth, and some inverse profiles were observed. These distributions may result from a high degree of plasticity of tree root systems to sense and adapt to fluctuating and heterogeneous soil conditions. The distortion of the tree root system was more pronounced for the walnut trees that only partially explored the soil volume: in the tree-only stand, the walnut rooting pattern was very superficial, but in the intercropped stand walnut trees developed a deep and dense fine root network below the crop rooting zone. The larger poplars explored the whole available soil volume, but the intercrop significantly displaced the root density from the topsoil to layers below 1 m depth. Most tree root growth models assume a decreasing fine root density with depth and distance from the tree stem. These models would not predict correctly tree–tree and tree–understorey competition for water and nutrients in 3D heterogeneous soil conditions that prevail under low-density tree stands. To account for the integrated response of tree root systems to such transient gradients in soils, we need a dynamic model that would allow for both genotypic plasticity and transient environmental local soil conditions.     

从空间分布特征认识珍稀植物领春木的种群动态

领春木(Euptelea pleiosperrnum)系第三纪孑遗植物和东亚特有种,目前已被列为国家Ⅲ级重点保护植物.基于空间定位数据以最近邻体距离统计研究了神农架地区领春木的空间分布特征,比较幼苗(DBH≤2.5cm)、幼树(2.5～7.5cm)和成树(＞7.5cm)各径级(代表各生活史阶段)形成的时间序列上的空间格局差异,进而探讨空间格局与立苗、补员、种内竞争等种群动态过程的相互关系.结果显示,在邻域尺度上,领春木的空间格局呈聚集态;幼苗(或幼树)的大小与其距离最近幼树(或成树)的远近没有相关性,幼树(或成树)周围一定距离以内出现同等大小个体的概率约等于幼苗(或幼树)出现的概率,且幼树与最近幼苗(或成树与最近幼树)的平均距离与幼树之间(或成树之间)的平均最近邻体距离没有显著差异;任意个体的大小、任意个体与相应最近邻体的大小之和与相应的最近邻体距离均为显著的正相关关系,但幼树间的最近邻体距离并不大于幼苗随机死亡产生的最近邻体距离,成树间最近邻体距离也不大于幼苗+幼树随机死亡产生的最近邻体距离.这些结果表明,领春木的聚集分布可能与种子散布、生境异质性对立苗格局的作用有关;已定植的大个体可能不限制其邻域内小个体的布局与生长,但是长期的补员过程与邻体间的相互作用不无关系;邻体间存在一定程度的竞争作用,但是竞争强度并未充分激化至发生距离依赖的死亡.     

Ecological observations onHeteropsis Spp. (Araceae) in Southern Venezuela

This article contributes a brief review of the ethnobotany and ontogeny ofHeteropsis spp. (Araceae), reports the distribution and density of Heteropsis spp. in a tropical lowland rainforest in southern Venezuela, and explores the environmental variables that correlate best with the observedHeteropsis densities.Heteropsis occurred on 26% of the 4091 trees (≥10 cm DBH) inventoried in 67 plots (of 0.1 hectare, each). Mean Heteropsis colonization densities differed significantly between 11 local forest types and ranged from 0% (in seasonally deeply flooded forest and in semideciduous hill forest) to 74% (in sporadically flooded forest near small streams). Across forest types,Heteropsis occurred on a significantly greater number of trees between 20 and 50 cm DBH than expected for an even distribution over all size classes. Of the 90 most common potential host species in the plots, the giant herb Phenakospermum guyannense (L. C. Rich.) Endl. was the only one consistently and significantly avoided by Heteropsis, and no host species was significantly preferred across all forest types. Heteropsis densities were positively correlated with the depth of the fine root mat and the diversity of big lianas. They were negatively correlated with the concentration of exchangeable potassium, flooding depth, and the density of small lianas. We conclude that Heteropsis shows clear habitat preferences that reflect site differences in soil fertility, flooding regime and forest structure and could not be explained by the distribution of preferred or avoided host tree sizes or species.     

天山云杉种群空间格局与动态

天山云杉(Picea schrenkiana)林是天山林区的重要针叶林。研究调查了两块分别代表天山云杉不同演替阶段的标准地,应用Ripley’s K系数法研究了天山云杉种群空间格局与动态。结果表明：天山云杉是聚集型种群,天山云杉活立木、枯死木、天山桦(Betula tianschanica Rupr．)和天山柳(Salix tianschanica Rgl．)的空间格局均为聚集型;天山云杉枯死木的聚集强度大于天山云杉活立木的聚集强度;天山桦和天山柳的聚集强度大于天山云杉枯死木的聚集强度;天山桦和天山柳的空间格局随种群所处的演替阶段不同而不同,增长型种群在所有尺度上其空间格局都为聚集型,在大于70m尺度上表现为均匀格局,而天山云杉成熟林中的天山桦和天山柳只在小尺度(0～40m)上表现为聚集。随着天山云杉的生长,其聚集强度逐渐减小,聚集半径不断增大。从50a以下天山云杉到50～100a的天山云杉其聚集强度急速减小,这有利于天山云杉幼树获得足够的资源,是天山云杉幼树的一种生存策略或适应机制。150a以上天山云杉的聚集强度增加,这是由于天山云杉生长到150a左右时开始出现成熟后死亡,形成林窗有利于天山云杉林的更新。研究还对Ripley’s K系数法和频次检验法进行了比较,Ripley’s K系数法能够分析各种尺度下的种群空间格局,且不受样方大小的影响,结果清楚、直观。     

Factors of pine-stand transformation in the city of Yekaterinburg

The relationships between the health of Pinus sylvestris trees and stands and the levels of anthropogenic stress and fragmentation of habitats have been studied based on the example of pine stands of natural origin in Yekaterinburg and its vicinity (48 sampling plots located at different distances from the center of the city). The distances from the city center and from the boundary of a built-up area to a sampling plot and the population density around this plot are taken to characterize the level of anthropogenic stress. The area and perimeter of a forest site; the distance from the boundary of a sampling plot to the forest edges; and the shape of forest edges are used to characterize the level of fragmentation of habitats. We have found that the average morphological metrics of trees have slight changes, while the traits of tree health are significantly altered under urban environment. The overall performance of stands decreases by 22–35% in the urbanization gradient. The health of stands is most substantially influenced by the forest-site area. The population density around sampling plots and the distance of these plots from the megalopolis center have a lower effect on the health of trees and stands. Fragmentation of forests in the city leads to a decrease in the size of forest sites, which causes a decrease in wood stocks and the diameter and height of trees and the deterioration of their health. The lowest area of the forest to make it sustain an urban environment is about 30 ha. The untransformed core of forest is located no less than 70 m from the forest edge.     

Biomass and distribution of fine and coarse roots from blue oak (Quercus douglasii) trees in the northern Sierra Nevada foothills of California

This research adds to the limited data on coarse and fine root biomass for blue oak (Quercus douglasii Hook and Arn.), a California deciduous oak species found extensively throughout the interior foothills surrounding the Central Valley. Root systems of six blue oak trees were analyzed using three methods — backhoe excavation, quantitative pits, and soil cores. Coarse root biomass ranged from 7 to 177 kg per tree. Rooting depth for the main root system ranged from 0.5 to 1.5 m, with an average of 70% of excavated root biomass located above 0.5 m. Of the total biomass in excavated central root systems, primary roots (including burls) accounted for 56% and large lateral roots (> 20 mm diameter) accounted for 36%. Data from cores indicated that most biomass outside of the root crown was located in fine roots and that fine root biomass decreased with depth. At surface depths (0–20 cm), small-fine (< 0.5 mm diameter) roots accounted for 71%, large-fine (0.5–2.0 mm) for 25%, and coarse (> 2 mm) for 4% of total root biomass collected with cores. Mean fine root biomass density in the top 50 cm was 0.43 kg m⁻³. Fine root biomass did not change with increasing distance from the trees (up to approximately 5 m). Thus, fine roots were not concentrated under the tree canopies. Our results emphasize the importance of the smallest size class of roots (<0.5 mm), which had both higher N concentration and, in the area outside the central root system, greater biomass than large fine (0.5–2.0 mm) or coarse (> 2.0 mm) roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

哈尔滨行道树的空间异质性分析

城市行道树空间异质性分析是优化城市森林调查、科学管理与生态服务功能提升的基础。本研究以哈尔滨为例,基于网络街景测定哈尔滨市879个样方、26140棵行道树的树高、胸径、冠幅、冠下高等指标,半方差函数和分形分析相结合,旨在确定树木空间异质性特征,为分析城市森林合理采样布点提供依据。结果发现,不同指标存在明显的空间异质性,表现为自相关距离明显差异,但是没有明显的方向性(在0°、45°、90°、135°方向上各向同性)。这些空间异质性受结构、随机因素影响,但是不同指标明显不同,即:冠幅空间变化中随机因素占比为26.56%,而冠下高、树高、胸径的占比分别为8.16%、8.14%、12.80%,后者更多的受城市化相关的结构因素影响(>88%)。冠幅、冠下高、树高、胸径的变程分别为2340、1320、1470、1890m,考虑到采样间距应控制在变程之内就可以有效揭示空间格局特征,测量不同指标的最小采样数量为:冠幅156个样方;冠下高440个样方;树高360个样方;胸径224个样方。分形分析结果显示,哈尔滨树木冠幅、冠下高、树高、胸径的D值分别为1.957、1.961、1.961和1.971,都接近于2,说明空间变异主要发生在各个样方间(距离:666m),与半方差函数分析交互验证。我们的研究结果为哈尔滨市城市森林研究与管理提供了基础数据支持,有助于今后研究确定合理的采样方案。     

元江干热河谷木质藤本的多样性及其与宿主树木的关系

木质藤本是森林生态系统的重要组分。本研究在元江干热河谷地区随机设置了30个20 m×20 m的样方,调查样方中胸径≥0.5 cm的木质藤本多样性及其与宿主树木之间的关系。结果显示:30个样方中记录到胸径≥0.5 cm的木质藤本植物共945株(隶属于22种20属11科),其中,豆科木质藤本的丰富度和多度最高;胸径≤2 cm的木质藤本占个体总数的63.7%;茎缠绕类木质藤本的个体数最多。样方中胸径≥5 cm的树木共有1060株(隶属于38种31属16科),36.0%的树木上至少附藤1株。不同径级和不同树皮粗糙度的树木被木质藤本侵扰的百分比之间存在极显著差异(P0.001)。随着宿主树木平均枝下高的增加,附藤率呈下降趋势。76.5%的木质藤本选择离其根生长点最近的树木进行攀援。表明元江干热河谷中的木质藤本以小径级占优势,树木胸径、枝下高、树皮粗糙度和木质藤本根生长点到树木的距离是影响木质藤本侵扰树木的重要因素,支持木质藤本对宿主树木的侵扰具有选择性的假说。研究结果对中国西南干热河谷退化植被的恢复与物种多样性保护具有重要意义。