火干扰对苍山云南松林步甲群落的影响

在云南省大理市苍山火烧迹地采用陷阱法初步研究了火干扰对苍山云南松林步甲群落的影响.其中未火烧迹地步甲群落由7属14种组成;火烧迹地步甲群落由6属8种组成,样地同多度没有显著差异.未火烧迹地步甲群落物种组成不同于火烧迹地,但部分火烧迹地与未火烧迹地接近;健步甲Carabus solidior是森林生境良好的指示物种(IndVal=0.9489,P=0.001).研究显示,火干扰已经改变了云南松林步甲群落组成,降低了步甲群落的多样性.     

福建梅花山常绿阔叶林植物物种多样性及其海拔梯度格局

常绿阔叶林是福建梅花山国家级自然保护区地带性植被。采用样带与典型群落调查法对区内的常绿阔叶林14400m2样地展开调查,并对植物多样性海拔梯度格局进行分析,结果表明：（1） 群落植物物种丰富度、Gleason丰富度指数、Simpson指数、Shannon Wiener指数和Pielou均匀度指数的均值分别为64.42、10.75、5.75、3.50、0.58,且这5种指数在各样带间差异极为显著,并随海拔的升高均呈单峰曲线变化,峰值出现在海拔700m~900m。（2） 群落各层次的植物物种丰富度、Shannon Wiener指数均呈现灌木层（包括幼树和层间植物）〉乔木层〉草本层的特征。乔木、灌木层物种丰富度与乔木层Shannon Wiener指数在海拔梯度上的样带间差异极显著,变化趋势与群落相似;灌木层与草本层Shannon Wiener指数以及草本层物种丰富度随海拔梯度变化不明显。因此,梅花山自然保护区常绿阔叶林植物物种多样性的海拔梯度格局呈现单峰分布,并支持中间高度膨胀模式（mid domain model）。     

三江并流地区干旱河谷植物物种多样性海拔梯度格局比较

在滇西北三江并流地区典型干旱河谷段, 在怒江、澜沧江和金沙江的东、西坡共设置了6条海拔梯度样带, 通过标准样地的植物群落调查, 分析各条样带植物的物种丰富度、物种更替率的海拔梯度格局, 并比较了地理和植被变量对分布格局的解释。干旱河谷植被带位于海拔3,000 m以下, 以灌丛和灌草丛为主, 其在各河谷的分布上限自西向东依次升高。植物物种丰富度的分布主要与海拔、流域、经纬度和植被带有关, 沿纬度和海拔梯度升高而显著增加的格局主要表现在草本层和灌木层, 灌木物种丰富度还呈现自西向东显著增加的趋势。怒江的灌木和草本种物种丰富度显著高于金沙江和澜沧江, 三条江的乔木种丰富度差异则不显著。森林带的样方草本物种丰富度显著低于灌草丛带样方, 并且还拥有后者没有的乔木种。不同样带的植物物种更替速率呈现了不一致的海拔梯度格局, 但均在样带海拔下部的灌草丛群落与海拔上部森林群落之间的交错带出现峰值。森林-灌草丛植被交错带在怒江样带处于海拔1,900-2,100 m处, 在澜沧江河谷位于海拔2,300-2,400 m, 在金沙江河谷位于海拔2,700-2,900 m。所有海拔样带的森林段或灌草丛段相对于同一样带不同植被段之间的物种更替程度为最小, 不仅小于同一流域不同样带相同植被段之间物种更替率的均值, 更小于所有样带相同植被段之间的更替率均值。在三条河流6条海拔样带的12个植被带段之间的物种更替变化中, 空间隔离因素可以解释34.2%, 而植被类型差异仅能解释不到0.5%。本研究结果显示了环境差异对不同植被类型物种丰富度的首要影响, 和各河流之间的空间隔离对植物群落构建和物种构成的主要作用。     

香溪河流域河岸带植物群落物种丰富度格局

通过不同海拔高度的样带调查来研究香溪河流域河岸植物群落物种丰富度格局,并探讨河岸带中生物多样性维持的生态学机制。结果表明：河岸植物群落总的物种丰富度、乔木层物种丰富度和草本层物种丰富度沿海拔梯度均表现出相似的格局特征,利用抛物线方程进行拟合,物种丰富度与海拔之间有显著的相关性。灌木层物种丰富度和藤本植物物种丰富度格局特征不明显,且物种丰富度与坡度相关,在流域尺度上,海拔对物种丰富度有着重要的控制作用;在局部尺度上,季节性洪水干扰导致的空间异质性和小地形对群落的生物多样性有着重要的影响,研究结果支在于总的物种多样性在原始河流的中间河段将达到最大值的预测。     

不同火烧强度迹地林下灌草层物种多样性及其与土壤因子的关系

为揭示胶东丘陵区麻栎黑松混交林过火后林下灌丛群落结构和多样性变化,探究群落物种分布和多样性指数与土壤因子之间的相互关系,该研究以威海仙姑顶中度、轻度、未过火林地为研究对象,对不同火烧强度林地进行土壤的定量分析和植物物种多样性调查,并运用典范对应分析法(CCA)和冗余分析法(RDA)进行排序,以明确影响不同火烧迹地林下灌丛群落物种多样性的关键土壤因子。结果表明:(1)各林地丰富度、多样性、均匀度指数在群落垂直方向上均表现为草本层大于灌木层。灌木层丰富度、多样性、均匀度指数均随火烧强度的增加先升后降,轻度火烧达到最大值,是灌丛群落特征变化的关键转折期;草本层Patrick、Shannon-Wiener和Simpson指数逐渐降低,Margalef指数先降低后微弱上升,均在未过火林地达到最大值,均匀度指数各林地无显著差别(P0.05)。(2)未过火与中度火烧地之间的Morista-Horn指数在灌木层、草本层和灌草层中均为最小,β多样性最高,林下物种组成差别迥异;轻度与中度火烧地在灌木层次上物种异质性较高,未过火与轻度火烧地在草本层次上拥有较高异质性的物种更替。(3)中度和轻度火烧地林下灌丛群落大致均可分为3个类群,未过火林下灌丛植物疏离分散,则未形成类群;中度火烧影响植物物种多样性的正向主要因子为碳氮比(C/N),逆向主要因子为全磷(TP)、全钾(TK);轻度火烧正向因子为氮磷比(N/P),逆向因子为pH;未过火林地物种多样性受多种土壤因子的共同作用。(4)火烧提高了林下灌丛群落物种更替速率,增加了灌木层物种多样性,降低了草本层物种多样性,轻度火烧地的物种丰富度水平较高,火烧迹地影响群落物种多样性的因子既有相似性又存在差异性,TK和TP是火烧迹地物种多样性的共同影响因子,磷(P)是火烧迹地物种多样性的共同限制性元素。     

长白山风倒区植被恢复26年后物种多样性变化特征

20世纪80年代后期,长白山遭受了罕见的台风袭击,原始森林遭到了大面积破坏。为了弄清风倒区自然恢复26a后的植被恢复状况,通过调查和对比分析风倒区和相邻的原始林区(对照区)3种典型森林类型的物种多样性的特征,评估了风倒区植被的恢复状况。结果表明,与没有受到干扰的对照区相比,阔叶红松林风倒区乔木层物种丰富度和α多样性差异性不显著(P0.05),而云冷杉林和岳桦林风倒区的乔木层物种丰富度和α多样性显著降低;阔叶红松林风倒区的灌木层物种丰富度和α多样性均呈降低趋势,且丰富度差异性显著,云冷杉林和岳桦林风倒区的灌木层α多样性显著升高;阔叶红松林和云冷杉林风倒区的草本层α多样性显著降低,但岳桦林风倒区草本层α多样性变化不显著。阔叶红松林乔木层更新恢复的较好,灌木层和草本层更新较差;云冷杉林和岳桦林均是乔木层更新较差,灌木层更新较好;云冷杉林草本层物种较单一,岳桦林变化不大。经过风干扰后的长白山不同海拔森林物种组成和多样性还需要较长时间才能恢复到干扰前水平。     

环境因子对北京低山区低效林林下植被物种组成和丰富度的影响

本文探讨了北京低山区油松、刺槐、侧柏3种典型低效林林下植物组成和物种丰富度与环境因子之间的关系,以揭示不同层次物种组成对环境因子的响应,确定影响灌草2层物种丰富度的主要环境因子。在北京低山区设置34个样地进行群落学调查的基础上,运用CCA排序法分析灌木和草本2层的物种组成与海拔、坡向、坡位、坡度、郁闭度共5个环境因子之间的关系,偏CCA测算各环境因子的重要程度,灰色关联度评估各环境因子对物种丰富度的作用大小。结果表明:海拔和坡度对灌木层物种组成的净效应达到显著水平(P0.05),郁闭度对草本层物种组成的净效应达到显著水平(P0.05)。坡度与灌木层物种丰富度的灰色关联度值为0.734,海拔与草本层物种丰富度的灰色关联度值为0.700。灌草2层的物种组成和物种丰富度对环境因子的响应存在差异,海拔和坡度是影响灌木层物种组成最主要的环境因子,郁闭度是影响草本层物种组成最主要的环境因子;坡度和海拔分别是影响灌木层和草本层物种丰富度最主要的环境因子。     

岷江干旱河谷灌丛α多样性分析

通过对岷江干旱河谷植被及其环境因子的系统取样调查 ,研究了该地区植物群落的α多样性及其与环境因子的关系。土壤、植被、地形三者之间的典范相关分析结果表明 ,三者两两之间均存在着较高的相关性。土壤因子与地形因子之间 ,海拔和坡向起较大的作用 ,主要影响土壤中的全氮、有机质和土壤含水量 ;地形因子和植被之间 ,海拔和坡向影响灌木层的多样性和盖度 ;植被和土壤因子之间 ,土壤中的全氮量、有机质和土壤含水量影响灌木层的盖度和多样性。随着海拔的增加 ,草本和灌木群落的多样性都呈现出先增加后减小而后又增加的趋势 ,草本层的α多样性明显高于灌木层的α多样性 ,草本层和灌木层均在14 0 0～ 16 0 0 m和 2 0 0 0～ 2 2 0 0 m两个海拔段有较高的α多样性 ;华帚菊 -小黄素馨灌丛、金花小檗 -忍冬灌丛、绣线菊灌丛有着较高的多样性 ,西南野丁香灌丛、莸灌丛、小马鞍羊蹄甲 -白刺花灌丛的群落多样性较低 ;样带的多样性 ,灌木层 :样带 3>样带 1>样带 2 ,草本层 :样带 1>样带 3>样带 2 ;不同坡向的多样性 ,灌木层 :阴坡 >半阴半阳坡 >阳坡 ,草本层 :半阴半阳坡 >阴坡 >阳坡 ;不同坡形上的多样性 ,无论是灌木层还是草本层 ,多样性大小为凹坡 >平坡 >凸坡 ;灌木层和草本层在不同坡位上的多样性大小均为上     

草海国家级自然保护区森林群落优势种群数量动态及物种多样性研究

该研究以草海国家级自然保护区森林群落乔木树种为依据进行聚类分析,将森林划分为4种群落类型,分别为云南松林、云南松-桤木林、桤木-滇杨林、桤木-华山松林。采用空间代替时间的方法,分析不同种群优势树种的年龄结构、存活曲线及静态生命表,应用时间预测模型对4种群落优势树种的发展趋势进行预测,并分析群落物种多样性,为研究区森林保护及可持续经营提供理论依据。结果表明:(1)云南松林和云南松-桤木林优势树种径级结构均呈现偏正态分布,衰退趋势明显,桤木-滇杨林、桤木-华山松林呈偏倒"J"型,衰退趋势相对较弱。(2)静态生命表及存活曲线分析表明,研究区内森林群落不同种群均出现不稳定状态,存活曲线不同程度偏离DeeveyⅢ型曲线。(3)时间序列分析表明研究区内经过未来2、4、6龄级时间后各种群数量出现增加,但中幼龄个体不断减少,老龄个体先增多后减少,如果不加以抚育管理,种群将不可避免走向衰退。(4)研究区内林下共有植物种类35科70属83种,其中灌木层植物17科23属29种,草本层植物21科48属54种。在3种群落类型中,物种丰富度指数(S)为草本层灌木层,Pielou指数(J_(sw))为灌木层草本层,而桤木-华山松林则呈现相反趋势,物种多样性存在明显差异。     

茂兰喀斯特森林植物物种丰富度的垂直分布特征及环境解释

茂兰喀斯特峰丛地貌森林是目前罕见的一类原生性强、人为干扰少的非地带性森林生态系统,与常态地貌地带性森林生态系统相比差异大。该研究采用典型样地调查方法对茂兰喀斯特森林海拔在620～910 m之间的垂直样带11个样方进行调查,分析研究区顶级群落物种丰富度的垂直梯度变化特征,并用冗余分析(RDA)法分析环境因子对物种丰富度的影响,以明确垂直梯度上物种丰富度与环境因子的关系,为喀斯特自然森林生态系统的维持与恢复、保护与管理提供理论基础。结果表明：(1)该调查茂兰喀斯特峰丛共记录有维管植物511种,隶属于124科272属。(2)单因素方差分析表明,该群落不同生活型的丰富度之间存在极显著差异(P<0.01);LSD多重比较分析表明,群落丰富度水平表现为总体>灌木层>草本层>乔木层。(3)随海拔梯度的升高,群落总物种丰富度和草本层物种丰富度与海拔呈显著负相关关系(P<0.05),乔木层丰富度和灌木层丰富度与海拔无明显规律。(4)冗余分析表明,土壤C/N/P的解释率达到58%,是影响物种丰富度的主要因素。     

Spatial patterns of species diversity in the herb layer of early post-fire regeneration in mixed Pinus yunnanensis forests

Herb layer plays an important role in maintaining ecosystem functioning of forests. The aims of this study were to determine the pattern of species diversity in early post-fire regeneration of the herb layer in mixed Yunnan pine forests and to identify the effects of topography, fire severity, pre-fire vegetation and herb species life-history feature on post-fire regeneration.     

Long-term post-fire vegetation dynamics in Pinus halepensis forests of Central Greece: A functional group approach

A hierarchical approach for plant functional classification was applied to describe long-term vegetation change in Pinus halepensis burned forests. Plant species were initially grouped according to their growth form and afterwards data on species modes of regeneration, persistence and dispersal, together with some other specific competitive advantages were explored, resulting in the identification of 29 different functional groups, 14 for woody and 15 for herbaceous species. Three types of Pinus halepensis forests were identified, according to the structure of the understorey. For each forest type, a post-fire chronosequence of communities was selected for sampling. Data sampling was performed for at least two consecutive years in each community, so as to reduce the shortcomings of the synchronic approach and to increase the age range of each chronosequence. Even though the vast majority of the functional groups proved to be persistent throughout the post-fire development of vegetation, their species richness and abundance did not remain stable. An increase of annual herb richness and abundance was recorded in the first years after the fire, with the leguminous species forming the dominant functional group. For perennial herbs, the most abundant group was of species with vivid lateral growth, while the group of species with subterranean resource organs included the highest number of species. Finally, as far as the woody species are concerned, the groups that played the most important role in defining vegetation structure were the mono-specific group of the pine, the group of resprouting sclerophyllous tall shrubs and the group of obligate seeder short shrubs (with Cistusspp., among others). A negative relationship between the abundance of woody obligate resprouters and the regeneration of woody obligate seeders was found. The advantage of the proposed functional group approach over classical floristic or structural approaches for the long-term study of communities is discussed, together with the applicability of this approach in studies of vegetation risk assessments due to fire regime alterations.     

The occurrence of herbs and woody juveniles in a hardwood floodplain forest in relation to flooding and light

Abstract. A study of the distribution of herbs, seedlings and vegetative propagules of woody species in a hardwood flood-plain forest along the Upper Rhine in France revealed that the occurrence of most species is significantly correlated to elevation above river level and light transmission in summer. Species confined to higher-lying sites which are only occasionally and briefly flooded in the growing season show most damage upon flooding. Tall herb species occur on sites where more than 5% daylight reaches the herb layer and they only reach a dense cover where flooding is occasional. The occurrence of woody juveniles is negatively correlated with tall herb cover and largely confined to more shaded sites or more frequently flooded sites. The results indicate that both shading and flooding are important for regeneration of woody species and for maintaining species diversity in hardwood flood-plain forests.     

Effects of heterogeneity of pre-fire forests and vegetation burn severity on short-term post-fire vegetation density and regeneration in Samcheok,Korea

This study investigated the combined effects of heterogeneity of pre-fire forest cover and vegetation burn severity on post-fire vegetation density and regeneration at an early stage in Samcheok, Korea. To measure the spatial heterogeneity of pre-fire forests, spatial pattern metrics at a landscape level and class level were adopted, and a regression tree analysis for post-fire vegetation density and regeneration was used to avoid spatial autocorrelation. Two regression tree models were estimated for post-fire vegetation density and post-fire vegetation regeneration with the same independent variable sets, including heterogeneity of pre-fire forest cover and vegetation burn severity. The estimated model suggested that the percentage of Japanese red pine and burn severity were the most significant variables for post-fire vegetation density and regeneration, respectively. The compositional and spatial heterogeneity of pre-fire forest and burn severity, as well as the degree of burn severity, was found to have significant impacts on post-fire vegetation density and regeneration. Overall, more rapid vegetation regeneration can be expected in more severely burned areas. However, this rapid vegetation regeneration at an early stage is due mostly to perennials and shrubs, not to the sprouting or regrowth of trees. The study results strongly indicated that a susceptible forest cover type and its spatial patterns directly influence the heterogeneity of burn severity and early vegetation density and regeneration. Hence, the management of susceptible forest cover types is particularly critical for establishing more fire-resilient forests and for post-fire forest restoration.     

Pinus sylvestris forest regeneration under different post-fire restoration practices in the northwestern Italian Alps

It is frequently believed that a post-fire environment requires immediate actions in order to be restored. Salvage logging followed by plantation is a common post-fire restoration practice in many forests of the northwestern Italian Alps.The objectives of this study were to assess the impact of active and passive management techniques on the restoration of a burned area of the Aosta Valley and to determine which approach is the most suitable for enhancing Pinus sylvestris regeneration after stand replacing wildfires.The influence of five management options (no intervention; salvage logging; broadleaves plantation; Larix decidua plantation; P. sylvestris or Pseudotsuga menziesii plantation) and environmental variables on natural regeneration structure and composition was evaluated through direct gradient analysis.Pinus sylvestris and Populus tremula were the dominant tree species (40 and 29%, respectively) in the regeneration layer. Density, size, and structural diversity of natural regeneration were higher in the no intervention area. The proximity to forest edge was found to be the most important environmental variable.This study provided evidence that taking advantage of natural restoration processes may be a suitable alternative strategy to the active restoration practices adopted according to the Aosta Valley policy of post-fire management.     

Lack of tree layer control on herb layer characteristics in a subtropical forest,China

Question: Knowledge of the interaction between understorey herb and overstorey tree layer diversity is mostly restricted to temperate forests. How do tree layer diversity and environmental variables affect herb layer attributes in subtropical forests and do these relationships change in the course of succession? Do abundance and diversity of woody saplings within the herb layer shift during succession? Location: Subtropical broad‐leaved forests in southeast China (29°8′18″‐29°17′29″N, 118°2′14″118°11′12″E). Methods: A full inventory of the herb layer including all plants below 1‐m height was done in 27 plots (10 × 10 m) from five successional stages (<20, <40, <60, <80 and ≥80 yr). We quantified the contribution of different life forms (herbaceous, woody and climber species) to herb layer diversity and productivity and analysed effects of environmental variables and tree layer diversity on these attributes. Results: Herb layer composition followed a successional gradient, as revealed by non‐metric multidimensional scaling (NMDS), but diversity was not correlated to the successional gradient. There was no correlation of diversity across layers. Herb layer productivity was neither affected by tree layer diversity nor by herb layer diversity. Although abundance of woody species in the herb layer decreased significantly during succession, woody species contributed extraordinarily to herb layer species diversity in all successional stages. All environmental factors considered had little impact on herb layer attributes. Conclusions: The subtropical forest investigated displays an immense richness of woody species in the herb layer while herbaceous species are less prominent. Species composition of the herb layer shows a clear successional pattern, however, the presence or absence of certain species appears to be random.     

The species richness–productivity relationship in the herb layer of European deciduous forests

Aim In contrast to non‐forest vegetation, the species richness–productivity (SR‐P) relationship in forests still remains insufficiently explored. Several studies have focused on the diversity of the tree layer, but the species richness of temperate deciduous forests is mainly determined by their species‐rich herb layer. The factors controlling herb‐layer productivity may differ from those affecting tree layers or open herbaceous vegetation, and thus the SR‐P relationship and its underlying processes may differ. However, the few relevant studies have reported controversial results. Here we explore the SR‐P relationship in the forest herb layer across different areas from oceanic to continental Europe, and put the effect of habitat productivity on species richness into context with other key factors, namely soil pH and light availability. Location North‐western Germany, Czech Republic, Slovakia and southern Urals (Russia). Methods We measured herb‐layer species richness and biomass, soil pH and tree‐layer cover in 156 vegetation plots of 100 m² in deciduous forests. We analysed the SR‐P relationship and the relative importance of environmental variables using regression models for particular areas and separate forest types. Results We found a consistent monotonic increase in the herb‐layer species richness with productivity across all study areas and all forest types. Soil pH and light availability also affected species richness, but their relative importance differed among areas. Main conclusions We suggest that the monotonically increasing SR‐P relationship in the forest herb layer results from the fact that herb‐layer productivity is limited by canopy shading; competition within the herb layer is therefore not strong enough to exclude many species. This differs fundamentally from open herbaceous vegetation, which is not subject to such productivity limits and consequently exhibits a unimodal SR‐P relationship. We present a conceptual model that might explain the differences in the SR‐P relationship between the forest herb layer and open herbaceous vegetation.     

Long-term post-fire dynamics of co-occurring woody species in Pinus brutia forests: the role of regeneration mode

Regeneration mode is one of the key attributes determining population structure and dynamics of plant species. We investigated long-term patterns after fire in the cover of plant species in a 100-year chronosequence of burned Pinus brutia forests in a humid Mediterranean climate region in Turkey. Significant trends were present in the change of cover in major species through post-fire chronosequence, and species with similar trends were clustered in relation to their regeneration modes. Obligate resprouters increased their cover from the early post-fire years to the later stages, while cover of obligate seeders with a soil seed bank increased in the early years, but then decreased through time. Facultative resprouters were at an intermediate position, with an increase in cover until mid-successional stages and then a decrease through time. The cover of the only obligate seeder with a canopy seed bank (P. brutia) followed a linear increasing trend during the succession. When species with the same regeneration mode were grouped, the same trends were observed with more explained variances. A few life-history traits were enough to explain the observed trends. Our study shows that regeneration mode is an explanatory functional grouping system for describing long-term post-fire dynamics of Mediterranean Basin woody species. We suggest that regeneration mode must be a major component of any vegetation or forest stand dynamics model in the Mediterranean Basin. This result has important implications for the management of Mediterranean Basin ecosystems, and can potentially be extrapolated to other Mediterranean-type fire-prone ecosystems.     

Role of culturally protected forests in biodiversity conservation in Southeast China

Culturally protected forests (CPFs), preserved and managed by local people on the basis of traditional practices and beliefs, have both social and ecological functions. We investigated plant species richness and diversity within the tree layer, shrub layer and herb layer in three types of CPFs (community forests, ancestral temple forests, cemetery forests) as well as nearby forests without cultural protection (NCPFs) in Southeast China. A total of 325 species belonging to 85 families and 187 genera were recorded in CPFs, including 17 protected species in China Species Red List and IUCN Red List, which accounted for 17 % of counties’ endangered species. Compared with NCPFs, the tree layer of CPFs had larger DBH and lower species density, especially in the cemetery forests. CPFs had higher alpha diversity values generally, particularly in the tree layer. The differences in tree layer were substantial, and CPFs covered nearly 85.4 % of the tree species in the surveyed sites. The similarities between CPFs and NCPFs were higher in the herb and shrub layers than in the tree layer. These differences of species diversity may be attributed to differences in resource use and management between CPFs and NCPFs. Our field investigation results suggested that local CPFs harbor many plant species, high biodiversity, and contribute to the conservation of a substantial proportion of the local species pool.     

Herb layer response to broadleaf tree species with different leaf litter quality and canopy structure in temperate forests

Question: How do broadleaf tree species affect humus characteristics, herb layer composition and species diversity through their leaf litter quality and canopy structure? Location: Mixed broadleaf forests in Brandenburg, NE Germany. Methods: We studied the herb and tree layer composition in 129 undisturbed stands using a 10‐degree cover‐abundance and percentage scale, respectively. The main floristic gradients were extracted by non‐metric multidimensional scaling. Effects of tree species on the herb layer were analysed with partial Spearman rank correlation. We assessed affinities for specific tree species using indicator species analysis. Results: Both beech and oak influenced herb layer composition mainly through their litter quality, which resulted in deep Ol and Of horizons, respectively. The less dense canopy of oak, in contrast to the dense beech canopy, enhanced species diversity in favour of indifferent herb species (species not closely tied to forests). Lime was correlated with a distinct floristic gradient, but a direct effect on the herb layer cannot be proven with the available data. Effects of hornbeam were less pronounced. Conclusions: The relationship between the tree and herb layer must be partly attributed to pH differences. However, tree species effects on humus characteristics and on light flux to the ground were largely responsible as well. The results suggest that tree species can influence herb layer composition and diversity, but the missing correlation with lime and hornbeam raise questions requiring further detailed investigation.