Tree and stand level variables influencing diversity of lichens on temperate broad-leaved trees in boreo-nemoral floodplain forests

Tree and stand level variables affecting the species richness, cover and composition of epiphytic lichens on temperate broad-leaved trees (Fraxinus excelsior, Quercus robur, Tilia cordata, Ulmus glabra, and U. laevis) were analysed in floodplain forest stands in Estonia. The effect of tree species, substrate characteristics, and stand and regional variables were tested by partial canonical correspondence analysis (pCCA) and by general linear mixed models (GLMM). The most pronounced factors affecting the species richness, cover and composition of epiphytic lichens are acidity of tree bark, bryophyte cover and circumference of tree stems. Stand level characteristics have less effects on the species richness of epiphytic lichens, however, lichen cover and composition was influenced by stand age and light availability. The boreo-nemoral floodplain forests represent valuable habitats for epiphytic lichens. As substrate-related factors influence the species diversity of lichens on temperate broad-leaved trees differently, it is important to consider the effect of each tree species in biodiversity and conservation studies of lichens. Nomenclature Randlane et al. (2007) for lichens; Leht (2007) for vascular plants.     

Non-dominant trees significantly enhance species richness of epiphytic lichens in subtropical forests of southwest China

Host species has an important influence on the distribution of epiphytic lichens in forests. However, the importance of non-dominant trees in shaping lichen communities has been poorly studied owing to the relative rarity of individuals. The importance of dominant and non-dominant trees for distribution of epiphytic lichens was determined in eight subtropical forests in southwestern China. Dominant trees supported more abundant total and exclusive lichen species only in secondary forests. The occurrence of non-dominant trees promoted lichen diversity within forest types and influenced lichen communities on both tree groups. The effects of total tree species on lichen distribution largely resulted from the presence of non-dominant trees. Dominant and non-dominant trees supported distinct lichen assemblages within forest types, and ordination analyses showed a clear separation. Our study, therefore, reinforces the importance of non-dominant trees for conserving epiphytic lichens, and highlights that lichen assemblages are shaped by both dominant and non-dominant trees.     

Species richness and vertical stratification of epiphytic lichens in subtropical primary and secondary forests in southwest China

An entire-tree investigation was conducted in two primary and three secondary forest types in the subtropical Ailao Mountains of southwest China to determine whether species richness and vertical stratification of epiphytic lichens responded to forest type and host attributes. Lichen species number, composition and cover differed significantly among forest types and tree species, while tree diameter and tree height had a modest influence. Epiphytic lichen species and functional groups showed clear vertical stratification. Epiphytic lichens were richer in canopies than on trunks and exhibited a great preference for the intermediate zones of trees, while five lichen groups showed distinct vertical diversification. The stratification patterns are clearly related to forest type and may reflect the microclimatic requirements of individual species, e.g. light availability and humidity.     

Effects of forest continuity and tree age on epiphytic lichen biota in coniferous forests in Estonia

Epiphytic lichen biota on Picea abies and Pinus sylvestris in Estonia was studied. Twenty-one spruce and 21 pine sample plots were located in old forests with long forest continuity, and 12 spruce and 12 pine sample plots in young first-generation forests (<100 years). Altogether 103 lichen species were recorded on the 330 sampled trees. Lichen species richness per plot was significantly higher in old forests in case of both tree species; 31 lichen species, including red-listed and protected species, were found only in old forests. Tree age had a positive effect on lichen species richness on tree stem in old and young spruce forests and in young pine forests. Tree age also had an effect on the presence of several species. Both tree age and forest continuity affected lichen species composition. Arthonia leucopellaea, Chrysothrix spp. and Lecanactis abietina were found in at least every third old spruce or pine forest and in no young forests, and can be regarded as good indicators of old coniferous forests with long continuity in Estonia.     

A survey method for assessing the richness of epiphytic lichens using growth forms

The species richness of epiphytic lichens is continuously decreasing by degradation and loss of habitat. Considering that taxonomic identification of all species is time and resource consuming, rapid assessment methods to extrapolate the total number of species are needed for practical conservation. This paper describes an alternative method using the correlation between lichens growth forms and species richness. The study was conducted in 406 forest stands located in Central Spain, covering a wide range of mediterranean-climate ecosystem regions, management intensity levels, canopy cover conditions, and tree sizes. The presence/absence of epiphytic lichens was determined in 6090 trees, which were dominated by oak species (Quercus ilex, Q. faginea, and Q. pyrenaica). In all type of forests, the diversity of growth forms was positively correlated with the total epiphytic lichen richness. In all cases, species richness increased in non-managed forest stands with dense canopies. Thus, we propose the use of lichen growth forms as a helpful surrogate of species richness to detect potentially conservation priority areas in the Mediterranean region.     

云南哀牢山原生林及次生林群落附生地衣物种多样性与分布

附生地衣是森林附生植物的重要类群之一, 在维护森林生态系统的物种多样性以及水分和养分循环等方面发挥着重要作用。作者于2005年12月至2006年5月利用树干取样法调查了云南哀牢山徐家坝地区原生山地常绿阔叶林及其次生群落栎类萌生林、滇山杨(Populus bonatii)林和花椒(Zanthoxylum bungeanum)人工林中525株不同种类和径级树木距地面 0–2.0 m处附生地衣的组成和分布, 并收集了各个群落地面上凋落的地衣, 分析了林冠层附生地衣的物种组成。研究结果表明, 该区森林中附生地衣物种比较丰富。共收集到附生地衣61种, 分属17科29属, 其中原生林、栎类萌生林、滇山杨林和花椒人工林分别有51、53、46和23种。在树干距地面 0–2.0 m位置, 各群落中的附生地衣组成明显不同;但在林冠层中, 各群落内的附生地衣基本相似。原生林中附生地衣种类较多, 但分布不均匀。树干附生地衣的Shannon-Wiener和Simpson多样性指数以栎类萌生林最高, 分别为2.71和0.89;花椒林和滇山杨林次之, 分别为2.43–2.45和0.88–0.89;原生林最低, 为1.25和0.67。树干方位、宿主种类和宿主径级等都对附生地衣的物种组成和多样性有着重要影响, 附生地衣更多地出现于树干南向方位, 云南越桔(Vaccinium duclouxii)的附生地衣最为丰富, 胸径5.0–25.0 cm的树木上附生地衣较多。哀牢山山地森林群落中丰富的附生地衣种类及物种多样性在维系本区山地森林生态系统生物多样性格局方面具有重要的作用。     

Factors influencing epiphytic bryophyte and lichen species richness at different spatial scales in managed temperate forests

The effect of management related factors on species richness of epiphytic bryophytes and lichens was studied in managed deciduous-coniferous mixed forests in Western-Hungary. At the stand level, the potential explanatory variables were tree species composition, stand structure, microclimate and light conditions, landscape and historical variables; while at tree level host tree species, tree size and light were studied. Species richness of the two epiphyte groups was positively correlated. Both for lichen and bryophyte plot level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for bryophytes the presence of large trees, while for lichens amount and heterogeneity of light were important. Tree level richness was mainly determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size generally increased tree level species richness, except on pine for bryophytes and on hornbeam for lichens. The key variables for epiphytic diversity of the region were directly influenced by recent forest management; historical and landscape variables were not influential. Forest management oriented to the conservation of epiphytes should focus on: (i) the maintenance of tree species diversity in mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks); (iii) conserving large trees within the stands; (iv) providing the presence of shrub and regeneration layer; (v) creating heterogeneous light conditions. For these purposes tree selection and selective cutting management seem more appropriate than shelterwood system.     

The importance of host tree age, size and growth rate as determinants of epiphytic lichen diversity in boreal spruce forests

The amount of large and old trees has decreased in the boreal forests during the last centuries of forestry. Such trees are important habitats for epiphytic lichens and there is a growing concern for lichen species that are associated with large and old trees. However, only little is known about the relative importance of tree size versus age as determinants of lichen diversity. Here we have determined the size, age and growth rate of 157 Norway spruce trees and recorded the occurrence of epiphytic lichen species on their branches and lower stems. The study includes crustose lichens and was done in two old-growth forests in SE Norway. Tree age and tree size were the parameters that explained the largest part of epiphytic lichen diversity. Only the growth rate of the most recent time period, i.e. 1984–2004, showed a statistically significant relationship to diversity. There was no indication of a stabilising species number with increasing tree age. Slow-growing and old trees were, however, mainly of importance to the lichen species growing on stems, and this set of species were in general adversely affected by a large amount of branches. The opposite was the case for the species that were confined to branches as their diversity increased when the amount of branches increased. Our study adds empirical data to support the importance of large and old trees as bearers of biodiversity in boreal forests. Site preservation and patch retention of groups of old and large trees is recommended as measures to maintain epiphytic lichen diversity.     

Vertical distribution of epiphytic lichens on Quercus laurina Humb. & Bonpl. in a remnant of cloud forest in the state of Veracruz,México

In the tropics, corticolous lichen richness and cover tend to increase from the trunk base to the top of the crown of trees. In this study we calculated the total beta diversity of the lichen community along a vertical gradient on Quercus laurina in Mexican cloud forest. By comparing the richness and cover of the lichens by zone, we show that foliose and fruticose lichens are a minor component of the total lichen species richness, but have a higher cover than the crustose lichens. Five zones were identified along each phorophyte (n = 15) with a diameter at breast height >40 cm. A total of 92 species were identified. Of these, 38% were found only in a single zone, 51% were shared between the different zones and 11% occurred across all zones. Species richness and cover increased from the lowest to the highest zones of the phorophytes. Dissimilarity in species composition between the zones could be explained by species replacement. An indicator species analysis revealed that only a few species, e.g. Hypotrachyna vexans, H. cf. sublaevigata and Ramalina cf. sinaloensis prefer a particular zone. The results show that the lichen community associated with Quercus laurina phorophytes is highly diverse and suggest that species richness and cover are related to the zone and the various growth forms.     

Lichen diversity and red-listed lichen species relationships with tree species and diameter in wooded meadows

This study provides a unique large dataset of total epiphytic lichen diversity (fruticose, foliose and crustose species) and composition on 1,294 trees of 17 tree species in wooded meadows in Sweden and Estonia, the Baltic region. The inventory (25,380 observations and 246 lichen taxa) clearly illustrated that Ulmus minor, Quercus robur and Fraxinus excelsior contributed most significantly to epiphytic lichen richness and number of red-listed species. In Sweden, average single tree α richness was 22.2 on Ulmus (only in Sweden), 21.6 on Quercus (25.0 in Estonia) and 19.8 on Fraxinus (16.7 in Estonia), respectively. Ulmus hosted on average one red-listed species per tree, compared with 0.7 on Fraxinus (0.6 in Estonia), 0.4 on Quercus (0.7 in Estonia) and only 0.05 on Betula (same in Estonia). Lichen species composition and the average number of red-listed lichens were influenced by tree diameter on Fraxinus and Quercus, whilst no such pattern was evident on Ulmus. Randomized species accumulation curves of the dominating tree species illustrated that Fraxinus, Quercus and Ulmus supported α dominated lichen communities where individual trees hosted a substantial part of the total richness. Betula, on the other hand, supported β dominated communities where individual trees tended to be dissimilar and, therefore, more of the total richness existed as species turnover among host trees. Lichen species composition was influenced by tree species, and most notably, lichen species on Ulmus had a strong consistent clumping in ordination graphs, with many rare and red-listed lichens. The broadleaved deciduous trees within the wooded meadows clearly contribute greatly to the biodiversity of the Baltic region.     

Lichen diversity and composition in Araucaria forests and tree monocultures in southern Brazil

Tree plantations for commercial use have been replacing native ecosystems all over the world. We investigated how forest conversion to plantations of exotic and native tree species may influence lichen diversity and composition in a southern Brazilian landscape. The lichen community from the National Forest of São Francisco de Paula was studied using three stands of each of the four vegetation types: native Araucaria forest and plantations of Araucaria, Pine and Eucalyptus trees. All plantation stands were surrounded by native Araucaria forest, were of smaller size and were allowed to endure longer than commercially managed plantations. Lichen species and their cover abundance were recorded on tree trunks from 30 to 150 cm above soil level in ten host-trees that were randomly selected in each replication. Seventy-eight lichen species, from 18 genera and 9 families, were registered. Conversion of native forest to plantations of exotic tree species altered species composition by reducing the occurrence of shade tolerant lichens. Plantations of Araucaria angustifolia sustained the highest lichen diversity measured, because this is an excellent host species. These results suggest that a greater diversity of lichens can be preserved in the landscape, if plantations of the exotic Pinus and Eucalyptus genera are replaced by plantations of this native species.     

Tree Species Composition Predicts Epiphytic Lichen Communities in an African Montane Rain Forest

The ecology of many tropical rain forest organisms, not the least in Africa, remains poorly understood. Here, we present a detailed ecological study of epiphytic lichens in the equatorial montane rain forest of Bwindi National Park (331 km²), Uganda. We evaluated all major lichen growth forms, including selected groups of crustose lichens. In 14 transects at elevations of 1290 m to 2500 m, we sampled 276 trees belonging to 60 species. We recorded all lichen species on each tree trunk between ground level and 2 m above the ground, yielding 191 lichen species in 67 genera, with a mean of 4.7 species per tree. We used non‐metric multi‐dimensional scaling to separate epiphytic lichen assemblages according to tree species composition and elevation. Structural equation modeling indicated that elevation influenced tree species composition and that tree species composition largely determined lichen species composition. Thus, elevation acted indirectly on the lichen assemblages. Further studies examining factors such as bark properties and lichen colonization ecology may clarify what determines the association between tree species and lichen assemblages. The link between lichen assemblages and large‐scale elevation patterns, as well as disturbance and regrowth histories, warrants further study. An analysis of lichen species composition on individual tree species that occur over large elevation ranges would distinguish the effect of tree species on lichen assemblages from the effect of elevation and thus climate. Our study highlights the limited extent of our knowledge of tropical epiphytic lichens.     

Species richness of vascular plants,bryophytes, and lichens along an altitudinal gradient in western Norway

Species richness patterns of ground-dwelling vascular plants, bryophytes, and lichens were compared along an altitudinal gradient (310–1135 m a.s.l.), in western Norway. Total species richness peaked at intermediate altitudes, vascular plant species richness peaked immediately above the forest limit (at 600–700 m a.s.l.), bryophyte species richness had no statistically significant trend, whereas lichen richness increased from the lowest point and up to the forest limit, with no trend above. It is proposed that the pattern in vascular plant species richness is enhanced by an ecotone effect. Bryophyte species richness responds to local scale factors whereas the lichen species richness may be responding to the shading from the forest trees.     

Hidden crown jewels: the role of tree crowns for bryophyte and lichen species richness in sycamore maple wooded pastures

Tree crowns typically cover the vast majority of the surface area of trees, but they are rarely considered in diversity surveys of epiphytic bryophytes and lichens, especially in temperate Europe. Usually only stems are sampled. We assessed the number of bryophyte and lichen species on stems and in crowns of 80 solitary sycamore maple trees (Acer pseudoplatanus) at six sites in wooded pastures in the northern Alps. The total number of species detected per tree ranged from 13 to 60 for bryophytes, from 25 to 67 for lichens, and from 42 to 104 for bryophytes and lichens considered together. At the tree level, 29 % of bryophyte and 61 % of lichen species were recorded only in the crown. Considering all sampled trees together, only 4 % of bryophyte, compared to 34 % of lichen species, were never recorded on the stem. Five out of 10 red-listed bryophyte species and 29 out of 39 red-listed lichen species were more frequent in crowns. The species richness detected per tree was unexpectedly high, whereas the proportion of exclusive crown species was similar to studies from forest trees. For bryophytes, in contrast to lichens, sampling several stems can give a good estimation of the species present at a site. However, frequency estimates may be highly biased for lichens and bryophytes if crowns are not considered. Our study demonstrates that tree crowns need to be considered in research on these taxa, especially in biodiversity surveys and in conservation tasks involving lichens and to a lesser degree also bryophytes.     

Dispersal mode,shade tolerance,and phytogeographical affinity of tree species during secondary succession in tropical montane cloud forest

Secondary succession following land abandonment, represented by a chronosequence of 15 old fields (0–80 years old) and two old-growth forests, was studied in the tropical montane cloud forest region of Veracruz, Mexico. The objective was to determine successional trajectories in forest structure and species richness of trees ≥5 cm DBH, in terms of differences in seed dispersal mode, shade tolerance, and phytogeographical affinity. Data were analyzed using AIC model selection and logistic regressions. Mean and maximum canopy height reached values similar to old-growth forest at 35 and 80 years, respectively. Species richness and diversity values were reached earlier (15 and 25 years, respectively) while basal area and stem density tended to reach old-growth forest values within 80 years. Along the chronosequence, the proportion of species and individuals of wind-dispersed trees declined, that of bird dispersed small seeded trees remained constant, while that of gravity and animal dispersed large seeded trees increased; shade-intolerant species and individuals declined, while intermediate and shade-tolerant trees increased. Shade-tolerant canopy trees were rare during succession, even in the old-growth forest. Tropical tree species were more frequent than temperate ones throughout the chronosequence, but temperate tree individuals became canopy dominants at intermediate and old-growth forest stages.     

Vertical distribution of epiphytic bryophytes and lichens emphasizes the importance of old beeches in conservation

During storms in 2005, a number of beech trees fell over at Biskopstorp, SW Sweden, offering the opportunity to study epiphytes along entire stems. In total 16 beech trees in four beech stands representing three different age classes were included. For each tree, 2 m segments from the base to the top were surveyed. In total 115 species were found (76 lichens, 39 bryophytes), of which 30 were considered to be of conservation concern (22 lichens, 8 bryophytes). For lichens significantly more species were recorded above 2 m in height, whereas more bryophytes were recorded below 2 m in height. Certain red-listed lichens were recorded only above 2 m in height on old trees. In a second data set from the same area 140 age-determined beech trees were surveyed for species of conservation concern at the heights 0–2 and 2–5 m, respectively. These species were found almost exclusively on old beech trees, and presence at 2–5 m was recorded, with one exception, only on those trees which also had species of conservation concern at 0–2 m. Records of these species correlated significantly to microhabitat variables, i.e. the presence of rough bark and moss cover higher up the stems on the old trees. This study indicates that surveying only the base in really old beech forests can underestimate both the number of species of conservation concern and their population sizes. However, surveys restricted to the base in rather even-aged beech stands catch a large proportion of the trees with species of conservation concern.     

Native tree regeneration in native tree plantations: understanding the contribution of Araucaria angustifolia to biodiversity conservation in the threatened Atlantic Forest in Argentina

Deforestation is a global process that has strongly affected the Atlantic Forest in South America, which has been recognised as a threatened biodiversity hotspot. An important proportion of deforested areas were converted to forest plantations. Araucaria angustifolia is a native tree to the Atlantic Forest, which has been largely exploited for wood production and is currently cultivated in commercial plantations. An important question is to what extent such native tree plantations can be managed to reduce biodiversity loss in a highly diverse and vulnerable forest region . We evaluated the effect of stand age, stand basal area, as a measure of stand density, and time since last logging on the density and richness of native tree regeneration in planted araucaria stands that were successively logged over 60 years, as well as the differences between successional groups in the response of plant density to stand variables. We also compared native tree species richness in planted araucaria stands to neighbouring native forest. Species richness was 71 in the planted stands (27 ha sampled) and 82 in native forest (18 ha sampled) which approximate the range of variation in species richness found in the native forests of the study area. The total abundance and species richness of native trees increased with stand age and time since last logging, but ecological groups differed in their response to such variables. Early secondary trees increased in abundance with stand age 3–8 times faster than climax or late secondary trees. Thus, the change in species composition is expected to continue for a long term. The difference in species richness between native forest and planted stands might be mainly explained by the difference in plant density. Therefore, species richness in plantations can contribute to local native tree diversity if practices that increase native tree density are implemented.     

西藏地衣物种多样性的海拔梯度分析

根据西藏地衣分类和区系的文献资料,对西藏地衣物种多样性的海拔梯度进行了分析。267个分类群按照生长型或者基物被分为六组。每一组地衣的物种丰度随海拔增加呈现单峰曲线形式的变化。多数组物种丰度的峰值出现在海拔3400~3900m之间,对应于山地寒温带针叶林带的上半部分,比尼泊尔对应类群出现极值的海拔要高。此植物带谱内复杂的生态系统可能是物种多样性高的主要原因。壳状地衣物种丰度的峰值出现在5100~5400m区间则可能是因为该区内高大的树木的消失以及具有充裕的阳光。西藏的地衣物种多样性远低于尼泊尔,两地共有的物种数量很少。对西藏地衣物种多样性的调查不充分应当是其主要原因,因此今后中国地衣学工作者应当加强西藏地衣多样性的研究。     

Robinia pseudoacacia as a surrogate for native tree species for saproxylic beetles inhabiting the riparian mixed forests of northern Italy

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