Quantifying the role of multiple landscape-scale drivers controlling epiphyte composition and richness in a conservation priority habitat (juniper scrub)

Recent concern over human-induced climate warming has activated bioclimatic research projecting the species-response to climate change scenarios. However, climate change is one of a range of human-induced environmental drivers controlling biodiversity, and for many species should be considered together within a framework of relevant stresses and threats. This paper critically assesses the sensitivity of epiphyte assemblages to regional gradients in climate, pollution regime and landscape-scale habitat structure (woodland extent and fragmentation). We examine lichen epiphytes associated with juniper scrub (a conservation priority habitat in Europe), sampled across a network of protected sites in Britain (Special Areas of Conservation). Results point to significant differences in associated epiphyte diversity between conservation priority sites. Historic woodland structure was identified as of greater importance than present-day woodland structure in controlling species composition and richness, pointing to an extinction debt among lichen epiphytes. Climatic setting was important in controlling species composition, but not species richness. However, we demonstrate that pollution regime exerts the dominant controlling force for epiphyte assemblages across regional gradients. As a corollary, we caution that for many species groups - for example those sensitive to pollutants, or landscape structure - an exclusive focus on climate is restricting, and that climate change models should expand to include a range of multiple interacting factors.     

Antimicrobial activity and phytochemical studies of some lichens from south of Spain

The antimicrobial activity of some lichens from south Spain has been studied and some of plant constituents were identified. Activity against some Gram (+) bacteria has been observed in lichens containing usnic acid.     

Differential effects of lichens and mosses on soil enzyme activity and litter decomposition

In the New Jersey Pinelands, canopy gaps in the pine-dominated forest support patches of lichens, mosses, and caespitose grasses. We tested the hypotheses that non-vascular plants and lichens can affect nutrient cycling processes and that mosses and lichens would differ from each other. We predicted that (1) lichen tissues would decompose more slowly than pine or moss tissues, (2) all plant materials would decompose more slowly beneath lichens than beneath mosses, and (3) soil enzyme activities would be higher under lichens than under mosses or grasses, reflecting greater nutrient limitation. We compared rates of decomposition of the litter of Pinus rigida and moss and lichen tissues, and measured soil enzyme activities responsible for nutrient mineralization from litter (acid and alkaline phosphatases, chitinase, β-glucosidase, aminopeptidase, and phenol oxidase) under three types of groundcover (lichens, mosses, and grasses) and unvegetated soil at two sites. While groundcover affected enzyme activities, the patterns of enzyme activities differed markedly between the two sites. In general, the enzyme activities were uniformly low. Decomposition rates were more strongly affected by the groundcover than by litter materials. While all litters tended to decompose more slowly under lichens than under mosses, supporting one of our initial hypotheses, the rates of decomposition were markedly different between the two sites. These results suggest that while mosses and lichens create patches of different soil function in both sites, the differences between the sites in unknown factors cause the enzyme activities and decomposition rates to differ.     

Are threatened lichen species well-protected in Spain? Effectiveness of a protected areas network

Several modelling species distribution studies have been developed, in last years, though mainly applied in higher plants, mammals or birds. However, little is known about overlooked taxa like lichens. We have evaluated the potential distribution of eleven threatened lichens in Spain and how the Natura 2000 network contributes to protect them. To overcome difficulties related to the lack of systematic surveys in those poorly known species we used only-presence data by means of ENFA (ecological-niche factor analysis). Then, we used ENFA to model the environmental niche of each species and to obtain the habitat suitability maps. In order to test the effectiveness of the Natura 2000 network, the habitat high suitability map for all species was overlapped with the network map. Our results show that all species considered present habitats requirements different from the average conditions of Spain, although clear differences exist among the species. That is, Peltigera elisabethae shows an extremely narrow niche, whereas Peltigera neckeri presents the highest ecological breadth. High temperature and long drought periods are the variables which restrict more the occurrence of these species. So, all species appear mainly confined to well-conserved forest and mountain ranges where these variables are dimmed. This mainly occurs in the oceanic northern fringe and in the higher Mediterranean mountains. In relation to the success of the Natura 2000 network, our results show that the capability of this network to protect key habitats for these species seem to be guarantied, probably because most reserves appear in mountainous areas in Spain. Evaluation of reserve network effectiveness needs the use of this type of gap analysis and especially the inclusion of ‘not charismatic’ organisms such as lichens.     

Determinants of cryptogamic epiphyte diversity in a river valley (Flanders)

We studied cryptogamic epiphytes in a river valley in northern Belgium in order to investigate the effects of potential environmental and ecological determinants on epiphyte diversity. The study was done on ecotope level. In practice different habitat types, historical variables (forest history, tree age) and ecological indicator values of the epiphytes were used as explaining variables. The environmental variables were linked with ecological indicator values by means of canonical correlation analysis. Thereby correlations between indicator values and epiphyte diversity were calculated in a qualitative as well as in a quantitative sense. Classification and regression trees were applied to study the importance of the different environmental variables for epiphyte diversity. Cryptogamic epiphyte diversity of old forests proved to be low, contradicting the ‘ecological continuity’ hypothesis, while forests or shrubs with a high quantity of young trees were most suitable for epiphytes. These woodlands have a short forest history and are situated on alluvial soils in the centre of the valley, on former pastures. Main reasons for a high diversity in the young forests are elevated (air) humidity levels as well as the prominent presence of (several types of) wet broad-leaved forests, causing a high (micro)habitat diversity and diverse site conditions. As also structural aspects are important for the α-diversity of cryptogamic epiphytes, right actions should be implemented in management practices.     

历山自然保护区地衣的种类和结构初探

对采自历山自然保护区的地衣进行分析鉴定,共发现地衣6科7属5种,由于附属结构不完整,有2种只鉴定到属,与山西有文献记载的地衣植物进行对比,发现有1科2属3种为山西省新纪录。借助显微摄影系统记录了标本的显微结构。     

Lichens and bryophyte communities of planted and semi-natural forests in Britain: the influence of site type, stand structure and deadwood

Lichen and bryophyte communities of spruce and pine plantations in different parts of Britain were surveyed and compared to those of semi-natural pine and oak woodlands. In total, 202 lichen species and 111 bryophytes were recorded. Community composition and species-richness were related to measures of climate, stand structure and deadwood (snags, logs and stumps). Plantations had a less species-rich lichen flora than semi-natural stands related to reduced light availability and lack of old trees. Bryophyte species-richness was similar in plantations and semi-natural stands, and was positively correlated with large diameter (>20 cm), well-decayed logs and stumps. Lichens species-richness was higher on decorticate snags (especially in semi-natural Scots pine stands in the Scottish Highlands). Early successional stands were often the richest for lichens, stumps being important for Calicium and Cladonia species. Three strategies are suggested for enhancing lower plant diversity in planted forests: (1) extending felling rotations; (2) introducing alternative silvicultural systems to clear-felling (e.g. single-tree selection) to foster continuity of woodland conditions and increase deadwood volumes; (3) modifying restocking practices on clear-fells to avoid excessive shading of deadwood.     

Biotic interactions in Antarctic terrestrial ecosystems: Are they a factor?

Antarctic terrestrial ecosystems are noted for their relative simplicity and limited trophic structure. In this context, knowledge of biotic interactions in structuring terrestrial soil communities would seem beneficial from a theoretical perspective as well as from a conservation perspective. Unfortunately, although biotic interactions are generally seen as being insignificant in these unique ecosystems, this view is based upon few explicit studies and very little is known of the role that biotic interactions may play. Accordingly, we review our current understanding of these interactions, including analogues from other appropriate ecosystems. On the basis of this review, we conclude that: (1) Antarctic terrestrial systems are predominantly abiotically-driven systems; and (2) a network of manipulative field and laboratory experiments are needed for establishing any role for biotic interactions in structuring Antarctic soil environments.     

Nested plant and fungal communities; the importance of area and habitat quality in maximizing species capture in boreal old-growth forests

Knowledge of the distribution of rare species is crucial for species conservation in fragmented habitats. Species communities often exhibit nestedness, i.e. species in species-poor sites comprise a subset of richer ones. Thus, rare species are confined to species-rich sites. We evaluate whether plant and fungal communities in 46 old-growth spruce forest patches (0.17-12 ha) exhibit nestedness. The question whether a single large patch or several small patches capture most species (i.e. the SLOSS-issue) is evaluated in combination with species saturation analyses. All species groups exhibited significant nestedness. Area was generally related to nestedness, i.e. rare species were over-represented in the largest patches. Species saturation analysis indicated that large patches accumulated more Red-list species in patch interiors than small patches. Thus, rare and Red-list species were best captured in large patches. However, nestedness also emerged in equal sized sample plots, i.e. rare species were over-represented in high quality habitats. Thus, small habitats of high quality should not be neglected in a conservation perspective.