Long‐term impacts of nitrogen and sulphur deposition on forest floor vegetation in the Northern limestone Alps,Austria

Question: Are there effects of long‐term deposition of airborne nitrogen and sulphur on the forest floor vegetation from permanent plots collected in 1993 compared to 2005. Location: Northern limestone Alps in Austria. Methods: Single species responses were analysed by correlating trends in cover‐abundance values, as derived from marginal models, with Ellenberg indicator values. Changes in the species composition of plots were analysed by correlating changes in mean Ellenberg indicator values with the displacement of plots within a multidimensional scaling ordination. Results: Trends in single species abundance were positively correlated with indicator values of soil pH but were independent of nutrient availability. A general trend towards the homogenisation of vegetation, due to convergent time vectors of the relevés, became obvious. Oligotrophic sites previously situated at the distal ends of ordination axes shifted towards the centre since they were enriched by species preferring mesotrophic conditions. The bulk of plots with intermediate site conditions hardly showed any trends. A concomitant analysis demonstrated that temporal changes in species composition exceed the variation in cover abundance estimates among different field botanists. Conclusions: N deposition can lead to a homogenisation of forest floor vegetation. Larger limestone areas with diverse soil conditions, such as the Northern limestone Alps in Austria, as a whole are thus negatively affected by airborne N deposition. Nevertheless, the vegetation was at least as strongly affected by an increase of basiphilous species as a result of decreasing S deposition.     

Assessment of environmental quality by the diversity of epiphytic lichens in a semi-arid mediterranean area (Val Basento, South Italy)

The results of a bioindication study based on the diversity of epiphytic lichens in a semi-arid area of South Italy are presented. The area features the presence of an industrial zone located in a rural context. The survey was performed in 20 sampling sites. The lichen diversity values (LDV) were determined by the frequencies of all lichen species within a sampling grid placed on tree trunks. Lichens demonstrated a condition of environmental alteration extending to the industrial zone, and tending towards a recovery in the rural surroundings. The survey also showed evidence of eutrophication all over the study area.     

Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts

Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi‐natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition to biodiversity at the global scale. In particular, rates of N deposition within the newly defined 34 world biodiversity hotspots, to which 50% of the world's floristic diversity is restricted, has not been quantified previously. Using output from global chemistry transport models, here we provide the first estimates of recent (mid‐1990s) and future (2050) rates and distributions of N deposition within biodiversity hotspots. Our analysis shows that the average deposition rate across these areas was 50% greater than the global terrestrial average in the mid‐1990s and could more than double by 2050, with 33 of 34 hotspots receiving greater N deposition in 2050 compared with 1990. By this time, 17 hotspots could have between 10% and 100% of their area receiving greater than 15 kg N ha^?1 yr^?1, a rate exceeding critical loads set for many sensitive European ecosystems. Average deposition in four hotspots is predicted to be greater than 20 kg N ha^?1 yr^?1. This elevated N deposition within areas of high plant diversity and endemism may exacerbate significantly the global threat of N deposition to world floristic diversity. Overall, we highlight the need for a greater global approach to assessing the impacts of N deposition.     

Diversity and biovolume of tree species in natural forest ecosystem in the bitumen-producing area of ondo state,Nigeria: a baseline study

Tree species diversity, biovolume and forest stand structure were investigated in natural forest ecosystem located around some selected communities in the bitumen-producing area of Ondo state, Nigeria. Two forest reserves and four free areas distributed in 4 Local Government Areas (LGA) of the state were selected for data collection, out of the total 6 LGAs in the bitumen belt of the state. The two forest reserves are Oluwa FR at Legge in Odigbo LGA and Eba Island FR in Ese-Odo LGA while the four free areas are located close to each of Omotoso community (Odigbo LGA), Ode-Aye community (Okitipupa), Igbo-Egunrin community (Ilaje) and Igbotako community (Okitipupa). Eight plots of equal size (20 × 20 m) were located in each of the selected location, using systematic line transect sampling design. In each plot, all living trees with dbh ≥ 10 cm were identified with their botanical names and their dbhs were also measured. The results of the study reveal that there were ninety nine (99) tropical hardwood timber species (range: 21 to 48 species per selected forest). These species were distributed among twenty nine (29) families. While Funtumia elastica has the highest population distribution across the selected communities’ forest, Euphorbiaceae was the dominant family in the entire area. Although there was a moderate variation in the biodiversity indices among the selected communities’ forest, the Shannon-Weiner diversity index of H¹ = 4.02 and species evenness of E = 0.88 were obtained for the entire study area. Tree density summing up to 2,740 trees/6 ha varied moderately, with a range of 361–609 tree/ha, among the communities. Though most of the trees encountered belonged to the lowest diameter size class, the mean basal area and biovolume were 26.69 m²/ha and 262.36 m³/ha respectively. Recommendations guiding the decision on the allocation of the communities’ forest to the bitumen exploratory industries are made and the need for good forest management of the prospective area of bitumen exploration of Ondo state is emphasized. This is to prevent the imminent loss of biological diversity that would eventually accompany the exploration.     

Vascular diversity patterns of forest ecosystem before and after a 43-year interval under changing climate conditions in the Changbaishan Nature Reserve, northeastern China

The Changbaishan Nature Reserve (CNR) is the largest protected temperate forest in the world. It was established in 1960 to protect the virgin Korean pine (Pinus koraiensis) mixed hardwood forest, a typical temperate forest of northeast China. Studies of vascular diversity patterns on the north slope of the CNR mountainside forest (800–1700 m a.s.l.) were conducted in 1963 and in 2006. The aim of this comparison was to assess the long-term effects of the protected status on plant biodiversity during the intervening 43 years. The research was carried out in three forest types: mixed coniferous and broad-leaved forest (MCBF), mixed coniferous forest (MCF), and sub-alpine coniferous forest (SCF), characterized by different dominant species. The alpha diversity indicted by species richness and the Shannon–Wiener index were found to differ for the same elevations and forest types after the 43-year interval, while the beta diversity indicated by the Cody index depicted the altitudinal patterns of plant species gain and loss. The floral compositional pattern and the diversity of vascular species were generally similar along altitudinal gradients before and after the 43-year interval, but some substantial changes were evident with the altitude gradient. In the tree layer, the dominant species in 2006 were similar to those of 1963, though diversity declined with altitude. The indices in the three forest types did not differ significantly between 1963 and 2006, and these values even increased in the MCBF and MCF. However, originally dominant species, such as Pinus koraiensis, tended to decline, the proportion of broad-leaved trees increased, and the species turnover in the succession layers showed a trend to shift to higher altitudes. The diversity pattern of the understory fluctuated along the altitudinal gradient due to micro-environmental variations. A comparison of the alpha diversity indices among the three forest types reveals that the diversity of the shrub and herb layer decreased, and some rare and medicinal species disappeared. Meteorological records show that climate has changed significantly in this 43-year intervening period, and information collected from another field survey found that the most severe human disturbances to the CNR forests stemmed from the exploitation of Ginseng roots and Korean pine nuts. W. Sang and F. Bai are contributed equally to this research.     

Functional diversity of photosynthesis during drought in a model tropical rainforest – the contributions of leaf area, photosynthetic electron transport and stomatal conductance to reduction in net ecosystem carbon exchange

The tropical rainforest mesocosm within the Biosphere 2 Laboratory, a model system of some 110 species developed over 12 years under controlled environmental conditions, has been subjected to a series of comparable drought experiments during 2000–2002. In each study, the mesocosm was subjected to a 4–6 week drought, with well‐defined rainfall events before and after the treatment. Ecosystem CO₂ uptake rate (A_eco) declined 32% in response to the drought, with changes occurring within days and being reversible within weeks, even though the deeper soil layers did not become significantly drier and leaf‐level water status of most large trees was not greatly affected. The reduced A_eco during the drought reflected both morphological and physiological responses. It is estimated that the drought‐induced 32% reduction of A_eco has three principal components: (1) leaf fall increased two‐fold whereas leaf expansion growth of some canopy dominants declined to 60%, leading to a 10% decrease in foliage coverage of the canopy. This might be the main reason for the persistent reduction of A_eco after rewatering. (2) The maximum photosynthetic electron transport rate at high light intensities in remaining leaves was reduced to 71% for three of the four species measured, even though no chronic photo‐inhibition occurred. (3) Stomata closed, leading to a reduced ecosystem water conductance to water vapour (33% of pre‐drought values), which not only reduced ecosystem carbon uptake rate, but may also have implications for water and energy budgets of tropical ecosystems. Additionally, individual rainforest trees responded differently, expressing different levels of stress and stress avoiding mechanisms. This functional diversity renders the individual response heterogeneous and has fundamental implications to scale leaf level responses to ecosystem dynamics.     

Analysis of Late Jurassic to Early Cretaceous algal debris-facies of the Plassen carbonate platform in the Northern Calcareous Alps (Germany,Austria) and in the Kurbnesh area of the Mirdita zone (Albania): a tool to reconstruct tectonics and palaeogeography of eroded platforms

A characteristic microfacies of the Late Jurassic to Early Cretaceous allodapic Barmstein Limestone of the Northern Calcareous Alps are clasts of wackestones with numerous fragments of calcareous algae (“algal debris-facies”). According to dasycladale palaeocoenoses, several subtypes comprising different associations can be distinguished. One association is characterized by the debris of an unknown large dasycladalean alga reported as dasycladalean alga indet. sp. 1 from different localities in the Northern Calcareous Alps, typically forming a monospecific assemblage. Another microfacies type contains star-like calcitic bodies tentatively referred to the morphospecies Coptocampylodon pantici Ljubović-Obradović and Radoičić, originally described as being from the Turonian of NW-Serbia. Other Coptocampylodon-like bodies represent the calcified tufts of the laterals of Selliporella neocomiensis (Radoičić). The occurrence of Coptocampylodon pantici-like microfossils in the Late Tithonian to Early Berriasian, shows that obviously different species of dasycladaleans display identical to similar shaped tufts of laterals in transverse sections when becoming fragmented. Coptocampylodon pantici Ljubović-Obradović and Radoičić was observed only from different occurrences of Barmstein Limestone, but not from the autochthonous platform carbonates of the Plassen carbonate platform. The Coptocampylodon algal debris-facies is also reported from the Late Jurassic of Albania, Mirdita zone. Occurrences of different types of algal debris-facies in components of mass-flow deposits can be used as a tool to reconstruct eroded carbonate platforms and tectonics, as demonstrated in the Northern Calcareous Alps and the Albanides. Finally, the general occurrences of algal debris-facies in both settings—intra-Tethyan mostly isolated platforms (Alps, Albanides) vs. extended epeiric platforms (Middle East)—are compared and discussed.