Forest age and plant species composition determine the soil fungal community composition in a Chinese subtropical forest

Non peer reviewedPublisher PD

Predator diversity and abundance provide little support for the enemies hypothesis in forests of high tree diversity

Peer reviewedPublisher PD

Foliar fungi of Betula pendula:impact of tree species mixtures and assessment methods

Foliar fungi of silver birch (Betula pendula) in an experimental Finnish forest were investigated across a gradient of tree species richness using molecular high-throughput sequencing and visual macroscopic assessment. We hypothesized that the molecular approach detects more fungal taxa than visual assessment, and that there is a relationship among the most common fungal taxa detected by both techniques. Furthermore, we hypothesized that the fungal community composition, diversity, and distribution patterns are affected by changes in tree diversity. Sequencing revealed greater diversity of fungi on birch leaves than the visual assessment method. One species showed a linear relationship between the methods. Species-specific variation in fungal community composition could be partially explained by tree diversity, though overall fungal diversity was not affected by tree diversity. Analysis of specific fungal taxa indicated tree diversity effects at the local neighbourhood scale, where the proportion of birch among neighbouring trees varied, but not at the plot scale. In conclusion, both methods may be used to determine tree diversity effects on the foliar fungal community. However, high-throughput sequencing provided higher resolution of the fungal community, while the visual macroscopic assessment detected functionally active fungal species

On the run for water - Root growth of two phreatophytes in the Taklamakan Desert

Desert phreatophytes require extremely fast root growth for a successful establishment We measured the speed of seedling root growth of two phreatophytic plant species, Alhagi sparsifolia and Karelinia caspia, which form dominant or codominant stands around the river oases at the southern fringe of the Taklamakan Desert. As A sparsifolia occurs at sites with deeper groundwater, we expected the roots of this species to reach down more rapidly than those of K caspia. Furthermore, we expected seedlings experiencing no irrigation and low fertilization to have deeper reaching roots than seedlings with irrigation and fertilization. Seeds of both species were sown into 1 and 2 m long tubes in a glasshouse and in a field experiment, respectively. After 16 weeks of growth in the field roots of K. caspia and A. sparsifolia reached down 2 2 m and 1.7 m, respectively. In accordance with a faster growth, K. caspia had a higher water use, which resulted in a faster decrease of water content in the tubes. Species differences in the vertical reach of roots in the glasshouse experiment were comparable to those in the field experiment After 12 weeks without irrigation, A sparsifolia had a higher rooting depth (0.45 m) than with irrigation (0 30 m), while root depths of K caspia showed the opposite pattern with 062 m and 0 72 m, respectively Fertilizing increased total biomass of both species, while low level of fertilization had the tendency to increase the root shoot ratio and the specific root lengths (SRL), most likely a response to acquire nutrients at lower costs. However, plants of K. caspia showed an increase in SLR already after 12 weeks, while it took 16 weeks for A sparsifolia to increase SRL in the low fertilization level. Our results show clearly that both species are able to reach the groundwater table in the river valleys (6 5 m) within a time span of five to six months after germination However, the encountered vegetation pattern is probably not caused by differences in the speed of rooting depth, but might be the result of a higher capability of growing up with sand accumulation of A sparsifolia. As additional irrigation and fertilization did not enhance rooting depth in both species, these factors will have little impact in restoration procedures (C) 2010 Elsevier Ltd All rights reserve

Tree species traits but not diversity mitigate stem breakage in a subtropical forest following a rare and extreme ice storm

Peer reviewedPublisher PD

Designing forest biodiversity experiments : general considerations illustrated by a new large experiment in subtropical China

Funded by German Research Foundation. Grant Number: DFG FOR 891/1 and 2 National Natural Science Foundation of China. Grant Numbers: NSFC 30710103907, 30930005, 31170457 , 31210103910 Swiss National Science Foundation (SNSF) Sino-German Centre for Research Promotion in BeijingPeer reviewedPublisher PD

Regulation of the water status in three co-occurring phreatophytes at the southern fringe of the Taklamakan Desert

Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes (Alhagi sparsifolia, Populus euphratica, Tamarix ramosissima) at typical sites of their occurrence at the Southern fringe of the hyperarid Taklamakan Desert (north-west China). Methods In the foreland of the river oasis of Qira (Cele), we determined meteorological variables, plant biomass production, plant water potentials (psi(l)) and the water flux through the plants. We calculated the hydraulic conductance on the flow path from the soil to the leaves (k(SL)) and tested the effects of k(SL) psi(L) and the leaf-to-air difference in the partial pressure of water vapour (Delta w) on stomatal regulation using regression analyses. Important Findings Despite high values of plant water potential at the point of turgor loss, all plants sustained psi(L) at levels that were high enough to Maintain transpiration throughout the growing season. In A. sparsitolia, stomatal resistance (r(s); related to leaf area or leaf mass) was most closely correlated with k(SL);. whereas in P. euphratica, similar to 70%, of the variation in r(s) was explained by Delta w. In T. ramosissima, leaf area-related r(s) was significantly correlated with psi(L) and k(SL). The regulation mechanisms are in accordance with the growth patterns and the Occurrence of the species in relation to their distance to the ground water

Fungal disease incidence along tree diversity gradients depends on latitude in European forests

European forests host a diversity of tree species that are increasingly threatened by fungal pathogens, which may have cascading consequences for forest ecosystems and their functioning. Previous experimental studies suggest that foliar and root pathogen abundance and disease severity decrease with increasing tree species diversity, but evidences from natural forests are rare. Here, we tested whether foliar fungal disease incidence was negatively affected by tree species diversity in different forest types across Europe. We measured the foliar fungal disease incidence on 16 different tree species in 209 plots in six European countries, representing a forest-type gradient from the Mediterranean to boreal forests. Forest plots of single species (monoculture plots) and those with different combinations of two to five tree species (mixed species plots) were compared. Specifically, we analyzed the influence of tree species richness, functional type (conifer vs. broadleaved) and phylogenetic diversity on overall fungal disease incidence. The effect of tree species richness on disease incidence varied with latitude and functional type. Disease incidence tended to increase with tree diversity, in particular in northern latitudes. Disease incidence decreased with tree species richness in conifers, but not in broadleaved trees. However, for specific damage symptoms, no tree species richness effects were observed. Although the patterns were weak, susceptibility of forests to disease appears to depend on the forest site and tree type

Versuche zur Beweidung von Bergwiesen im Harz

Scheidel, U.; Bruelheide, H.: Experimental studies on the effect of cattle grazing of montane meadows in the Harz Mountains.- Hercynia N.F. 37 (2004): 87–101.Montane meadows in the Harz Mountains have traditionally been mown for hay making. In the last decades, this type of landuse has been steadily declining which led the nature conservation authorities to search for alternative types of management, such as cattle grazing. As the effects of cattle grazing on montane meadows were largely unknown, an experiment was carried out in a meadow near Bad Lauterberg in the southern Harz Mountains. This meadow has been grazed by cattle since 1999 following some decades of irregular use of low intensity. In the same year, three plots in each of four different vegetation types were established to compare the vegetation of grazed plots to manually mown and abandoned areas for five subsequent years. In general, changes in the vegetation during the course of the experiment were relatively small and to a large extent weather-dependent. The most important management effects were the reduction of the litter layer and the reduced dominance of species which profit from abandonment such as Rubus idaeus, Thelypteris limbosperma and Galeopsis tetrahit. In this respect, mowing was more effective than grazing. At wet sites and in remote areas that were only grazed with low intensity grazing effects did not differ from abandoned use. However, clearly negative effects of grazing could also not be detected. The conclusion of our study is that grazing as a management practice in montane hay meadows involves the risk of being not effective. Larger time spans than five years are needed to detect significant grazing effects compared to abandoned use. Activities to improve the effectiveness of grazing are discussed.Die Hercynia publiziert Originalbeiträge mit dem Schwerpunkt Ökologie (mit ihren vielseitigen Aspekten der Biodiversität), Botanik, Zoologie, Geologie und Geografie, den anwendungsorientierten Bereichen des Natur- und Umweltschutzes, sowie der Land- und Forstwirtschaft

Functional signatures of surface pollen and vegetation are broadly similar : good news for past reconstructions of vegetation

Pollen assemblages are widely used to infer paleoenvironment features, aiming at reconstructing both past climates and biomes. However, the functional link between environmental conditions and pollen assemblages is not straightforward and requires thorough testing to be used confidently. Here, we use a trait-based approach to assess the consistency of functional signatures between pollen and plant assemblages. We assess whether trait values and trait distributions are consistent for surface pollen samples and extant vegetation in the Arid Central Asia biogeographic region. A working plant checklist was compiled for ACA in order to assign trait values to pollen types and vegetation taxa. This was done for two widely used methods of pollen aggregation schemes (coarse and fine pollen type depend on the level of pollen identification). The functional signatures of pollen and vegetation samples were compared both at the taxon and community levels, using large-scale trait and vegetation databases, for the six traits of the global spectrum of plant form and function (i.e., plant height, seed mass, leaf area, specific leaf area, nitrogen content per leaf mass, and stem-specific density). Trait distributions and bivariate trait relationships were broadly similar for pollen types and vegetation taxa, which is also the case for the multivariate spaces of the global spectrum of plant form and function. At the community scale, the trait values weighted by taxon abundance significantly differed among biomes, and these differences were consistent for both pollen aggregation schemes and extant. The pollen aggregation scheme does not impact the organisation of the functional space of the global spectrum of plant form and function, which compares well with that based on species actually present in the vegetation plots. This is also true at the community scale. These findings are very promising for improving climate and biome reconstructions from pollen assemblages and pave the way to a “pollen functional biogeography”