Tree species effect on natural control of H. albipunctella de Joannis in a millet agroforestry system in Senegal

Association of several tree species in and around a plot can have a positive impact on ecosystem services. Thus, traditional agroforestry systems, characterized by a high plant diversity, constitute an ideal model of study to test if the natural tree vegetation provides both shelter and food resources for insects that could potentially improve biocontrol services. The main objective of this study was to test if tree species presence and diversity could enhance the natural regulation of the millet head miner Heliocheilus albipunctella (MHM) in agroforestry systems of the Senegalese Peanut Basin. To address our objective, we realized an inventory of tree species in a total of 30 millet fields surveyed in Bambey area, during 2013 and 2014 (Fig.1). These data were used to calculate indices related to the abundance and diversity of tree species. The natural regulation was estimated using the biocontrol service index (BSI) for each millet field. In addition, data on MHM egg and larval predation and parasitism rates were also collected to estimate biocontrol services. Statistical analysis of the effect of tree presence and diversity on natural regulation variables were tested using a linear regression. Surprisingly, we found that BSI decreased with tree diversity and that it increased with the presence of the tree species Faidherbia albida. Morever, the presence of Anogeissus leiocarpus enhanced MHM egg parasitism and the presence of Azadirachta indica favored MHM egg predation

The Fair Proportion is a Shapley Value on phylogenetic networks too

The Fair Proportion of a species in a phylogenetic tree is a very simple measure that has been used to assess its value relative to the overall phylogenetic diversity represented by the tree. It has recently been proved by Fuchs and Jin to be equal to the Shapley Value of the coallitional game that sends each subset of species to its rooted Phylogenetic Diversity in the tree. We prove in this paper that this result extends to the natural translations of the Fair Proportion and the rooted Phylogenetic Diversity to rooted phylogenetic networks. We also generalize to rooted phylogenetic networks the expression for the Shapley Value of the unrooted Phylogenetic Diversity game on a phylogenetic tree established by Haake, Kashiwada and Su.Comment: 12 page

Disturbance and Clonal Reproduction Determine Liana Distribution and Maintain Liana Diversity in a Tropical Forest

Negative density dependence (NDD) and habitat specialization have received strong empirical support as mechanisms that explain tree species diversity maintenance and distribution in tropical forests. In contrast, disturbance appears to play only a minor role. Previous studies have rarely examined the relative strengths of these diversity maintenance mechanisms concurrently, and few studies have included plant groups other than trees. Here we used a large, spatially explicit data set from Barro Colorado Island, Panama (BCI) to test whether liana and tree species distribution patterns are most consistent with NDD, habitat specialization, or disturbance. We found compelling evidence that trees responded to habitat specialization and NDD; however, only disturbance explained the distribution of the majority of liana species and maintained liana diversity. Lianas appear to respond to disturbance with high vegetative (clonal) reproduction, and liana species\u27 ability to produce clonal stems following disturbance results in a clumped spatial distribution. Thus, clonal reproduction following disturbance explains local liana spatial distribution and diversity maintenance on BCI, whereas negative density dependence and habitat specialization, two prominent mechanisms contributing to tree species diversity and distribution, do not

Degradation of Riparian Tree Diversity on Spring Fed Drains and Its Impacts to Water Quality, East Java

This research aimed to determine the impact of degradation riparian tree diversity on water quality along some spring to its drains in East Java. This descriptive research conducted in selected springs and itsdrains in Jember, Kediri, Pasuruan, and Malang on April 2012 to January 2013. We used a spring water of Meru Betiri National Park as a reference site. Quality of riparian trees diversity and water were sampled with three replication.Data were tabulated by statistical analyzed using cluster and Spearman correlation. The result showed that species richness ofriparian tree in spring water and its drains has found were 69 species belonging to 28 families. Moraceae was key family of natural riparian tree and almost all the spring and its drains (92.75 %) were grown by native trees except in Kediri. All observed spring were degrading comparing to the natural one in Meru Betiri National Park where trees grown in strata A to E, and shown a highest diversity index (H=3.2). All water spring were observed in high quality but water in its downstream become turbid depend on the quality of treesriparian diversity grown around spring waters. Quality of riparian diversity was strongly influenced by land use and human activities such as illegal logging, intensive agriculture, and settlement. There was a positive correlation between riparian tree diversity, water transparency and color, but it had a negative correlation with pH value of water.Low pH, high water transparency and colorless water were found in stations where we found high tree species richness, diversity index, riparian width and stratified of tree

Tanzanian forest tree plot diversity and elevation

Observed variation in species richness on ecological gradients and between regions has attracted several different explanations. Climatic factors, such as energy availability, precipitation and mean annual temperature, are frequently cited to explain differences in species richness (Wright et al. 1993). The relative amount of variation in these variables may be of importance as well as absolute values (Stevens 1989, 1992). Alternatively, the history of colonization and extirpation have been used to explain regional variation in diversity (Guo et al. 1998; Latham & Ricklefs 1993a, b). Area is an important factor, for example on an elevational gradient the tops of mountains are not only cooler than the bottoms, but they are also much smaller (Rahbek 1997)

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Linking forest diversity and tree health: preliminary insights from a large-scale survey in Italy

Forest health is currently assessed in Europe (ICP Forests monitoring program). Crown defoliation and dieback, tree mortality, and pathogenic damage are the main aspects considered in tree health assessment. The worsening of environmental conditions (i.e., increase of temperature and drought events) may cause large-spatial scale tree mortality and forest decline. However, the role of stand features, including tree species assemblage and diversity as factors that modify environmental impacts, is poorly considered. The present contribution reanalyses the historical dataset of crown conditions in Italian forests from 1997 to 2014 to identify ecological and structural factors that influence tree crown defoliation, highlighting in a special manner the role of tree diversity. The effects of tree diversity were explored using the entire data set through multivariate cluster analyses and on individual trees, analysing the influence of the neighbouring tree diversity and identity at the local (neighbour) level. Preliminary results suggest that each tree species shows a specific behaviour in relation to crown defoliation, and the distribution of crown defoliation across Italian forests reflects the distribution of the main forest types and their ecological equilibrium with the environment. The potentiality and the problems connected to the possible extension of this analysis at a more general level (European and North American) were discussed

Increasing turnover through time in tropical forests

Tree turnover rates were assessed at 40 tropical forest sites. Averaged across inventoried forests, turnover, as measured by tree mortality and recruitment, has increased since the 1950's, with an apparent pantropical acceleration since 1980. Among 22 mature forest sites with two or more inventory periods, forest turnover also increased. The trend in forest dynamics may have profound effects on biological diversity

Linkages between Phosphorus and Plant Diversity in Central European Forest Ecosystems—Complementarity or Competition?

The phosphorus nutrition status of European forests has decreased significantly in recent decades. For a deeper understanding of complementarity and competition in terms of P acquisition in temperate forests, we have analyzed α-diversity, organic layer and mineral soil P, P nutrition status, and different concepts of P use efficiency (PUE) in Fagus sylvatica L. (European beech) and Picea abies (L.) H. Karst. (Norway spruce). Using a subset of the Second National Soil Survey in Germany, we correlated available data on P in the organic layer and soil with α-diversity indices for beech and spruce forests overall and for individual vegetation layers (tree, shrub, herb, and moss layers). Moreover, we investigated α-diversity feedbacks on P nutrition status and PUE of both tree species. The overall diversity of both forest ecosystems was largely positively related to P content in the organic layer and soil, but there were differences among the vegetation layers. Diversity in the tree layer of both forest ecosystems was negatively related to the organic layer and soil P. By contrast, shrub diversity showed no correlation to P, while herb layer diversity was negatively related to P in the organic layer but positively to P in soil. A higher tree layer diversity was slightly related to increased P recycling efficiency (PPlant/Porganic layer) in European beech and P uptake efficiency (PPlant/Psoil) in Norway spruce. The diversity in the herb layer was negatively related to P recycling and uptake efficiency in European beech and slightly related to P uptake efficiency in Norway spruce. In spruce forests, overall and herb species richness led to significantly improved tree nutrition status. Our results confirm significant, non-universal relationships between P and diversity in temperate forests with variations among forest ecosystems, vegetation layers, and P in the organic layer or soil. In particular, tree species diversity may enhance complementarity and hence also P nutrition of dominant forest trees through higher PUE, whereas moss and herb layers seemed to show competitive relationships among each other in nutrient cycling.DFG, 241127382, PhosForDiv - Phosphatverfügbarkeit als Einflussgröße der Pflanzen-Biodiversität in Waldökosysteme