Benjamin F. Leutner , Manuel J. Steinbauer , Carina M. Müller , Andrea J. Früh , Severin Irl , Anke Jentsch and Carl Beierkuhnlein
Article: Mosses Like It Rough—Growth Form Specific Responses of Mosses, Herbaceous and Woody Plants to Micro-Relief Heterogeneity
Diversity 2012, 4(1), 59-73; doi:10.3390/d4010059 - published online 10 February 2012
Show/Hide AbstractAbstract: Micro-relief heterogeneity can lead to substantial variability in microclimate and hence niche opportunities on a small scale. We explored the relationship between plant species richness and small-scale heterogeneity of micro-relief on the subtropical island of La Palma, Canary Islands. Overall, we sampled 40 plots in laurel and pine forests at four altitudinal bands. Species richness was recorded separately for various growth forms (i.e., mosses, herbaceous and woody plants). Site conditions such as altitude, slope, aspect, and tree density were measured. Micro-relief heterogeneity was characterized by surface structure and a subsequently derived surface heterogeneity index. The effect of micro-relief heterogeneity on species richness was analysed by means of linear mixed effect models and variance partitioning. Effects of micro-relief heterogeneity on species richness varied considerably between growth forms. While moss richness was affected significantly by micro-relief heterogeneity, herbaceous and woody plants richness responded mainly to larger-scale site conditions such as aspect and tree density. Our results stress the importance of small-scale relief heterogeneity for the explanation of spatial patterns of species richness. This poses new challenges as small-scale heterogeneity is largely underrepresented, e.g. with regard to its application in species distribution models.

Justin L. Kirsch , Dylan G. Fischer , Alexandra N. Kazakova , Abir Biswas , Rachael E. Kelm , David W. Carlson and Carri J. LeRoy
Article: Diversity-Carbon Flux Relationships in a Northwest Forest
Diversity 2012, 4(1), 33-58; doi:10.3390/d4010033 - published online 29 December 2011
Show/Hide AbstractAbstract: While aboveground biomass and forest productivity can vary over abiotic gradients (e.g., temperature and moisture gradients), biotic factors such as biodiversity and tree species stand dominance can also strongly influence biomass accumulation. In this study we use a permanent plot network to assess variability in aboveground carbon (C) flux in forest tree annual aboveground biomass increment (ABI), tree aboveground net primary productivity (ANPP_tree), and net soil CO₂ efflux in relation to diversity of coniferous, deciduous, and a nitrogen (N)-fixing tree species (Alnus rubra). Four major findings arose: (1) overstory species richness and indices of diversity explained between one third and half of all variation in measured aboveground C flux, and diversity indices were the most robust models predicting measured aboveground C flux; (2) trends suggested decreases in annual tree biomass increment C with increasing stand dominance for four of the five most abundant tree species; (3) the presence of an N-fixing tree species (A. rubra) was not related to changes in aboveground C flux, was negatively related to soil CO₂ efflux, and showed only a weak negative relationship with aboveground C pools; and (4) stands with higher overstory richness and diversity typically had higher soil CO₂ efflux. Interestingly, presence of the N-fixing species was not correlated with soil inorganic N pools, and inorganic N pools were not correlated with any C flux or pool measure. We also did not detect any strong patterns between forest tree diversity and C pools, suggesting potential balancing of increased C flux both into and out of diverse forest stands. These data highlight variability in second-growth forests that may have implications for overstory community drivers of C dynamics.

Christian Leclerc and Geo Coppens d’Eeckenbrugge
Article: Social Organization of Crop Genetic Diversity. The G × E × S Interaction Model
Diversity 2012, 4(1), 1-32; doi:10.3390/d4010001 - published online 21 December 2011
Show/Hide AbstractAbstract: A better knowledge of factors organizing crop genetic diversity in situ increases the efficiency of diversity analyses and conservation strategies, and requires collaboration between social and biological disciplines. Four areas of anthropology may contribute to our understanding of the impact of social factors on crop diversity: ethnobotany, cultural, cognitive and social anthropology. So far, most collaborative studies have been based on ethnobotanical methods, focusing on farmers’ individual motivations and actions, and overlooking the effects of farmer’s social organization per se. After reviewing common shortcomings in studies on sorghum and maize, this article analyzes how social anthropology, through the analysis of intermarriage, residence and seed inheritance practices, can contribute to studies on crop genetic diversity in situ. Crop varieties are thus considered social objects and socially based sampling strategies can be developed. Such an approach is justified because seed exchange is built upon trust and as such seed systems are embedded in a pre-existing social structure and centripetally oriented as a function of farmers’ social identity. The strong analogy between farmers’ cultural differentiation and crop genetic differentiation, both submitted to the same vertical transmission processes, allows proposing a common methodological framework for social anthropology and crop population genetics, where the classical interaction between genetic and environmental factors, G × E, is replaced by a three-way interaction G × E × S, where “S” stands for the social differentiation factors.

Gabriela Lopez-Velasco , Gregory E. Welbaum , Joseph O. Falkinham III and Monica A. Ponder
Article: Phyllopshere Bacterial Community Structure of Spinach (Spinacia oleracea) as Affected by Cultivar and Environmental Conditions at Time of Harvest
Diversity 2011, 3(4), 721-738; doi:10.3390/d3040721 - published online 20 December 2011
Show/Hide AbstractAbstract: Modern molecular ecology techniques were used to demonstrate the effects of plant genotype and environmental conditions prior to harvest on the spinach epiphytic bacterial community. Three cultivars of spinach with different leaf topographies were collected at three different periods during the fall growing season. Leaf surface topography had an effect on diversity and number of culturable bacteria on the phylloepiphtyic community of spinach. Savoy cultivars, which had larger surface area and more stomata and glandular trichomes, where bacterial aggregates were observed, featured more diverse communities with increased richness and larger bacterial populations compared to flat-leaved cultivars. Bacterial community richness was compared using denaturant gradient gel electrophoresis (DGGE), while abundance was quantified using 16s rRNA primers for major phyla. The most diverse communities, both in richness and abundance, were observed during the first sampling period, immediately following a period of rapid spinach growth. Exposure to lower air and soil temperatures and decreased precipitation resulted in significantly reduced bacterial population size and bacterial community richness in November and December. This study describes the effect of the plant characteristics and environmental conditions that affect spinach microbiota population size and diversity, which might have implications in the survival of food and plant bacterial pathogens.

Masahiro Inagaki and Shigehiro Ishizuka
Article: Ecological Impact on Nitrogen and Phosphorus Cycling of a Widespread Fast-growing Leguminous Tropical Forest Plantation Tree Species, Acacia mangium
Diversity 2011, 3(4), 712-720; doi:10.3390/d3040712 - published online 28 November 2011
Show/Hide AbstractAbstract: Symbiotic nitrogen fixation is one of the major pathways of N input to forest ecosystems, enriching N availability, particularly in lowland tropics. Recently there is growing concern regarding the wide areas of fast-growing leguminous plantations that could alter global N₂O emissions. Here, we highlight substantially different N and phosphorus utilization and cycling at a plantation of Acacia mangium, which is N₂-fixing and one of the major plantation species in tropical/subtropical Asia. The litterfall, fresh leaf quality and fine-root ingrowth of A. mangium were compared to those of non-N₂-fixing Swietenia macrophylla and coniferous Araucaria cunninghamii in wet tropical climates in Borneo, Malaysia. The N and P concentrations of the A. mangium fresh leaves were higher than those of the other two species, whereas the P concentration in the leaf-litterfall of A. mangium was less than half that of the others; in contrast the N concentration was higher. The N:P ratio in the A. mangium leaf was markedly increased from fresh-leaf (29) to leaf-litterfall (81). Although the N flux in the total litterfall at the A. mangium plantation was large, the fine-root ingrowth of A. mangium significantly increased by applying both N and P. In conclusion, large quantities of N were accumulated and returned to the forest floor in A. mangium plantation, while its P resorption capacity was efficient. Such large N cycling and restricted P cycling in wide areas of monoculture A. mangium plantations may alter N and P cycling and their balance in the organic layer and soil on a stand level.

Carine Luque , Luc Legal , Peter Winterton , Nestor A. Mariano and Charles Gers
Article: Illustration of the Structure of Arthropod Assemblages (Collembola and Lepidoptera) in Different Forest Types: An Example in the French Pyrenees
Diversity 2011, 3(4), 693-711; doi:10.3390/d3040693 - published online 18 November 2011
Show/Hide AbstractAbstract: To analyze the impact of management choices on diversity in Pyrenean forests, we selected two ecological indicators: springtails; indicators of long-term responses to perturbation, and moths; which respond quickly to changes in their environment. Our data show that monoculture has a short-term impact on overall diversity and richness of species but with a relative resilience capacity of the forest ecosystem. More precisely, real impacts are visible on dynamics and abundances of certain species, depending on the vertical distribution of the biota and on the composition of soil and forest floor.