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Background and aims: Restoring healthy ecosystem depends on recovering not only biodiversity, but also ecosystem processes and functionality. We investigated the effects of tree community parameters and site abiotic conditions on nutrient cycling in restored forests. Methods: We assessed litter production and nutrient inputs in five 16-year old restored forests established using different restoration methods and species combinations, i.e. unplanted control (natural regeneration), direct seeding, agroforestry, mixed commercial species plantation (commercial mix), and high-diversity plantation, replicated at two sites that differed in soil fertility. We used adjacent seasonal semideciduous forest remnants as references. Results: Restoration treatments with intermediate and high species richness had higher litter and nutrient inputs and did not differ from the reference forest. In the more fertile site, litter and nutrient inputs increased across different treatments with increasing stand density, whereas in the low fertility site, litter and nutrient inputs in the different treatments increased with increasing tree species richness and the proportion of putative nitrogen-fixing tree species. Conclusions: Restoration treatments, even those with low species richness, but with a relatively high proportion of trees with nitrogen-fixing capability might be effective in restoring nutrient cycles in lower fertility soils, whereas in the more fertile soils it is possible to increase nutrient inputs by establishing restoration treatments at high stem densities. Our results suggest that the magnitude of relationships among plant community parameters and nutrient cycling depends strongly on site conditions. [ABSTRACT FROM AUTHOR]

Soil communities exert strong influences on the processing of organic matter and nutrients. Plantations of trees, especially of nitrogen fixing ones, may affect the soil macrofauna through litter quality and quantity. This study was conducted in a randomized block design with three blocks consisting of Populus euphratica, Eucalyptus camaldulensis, Eucalyptus microtheca, Acacia farnesiana, Acacia salicina, Acacia saligna, Acacia stenophylla and Dalbergia sissoo monoculture plantations that were established in 1992. Soils and soil macrofauna were sampled in November 2006. Leaf litterfall was collected from November 2006 to November 2007 at bi-weekly intervals. Macroinvertebrate abundance and biomass were consistently higher in A. salicina plantations than in the others, whereas they were lowest in E. camaldulensis. Tree species and nitrogen fixing trees significantly influenced the soil macrofauna richness. The results suggest that the earthworm distribution is regulated by leaf litter quality (Ca, C and N) whereas the macrofauna richness is regulated by leaf litter mass, soil organic carbon and leaf litter Mg. Totally, it was revealed that the tree species clearly affected macrofauna whereas nitrogen fixation did not.

Key message: This study shows that functional grouping of the species based on nitrogen fixing ability along with initial leaf litter C/P, C/N, P and N could help us predicting leaf litter decomposition rate. Abstract: Grouping species into functional groups is a good approach to understanding exotic plants impacts on ecosystem functioning in their new environment. One key plant trait that has large ecosystem-level consequences is the ability of plants to fix atmospheric nitrogen into plant available forms. Most previous studies have reported faster leaf litter decomposition rates of nitrogen fixing than non-nitrogen-fixing species, supporting the separation of these as functional groups. Here, we present a multispecies monitoring of litter decomposability of seven tree species in a 1 year decomposition experiment in outdoor litter bed common garden experiment in river floodplain in South Western Iran. We tested within- and between-functional-groups for rates of leaf litter decomposition and nutrient dynamics. Our results highlight that nitrogen-fixing trees and non-nitrogen-fixing trees can be distinguished based on specific leaf area and leaf litter traits. The interesting results were that the leaf litter decomposition rates of the two functional groups were related to different initial leaf litter traits. Leaf litter decomposition rates of nitrogen-fixing trees were related to initial leaf litter C/P, C/N, N, P and Ca, while leaf litter decomposition rates of non-nitrogen-fixing trees were only related to initial leaf litter Ca. Whereas specific leaf area was the best predictor of leaf litter decomposition rates among all the species. Therefore, our results revealed that both initial leaf litter traits and functional groups were predicting leaf litter decomposition rates. [ABSTRACT FROM AUTHOR]

The article demonstrates the stand characteristics, nitrogen accumulation, and rates of nitrogen fixation in regenerating stands of Acacia koa. It notes the increase of the tree's breast height, and the decline of stem density, dbh increment, and leaf area index. Results showed that nitrogen fertilization did not affect dbh increment, while measurements of foliar and root phosphorus suggest a decline in phosphorus availability which may have contributed to the decline in nitrogen fixation.

The article presents information on KX4-Hawaii, a tropical, seedless, multipurpose legume tree. It was developed at the College of Tropical Agriculture and Human Resources of the University of Hawaii. Its male parent was provenance K838 of Leucaena esculenta, which is widely growth in the highlands of Mexico. Information is also presented on its yield and psyllid resistance.