Home field advantage effects on decomposition of leaf litter in tropical riparian forests: effects of restoration age, litter quality and soil nutrients

Abstract

Decomposition of organic matter is influenced by several biotic and abiotic factors. Litter quality, soil nutrient concentration and plant-soil interactions are major factors influencing this ecosystem process in forests at local scales. The home field advantage effect (HFA) has been proven to accelerate decomposition rates for litter at its own home when compared to away sites, and is directly related to the previously mentioned factors. HFA effects can occur in natural forests, but it is still unknown if it can be detected in riparian areas under restoration. Here, we tested if litter quality, soil nutrient concentrations and restoration stage (age) influenced HFA. We carried out three-way reciprocal litter transplant experiments to test the following hypotheses: (1) areas under restoration of the same age, but with differences in soil nutrient concentration and litter quality, will show HFA in areas with low litter quality and soil nutrient concentration; (2) areas under restoration with different ages, but with similar content of soil nutrients and litter quality, will present HFA in older areas, given that decomposers and plants had more time to develop close-knit positive relationships; (3) riparian forest intact remnant areas (i.e., areas not undergoing restoration) that differ in soil nutrient concentrations and litter quality would present HFA in areas with low litter quality and soil nutrient concentrations. Our results indicated no effects of HFA in any hypotheses tested, although we found some support for hypothesis 1 as there was an ability effect in one area and a trend for a negative HFA effect in another. Leaf litter decomposed very fast across all areas possibly due to heavy rainfall in the end of the experiment, so that labile litter was likely totally decomposed, which could obscure HFA effects. We also analyzed the results of the three independent experiments simultaneously to test the additional hypotheses: (4) soil nutrients and litter quality would affect HFA and (5) higher dissimilarities in soil nutrient concentrations and litter quality between home and away sites would result in stronger HFA effects. We found a relationship between HFA and leaf litter quality, and also a relationship between HFA and dissimilarity in soil quality between home and away sites. Also, the most dissimilar areas were the remnant areas. In natural ecosystems, such as forest remnants, plants may have more time to develop relationships with the soil community, in comparison to the riparian forest fragments under restoration studied. This high dissimilarity among remnant areas could also be due to the development of other complex heterogenous plant-soil relationships, established throughout time. Therefore, our studies suggest that although these riparian forest areas under restoration can cover large areas, the time after restoration may not have been enough to recover microbial communities and more specialized ecosystem functions.