Cryptostegia Madagascariensis Alters the Litterfall and Nutrient Cycling of Litter Inputs in An Invaded Tropical Cambisol From North-Eastern Brazil

The invasive Cryptostegia madagascariensis occupies riparian areas covered by tropical Cambisols throughout the North-eastern Brazil however litter is known regarding its ability to impact litter inputs, and ecosystem processes. This study aimed to characterize the effects of the invader on the litter deposition, soil physical-chemical properties, litter nutrient content, and the litter decay rate in a Tropical Cambisol. Comparisons of native and invaded environments showed that C. madagascariensis alters the quantity of litter deposition during both dry and rainy seasons. In contrast to native species, C. madagascariensis litterfall displayed litter seasonal variation (rainy vs. dry season), however invaded sites had higher litter biomass compared to native sites. C. madagascariensis litter was enriched in soil organic matter, N, P, and K contents as compared to the native litter. Compared to native environments, invaded ones had significantly decreased soil temperature and soil water content. Results suggest that C. madagascariensis enhances litter and N, P, and K availability in ways that have potential to impact soil ecosystem in the Tropical Cambisols from Caatinga ecoregion, Brazil.

Effect of Biofertilizers Application on Soil Biodiversity and Litter Degradation in a Commercial Apricot Orchard

The aim of the present experiment was to determine if the supply of biofertilizers could differently stimulate the native microbiota, thus determining different patterns of organic material decomposition processes. The microbial composition of soil and litter was investigated by next generation sequencing using a metabarcoding approach. The chemical structure of the decomposing litterbags was investigated through the TG-DTA analysis and NIR spectroscopy. The study was conducted in an apricot orchard in Italy, and two different type of biofertilizers (AMF and Trichoderma spp.) were compared to unfertilized control over one year. Bacteria and fungi in soil, 162 days from litter deposition, evidenced differentiated clusters for control and both biofertilizers; on the other hand, only fungal composition of litterbags was modified as a consequence of Trichoderma spp. supply; no effect was observed in the bacterial community of litterbags. NIR and TG-DTA analysis evidenced a significant change over time of the chemical composition of litterbags with a faster degradation as a consequence of Trichoderma spp. supply testified by a higher degradation coefficient (1.9) than control (1.6) and AMF (1.7). The supply of biofertilizers partially modified the bacteria community of soil, while Trichoderma spp. Influenced the fungal community of the litter. Moreover, Trichoderma spp. Evidenced a faster and higher degradation of litter than AMF-biofertilizers, laying the foundation for an efficient use in orchard.

SEASONALITY IN LITTERFALL PRODUCTION IN A NATIVE FOREST IN THE CENTRAL REGION OF RS, BRAZIL

Studies on litter deposition are considered an important indicator of environmental quality of forest ecosystems. It is the main route of entry of organic matter and nutrients to forests. The objective of this study was to quantify the annual litterfall and seasonality in a fragment of native forest located in São Sepé in the Central Depression of Rio Grande do Sul. The experiment was conducted in a fragment of a Seasonal Semideciduous Forest. Inside this forest, in a place with homogeneous conditions, five plots of 20 m x 15 m length were systematically allocated 30 meters away from each other, where five litterfall traps were distributed in each plot (0,1963 m2 each trap), totaling 25 traps. The collection of all plant material deposited by the trees in the collectors was performed monthly in a four-year period. In the laboratory, the samples were separated into leaves, small twigs (diameter < 0.5 cm) and miscellaneous, and after they were oven dried and weighed on a precision balance. Higher litterfall was observed in the spring, with the highest return peaks mainly in October, indicating a seasonal deposition behavior. The mean litterfall was 6.56 Mg ha-1 year-1; of this total, the leaves were responsible for 67.61%, followed by the miscellaneous with 19.04% and the small twigs with 13.29%. Only a high significant correlation was obtained between the miscellaneous fraction and the temperature.