Spatial-temporal variation in litterfall in seasonally dry tropical forests in Northeastern Brazil

V F P Araújo,M R V Barbosa,A Vasconcellos,J P Araújo

doi:10.1590/1519-6984.192113

Abstract

The production of litterfall is essential for nutrient cycling in terrestrial ecosystems. From November 2009 to October 2011, analyzed the monthly litterfall production in two areas of Caatinga, a type of Seasonally Dry Tropical Forest located in the Cariri Paraibano, in the semiarid region of the Paraíba, Northeastern Brazil. One of the areas, Private Natural Heritage Reserve (RPPN) Fazenda Almas, is legally protected, and the other, Fazenda Moreiras, does not. The aims were to evaluate the effects of precipitation, evapotranspiration and vegetation structure on the temporal and spatial dynamics of litterfall production. Eight sampling points were randomly chosen at each site, and two 1 m2 collectors were installed 50 m apart from each other. The collected material was sorted, dried and weighed. Additionally, the characteristics (density, species richness, height and mean basal area) of the tree-shrub stratum in plots with a 10 m radius surrounding each collector. Total litterfall production was 4,500 kg ha-1 yr-1 for Fazenda Almas and 3,300 kg ha-1 yr-1 for Fazenda Moreiras; these values were within the expected range for Seasonally Dry Tropical Forests. The inter- and intra-annual variation in litterfall production was positively correlated with precipitation and evapotranspiration rates, and four months after the highest precipitation rates, there was a marked decrease in litterfall occurred during the dry season. Furthermore, the contributions of the material fractions were distinct with the leaf fraction representing for more than 60% of the litterfall, and the vegetation structure explained 75% of the variation in litterfall production. Therefore, climatic factors and vegetation structure affect the temporal and spatial dynamics of litterfall production and consequently influence nutrient dynamics in the semiarid region of Brazil.

Highlights

In Seasonally Dry Tropical Forests (SDTF), primary productivity is largely controlled by the amount and duration of rainfall, so seasonal variations in rainfall constrain and control the productivity and nutrient dynamics of these ecosystems (Lugo and Murphy, 1986; Dirzo et al, 2011)
The present study sought to evaluate the effect of precipitation, evapotranspiration and vegetation structure on the spatial-temporal dynamics of litterfall production in one of the driest region of SDTF
The quantities of litterfall deposition observed in this study were within the previously recorded ranges for Seasonally Dry Tropical Forests

Summary

Materials and Methods

Litterfall production is considered one of the main routes of nutrient transfer from the vegetation to the soil (Vitousek, 1984; Búrquez et al, 1999; Vital et al, 2004). The present study sought to evaluate the effect of precipitation, evapotranspiration and vegetation structure on the spatial-temporal dynamics of litterfall production in one of the driest region of SDTF in Northeastern Brazil. To analyze temporal variation, was correlated litterfall production, accumulated rainfall and actual evapotranspiration in both localities. The relationship between litterfall production and vegetation structure (density, species richness, medium height and mean basal area of tree and shrubby species) at each sampling point was investigated. The annual litterfall production for each sampling point was calculated with the average obtained from the two collectors. Repeated measures ANOVA were used to analyze the temporal variation in litterfall production between years and months, and Spearman’s correlations between litterfall production and climatic data (precipitation and evapotranspiration) recorded 30, 60, 90 and 120 days prior to the sampling events were estimated. The analyses were performed using STATISTICA 5.0 (StatSoft, 1995)

Results

Discussion

VII VIII I