Journal of Agricultural Science; Vol. 11, No. 5; 2019 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 362 Litterfall and Nutrient Return in Eucalyptus dunnii Maiden in the Pampa Biome, Brazil Dione Richer Momolli 1 , Mauro Valdir Schumacher 1 , Márcio Viera 1 , Aline Aparecida Ludvichak 1 , Claudiney do Couto Guimarães 1 & Huan Pablo de Souza 1 1 Department of Forest Sciences, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil Correspondence: Dione Richer Momolli, Laboratório de Ecologia Florestal, Federal University of Santa Maria, Santa Maria, RS, Brazil. Tel: 55-559-9727-1859. E-mail: dionemomolli@gmail.com Received: January 3, 2019 Accepted: February 16, 2019 Online Published: April 15, 2019 doi:10.5539/jas.v11n5p362 URL: https://doi.org/10.5539/jas.v11n5p362 Abstract The objective of this study was to evaluate litterfall and nutrient return in a Eucalyptus dunnii Maiden stand in the Pampa Biome. Four plots were established and four litter collectors per plot were distributed systematically with an area of 0.5 m² and four subplots used to collect large branches of > 0.5 cm diameter. The collections were carried out biweekly with monthly chemical analyzes over 12 months. The annual litterfall was 8.48 Mg ha -1 , of which 59% was composed of leaves. In general, the leaves had the highest macronutrient contents except for Mg. The total macronutrient return was 215 kg ha -1 , in the following order: Ca > N > K > Mg > S > P, with the leaves responsible for the return of 73% of the total. The litter represented an important source of organic matter and nutrients, and temperature is the climatic variable that best explains the pattern of production. Keywords: nutrient cycling, nutritional sustainability, eucalyptus plantations 1. Introduction Faced with the growth of population and their demand for products and forest by products, such as wood, cellulose, and energy, as well as the importance of forests in the regulation of the water cycle and carbon stock, companies in this sector and state development agencies see this as an opportunity to expand areas of tree cultivation. According to IBÁ (2016), the area occupied by eucalyptus plantations in the Brazil increased from 3.4 million hectares in 2005 to 5.6 million hectares in 2015. This scale of growth was also observed in the State of Rio Grande do Sul (RS), with the area of eucalyptus plantations increasing from 179.7 thousand hectares in 2005 to 309.1 thousand hectares in 2015. Most of this increase occurred in the Pampa Biome, a region with little silvicultural tradition. The soil of the Pampa Biome region is characterized by sandy texture and low natural fertility (IBGE, 2012). By understanding the dynamics of nutrient cycling, adequate forest management techniques can be determined, taking into account the rotation time and the input and output of nutrients (Gonçalves et al., 2005). According to Suertegaray and Silva (2009), about 3.000 years ago, this region of the Pampa biome had a semi-arid and non-rainy climate, as it is today. The sand cores present today in the western state of RS occur naturally due to erosion, transport, and subsequent water and wind sedimentation. Grazing and other agricultural practices have intensified and accelerated this natural process. Well known the production and decomposition of litter represents the main route of nutrient transfer to the soil, making it available again to the plants. Morphological characteristics, nutrient translocation capacity in different species, time of year, and management systems, determine the nutrient content (König et al., 2002). Among the different components of litter, leaves contribute the most mass and nutrient return to soil (Viera et al., 2014; Schumacher et al., 2013). Litterfall is influenced by several biotic and abiotic factors, such as temperature, light intensity, water and nutrients availability, population maturity, and population density (Viera et al., 2014). Eucalyptus dunnii Maiden has been planted in the southern region mainly due to its ability to tolerate temperatures as cold as -5 °C and to resist damage caused by frost (Mora & Garcia, 2000). Flores et al. (2016) classified this species has having high climatic suitability for the city of Alegrete-RS.