Diameter Growth of Eucalyptus Trees in Agroforestry Systems and Its Relation to Air Temperature and Precipitation

Abstract

Abstract In agroforestry systems, such as Integrated Crop-Livestock-Forest (iCLF), the agricultural, livestock and arboreal components are explored in the same field in rotation, succession or intercropping. Our objective was to investigate if the diameter growth of eucalyptus in agroforestry systems differs from those cultivated as a planted forest, as well as to assess whether there is a difference in its growth in face of the air temperature and precipitation. The study was held at Ponta Porã, Brazil, a region of humid subtropical climate with hot summers and soil classified as Oxisol, fertile, deep and clayey. Dendrometer bands measured the diameter growth of eucalyptus (Eucalyptus urograndis) cultivated as a forest and in iCLF, with eucalyptus rows distance of 12.5x12.5 m, 12.5 m one side x 25 m another side and 25x25 m. The study took place from four years and nine months after transplanting till six years and seven months (22 months). On iCLF, the inter-row was explored with grain crops (soybean or corn) and pasture. Climate data of air temperature and precipitation were used to investigate their influence or not on diameter growth. Eucalyptus diameter growth is higher when cultivated in agroforestry systems and this growth is as higher as larger is the distance between eucalyptus rows. Precipitation proved to strongly and positively influence the diameter growth, especially when cultivated in agroforestry systems. On the other hand, under the conditions of this study, air temperature showed little or no influence over the eucalyptus diameter growth.