Ground level photosynthetically active radiation dynamics in stands of Acacia mearnsii De Wild

• Published in: Anais da Academia Brasileira de Ciências Vol. 87; no. 3; pp. 1833 - 1845
• Main Authors: Péllico Netto, Sylvio, Sanquetta, Carlos R, Caron, Braulio O, Behling, Alexandre, Simon, Augusto A, Corte, Ana Paula D, Bamberg, Rogério
• Format: Journal Article
• Language: English
• Published: Brazil Academia Brasileira de Ciências 01-09-2015
• Subjects: Acacia - anatomy & histology; Acacia - classification; Acacia - growth & development; Brazil; função de Burr; intensidade luminosa; Light; modelos probabilísticos; Models, Biological; MULTIDISCIPLINARY SCIENCES; Photosynthesis - physiology; Soil - chemistry; Trees - anatomy & histology; Trees - classification; Trees - growth & development; variação temporal; intensidade luminosa; variação temporal; Burr function; light intensity; temporal variation; função de Burr; probabilistic models; modelos probabilísticos
• ISSN: 0001-3765; 1678-2690; 1678-2690
• DOI: 10.1590/0001-3765201520140080

The objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.