Soil properties discriminating Araucaria forests with different disturbance levels

Abstract

Soil biological, chemical, and physical properties can be important for monitoring soil quality under one of the most spectacular vegetation formation on Atlantic Forest Biome, the Araucaria Forest. Our aim was to identify a set of soil variables capable of discriminating between disturbed, reforested, and native Araucaria forest soils such that these variables could be used to monitor forest recovery and maintenance. Soil samples were collected at dry and rainy season under the three forest types in two state parks at São Paulo State, Brazil. Soil biological, chemical, and physical properties were evaluated to verify their potential to differentiate the forest types, and discriminant analysis was performed to identify the variables that most contribute to the differentiation. Most of physical and chemical variables were sensitive to forest disturbance level, but few biological variables were significantly different when comparing native, reforested, and disturbed forests. Despite more than 20 years following reforestation, the reforested soils were chemically and biologically distinct from native and disturbed forest soils, mainly because of the greater acidity and Al3+ content of reforested soil. Disturbed soils, in contrast, were coarser in texture and contained greater concentrations of extractable P. Although biological properties are generally highly sensitive to disturbance and amelioration efforts, the most important soil variables to discriminate forest types in both seasons included Al3+, Mg2+, P, and sand, and only one microbial attribute: the NO2- oxidizers. Therefore, these five variables were the best candidates, of the variables we employed, for monitoring Araucaria forest disturbance and recovery.

SOIL CHEMICAL ATTRIBUTES RELATIONSHIPS AROUND THE Araucaria angustifolia TREES IN AGROFORESTRY SYSTEMS

“…1 and Table 1). Both areas have a Cfb climate, according to the Köppen classification (ALVARES et al, 2013), mesothermic, humid to superhumid, without dry season, with fresh summers and with average of the hottest month below 22°C. Frosts are frequent (WREGE et al, 2018).…”

“…The gradual replacement by plantations (grains, forests and pastures) began in the late 19th century. The economic exploitation of Araucaria trees was intensified around 1930 and later depleted by the simple exhaustion of its reserves, in the early 70's (BITTENCOURT 2007;RIBEIRO et al, 2009;BERTINI et al, 2015). This aggressive exploration resulted in a strong fragmentation of the Ombrophilous Mixed Forest in Southern Brazil, placing A. angustifolia, a key-species in the structure and functioning of this ecosystem, among species threatened with extinction (REIS et al, 2014;PERALTA et al, 2016).…”