Does the Process of Passive Forest Restoration Affect the Hydrophysical Attributes of the Soil Superficial Horizon?

Abstract

There has been an increase in the area of secondary tropical forests in recent years due to forest restoration in degraded areas. Recent analyses suggest that the success of passive forest restoration is highly uncertain and needs to be better understood. This study aimed to investigate the behavior of saturated hydraulic conductivity (Ks) and some hydrophysical soil attributes between agricultural land uses, restored forests, and a degraded forest fragment. The areas evaluated are located in the municipality of Rio Claro, São Paulo, Brazil, under different types of land use: (i) two areas in the process of passive forest restoration: one of 18 and another of 42 years (NR18 and NR42); (ii) a degraded forest fragment (FFD); (iii) pasture (P), and (iv) sugarcane (SC). The hydraulic soil conductivity characterization was performed using the Beerkan method. Dry soil bulk density (BD), total porosity (Pt), macroporosity (Mac), microporosity (Mic), penetration resistance (PR), mean aggregate diameter (MWD), and soil organic carbon (OC) were also determined. The comparative analysis of the hydrophysical attributes of the soil superficial horizon in agricultural land uses (P and SC), restored forests (NR18 and NR42), and a degraded forest (DFF) confirms that the recovery of soil hydrological functioning in ongoing forest restoration processes can be a relatively slow process. In addition, the intensity of previous land use leaves footprints that can affect passive restoration areas for decades after agriculture abandonment, increasing the time for the recovery of Ks and soil hydrophysical attributes.

Shade-Grown Coffee in Colombia Benefits Soil Hydraulic Conductivity

“…Zwartendijk et al [53] point out that the full hydrological recovery of tropical degraded sites with a natural regeneration process, may take several decades. However, K s does not always increase during natural regeneration, in some cases the evolution of K s and hydrological functions can be a relatively slow process [15,50,54,55]. Pereira et al [15] showed for the Atlantic forest biome that after 42 years the natural regenerated forest still had similar K s values as the sugarcane site [15].…”

“…However, K s does not always increase during natural regeneration, in some cases the evolution of K s and hydrological functions can be a relatively slow process [15,50,54,55]. Pereira et al [15] showed for the Atlantic forest biome that after 42 years the natural regenerated forest still had similar K s values as the sugarcane site [15]. They attributed the results to the legacy effect of intense land degradation before forest regrowth.…”

“…Our study plots were located in a similar landscape position with similar slope (i.e., greater than 20%) and had the same soil type. The size and number of plots were chosen according to previous investigations [14,15]. The CO site (9°35′41.27″ N, 73°6′37.16″ W) is a 35-year-old polyculture with a low use of agrochemicals.…”

“…Our investigation focuses on the soil saturated hydraulic conductivity (K s ) because this variable is particularly sensitive to soil disturbance and is often used as an of the influence of land-use change on infiltration and soil hydrological functioning [10,14,15]. On the other hand, K s is one of the most variable infiltration parameters, affecting negatively the performance of hydrological models [16][17][18].…”

Key gaps in soil monitoring during forest restoration in Colombia

“…Although scientific literature has repeatedly highlighted the fundamental role of physical soil indicators associated with water movement through the soil (e.g. infiltration, Ks, water retention, percolation, soil water content, soil water repellency), they are rarely reported in forests undergoing restoration in tropical ecosystems (Zwartendijk et al 2017; Lozano‐Baez et al 2019; Mendes et al 2019; Pereira et al 2020). Few studies (23%) directly measured hydrological processes, such as erosion, runoff, and infiltration.…”