Land-Use Effect on Soil Carbon and Nitrogen Stock in a Seasonally Dry Tropical Forest

Abstract

Total organic carbon (TOC) and total nitrogen (TN) concentration in the soil are an indicator of soil degradation. To understand how land-use may impact these concentrations in seasonally dry tropical forests (SDTF), we analyzed the effect of four land-uses on TOC stocks (STK.TOC) and TN stocks (STK.TN) in a semi-arid region of Brazil. Soil samples were collected in 12 trenches (three sites × four land-uses—dense caatinga (DC), open caatinga (OC), pasture (PA) and agriculture (AG)), in the 0–10; 10–20 and 20–30 cm layers or as far as the bedrock. The data were compared by the Kruskal–Wallis test (p ≤ 0.05) and similarity investigated by cluster analysis. STK.TOC and STK.TN the surface layer (0–10 cm) showed no significant difference (p ≤ 0.05) between the DC; OC and PA land-uses. The similarity in STK.TOC and STK.TN values between DC, OC and PA, indicate that it is possible to explore SDTF to produce biomass and protein by adopting open caatinga and pasture land uses on Neosols with very low TOC stocks. The greatest reduction in STK.TOC and STK.TN in the agriculture land-use may lead to soil degradation and contribute to the addition of CO2 to the atmosphere.

Ecosystem function associated with soil organic carbon declines with tropical dry forest degradation

“…The alignment of forest states in the PCA biplots as well as the progressive reduction in the SQI with degradation indicates a clear gradient of declining soil quality that parallels the decline in vegetation biomass, complexity, and diversity from natural forest to arid land (Jara‐Guerrero et al, 2021; Ribeiro et al, 2019). Similar to other studies that have found differences in total C and N between undisturbed and disturbed SDTF (Andrade et al, 2020; Menezes et al, 2021; Schulz et al, 2016; Singh et al, 2017), our results show that these two fundamental constituents of SOM decreased steadily with degradation. SDTFs tend to have a larger proportion of biomass belowground compared to wet tropical forests (Murphy & Lugo, 1986), with high root biomass in the upper soil layers, especially fine roots (Castellanos et al, 1991).…”

“…Our results showed a consistent and steady reduction in soil quality and function along the gradient of ecosystem degradation in SDTF. While previous studies have shown loss of SOC (Andrade et al, 2020; Maestre et al, 2022; Menezes et al, 2021) and total nitrogen (Andrade et al, 2020) resulting from the conversion of SDTF to different land uses, few studies have focused explicitly on the effects on soil of SDTF degradation (Schulz et al, 2016). We show for the first time a significant and uniform decrease in POC and MAOC along a broad degradation gradient in SDTF.…”

Restoration and Conservation of Priority Areas of Caatinga’s Semi-Arid Forest Remnants Can Support Connectivity within an Agricultural Landscape

“…Based on previous studies in the Caatinga biome, we defined the following LULC classes: (1) water, (2) urban, (3) pasture, (4) agriculture (irrigated croplands), (5) open Caatinga (open native forest), and (6) dense Caatinga (dense native forest) [32,44,53]. We used a minimum mapping unit greater than 5 pixels [54], and the classification accuracy and the kappa index were evaluated through a confusion matrix between the reference data and the classified data [55].…”

Carbon, Nitrogen and Phosphorus Cycling in Cropland and Grassland Ecosystems

“…Then again, some areas are limited by N, while others are limited by phosphorus (P). For instance, to supplement P, intercropping with legumes delivering an enzyme activity (i.e., acid and alkaline phosphatase) and thus more available nutrients, might be a sustainable way [3,4]. Besides, to prevent nutrient leaching and erosion related to intense crop removal, some cropping systems may require the application of combined techniques including biochemical and organic fertilization, and intercropping [5], whereas other production systems, in particular semi-arid regions, may need novel land-use strategy schemes to provide sustainable agricultural systems [6].…”

“…Questions on sustainable land-use strategies to supply both fiber and protein production and soil health and fertility (i.e., soil carbon and nitrogen) has gained interest in recent years. The article by Andrade et al [3] evaluates effects of four main land uses on soil C/N stocks in a semi-arid region of Brazil. Among analyzed land uses, authors visited dense and open caatinga (i.e., area protected from cattle grazing and under forest regeneration), long-term pastures, and arable land cultivated with rain-fed maize (Zea mays.…”