Assessing soil and land health across two landscapes in eastern Rwanda to inform restoration activities

Abstract

Abstract. Land degradation negatively impacts water, food, and nutrition security and is leading to increased competition for resources. While landscape restoration has the potential to restore ecosystem function, understanding the drivers of degradation is critical for prioritizing and tracking interventions. We sampled 300–1000 m2 plots using the Land Degradation Surveillance Framework across Nyagatare and Kayonza districts in Rwanda to assess key soil and land health indicators, including soil organic carbon (SOC), erosion prevalence, vegetation structure and infiltration capacity, and their interactions. SOC content decreased with increasing sand content across both sites and sampling depths and was lowest in croplands and grasslands compared to shrublands and woodlands. Stable carbon isotope values (δ13C) ranged from −15.35 ‰ to −21.34 ‰, indicating a wide range of historic and current plant communities with both C3 and C4 photosynthetic pathways. Field-saturated hydraulic conductivity (Kfs) was modeled, with a median of 76 mm h−1 in Kayonza and 62 mm h−1 in Nyagatare, respectively. Topsoil OC had a positive effect on Kfs, whereas pH, sand, and erosion had negative effects. Soil erosion was highest in plots classified as woodland and shrubland. Maps of soil erosion and SOC at 30 m resolution were produced with high accuracy and showed strong variability across the study landscapes. These data demonstrate the importance of assessing multiple biophysical properties in order to assess land degradation, including the spatial patterns of soil and land health indicators across the landscape. By understanding the dynamics of land degradation and interactions between biophysical indicators, we can better prioritize interventions that result in multiple benefits as well as assess the impacts of restoration options.

Drivers of Field-Saturated Soil Hydraulic Conductivity: Implications for Restoring Degraded Tropical Landscapes

“…By contrast, fine-textured soils without aggregation have smaller pores which can, in cases such as vertisols, be further reduced during rainfall as a result of clay particles swelling, thereby inhibiting infiltration further (Medinski et al, 2009). We did not find a significant effect of soil pH on K fs (Table 2), although high pH has been associated with low infiltrability (Mills et al, 2006;Medinski et al, 2010;Winowiecki et al, 2021), an effect which may be ascribed to an increase in clay dispersibility at higher pH values (Chorom et al, 1994). The range of pH in our study may have been too limited to find a relationship between K fs and pH.…”

Woody species alongside earth contour bunds enhance the soil water‐infiltration capacity in the Sahel, West Africa

“…The field-saturated conductivity was also greater for G. sepium vegetated contour compared to A. colei, which did not differ from A. gayanus. Litter, the major source of soil carbon, may have contributed to such difference as related by Bargués-Tobella et al (2024) and Winowiecki et al (2021) who found that soil organic carbon positively influenced Kfs. G. sepium is recognized for its positive role in improving land fertility through the production of nitrogen-rich leafy biomass and the ability of its root system to produce nodules (Kwesiga et al, 2003;Rosenstock et al, 2014;Tangata & Alavalapati, 2003;Wambugu et al, 2011).…”

“…(2024) and Winowiecki et al. (2021) who found that soil organic carbon positively influenced Kfs. G. sepium is recognized for its positive role in improving land fertility through the production of nitrogen‐rich leafy biomass and the ability of its root system to produce nodules (Kwesiga et al., 2003; Rosenstock et al., 2014; Tangata & Alavalapati, 2003; Wambugu et al., 2011).…”

Spatiotemporal Changes of Cultivated Land System Health Based on PSR-VOR Model—A Case Study of the Two Lake Plains, China

“…In general, the health evaluation index of cultivated land systems should consider both macro-level management control and micro-level implementation feasibility due to the inherent characteristics of heterogeneity and diversity of cultivated land systems, the complexity and availability of multi-source data, and the varying objectives and needs of stakeholders at different levels. Future research should focus on the effects of climate change, annual accumulated temperature, annual precipitation index, ecosystem services, and other factors on the health of cultivated land systems on a macro scale [ 78 , 79 , 80 ] and on the effects of heavy metal pollution, soil organic carbon, soil erosion, soil organic matter, soil pH, soil nutrient elements (nitrogen, phosphorus, and potassium), soil texture, effective soil depth, and soil microorganisms on the health of cultivated land systems on a micro scale [ 17 , 81 , 82 ]. In addition, although the grid scale of 5 km × 5 km is utilized as the evaluation unit in this research, the scale effect of agricultural system health assessment must be studied further, with a focus on the impact of grid size on farming system health evaluation results and its spatial-temporal pattern.…”

“…The advancement of agricultural intensification, irrational fertilization, farming, grazing, crop types, and crop rotation plans will have a significant impact on the health of the cultivated land system [ 16 ], and environmental issues such as soil erosion, pollution, and biodiversity loss will become more prevalent. Agriculture has become the leading cause of environmental degradation on a global scale [ 17 , 18 ]. People have started to become more aware of the intimate connection that exists between healthy land and healthy people as a result of the complete promotion of an all-encompassing preservation strategy on the quantity, quality, and ecology of cultivated land [ 19 ].…”