Climate change could potentially affect agricultural and forest production in Chile through changes in soil moisture and temperature regimes. In Soil Taxonomy the Soil Moisture Regime (SMR) is used to classify soils at the Suborder, Great Group and Subgroup levels, whereas Soil Temperature Regime (STR) is mainly used at the Family level. Both SMR and STR can be calculated using climatic data input to the Newhall model. Therefore, the objective of this research was to test the hypothesis that long term climate change has already affected the SMR and STR in different locations of the country. Historical values (1912-2015) of monthly precipitation and temperature were input to the model, with the available soil water set to 180 mm, and the offset of air to soil temperature set to 2 °C. The climatic records indicated a general trend of less precipitation in central and south central Chile whereby the SMR changed in Concepción from Ustic-Udic Tropustic to Ustic-Typic Tropustic; in Puerto Montt from Perudic to Udic-Typic Udic; and in Punta Arenas from Aridic-Typic Aridic to Xeric-Typic Xeric. In general, the recent period had more frequent extreme dry years. There was also a general tendency for slightly cooler temperatures mainly along the coast, and warming in Santiago, but the dominant STRs did not change between periods. Additionally, in south central Chile there was a decrease of annual moist days when the soil temperature is ≥ 5 °C, which suggests that in some areas soil temperature and moisture conditions have become somewhat more limiting over time, and, if continued, will likely result in a southerly expansion of the Xeric SMR, and increased need for supplemental irrigation of crops.

In Chile, 49.1% of the national territory is affected by soil degradation (including erosion and loss of soil organic matter), whereby of the 51.7 Mha that have been historically associated with agricultural-livestock and forestry activities, only 35.5 Mha are being used at the present. Consequently, soil degradation has resulted in the release of about 11.8 Gg yr⁻¹ of carbon (C) equivalent (CO_2eq) to the atmosphere. Silvopastoral systems (SPS), however, can increase soil organic C (SOC) through sequestration (C→SOC), improve ecosystem services, and have been internationally recommended for sustainable land use. Therefore, it was proposed to determine the effects of SPS on soils, over five years, in degraded sites that were located in the Ranchillo Alto (SPS-RA) (37°04′52″ S, 71°39′14″ W), Ñuble region. The sites were rated according to previous canopy disturbance levels (+) as follows: open (O_p)+++, semi open (SO_p)++, and semi closed (SC)+. The analysis was performed on different physical and chemical soil properties (0–5 and 5–20 cm depths), that were expressed as soil indicators (S_IND) for chemical and physical properties, which were used to calculate a soil quality (SQ) index (SQI). The results indicated overall SQI values of 37.6 (SC) > 29.8 (O_p) > 28.8 (SO_p), but there were no significant variations (p < 0.05) in physical SQ, whereas chemical SQ varied in all conditions, mostly at 0–5 cm in O_p and SO_p. Increases of SOC were also observed (2015–2018 period) of 22.5, 14.5, and 4.8 Mg ha⁻¹ for SO_p, O_p, and SC, respectively, showing that SPS promote the reclamation of Ranchillo Alto soils.

Unsustainable management of the “Espinal” agroecosystem of central Chile has progressively lowered the organic matter content and fertility of soil as evidenced by decreasing forage production and lower coverage of espino (Acacia caven (Mol.) Mol.), a leguminous tree. This savannah-type ecosystem includes the soil Cauquenes clay loam (Ultic Palexeralfs; Umbric Acrisols) that formed in granitic residuum, and a Mediterranean-type climate having extended dry periods during the warmer months (November through March). Considering that productivity is related to soil organic matter, the objectives of this investigation were to determine the content of organic carbon (C) in soil of well preserved, typical and degraded Espinals; evaluate fractions of the soil organic matter as indicators of sustainable management; and use the Century model to determine the potential gains of C in the soils. Well-preserved, typical, and degraded Espinal sites were located near Cauquenes, Chile, and soil samples were collected in three representative subsites at 0–20 cm and 20–40 cm depths. In the laboratory, organic matter was fractionated using distilled water to isolate the light fraction, and C content was measured using dry combustion of the separate fractions. Century was calibrated to local conditions and simulations were run using current and less intensive management. The results indicated that total soil C of typical and degraded Espinals was 18 and 49% lower, respectively, than in soil of the well-preserved Espinal, and that the ratio of C in the light fraction between the two soil depths may be a useful indicator of sustainable management. Model simulations forecasted that soil C would slowly increase in the degraded Espinal by 3.19–3.86 Mg ha⁻¹, after 100 years.

Grazing and over-exploitation can severely degrade soil in native forests. Considering that productivity in ecosystems is related to soil organic matter (SOM) content and quality, the objectives of this study were to: (1) determine the influence of degraded (DEF), partly-degraded (PDF), and undisturbed (UNF) Nothofagus forests on the stocks of carbon (C) in tree biomass and SOM; (2) evaluate fractions of SOM as indicators of sustainable management; and (3) use the Century model to determine the potential gains of soil organic C (SOC). The forests are located in the Andes and Coastal mountains of southern Chile. The SOM was fractionated to separate the light fraction (LF), macroaggregates (>212 µm), mesoaggregates (212–53 µm), and microaggregates (<53 µm). In two measurement periods, the SOC stocks at 0–20 cm and 20–40 cm depths in macroaggregates were on average 100% higher in the Andean UNF, and SOC was over twice as much at 20–40 cm depth in Andean DEF. Century simulations showed that improved silvopastoral management would gradually increase total SOC in degraded soils of both sites, especially the Ultisol with a 15% increase between 2016 and 2216 (vs. 7% in the Andisol). Greater SOC in macroaggregates (p < 0.05) of UNF indicate a condition of higher sustainability and better management over the years.

Agroforestry systems (AFSs) have gained recognition as a land use strategy to address food security and climate change. They involve intentionally cultivating trees alongside crops and/or animals. AFSs cover approximately 5% of the global forest area and promote sustainable soil conservation, including soil organic carbon (C) sequestration (C_SEQ). In some areas of Chile, AFSs are used to preserve the ecological value of native forests. This study evaluates the effects of two AFSs, namely, an agroforest for fodder production (A_GROF_RST) and Silvopastoral (SPS), within a degraded native forest (Nothofagus obliqua sp.). The evaluation focuses on their impact on C_SEQ capacity and soil quality (SQ), using soil quality indexes (SQIs) derived from 30 soil quality indicators (SI_NDs) related to physical, chemical, and microbiological properties at two depths (0–5 and 5–20 cm). The results for the total depth analyzed (0–20 cm) indicate an average C_SEQ of 6.88 and 4.83 Mg C yr⁻¹ and a global SQI of 37.8% and 31.0% for A_GROF_RST and SPS, respectively. Among the thirteen SI_NDs that demonstrated significant differences (p < 0.05), five were associated with the considered depths (P⁺, Ca²⁺, S, ECEC, and Al_SAT), three differed between A_GROF_RST and SPS (BD, NH₄⁺, NO₃⁻), while SOC, K⁺, and Mg²⁺ varied across all conditions (e.g., combinations of systems and depths), and β-_GLU and N_MIN differed in a single condition. However, almost all 30 SI_NDs analyzed showed higher values at the 0–5 cm depth, indicating the positive effects of soil organic matter (SOM)/SOC additions. Significant interactions (Pearson’s correlation) revealed that SOC correlated with most SI_NDs (e.g., N, NH₄⁺, P⁺, K⁺, Ca²⁺, Mg²⁺, S, ECEC, N_MIN). These findings suggest that both A_GROF_RST and SPS systems have similar capabilities in restoring the ecological value of native Nothofagus forests while providing conditions for productive and complementary use. This sustainable option offers opportunities for cattle production alongside ecological restoration efforts and provides a possible strategy to generate public policies related to the ecosystem services of agroforestry systems.

Chile holds ~50% of temperate forests in the Southern Hemisphere, thus constituting a genetic–ecological heritage. However, intense anthropogenic pressures have been inducing distinct forest structural-regeneration patterns. Accordingly, we evaluated 22 soil properties at 0–5 and 5–20 cm depths in two protected sites, with similar perturbation records but contrasting post-disturbance regeneration stages: long-term secondary forest (~50 y) (SEC_FORST) (dominated by Chusquea sp.-understory) and a short-term forest after disturbance (~5 y) (FAD_IST) within a Nothofagus spp. forest to determine the potential of these soils to promote nutrient availability, water cycling, soil organic carbon (SOC) sequestration (CO₂→SOC), and microbiome. Results detected 93 correlations (r ≥ 0.80); however, no significant differences (p < 0.05) in physical or chemical properties, except for infiltration velocity (+27.97%), penetration resistance (−23%), SOC (+5.64%), and % Al saturation (+5.64%) relative to SEC_FORST, and a consistent trend of suitable values 0–5 > 5–20 cm were estimated. The SOC→CO₂ capacity reached 4.2 ± 0.5 (FAD_IST) and 2.7 ± 0.2 Mg C y⁻¹ (SEC_FORST) and only microbial abundance shifts were observed. These findings provide relevant insights on belowground resilience, evidenced by similar ecosystem services provision capacities over time, which may be influenced progressively by opportunistic Chusquea sp.