Agroforestry Systems最新文献

Nothofagus antarctica forest extends from 46 to 56° south latitude and its main use has been as silvopastoral systems (SPS). Several studies have characterized understory of N. antarctica SPS. However, other practices like pasture sowing, irrigation and fertilization, to improve understory yield, remains little documented. The aim of this work was to compare dry matter (DM) production and quality of natural understory vs. implanted pastures under different water and nutrient conditions. An experiment with fifteen plots of 6 × 6 m was established in a strip-split plot design, with species as the main factor, water as the sub-plot factor (rainfed vs. irrigated) and fertilizer application level as sub-sub-plot factor (low, medium and high). The species evaluated were: Dactylis glomerata, Bromus catharticus, Trifolium pratense, T. repens and natural understory. Total dry matter (DM) production, leaf N concentration and digestibility were measured after 1 and 2 years of experiment establishment. Significant differences were found in DM according to species and fertilization treatments. The highest DM production was for T. pratense with medium fertilization level (5194 kg DM ha⁻¹), followed by D. glomerata with 200 kg N ha⁻¹ (4984 kg DM ha⁻¹). Natural understory increased DM with nitrogen fertilization from 1427 to 3980 kg DM ha⁻¹. In terms of quality, T. repens had the highest digestibility values. This study showed that pure pastures of T. pratense or D. glomerata accompanied by N fertilization are viable options to increase forage yield and quality in N. antarctica SPS.

The aim of this research was to evaluate dietary inclusion of Leucaena diversifolia into a grass monoculture (GM) diet and its influence on enteric methane emissions, animal live weight gain and meat fatty acid content of steers. Two GM diets comprised Urochloa hybrid cv. Cayman or U. brizantha cv. Toledo; silvopastoral (SPS) mixed diets included an association of either grass with L. diversifolia in a 74:26 (grass:legume) planting ratio. The experiment was conducted over 16 months with 14 Brahman x Angus crossbred steers (374±7.5 kg body weight), divided into two diet groups. Steers were weighed periodically during the experiment, and methane emissions were quantified with the polytunnel technique. The meat quality and fatty acid profile were measured after slaughtering the steers. Energy density, total and digestible dry matter intake and crude protein were higher in steers fed SPS than GM (P≤0.05). At the end of the experiment, animals from SPS weighed on average 63 kg more than animals offered GM (535 vs. 472 kg; P=0.025). Net methane emitted by steers offered SPS was 142 g per day, this is equivalent to 15% less than emissions from animals that were offered GM (168 g; P=0.007). The meat fatty acid profile was similar between diets, except for cervoniv-DHA and omega-6: omega-3 ratio, which were higher in steers consuming GM diet (P≤0.05). The results of this study suggest that the inclusion of L. diversifolia improves nutrient intake, increases animal productivity, reduces daily enteric methane emission, and decreases the omega-6: omega-3 ratio in meat.

Integrating agricultural production with livestock systems can restore soil quality from poorly managed pastures, reduce greenhouse gas emissions, and increase carbon sequestration. We evaluated soil fertility, litter decomposition, and stabilization in extensive continuous grazing without management, intensified rotation grazing, integrated crop-livestock, livestock-forestry, crop-livestock-forestry systems, and a forest for comparison. Intensified systems showed the highest cation concentrations due to tree nutrient use while extensive systems had lowest nitrogen and carbon:nitrogen values. Forest sites had lower phosphorus and carbon:nitrogen ratios than pastures but higher organic matter, nitrogen, and nitrogen:phosphorus ratios. Higher decomposition rates and lower stabilization factors were found in open pastures compared to areas with trees and the forest. A structural equations model indicated direct negative effects of shading by trees on decomposition rates, possibly correlated with lower temperatures or different decomposer composition due to differential litter composition in systems with trees. Increased radiation had adverse effects on the stabilization factor and positive effects mediated by soil base saturation, which was higher in more open pastures. Integrated systems including forestry presented similar decomposition rates and stabilization factors to forest sites, although the responsible mechanisms may differ, with higher nutrient limitation for decomposers in forest sites due to higher nitrogen:phosphorus ratios. Therefore, our results indicate that better management practices can improve nutrient cycling in intensified and integrated livestock production systems and contribute to stabilizing the soil organic matter.

Microbial biomass (MB) is an important indicator of soil quality, being responsive to changes resulting from soil management and use. Although there are studies that evaluate changes in soil microbiological attributes in coffee growing systems, the effects of these systems on MB and its relationship with other soil attributes have rarely been investigated, especially in tropical climate conditions at altitude. Therefore, this study aimed to evaluate the effect of different coffee growing systems on biomass and microbial activity and how these responses relate to other soil and litter attributes. Our study was carried out in soils under three Coffea arabica cultivation systems (CCM—monoculture, CCB—consortium with banana, AFS—agroforestry system with Grevillea robusta) and under native forest (NF). Soil samples were collected at a depth of 0–10 cm and subjected to analysis to determine the microbial biomass carbon content (MB-C) by the fumigation-extraction method, accumulated respiration through released CO₂, soil organic carbon (SOC) and labile carbon by wet oxidation. There was a 45% reduction in SOC in coffee growing systems and a 75% reduction in MB-C in CCM compared to NF. The AFS is closer to native forest conditions due to its positive influence on the SOC content and the efficiency of converting this carbon into microbial carbon. The presence of the forestry component is positive and should be encouraged to mitigate the impacts of coffee growing on the soil.

Integrating livestock with afforestation in Silvopastoral Systems (SPS) can enhance livestock production while mitigating climate and economic fluctuations. In SPS, tree canopies modify solar radiation and wind speed, affecting pasture evapotranspiration and water availability. This work aims to contribute to understanding tree-pasture-environment interactions and the light-use efficiency of natural grassland in SPS with fast-growing forest species. The study site is in Reboledo, Florida, Uruguay (34° 1′15.16″S, 55°39′13.75″W), consisting of natural pastures lined with triple rows of Eucalyptus grandis and 14–19 m alleys. Two experiments were conducted, one in the field and one in growth chamber. Plots were established in three different tree ages (2012 (10y), 2013 (9y), 2019 (3y)) and a control. Each tree age had three zones relative to tree lines (Row (R), Intermediate (I) and Middle Alley (MA)). Results showed that variations between zones were less pronounced in the 10y trees compared to the 3y trees. Accumulated PAR differences ranged from 32% in 10y trees to 38% in 3y trees, in tree LAI (28–76%) and Soil Water Content (WC) (31–51%). Accumulated PAR in MA zone (3y trees) did not differ from the control without trees. Soil WC in R is the lowest among all situations in 3y plot and the highest in the 10y. Photosynthetic Active Radiation Use Efficiency (PARUE) for natural grassland sod pieces under simulated shade averaged 0.40 g mol⁻¹. Younger trees generated a more heterogeneous system with more pronounced zones, where the middle alley resembles the control without trees in the studied variables.

The department of Caquetá in the Amazon foothills of Colombia is one of the most dynamic in terms of cattle production in the country. Thousands of hectares have been replaced by pasture monoculture with negative consequences for the biodiversity. Silvopastoral systems (SPS) have been promoted in the region as an alternative to improve tree cover, biodiversity and productivity of cattle farms. To analyze the impact of SPS on plant and bird diversity, 22 plots with three silvopastoral arrangements (tree alleys: TA, scattered trees in pastures: STP, intensive silvopastoral systems: iSPS) and pasture monocultures (PM) were sampled using 20 × 50 m quadrats for vegetation and 50 m radius fixed points for birds. A total of 556 individuals of 26 families and 60 plant species were found. TA and STP had significantly higher abundance and richness of vegetation than PM. For bird fauna 2209 individuals belonging to 18 orders, 42 families and 149 species were present. Bird diversity and abundance were significantly higher in TA than PM. The diversity and abundance of plants, as well as vegetation structure had a positive and significant effect on the abundance and richness of birds, and on the richness of frugivorous, insectivorous, and omnivorous birds, and the richness of species with preferences for different habitats. Plant diversity and structure complexity is key to improve diversity of birds, frugivorous and insectivorous species and therefore should be considered when selecting plant species to be introduced in the cattle systems.

Perennial vegetation in farmlands can mitigate anthropogenic greenhouse gases (GHG) by capturing atmospheric carbon and storing it in the soil for extended periods. The objective of this study was to quantify soil organic carbon (SOC) concentrations and stocks under tree buffer (TB), grass buffer (GB), grass waterways (WW) and crop field (CS, corn-soybean rotation) to evaluate the significance of conservation measures in C sequestration projects. Soil samples were collected up to 1 m depth at upper, middle, and lower landscape positions from 26-year-old TB, GB, and WW in a watershed. The SOC concentration decreased with increasing soil depth for all four land uses. However, as expected, bulk density increased with increasing soil depth for all four land uses. It was highest for the CS land use. In 2023, for the depth of 0–10 cm, SOC increased by +0.63, +1.06, +1.37 and +1.63% in CS, GB, TB, and WW, respectively, since the land uses were established 26 years ago. Land uses had greater impacts on SOC stock in the top 50 cm depth, with WW (113.5 ± 12.9 Mg ha⁻¹), TB (106 ± 14.5 Mg ha⁻¹), and GB (102.4 ± 11.6 Mg ha⁻¹) compared to CS (90.9 ± 10.2 Mg ha⁻¹). However, at watershed level, with ~ 10% cover by TB or GB areas and the rest under CS, SOC stock up to 50 cm depth was respectively 91.6 and 91.2 Mg ha⁻¹ compared to 90 Mg ha⁻¹ by CS alone—1.3 to 1.8% increase. This is a significant increase in soil organic carbon across the landscape, which was realized with the conservation practices and agroforestry, while also playing a crucial role in protecting surface runoff in the landscape. Future studies may consider valuation of the overall ecosystem services due to the land uses (conservation measures) and the trees by considering optimization of incorporating such technologies in the farming systems to reduce negative trade-offs.

This study aimed to evaluate the effect of tree shading in silvopastoral systems (SPS) on forage production through long-term experiments, as well as to determine the correlation between dendrometric variables of eucalyptus trees and transmission of photosynthetically active radiation (PAR) to establish thereby the optimum forest cover for effective management in these systems. We evaluated four SPSs in São Carlos, SP (21° 57′ 42″ S, 47° 50′ 28″ W, 854 m.) and Campo Grande, MS (20° 24′ 55″ S, 54° 42′ 26″ W, 530 m.), Brazil, considering various factors such as tree age, management, and density. The systems included pastures with eucalyptus (Eucalyptus urograndis) or corymbia (Corymbia citriodora) trees planted in single rows at densities ranging from 83 to 357 trees ha⁻¹. During the rainy season, from October to March, we analyzed the correlation between PAR transmission and relative forage production (forage production in the SPS/forage production in full sun), as well as the correlation between dendrometric variables, such as diameter at breast height, volume and basal area per unit area and PAR transmission. The results showed a linear reduction in production in the SSPs due to the decrease in PAR transmission. The strongest correlation between tree growth and PAR transmission was obtained with the basal area per hectare variable (r = − 0.91). Thus, this study successfully established a linear relationship between basal area per hectare and PAR transmission, providing insights for the implementation of tree thinning management in SPSs to maintain the productive potential of forage plants in the understory of these systems.

We evaluated the annual net primary productivity (ANPP) on understory in secondary Nothofagus antarctica forests under silvopastoral systems in Patagonia. We assessed the effect of thinning and estimated understory ANPP using biomass cropping and remote sensing. Thinning was conducted with a remaining tree cover of 50–60% in high and intermediate forest condition. Exclusion fencing was implemented in grazing areas to establish 44 paired plots and 9 open surrounding areas. Two annual harvests were conducted over three growing seasons. Remote sensing was employed to indirectly estimate forest-covered area ANPP, using linear regressions adjusted to normalized difference vegetation index, active photosynthetically absorbed radiation, fraction of PAR absorbed by photosynthetic tissue in a vegetation canopy, canopy cover density, and ANPP. Understory ANPP found in thinned plots versus control plots were 788 versus 234 kg DM ha⁻¹ year⁻¹, respectively, with higher understory ANPP observed in intermediate compared to high forest condition. Adjusted models for estimating understory ANPP under ñire forest canopy showed 80% precision. It was possible to indirectly estimate understory ANPP under thinned ñire forest using optical remote sensing. The results of this study offer a valuable remote sensing decision making tool for stakeholders, enabling insights to be scaled up to broader territory and aiding in adjusting agroforestry systems’ livestock carrying capacity. Silvopastoral systems of N. antarctica subjected to moderate thinning experience increased forage production under remaining canopy, more than doubling production compared to control forests with full density, although it remains approximately half of production observed in open areas.

Silvopastoral systems may provide important production and environmental benefits. The loss of cool-season (C3) grasses from temperate grazed native grasslands is associated with selective grazing and excessive solar radiation that limit their survival. Silvopastoral systems integrate trees with grasslands that provide shade to both cattle and herbaceous plants, potentially favoring C3 species. There is limited information about the effect of trees on the species and functional composition of native grasslands in the Campos biome in South America. The objective of this study was to detect gradients in the botanical composition of grasslands as affected by changes in the shade associated with distance to the trees and cardinal orientation in three situations defined by the combination of soil and tree species (Prosopis on Solonetz, Acacia on Brunisols, and Eucalyptus on Brunisols). Soil cover of the herbaceous species under trees was recorded in double transects located in the four cardinal directions. In all situations there were changes in pasture composition in the different shaded regions (total shade, partial shade, or full sun). Under the canopy, there was an increase of cool-season grasses such as Bromus catharticus Vahl, Lolium multiflorum Lam., Stipa hyalina (Nees) Barkworth, and S. setigera J.Presl. At greater distances from trees, cover of warm-season grasses, such as Axonopus affinis Chase and Paspalum notatum Flueggé increased. These gradients suggest that trees in silvopastoral systems can increase the abundance of cool-season species and potentially improve the forage nutritive value of the native pasture.