Atributos do solo e serviços ambientais em sistemas agroflorestais com seringueira (Hevea brasiliensis Müll.Arg.) na zona da mata rondoniense

Abstract

In the current context of climate change and environmental issues, agroforestry systems (AFS) are important agricultural systems that can provide essential ecosystem services. However, this potential depends on many factors, such as floristic composition, planting density, age, management techniques and environmental characteristics. This work aims to determine soil quality, evaluate carbon stock e estimate ecosystem services in multi-stratified rubber-based (Hevea brasiliensis Müll.Arg.) agroforestry systems in Forest Zone of Rondônia, southwestern Amazon. For comparison, a pasture area and a forest fragment of the same region were evaluated as well. In the first article, we aim to determine soil quality, using physical and chemical attributes, and estimate ecosystem services related to soil in AFS, pasture and forest areas. In the second article, we aim to characterize these agroecosystems and determine carbon stocks in tree biomass, litter and soil. Five 30 x 30 m plots were installed in each area, where forest inventory was carried out. Litter samples and undisturbed, disturbed and soil monoliths samples were collected in these plots. Carbon stock was determined in three compartments: tree biomass, through allometric equations, in litter and soil, with the collection of material and chemical analyzes. The soil samples were used to determine soil physical and chemical attributes. Bulk density, porosity and aggregation were similar in all areas, showing the potential of AFS in maintaining the soil physical quality. The chemical attributes, mainly pH, aluminum and base saturation, confirmed the acid character and low chemical fertility, which is characteristic of most tropical soils. The ecosystem services related to nutrient cycling, water retention and maintenance of soil quality were mainly efficient for AFS in clay soils, which values were similar to the forest. For tree biomass, the values ranged from 22.92 to 79.20 Mg ha-1 , showing higher values in the forest and older AFS that have higher proportion of individuals with larger diameters. For litter, the values were between 2.60 and 4.08 Mg ha-1 due

to differences in vegetational structure. For soil, the values ranged from 72.68 to 108.06 Mg ha- 1

, being higher in the areas under clay soil. Considering all pools, the total carbon stock had the following order: forest (188.02 Mg ha-1

) > AFS (values between 99.08 and 181.36 Mg ha-1 ) >

pasture (88.19 Mg ha-1

). In general, carbon stocks varied due to differences in vegetational structure and soil texture, however, rubber-based AFS contribute to the mitigation of this greenhouse gas. Overall, the rubber-based agroforestry systems in Forest Zone of Rondônia have potential to provide diverse ecosystem services, especially maintenance of soil quality and carbon storage, proving to be an efficient alternative for associating agricultural production and conservation of natural resources.