FINE ROOT DENSITY ACROSS SOIL PROFILES IN TROPICAL MOUNTAIN CLOUD FOREST AND ADJACENT MANAGED FIELDS IN VERACRUZ (MEXICO): INFLUENCE OF SOIL PROPERTIES

Abstract

Background. Fine roots play a crucial in ecosystem functioning as they supply nutrients and water to plants and represent one of the main pathways for carbon transfer to the soil. Objective. This study assessed the vertical distribution of fine root density and analyzed its relationship with soil properties from a land use change perspective in three vegetation cover types (tropical mountain cloud forest, grassland, coffee crop). Methodology. Soil samples of known volume per horizon were extracted from the soil profile. In laboratory, fine roots (≤ 2 mm in diameter) were tweezers picked, rinsed with water and subsequently oven-dried (70 °C), and weighed. While, the soil was air-dried for chemical analysis. Results. In all soil profiles, average fine root density was greater in grassland (16.06 kg m-3 ± 3.5, average ± SE) than in tropical mountain cloud forest (8.45 kg m-3 ± 1.3), and coffee crop (2.73 kg m-3 ± 0.44). On average, grassland, tropical mountain cloud forest, and coffee crop showed 78.4%, 73.2%, and 65%, respectively, of fine root density on the first soil horizon. Implications. Soil properties were strong predictors of fine root density variation. For example, there was a significant positive correlation between fine root density and soil organic carbon, total soil nitrogen, and effective cation exchange capacity (nutrient availability) in all vegetation covers. A significant negative correlation was observed between fine root density and pH in tropical mountain cloud forest but was not correlated in grassland and coffee crop. In all vegetation covers, there was a significant negative correlation between fine root density and soil bulk density and a strong positive correlation between it and soil water content at field capacity. Conclusion. This research contributes data that will improve our understanding of fine root density-soil interactions in a changing regional environment.