Pantropical variation in soils of the tropical dry forest (TDF) biome is enormously high but has been poorly characterized. To quantify variation in the global distribution of TDF soil physical and chemical properties in relation to climate and geology, we produced a synthesis using 7500 points of data with gridded fields representing lithologic, edaphic, and climatic characteristics. Our analyses reveal that 75 TDF ecoregions across five biogeographic domains (Afrotropical, Australasian, Indo-Malayan, Neotropical, and Oceanian) varied strongly with respect to parent material: sediment (57%), metamorphic (22%), volcanic (13%), and plutonic (7%). TDF ecoregions support remarkably high variability in soil suborders (32), with the Neotropical and Oceanian realms being especially diverse. As a whole, TDF soils trend strongly toward low fertility with strong variation across biogeographic domains. Similarly, the exhibited soil properties marked heterogeneity across biogeographic domains, with soil depth varying by an order of magnitude and total organic C, N, and P pools varying threefold. Organic C and N pool sizes were negatively correlated with mean annual temperature (MAT) and positively correlated with mean annual precipitation (MAP). By contrast, the distribution of soil P pools was positively influenced by both MAT and MAP and likely by soil geochemistry, due to high variations in soil parent material across the biogeographic domains. The results summarized here raise important questions as to how climate and parent material control soil biogeochemical processes in TDFs.

The effects of converting native forests to livestock systems on soil C, N and P contents across various climatic zones are not well understood for the tropical region. The goal of this study was to test how soil C, N and P dynamics are affected by the land-use change from natural forests to livestock production systems (extensive pasture and intensive silvopastoral systems) across a rainfall gradient of 1611–711 mm per year in the Mexican tropics. A total of 15 soil-based biogeochemical metrics were measured in samples collected during the dry and rainy seasons in livestock systems and mature forests for land-use and intersite comparisons of the nutrient status. Our results show that land-use change from natural forests to livestock production systems had a negative effect on soil C, N and P contents. In general, soil basal respiration and C-acquiring enzyme activities increased under livestock production systems. Additionally, reduction in mean annual rainfall affected moisture-sensitive biogeochemical processes affecting the C, N and P dynamics. Our findings imply that land-use changes alter soil C, N and P dynamics and contents, with potential negative consequences for the sustainability of livestock production systems in the tropical regions of Mexico investigated.

Identifying how limited resources, such as nutrients, are allocated across plant organs can provide new insights into ecophysiological strategies, as well as ecosystem nutrient cycles. Plants may allocate different nutrients within a specific organ or the same nutrient among different organs. In this study, we explored the allocation strategies of nitrogen (N) and phosphorus (P) in the leaves, stems, and roots of nine dominant tree species in secondary tropical dry forests using scaling analysis. The results showing that N and P have different scaling relationships within and among plant organs. The scaling relationships of P versus N concentrations in non‐leaf organs were isometric across secondary succession and shifted in leaves from allometric (P concentration increased faster than N concentration) to isometric. The scaling relationships of N or P concentrations between metabolic (leaves vs. fine roots) or between structural (stems vs. coarse roots) plant organs tended to be isometric along succession. Whilst the scaling relationships of the same nutrient between metabolic versus structural plant organs tended to be allometric (N and P concentrations increased faster in woody organs than in metabolic organs) across succession. A principal component analysis suggests associations of nutrient allocation to woody organs with soil pH over the chronosequence and with vegetation structure and soil nutrient availability in the case of metabolic organs. These findings on the sensitivity in plant nutrient allocation to changes in soil and vegetation properties during secondary succession may have practical implications for carbon sequestration management and models and restoration of this threatened ecosystem.