Soil biogeochemistry across Central and South American tropical dry forests

Abstract

The availability of nitrogen (N) and phosphorus (P) controls the flow of carbon (C) among plants, soils, and the atmosphere, thereby shaping terrestrial ecosystem responses to global change. Soil C, N, and P cycles are linked by drivers operating at multiple spatial and temporal scales: landscape‐level variation in macroclimate and soil geochemistry, stand‐scale heterogeneity in forest composition, and microbial community dynamics at the soil pore scale. Yet in many biomes, we do not know at which scales most of the biogeochemical variation emerges, nor which processes drive cross‐scale feedbacks. Here, we examined the drivers and spatial/temporal scales of variation in soil biogeochemistry across four tropical dry forests spanning steep environmental gradients. To do so, we quantified soil C, N, and P pools, extracellular enzyme activities, and microbial community structure across wet and dry seasons in 16 plots located in Colombia, Costa Rica, Mexico, and Puerto Rico. Soil biogeochemistry exhibited marked heterogeneity across the 16 plots, with total organic C, N, and P pools varying fourfold, and inorganic nutrient pools by an order of magnitude. Most soil characteristics changed more across space (i.e., among sites and plots) than over time (between dry and wet season samplings). We observed stoichiometric decoupling among C, N, and P cycles, which may reflect their divergent biogeochemical drivers. Organic C and N pool sizes were positively correlated with the relative abundance of ectomycorrhizal trees and legumes. By contrast, the distribution of soil P pools was driven by soil geochemistry, with larger inorganic P pools in soils with P‐rich parent material. Most earth system models assume that soils within a texture class operate similarly, and ignore subgrid cell variation in soil properties. Here we reveal that soil nutrient pools and fluxes exhibit as much variation among four Neotropical dry forests as is observed across terrestrial ecosystems at the global scale. Soil biogeochemical patterns are driven not only by regional differences in soil parent material and climate, but also by local‐scale variation in plant and microbial communities. Thus, the biogeochemical patterns we observed across the Neotropical dry forest biome challenge representation of soil processes in ecosystem models.

Beyond leaf habit: generalities in plant function across 97 tropical dry forest tree species

“…S5). This suggests that edaphic conditions could be the cause of this variation as these traits are positively correlated to soil fertility (Ordoñez et al ., 2009), which is consistent with CO having more fertile soils (Waring et al ., 2021). Furthermore, Ψ P50‐leaf and HSM also varied significantly among evergreen species (Fig.…”

“…Last, the plots in PR have shallow clay loams developed on a limestone bedrock, with low extractable nutrient availability (Lugo & Murphy, 1986). We used data on soil particle‐size distribution collected in the plots described later (Waring et al ., 2021).…”

“…TDF often has high species turnover among sites, resulting in areas of unique species composition (Dryflor et al, 2016). Within this context of broad climatic, edaphic (Waring et al, 2021), and biological diversity, we selected four sites in public and private protected land that encompassed the breadth of this variation (Fig. 1): the Área de Conservación Guanacaste in north-western Costa Rica (CR: 10°43 0 31.39″N, 85°35 0 46.99″W), the Kaxil Kiuic Reserva Biocultural in the Yucatán peninsula (MX: 20°5 0 26.73″N, 89°33 0 47.66″W), the Bosque Estatal de Guánica in Puerto Rico (PR: 17°58 0 2.17″N, 66°53 0 17.54″W), and a private farm in Tolima, Colombia (CO: 5°3 0 36.00″N, 74°49 0 48.00″W).…”

Litter inputs and phosphatase activity affect the temporal variability of organic phosphorus in a tropical forest soil in the Central Amazon

“…The hydroxide extractable organic P fraction showed the opposite pattern however. Studies in drier tropical forests also indicate the importance of precipitation in the P-cycle, both in terms of litter dynamics (Valdespino et al 2009), and sorption of P (Campo et al 1998), while Waring et al (2021) compared different forests and found that soil development stage was the major driver of the soil P balance.…”

Discovering the forest in plain sight: a pop‐up Symposium focusing on seasonally dry tropical forests

“…Also, we need to focus on intra‐specific trait variation, rather than on inter‐specific variation where only mean trait values for species are considered. As SDTFs encompass high climatic and soil heterogeneity (Allen et al ., 2017; Waring et al ., 2021), species’ responses to these gradients may depend more on individual's performances across the extent of species’ biogeographical ranges. Greater understanding of the covariation between statistical moments in trait distributions and life‐history traits (e.g.…”