Lithological substrates influence tropical dry forest structure, diversity, and composition, but not its dynamics

Abstract

IntroductionTropical dry forests (TDF) are not only the most widespread tropical forest type but also the most threatened forest ecosystem worldwide. Yet, because their dynamics have been insufficiently studied, our knowledge about the factors responsible for the spatial and temporal variability in TDF dynamics remains very limited. In this study, we aimed (1) to assess the effects of two lithological substrates on TDF structure, diversity, and species composition, and (2) to determine whether and how these substrates affect temporal dynamics on TDF attributes.MethodsWe used information gathered through a 12-year long annual monitoring of 14 old-growth TDF permanent plots in southern Mexico, seven of which were established on limestone and seven on phyllite. Previous work shows that limestone-derived soils have higher humidity, conductivity, and phosphorous and calcium contents, but lower nitrogen content.ResultsTDF structure and diversity attributes were consistently higher on limestone TDF, while canopy height was higher on phyllite TDF. By contrast, temporal variation in TDF attributes, demographic rates (recruitment, growth, and mortality) and attribute residence times were indistinguishable between substrates. We also found a strong differentiation of species composition between substrates, yet substrates did not influence the temporal behavior of composition.DiscussionOur results suggest that limestone is a more favorable environment for TDF development (soil-effects mechanism), but the flora of the forest on phyllite seems to be better adapted to cope with harsher environmental conditions (composition-effects mechanism), which counterbalances the environmental advantage of limestone, ultimately resulting in spatially homogeneous TDF dynamics at the landscape level. Future studies should examine the role of functional attributes on old-growth TDF dynamics, as this will allow a better understanding of the impacts of extreme climatic events on forest attributes and their dynamics, as well as to foresee potential ecosystem state shifts and tipping points.

Land use legacies affect early tropical forest succession in Mexico

“…on the Pacific watershed of the Isthmus of Tehuantepec. Mean annual temperature is 27.7°C, with a mean annual precipitation of 900 mm (Muñoz et al., 2023). Rainfall is highly seasonal, with 90% of the rainfall occurring between late May and mid‐October.…”

Environmental heterogeneity influences liana community differentiation across a Neotropical rainforest landscape

“…Geomorphological factors (e.g., slope aspect and inclination, elevation, parental material) drive variation in soil properties and thus may influence plant community assembly (Baldeck et al., 2013 ; Durán et al., 2006 ; Guo et al., 2017 ; Rodrigues et al., 2019 ). Numerous studies in tropical forests have shown evidence that tree communities respond to the environmental heterogeneity associated with geomorphology and soils (e.g., Clark & Clark, 2000 ; Denslow et al., 2019 ; Durán et al., 2006 ; Fayolle et al., 2012 ; Guo et al., 2017 ; Jucker et al., 2018 ; Muñoz et al., 2023 ; Navarrete‐Segueda et al., 2021 ). However, studies focusing on liana communities are scarce (Addo‐Fordjour et al., 2014 ; DeWalt et al., 2006 ; Ibarra‐Manríquez & Martínez‐Ramos, 2002 ).…”

Leaf functional diversity and environmental filtering in a tropical dry forest: Comparison between two geological substrates

“…Conversely, more benign conditions, i.e., where limiting conditions do not strongly impact individual performance (such as milder temperatures, deeper and richer soils, and higher water availability) have been associated with more functionally diverse plant communities (Ding et al, 2019; Ottaviani et al, 2016; Spasojevic et al, 2013). The lithology and morphogenetic characteristics of geological substrates have effects on topography, soil nutrient availability, and soil physicochemical properties, all of which induce changes in species composition and abundance (de Souza et al, 2023; Durán et al, 2006; Gerrard, 1992; Muñoz et al, 2023; Pérez‐García et al, 2010). Geological substrate, a relevant factor for plant growth, can act as an environmental filter capable of shaping species distributions and functional diversity, depending on variations in the water retention potential and fertility of its derived soil (Fayolle et al, 2012).…”

“…In the region of Nizanda (S Mexico), two different tropical dry forest communities occur, each one being associated with a different geological substrate (limestone or siliciclastic phyllite; Figure 1). Previous work in this region has shown that despite shared characteristics that warrant their classification as the same vegetation type (Pérez‐García et al, 2010), notable differences exist between them: the forest associated with limestone is more developed (e.g., it has higher basal area and density, and higher diversity), suggesting that it grows in a more benign habitat than its counterpart growing on phyllite (Muñoz et al, 2023). These contrasts motivated us to compare the functional diversity of these two tropical dry forest communities to test the hypothesis that geological substrate constitutes an environmental filter that shapes community leaf functional diversity.…”