Overcoming the regeneration barriers of tropical dry forest: effects of water stress and herbivory on seedling performance and allocation of key tree species for restoration

Abstract

Tropical dry forests (TDF) are one of the most threatened and poorly protected ecosystems in the Americas. Although there are international efforts for the restoration of TDF, how stress factors such as herbivory or water limitation due to changes in precipitation, impact the regeneration dynamics of these forests is poorly understood. Specifically, how seedlings of key tree species for TDF restoration cope with current abiotic pressures such as the intensification of climatic events, and biotic factors like herbivory, is not yet fully understood. Here, we compared seedling performance, and allocation of biomass, and water to roots vs. shoots for three legume, and one non-legume TDF tree species, as a response to water limitation and herbivory in an 8-month greenhouse experiment. Contrary to our expectations, we found that the non-legume species, G. ulmifolia, had the best performance compared to legumes, while N-fixing and non-fixing legumes showed similar performance. Based on our findings, we suggest the use of G. ulmifolia in TDF restoration projects due to its high performance despite abiotic and biotic stress factors, its allocation of biomass and water to belowground structures. We also recommend the use of N-fixing legume species owing to their ability to fix nitrogen, which guarantees an N input to the soil, important in the first stages of succession. However, the legume species used in this experiment do not appear to resist the abiotic and biotic stressors studied. Thus, more studies exploring the response of dry forest plant species to stress factors are key for informing and assuring more effective TDF restoration efforts.

Soil nitrogen dynamics in natural forest ecosystem: a review

“…Black pine (Pinus thunbergii) trees and a mixed stand with black locust trees had higher N-fixing ability when assessed in a study from 2000 to 2019 time period. Cárdenas et al (2022) reported that using an N-fixing legume and one non-legume tree species in a tropical dry forest results in similar performances across N-fixing and non-fixing legumes in the study area. Similarly oak and non-oak tree species also have different plant litter decomposition rates (Babl-Plauche et al, 2022).…”

Seedling responses to herbivory are driven by nutrient enrichment, grass competition and functional attributes

“…Further, leaf age, and leaf chemistry, in addition to plant size, can also in uence the feeding behaviour of herbivores and thereby damage from herbivores (Ahrestani et al 2011). For example, young leaves and seedlings are relatively more susceptible to damage by herbivores (Coley 1996; Muehleisen et al 2000), which further in uences growth, survival, and reproduction (Aide 1992, Cárdenas et al 2022, Gerhardt 1998). However, to circumvent the damage from herbivory, plants develop several inherent mechanisms such as synchronized leaf ushing and leaf production (Aide 1992, Brenes-Arguedas et al Crawley 1983Silva et al 2021.…”