Changes in phenology and seeds functional traits along a successional gradient in secondary Andean Tropical Mountain Forest

Secondary forests are becoming dominant in tropical landscapes due to strong and widespread human-driven disturbance. Andean Tropical Mountain Forests (ATMF) have been intervened for centuries and, in country such as Colombia, fewer than 20 % of the original cover remain. Thus, there is an urgent need to quantify the biodiversity and dynamics of secondary and mature ATMF remnants. Successional dynamics in forests depend on some critical processes such as seed dispersion, seed persistence, and seedlings establishment. During the regeneration, mechanistically, the dominance of pioneer species at the beginning of succession is attributed to their capacity to acquire resources rapidly (acquisitive strategies); and the dominance of shade-tolerant species later in succession is due to their more conservative strategies that reduce susceptibility to stress. These processes can be understood by studying functional traits related to phenology (e.g., the production cycle of flower and fruit), seeds, and whole plant. For instance, it is known leaf functional traits are associated with the capacity of fast-growing species thrive in the rich light environment ofw early-successional stages (e.g., high specific leaf area-SLA and low leaf dry matter content-LDMC) and, the slow-growing species that dominate under the low light environment of late-successional stages (e.g., low SLA and higher LDMC). Moreover, seed mass may affect processes like dispersal and seedling establishment, while seed traits such as coat thickness and embryo-endosperm ratio can determine germination. However, the successional dynamics in ATMF are very poorly known, and my general objective is to understand how plant phenology, seed and plant functional traits, and soil seed banks change along a successional gradient in ATMF. Which will include the study of the relationship between seed, leaf, and stem functional traits, the analysis of changes in seed functional traits along the successional gradient, and comparison between species taxonomic and functional diversity in the soil seed bank, with adult, juvenile, and seedlings of woody plants. The study will be done in a network of permanent plots around the Bogota Sabana in four sites. To study phenological dynamics, I will record phenophase intensity, duration, and seasonality. Seeds will be collected in the field, in parallel with the phenology census. These seeds will be used in the germination experiments to measure ten (10) functional seed traits (seed dry mass, dispersal syndrome, embryo-endosperm ratio, seed coat thickness, seed permeability, seed respiration rate, seed nitrogen, phosphorus, and carbon content, and seed germination rates). Pre-existing measurements of eight (8) leaf and woody functional traits (specific leaf area (SLA cm2 g-1), leaf dry matter content (LDMC, mg g-1), leaf thickness (T, mm), maximum carbon fixation rate (Amax µmol CO m-2 s-1), maximum species height (Hmax, m), wood density, and leaf nitrogen (NL) and carbon (CL) content) will be related to see traits. Finally, I will quantify soil seed bank (SSB) dynamics by measuring seedling emergence and analyzing the change in the taxonomic and functional diversity of seedlings from the soil seed bank (SSB), juveniles, and adults in the successional gradient.

Rasgos funcionales
Dispersión
Persistencia
Germinación
Regeneración

Tesis de doctorado
2 artículos de investigación