Linkages of elements in soils and plants with mycorrhizae along Philippine and pantropical elevational gradients

Tropical mountains are biodiversity hotspots where a zonation of biota occurs with environmental conditions as one ascends. Patterns of vegetation types are well documented, as is the decline of plant-available nitrogen (N) relative to phosphorus (P) with elevation. However, how absolute and relative availabilities of essential elements beyond the well-studied N, P and carbon (C) vary in such mountains remains poorly understood, despite evidence that base cations and micronutrients do indeed affect tropical forests’ and other ecosystems’ functioning. Potentially important but overlooked factors that may confound elevational patterns of elemental availabilities are the type, dominance and abundance of mycorrhizal fungi, which in turn are also affected by biogeochemical cycling, directly or through shifts in vegetation. Here, I address these knowledge gaps by investigating patterns of C, N, P, potassium (K), calcium (Ca), magnesium (Mg) and micronutrients, and their association with mycorrhizae across three distinct Philippine tropical mountains. While fungal and particularly plant biodiversity in these areas are well documented, biogeochemical patterns remain largely unexplored. PHILANTROPIC-ELEMYCO will test the hypothesis that absolute and relative availabilities of these elements are associated with both elevation and mycorrhizae. Specifically, the project will (1) analyze concentrations and stoichiometry of species- and community-weighted leaf, litter and soil elements along elevational gradients, (2) assess the co-occurrence thereof with association type, abundance and diversity of mycorrhizae, and (3) conduct a systematic review comparing mycorrhiza-nutrient relationships among tropical regions. By uniquely integrating expertise and approaches from tropical forest ecology, biogeochemistry, botany, mycology and molecular biology, I aim to contribute to an improved understanding of plant-soil-mycorrhiza-stoichiometry patterns in tropical mountains.