Geographic, environmental and biotic sources of variation in the nutrient relations of tropical montane forests

Abstract

Tropical montane forests (TMF) are associated with a widely observed suite of characteristics encompassing forest structure, plant traits and biogeochemistry. With respect to nutrient relations, montane forests are characterized by slow decomposition of organic matter, high investment in below-ground biomass and poor litter quality, relative to tropical lowland forests. However, within TMF there is considerable variation in substrate age, parent material, disturbance and species composition. Here we emphasize that many TMFs are likely to be co-limited by multiple nutrients, and that feedback among soil properties, species traits, microbial communities and environmental conditions drive forest productivity and soil carbon storage. To date, studies of the biogeochemistry of montane forests have been restricted to a few, mostly neotropical, sites and focused mainly on trees while ignoring mycorrhizas, epiphytes and microbial community structure. Incorporating the geographic, environmental and biotic variability in TMF will lead to a greater recognition of plant-soil feedbacks that are critical to understanding constraints on productivity, both under present conditions and under future climate, nitrogen-deposition and land-use scenarios.

Relationship between soil properties and leaf functional traits in early secondary succession of tropical montane cloud forest

“…It was observed that potential net rate of N mineralization increased as a function of years since abandonment (Figure d). This result is difficult to explain since it is opposite to what has been reported for other TMCFs (Dalling et al, ). It may be possible that the older plots which had greater tree density, captured a greater concentration of deposited N from sky, which potentially can infiltrate into soil with enough concentration to increase N mineralization processes.…”

“…Accumulation of organic material may increase gradually in older plots (Negrete‐Yankelevich et al, ), because there is a greater input of leaf litter due to a higher density of individuals per unit area through succession (Table ). Decreases in soil N relative to soil C over time may be a consequence of poor litter quality which is characteristic of these ecosystems (Dalling, Heineman, González, & Ostertag, ). Our results show that PNRCM did not change with time, which implies that the soil heterotrophous microbial community did not increase its C transformation capacity with time in the ESS.…”

Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years

“…A subsequent analysis by Geml et al [57] from the same mountain showed that the peak in species richness of ectomycorrhizal fungi at lower-middle elevation was primarily tied to narrow environmental niches and not the result of broad-range species overlapping in the middle of the gradient (known as the mid-domain effect). Sensitivities of tropical montane organisms to changes in environmental factors is important in the context of climate change [18,19,51,58], but not all changes in biota are direct responses to environment [51]. For example, restriction to neotropical cloud forests of certain Ascomycete species in the genus Xylaria was related to their specificity to endemic cloud forest plants rather than to the environment per se [51].…”

Vapor pressure deficit predicts epiphyte abundance across an elevational gradient in a tropical montane region

“…Because of the difficulty of terrain and remoteness, TMCFs have been understudied relative to their lowland counterparts (Bruijnzeel et al, 2011b). In the last 20 yr however, there has been an increase in research in TMCF's, with recent syntheses (Oliveira et al, 2014; Dalling et al, 2015; Fahey et al, 2016; Crausbay and Martin, 2016; Gotsch et al, 2016a, b; Hu and Riveros‐Iregui, 2016). However, it is still difficult to compare results across sites because of differences in nomenclature, sampling protocols, and analyses in different TMCF regions (Hamilton et al, 1995; Ashton, 2003; Bach, 2004; Bubb et al, 2004; Martin et al, 2007; Mulligan, 2011; Bruijnzeel et al, 2011b).…”