Rising Mean Annual Temperature Alters Nutrient Cycling and Availability in Hawaiian Tropical Montane Wet Forest
Abstract
Rising temperatures are predicted to influence nutrient cycling and availability in terrestrial ecosystems. Changes in nutrient availability, in turn, have important implications for terrestrial ecosystem C cycling and storage. However, the magnitude and direction of temperature-induced changes in nutrient availability remain poorly constrained, particularly in tropical forests which play a disproportionately large role in global C cycling. Prior cross-site syntheses indicate that nitrogen availability increases with experimental warming in terrestrial ecosystems. However, whole ecosystem warming experiments are rare, most environmental gradients are confounded by changes other than temperature, few studies have been conducted in the tropics, and the effect of warming on other essential nutrients is largely unknown. The return of nutrients to soil via aboveground litterfall is a sensitive, integrated index of stand-level biogeochemical process rates. As such, we examined litterfall, live foliar nutrient concentration, foliar nutrient resorption efficiency (NRE), nutrient return via litterfall, foliar nutrient use efficiency (NUE), and ecological stoichiometry of live foliage and litterfall to assess how increasing mean annual temperature (MAT) impacts nutrient cycling and availability in tropical montane wet forests along a 5.2°C MAT gradient on the Island of Hawaii. Live foliar N and K increased with MAT, while C and Mn decreased. Foliar NRE did not vary with MAT for any nutrient. Because litterfall increased with MAT, nutrient return via litterfall increased with MAT for N, K, Mg, and Zn, but decreased for Cu. Foliar NUE decreased with MAT for K, and increased for Mn and Cu. Live foliar C:N decreased with MAT, while N:P of live foliage and litterfall increased with MAT. These findings indicate that the availability of N and some other essential nutrients will increase with MAT in tropical montane wet forests, while ecological stoichiometry suggests that P will increasingly limit forest productivity with rising MAT.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B44D..06L
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY