Metcalfe, Daniel
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
Research article2013Peer reviewed
Fisher, Joshua B.; Malhi, Yadvinder; Torres, Israel Cuba; Metcalfe, Daniel; van de Weg, Martine J.; Meir, Patrick; Espejo, Javier E. Silva; Huasco, Walter Huaraca
We report results from a large-scale nutrient fertilization experiment along a "megadiverse" (154 unique species were included in the study) 3,000-m elevation transect in the Peruvian Andes and adjacent lowland Amazonia. Our objectives were to test if nitrogen (N) and phosphorus (P) limitation shift along this elevation gradient, and to determine how an alleviation of nutrient limitation would manifest in ecosystem changes. Tree height decreased with increasing elevation, but leaf area index (LAI) and diameter at breast height (DBH) did not vary with elevation. Leaf N:P decreased with increasing elevation (from 24 at 200 m to 11 at 3,000 m), suggesting increased N limitation and decreased P limitation with increasing elevation. After 4 years of fertilization (N, P, N + P), plots at the lowland site (200 m) fertilized with N + P showed greater relative growth rates in DBH than did the control plots; no significant differences were evident at the 1,000 m site, and plots fertilized with N at the highest elevation sites (1,500, 3,000 m) showed greater relative growth rates in DBH than did the control plots, again suggesting increased N constraint with elevation. Across elevations in general N fertilization led to an increase in microbial respiration, while P and N + P addition led to an increase in root respiration and corresponding decrease in hyphal respiration. There was no significant canopy response (LAI, leaf nutrients) to fertilization, suggesting that photosynthetic capacity was not N or P limited in these ecosystems. In sum, our study significantly advances ecological understanding of nutrient cycling and ecosystem response in a region where our collective knowledge and data are sparse: we demonstrate N limitation in high elevation tropical montane forests, N and P co-limitation in lowland Amazonia, and a nutrient limitation response manifested not in canopy changes, but rather in stem and belowground changes.
Fertilization; Forest; Montane; Nitrogen; Phosphorus; Tropical
Oecologia
2013, Volume: 172, number: 3, pages: 889-902
Publisher: SPRINGER
Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
Forest Science
DOI: https://doi.org/10.1007/s00442-012-2522-6
https://res.slu.se/id/publ/52614