Nutrient addition effects on tropical dry forests: a mini-review from microbial to ecosystem scales

Abstract

Humans have more than doubled inputs of reactive nitrogen globally and greatly accelerated the biogeochemical cycles of phosphorus and metals. However, the impacts of increased element mobility on tropical ecosystems remain poorly quantified, particularly for the vast tropical dry forest biome. Tropical dry forests are characterized by marked seasonality, relatively little precipitation, and high heterogeneity in plant functional diversity and soil chemistry. For these reasons, increased nutrient deposition may affect tropical dry forests differently than wet tropical or temperate forests. Here, we review studies that investigated how nutrient availability affects ecosystem and community processes from the microsite to ecosystem scales in tropical dry forests. The effects of N and P addition on ecosystem carbon cycling and plant and microbial dynamics depend on forest successional stage, soil parent material, and rainfall regime. Responses may depend on whether overall productivity is N-vs. P-limited, although data to test this hypothesis are limited. These results highlight the many important gaps in our understanding of tropical dry forest responses to global change. Large-scale experiments are required to resolve these uncertainties.

An individual‐based forest model to jointly simulate carbon and tree diversity in Amazonia: description and applications

“…), nutrient addition experiments (Powers et al. ), and other in situ experimental approaches (Fayle et al. ), all provide opportunities of data‐model interactions and hypothesis testing on poorly known processes (Medlyn et al.…”

“…, Powers et al. ; Appendix : Fig. S1) given the on‐going alteration of nutrient availability by humans (Peñuelas et al.…”

Nutrient-Induced Modifications of Wood Anatomical Traits of Alchornea lojaensis (Euphorbiaceae)

“…Since the beginning of the industrial age, both P and N cycles have skipped out of balance due to human activities and the use of fertilizer and fossil fuel (Smil, 2000;Wright, 2005;Galloway et al, 2008). Galloway et al (2003) described the potential effect chains of increasing reactive N within the biogeochemical cycle, stressing that especially forests have a high potential to accumulate and transform reactive N. In particular, tropical forests will sensitively react to expected higher N and P inputs, but the full extent of their responses is discussed controversially (e.g., Tanner et al, 1990;Homeier et al, 2012;Fisher et al, 2013;Powers et al, 2015). Goldstein et al's.…”

Amazon Forest Ecosystem Responses to Elevated Atmospheric CO2 and Alterations in Nutrient Availability: Filling the Gaps with Model-Experiment Integration

“…Nutrient limitations might restrain plant productivity, and reduce the proposed C sink strength of Amazonian forests, as has been shown for other tropical forests (Kaspari et al, 2008;Wright et al, 2011;Lambers et al, 2015;Powers et al, 2015). To date, three stand-scale nutrient addition experiments conducted in high diversity lowland tropical forests, indicate colimitations of several nutrients regulating key plant physiological and ecosystem processes (Mirmanto et al, 1999;Kaspari et al, 2008;Wright et al, 2011;Pasquini and Santiago, 2012;AlvarezClare et al, 2013).…”

“…Ecosystem C-N models integrating above-and belowground interactions, and including constraints of plant stoichiometry strongly improved the representation of eCO 2 responses of two temperate FACE experiments . There is growing recognition that P-dynamics and N:P interactions, particularly for the tropics, are poorly represented in ecosystem models (Wang et al, 2010;Yang et al, 2011;Goll et al, 2012;Powers et al, 2015;Reed et al, 2015) For example, when N and P availability are included in global ecosystem models NPP is reduced by up to 25%, potentially compensating eCO 2 effects and turning the terrestrial biosphere into a net C source by 2100 (Wieder et al, 2015).…”