Variable effects of nutrient enrichment on soil respiration in mangrove forests
Background and Aims
Mangrove forests are globally important sites of carbon burial that are increasingly exposed to nutrient pollution. Here we assessed the response of soil respiration, an important component of forest carbon budgets, to nutrient enrichment over a wide range of mangrove forests.
We assessed the response of soil respiration to nutrient enrichment using fertilization experiments within 22 mangrove forests over ten sites. We used boosted regression tree (BRT) models to determine the importance of environmental and plant factors for soil respiration and its responsiveness to fertilizer treatments.
Leaf area index explained the largest proportion of variation in soil respiration rates (LAI, 45.9 %) followed by those of site, which had a relative influence of 39.9 % in the BRT model. Nutrient enrichment enhanced soil respiration only in nine out of 22 forests. Soil respiration in scrub forests showed a positive response to nutrient addition more frequently than taller fringing forests. The response of soil respiration to nutrient enrichment varied with changes in specific leaf area (SLA) and stem extension, with relative influences of 14.4 %, 13.6 % in the BRT model respectively.
Soil respiration in mangroves varied with LAI, but other site specific factors also influenced soil respiration and its response to nutrient enrichment. Strong enhancements in aboveground growth but moderate increases in soil respiration with nutrient enrichment indicated that nutrient enrichment of mangrove forests has likely increased net ecosystem production.
KeywordsSoil CO2 efflux Nitrogen Phosphorus Avicennia Rhizophora Growth Salinity Carbon cycling
- Alongi DM (2009) The energetics of mangrove ecosystems. Springer, DortrechtGoogle Scholar
- Bouillon S, Borges AV, Castaneda-Moya E, Diele K, Dittmar T (2008) Mangrove production and carbon sinks: a revision of global budget estimates. Glob Biogeochem Cycl 22: doi:10.1029/2007GB003052
- Breithaupt JL, Smoak JM, Smith III TJ, Sanders CJ, Hoare A (2012) Organic carbon burial rates in mangrove sediments: Strengthening the global budget, Glob Biogeochem Cycl 501: doi 10.1029/2012GB004375
- Brouwer R (1962) Distribution of dry matter in the plant. Nether J Agric Sci: 399–408Google Scholar
- Krauss KW, McKee KL, Lovelock CE, Cahoon DR, Saintilan N, Reef R, Chen L (2013) How mangrove forests adjust to rising sea level. Tansley Review. New PhytolGoogle Scholar
- Magnani M, Mencuccini M, Borghetti M, Berbigier P, Berninger F, Delzon S, Grelle A, Hari P, Jarvis PG, Kolari P, Kowalski AS, Lankreijer H, Law BE, Lindroth A, Loustau D, Manca G, Moncrieff JB, Rayment M, Tedeschi V, Valentin R, Grace J (2007) The human footprint in the carbon cycle of temperate and boreal forests. Nature 447:849–851CrossRefGoogle Scholar
- Maher DT, Santos IR, Golsby-Smith L, Gleeson J, Eyre BD (2013) Groundwater-derived dissolved inorganic and organic carbon exports from a mangrove tidal creek: The missing mangrove carbon sink? Limnol Oceanogr 58:475–488Google Scholar
- McKee KL, Feller IC, Popp M, Wanek W (2002) Mangrove isotopic fractionation (δ15N and δ13C) across a nitrogen versus phosphorus limitation gradient. Ecology 83:1065–1075Google Scholar
- Morrisey DA, Swales A, Dittmann S, Morrison MA, Lovelock CE, Beard CM (2010) The ecology and management of temperate mangroves. Oceanogr Mar Biol Ann Rev 48:43–160Google Scholar
- Nui S, Wu M, Han Y, Xia J, Zhang Z, Yang J, Wan S (2009) Nitrogen effects on net ecosystem carbon exchange in a temperate steppe. Glob Change Biol 16:144–155Google Scholar
- Raich JW, Nadelhoffer KJ (1989) Belowground carbon allocation in forest ecosystems. Glob Trend Ecol 70:1346–1354Google Scholar
- Ridgeway G (2006) Generalized boosted regression models. Documentation on the R package “gbm”, version 1.5-7. http://www.i-pensieri.com/gregr/gbm.shtml.
- Wright IJ, Reich PB, Westoby M, Ackerly DD, Baruch Z, Bongers F, Cavender-Bares J, Chapin FS, Cornelissen JHC, Diemer M, Flexas J, Garnier E, Groom PK, Gulias J, Hikosaka K, Lamont BB, Lee T, Lee W, Lusk C, Midgley JJ, Navas M-L, Niinemets Ü, Oleksyn J, Osada N, Poorter H, Poot P, Prior L, Pyankov VI, Roumet C, Thomas SC, Tjoelker MG, Veneklaas EJ, Villar R (2004) The world-wide leaf economics spectrum. Nature 428:821–827PubMedCrossRefGoogle Scholar