Effects of Nutrient Enrichment on within-Stand Cycling in a Mangrove Forest

Abstract

Within-stand nutrient cycling is dependent on many factors, including primary productivity, nutrient-use efficiency, nutrient resorption, sclerophylly, decomposition, nutritional quality of plant tissue, and allocation to defense. The efficiency of these plantmediated processes depends on nutrient availability in the environment and inherent functional properties of plants. However, little is known about how nutrient availability will affect these processes in forested wetlands in the tropics. In a factorial experiment we fertilized 48 dwarfed Rhizophora mangle (red mangrove) trees along tidal-elevation and water-depth gradients at Twin Cays, a range of intertidal, peat-based offshore mangrove islands in Belize, Central America. Initial results indicated that phosphorus (P) deficiency is a major factor limiting primary productivity. Phosphorus-fertilized trees had a significant decrease in P-use efficiency and P-resorption efficiency, but a significant increase in nitrogen (N)-use efficiency and N-resorption efficiency in their leaves compared with controls and N-fertilized trees. Sclerophylly decreased dramatically in P-fertilized trees, while the nutritional quality of the plant tissue increased. Phosphorus fertilization did not affect P leaching from green leaves. We found no fertilizer effect on the decomposition rates of leaf tissue, possibly due to higher phenolic concentrations in the P-fertilized trees compared with controls and N-fertilized trees. However, belowground decomposition of cotton strips increased in the substrate associated with P-fertilized trees. Environmental conditions related to position along a tidal gradient may be as important as nutrients in controlling belowground decomposition.

Phenolic content and growth of wetland macrophytes: Is the allocation to secondary compounds driven by nutrient availability?

“…These findings agree with the protein competition model (PCM) hypothesis predicting an increase in phenolic synthesis when protein synthesis (and consequently growth) is low due to limited resource availability. Contrasting results were reported by Feller et al (1999), who found increased levels of phenolics in mangrove leaves in response to P enrichment. Similarly, treatments that strongly enhanced growth (N, P addition) did not reduce the concentration of phenolics in Populus balsamifera in Alaska (Reichardt et al 1991).…”

N availability and mechanisms of N conservation in deciduous and semideciduous tropical forest legume trees

“…6) resulted in lower NUE values, confirming previous reports (Vitousek 1982;Knops et al 1997;Cordell et al 2001;Distel et al 2003). According to Feller et al (1999) and Hiremath et al (2002) the NUE value is inversely proportional to soil nutrient availability. They concluded that this parameter helps to explain the species distribution in natural communities, since the species with a greater efficiency in using minerals are more adapted to colonize less fertile environments.…”

“…The decrease in NRE given a greater availability of N is further evidence of the existence of a negative feedback mechanism between resorption efficiency and soil fertility (Berendse 1994;Jones et al 1994;Aerts 1995;Feller et al 1999;Enoki & Kawaguchi 1999;Anderson & Eickmeier 2000). Moreover, NRE is reportedly lower in species with SNF than in species that do not fix N 2 (Côte & Dawson 1986;Côte et al 1989;Killingbeck 1993).…”

Examining the Influence of Seasonality, Condition, and Species Composition on Mangrove Leaf Pigment Contents and Laboratory Based Spectroscopy Data

“…These forests provide a variety of environmental functions such as a nursery habitat for both terrestrial and marine fauna; they act as a natural barrier against tropical storms and hurricanes; and are an important resource for local communities [3]. Mangrove forests are also extremely important contributors to global organic carbon dynamics [4][5][6], to primary productivity [7,8], for nutrient recycling [5,9], and can help to mitigate climate change impacts [10]. Despite their ecological relevance, mangrove forests are under considerable degradation due to anthropogenic perturbations including aquaculture expansion [11,12].…”