Is the relation between nutrient supply and biodiversity co‐determined by the type of nutrient limitation?

Abstract

Correlative studies have shown a ‘hump‐backed’ relation between the vegetation N:P ratio and plant species diversity with the highest diversity at balanced N:P ratios (between 10 and 14). We tested the hypothesis that adding growth‐limiting nutrients to mesotrophic grasslands that were in shortage of either N (N:P ratio<10) or P (N:P ratio>14) would lead to an increase of plant diversity. Thereto, we studied the effects of long‐term (11 yr) experimentally increased N and/or P supply on soil nutrient pools, vegetation nutrient dynamics and biodiversity in a riverine grassland in the Netherlands with a low soil N:P ratio (N shortage) and a peat grassland with a high soil N:P ratio (P shortage), respectively. Eleven years of nutrient addition hardly had any effects on the total stocks of C, N and P in the soils of both sites, due to the large size of the soil nutrient pools already present and to the management at both sites (annual hay‐making and ‐removal). However, in the riverine grassland the treatments increased the cycling of the small pool of labile N and P compounds resulting in large increases in annual fluxes of especially N. In the unfertilised controls, species establishments balanced more or less species losses during an 11 year period, thus leading to a dynamic equilibrium of the species pool. However, contrary to our hypothesis, addition of the growth‐limiting nutrient led at both sites to a reduction of species diversity even when total biomass remained below critical levels. Species diversity and species evenness were strongly determined by N mineralisation and to a lesser extent by total soil N and extractable P, respectively. Total aboveground biomass of the vegetation was determined by total soil N. Our study shows that patterns found in correlative studies of the relation between plant diversity and soil and vegetation N:P ratio can not be translated into successful experimental manipulations to enhance biodiversity. The most likely explanation is that colonization limitation occurred in the fertilized plots and that not sufficient diaspores of potentially new species could reach and/or colonize the plots to compensate for the species extinctions as a result of increased nutrient supply.

N–P stoichiometry in soil and leaves of Pinus massoniana forest at different stand ages in the subtropical soil erosion area of China

“…In most terrestrial ecosystems, N-P availability can limit plant growth and affect plant traits, community composition, and biodiversity (Aerts et al 2003;Güsewell et al 2005). Thus, the plant N:P ratio is one of the most simple and effective indicators for assessing limiting elements in plant growth (Koerselman and Meuleman 1996;Güsewell 2004).…”

“…Large quantities of C were synthesized through photosynthesis, and N and P were consumed during plant growth, and the concentrations of these elements in habitats directly affect plant growth, thereby limiting ecosystem productivity (Vitousek and Howarth 1991;Elser et al 2010). Many studies showed that the concentrations of available N and P significantly influence plant growth (Aerts et al 2003). High P leaching may lead to limitation of P for plant growth in areas with high rainfall and intense soil erosion, while N might restrict plant growth in those areas with low rainfall, weak soil erosion and thus relatively low P leaching (Aerts et al 2003;Reich and Oleksyn 2004).…”

“…The elements carbon (C), nitrogen (N), and phosphorus (P) are the fundamental chemical elements of an organism. The stoichiometry of an organism is closely related to the important ecological processes such as ecosystem species composition and diversity, adaptation of organisms to environmental stress, and interspecific relationships (Venterink et al 2003;Woods et al 2003;Aerts et al 2003;Güsewell et al 2005).…”

“…Many studies showed that the concentrations of available N and P significantly influence plant growth (Aerts et al 2003). High P leaching may lead to limitation of P for plant growth in areas with high rainfall and intense soil erosion, while N might restrict plant growth in those areas with low rainfall, weak soil erosion and thus relatively low P leaching (Aerts et al 2003;Reich and Oleksyn 2004). In recent years, atmospheric N deposition results in an imbalance of the N:P ratio and an impact on the stoichiometry of ecosystems (Galloway et al 2003;Feller et al 2007;Elser et al 2009).…”

The Relation Between Unpalatable Species, Nutrients and Plant Species Richness in Swiss Montane Pastures

“…In a study of 74 grassland plots, Braakhekke and Hooftman (1999) found the highest species richness at vegetation N:P ratios of 10-14, with lower species richness at both higher and lower values. This may be explained by the absence of species adapted to N limitation (indicated by lower N:P ratios; Aerts et al 1992;Shaver and Chapin 1995;Koerselman and Meuleman 1996) or P limitation (higher N:P ratios) in habitats where one of these nutrients is limiting (Braakhekke and Hooftman 1999;Aerts et al 2003). In habitats where resources are balanced, both types of species may be able to persist.…”