Toward understanding the consequences of soil heterogeneity for plant populations and communities

Hutchings, Michael J, John, Elizabeth A and Wijesinghe, Dushyantha K (2003) Toward understanding the consequences of soil heterogeneity for plant populations and communities. Ecology, 84 (9). pp. 2322-2334. ISSN 0012-9658

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Abstract

Several recent studies demonstrate that yield of individual plants, and their allocation of biomass between roots and shoots, can be profoundly affected by the pattern of supply of soil-based resources. Patchy provision of soil-based resources can affect the location of root biomass, as roots often proliferate in nutrient-rich patches. Root system size is important in determining whether plants access nutrient-rich patches, and the proportion of root systems located within such patches. This proportion will alter as growth proceeds. Species with small root systems have a limited ability to place roots in nutrient-rich patches even when they are very close. Of four species with different root system sizes, the growth of the species with the smallest root system was significantly limited by being located in nutrient-poor substrate even when nutrient-rich substrate was only 3.5 cm away, whereas three species with larger root systems were not disadvantaged. Both in the laboratory and in the field, root density is higher in nutrient-rich patches, and such patches can contain roots of many plants. Recent work showing that plants can respond to non-self roots sharing the same nutrient supply suggests that competition will be more severe in nutritionally patchy substrates than in homogeneous environments with the same overall nutrient supply. Taken together, these facts lead to the prediction that inter- and intraspecific plant interactions will be influenced by patterns of nutrient supply. We present evidence supporting this prediction, and indicating that population and community structure are also affected by patterns of nutrient supply. Significant differences in population yield, plant size distribution, and mortality have been recorded between populations growing under patchy and uniform conditions. Plant communities grown from identical seed inocula, with the same overall nutrient supply, provided in different spatial and temporal patterns, differed by up to 44% in total biomass, up to 70% in root biomass, and differed in species composition. These significant effects of heterogeneous resource supply on plants merit further detailed study. We present a framework of predictions of the impacts of different types of spatial heterogeneity in nutrient supply on the performance of single plants, and on plant interactions, plant populations, and plant communities.

Item Type: Article
Additional Information: This paper was produced by Hutchings and John. The ability of plants to select more favourable sites for root placement is shown to alter as root system size increases. Distance from nutrient-rich patches strongly determines individual plant performance, and can reverse competitive outcomes, even between species of strikingly different sizes.
Schools and Departments: School of Life Sciences > Biology and Environmental Science
Depositing User: Michael Hutchings
Date Deposited: 06 Feb 2012 19:54
Last Modified: 21 Mar 2012 10:02
URI: http://sro.sussex.ac.uk/id/eprint/22908
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