Resource competition and fire-regulated nutrient demandin carnivorous plants of wet pine savannas

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Abstract

Question:

What are the mechanisms by which fire reduces competition for both a short-lived and a long-lived species in old-growth ground-cover plant communities of wet pine savannas (originally Pinus palustris, replaced by P. elliottii)?

Location:

Outer coastal plain of southeastern Mississippi, USA.

Methods:

I reviewed previous competition experiments and proposed a new hypothesis to explain the relationship between fire, competition, and species co-existence in wet longleaf pine savannas. The first study is about growth and seedling emergence responses of a short-lived carnivorous plant, Drosera capillaris, to reduction in below-ground competition and above- plus below-ground competition. The second study deals with growth and survival responses of a long-lived perennial carnivorous plant, Sarracenia alata, to neighbour removal and prey-exclusion to determine if a reduction in nutrient supply increased the intensity of competition in this nutrient-poor system.

Results:

Fire increased seedling emergence of the short-lived species by reducing above-ground competition through the destruction of above-ground parts of plants and the combustion of associated litter. Prey exclusion did not increase competitive effects of neighbours on the long-lived species. However, because the experiment was conducted in a year without fire, shade reduced nutrient demand, which may have obviated competition for soil nutrients between Sarracenia alata and its neighbours.

Conclusion:

Repeated fires likely interact with interspecific differences in nutrient uptake to simultaneously reduce both above-ground competition and competition for nutrients in old-growth ground cover communities in pine savannas. Restoration practitioners should consider the possibility that the composition of the plant community is just as important as fire in ensuring that frequent fires maintain species diversity.

Nomenclature:

Clewell (1985) and Schnell (1976).

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