Chau, Marian , Walker, Lawrence , Mehltreter, Klaus .
The invasive Australian tree fern alters soil and plant nutrient dynamics in Hawaii.
Tree ferns that have higher leaf N and P content than co-occurring plant species have strong potential to influence nutrient cycling. The native Cibotium glaucum tree fern, a keystone species in Hawaiian forests, is displaced by Sphaeropteris cooperi, the non-native Australian tree fern. Sphaeropteris cooperi invades intact forests, producing more leaves that grow faster, contain more N and P, and decompose faster than C. glaucum leaves. Our experiment tested the effects of native and non-native tree fern leaf litter addition on the growth and nutrient content of four native angiosperm species in forest (high-fertility) and landslide (low-fertility) soils. Leaf litter of both types inhibited growth initially in all species, but subsequent responses were species-specific. Relative growth rates were higher in the faster-growing Carex wahuensis and Hibiscus arnottianus with S. cooperi litter, especially in landslide soil. Leaf N in C. wahuensis was highest with forest soil and S. cooperi litter, as expected, but other leaf nutrient responses showed some evidence of nutrient immobilization from litter addition. Several growth measures were highest with forest soil and S. cooperi litter, indicating that N availability is the strongest driver of growth. Our results show that S. cooperi can alter nutrient cycling in Hawaiian plants, sometimes with positive effects, but in forest environments it eventually out-competes other species by the same means with which it initially facilitates them. Because S. cooperi is such a pervasive threat to Cibotium and native forests, our results support continued efforts to eradicate this invasive tree fern.
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1 - University of Hawaii at Manoa, Department of Botany, 3190 Maile Way, Room 101, Honolulu, HI, 96822, USA
2 - University of Nevada Las Vegas, School of Life Sciences, 4505 Maryland Parkway, Las Vegas, NV, 89154, USA
3 - Instituto de Ecología, A.C., Red de Ecología Funcional, Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, México
Presentation Type: Oral Paper:Papers for Sections
Location: Waterman Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 9:30 AM