PARENT SESSION
Oral Session # 8: Plant Ecology I: Physiology and Function I.
Presiding: E Hamerlynck
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 200.
Cost of leaf construction among native and invasive plant life forms within and across biomes.
Ostertag, Rebecca*,1, Vuong, Linh2, Cordell, Susan3, 1 University of Hawaii at Hilo, Hilo, HI2 University of Puget Sound, Tacoma, WA3 Institute of Pacific Islands Forestry, Hilo, HI
ABSTRACT- The cost of construction measures the amount of energy required to build new leaf tissues and has the potential to be an integrative variable linking leaf level traits, plant growth rates, and resource use efficiency. Using bomb calorimetry, we evaluated cost of construction across different ecosystems in Hawaii, comparing across life forms and between ecologically similar native and invasive species. Cost of leaf construction on an area basis (CCarea) was consistently lower for invasive species (101.3 kJ/m2 ± 11.6 SE) than for native ones (235.8 kJ/m2 ± 17.7 SE). CCarea was also lowest in herbaceous species (121.2 kJ/m2 ± 22.5 SE) , intermediate in shrubs (163.0 kJ/m2 ± 15.8 SE), and highest in trees (279.1 kJ/m2 ± 24.0 SE). Across ecosystems, the alpine shrubland had much higher CCarea regardless of life form and notably lacked any invasive species. Dry forest, lowland wet forest, and sub-alpine forest did not differ in their overall mean CCarea, but individual species that could be found in several ecosystems due to the wide ecological amplitude of Hawaiian flora did differ in CCarea, with highest costs in the alpine ecosystem. For all life forms, CCarea was highly correlated ( r > ± 0.6) with several leaf traits, including specific leaf area (SLA), N concentration, and C:N of plant tissues, with strongest patterns emerging for trees. Previous research has demonstrated that invasive species tend to exhibit traits such as high SLA, high N concentrations, and lower C:N, and we suggest that CCarea data may provide one explanation of the mechanism by which invasive species can outcompete native species for resources across a variety of climatic regimes.
Key words: resource use, invasive species, leaf level traits, Hawaii