I am interested in the origin and maintenance of biodiversity in ecological communities. I seek to understand the ecological constraints that create patterns of relative abundance and species richness in ecosystems. As stated by G.E. Hutchinson in 1959, “why are there so many kinds of animals?” Further, why are some species rare and others common? How does this diversity relate to the functions and processes of ecosystems? It is shocking that, as habitat loss accelerates globally and species are permanently exterminated, we still cannot estimate the number of species on earth within orders of magnitude. We may not understand the role or function of all this staggering diversity before it is gone forever.

My dissertation research applies large-scale surveys, combined with manipulative field experiments at a single site, to the understanding of both pattern and process in ecosystems in the Hawaiian Islands. I examine the food chain dynamics of avian insectivores, arthropod predators and herbivores, and their hostplant, the Hawaiian tree `ohi`a lehua (Myrtaceae: Metrosideros polymorpha). In October 1997, I surveyed arthropod abundance and diversity at sites along a highly constrained gradient of volcanic substrate age from Hawai`i to Kauai (300 years--4.1 million years old). This long chronosequence allows me to disentangle structural patterns created by local ecosystem fluxes from the accumulation of species expected over time by biogeographical or historical hypotheses. I followed this with a 3-year field experiment manipulating resources (by fertilization) and bird predators (by caging) on large (400 m2), well-replicated plots. From these manipulations I created a detailed mechanistic picture of how resources and predators influence the relative abundance, biomass and species diversity of insect and spider communities.

In separate applied projects, I have looked at impacts and control of introduced social insects, such as vespid wasps and ants. No social insects (e.g. ants, wasps, termites) are native to the Hawaiian Islands. Thus, one would expect them to have large impacts on the native flora and fauna. I have worked extensively with K-12 students and teachers to document the spread of these exotics in the islands, and to experiment with management solutions. Please visit www.hawaii.edu/ant for more information.

I have worked extensively throughout the Hawaiian Islands, with shorter stints in upstate New York, Costa Rica, Fiji, and Palmyra Atoll. I am interested in expanding my current work to other areas of the Pacific.

Representative Publications
Gruner, D.S. Biotic resistance conferred by an insectivorous bird assemblage on Hawai`i Island (Ecology Letters, in prep.).

Gruner, D.S. and A.D. Taylor. Interacting influences of birds and resources on arthropod trophic structure on Hawai`i Island (Ecology, in prep.).

Gruner D.S., R.A. Heu, and M. Chun. 2003. Two ant species (Hymenoptera: Formicidae) new to the Hawaiian Islands. Bishop Museum Occasional Papers 74:35-40.

Gruner, D. S. 2003. Regressions of length and width to predict arthropod biomass in the Hawaiian Islands. Pacific Science 57(3):325-336.

Gruner, D. S., and D. A. Polhemus. 2003. Arthropod communities across a long chronosequence in the Hawaiian Islands. Pages 135-145 in Y. Basset, V. Novotný, S. E. Miller, and R. L. Kitching, eds. Arthropods of Tropical Forests: Spatio-Temporal Dynamics and Resource Use in the Canopy. Cambridge University Press, London.

D.S. Gruner and D. Foote. 2002. Management Strategies for Western Yellowjackets in Hawaii. Report to the Packard Foundation (via the Secretariat for Conservation Biology).

Wetterer, J.K., D.S. Gruner, and J E Lopez. 1998. Foraging and nesting ecology of the leaf-cutting ant, Acromyrmex octospinosus, in a Costa Rican tropical dry forest. Florida Entomologist 81(1):61-67.


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