PARENT SESSION
Poster Session #37: Plant Ecology: Populations.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Distribution, demography and mycorrhizal interactions of a terrestrial orchid across environmental gradients.

Diez, Jeff^*,1, Pulliam, H. Ronald¹, ¹ Institute of Ecology, Athens, GA

ABSTRACT- The geographic ranges of many species are characterized by strong gradients in abiotic conditions and species distributions over multiple spatial and temporal scales. We are attempting to understand how understory plant species respond to climatic and land use gradients by studying the distributions and demography of six understory forb species exhibiting a range of life history characteristics (Tipularia discolor, Goodyerea pubescens, Polygonatum biflorum, Smilacina racemosa, Hepatica americana, and Hexastylis arifolia ). I focus here on the abiotic and biotic interactions of a terrestrial orchid, Goodyera pubescens. Long-term study plots have been established along a gradient from the southeastern Piedmont to the southern Appalachian mountains, encompassing a wide range of environmental conditions, of which temperature, soil moisture, light levels, and soil nutrients are monitored at each study plot. The terrestrial orchids are unique among the forbs in their obligate dependence upon particular groups of fungi in order to germinate and reach photosynthetic stage. However, very little is known about the distribution of the fungi, which for Goodyera belong to the basidiomycete genus Tulasnella. Through coupled field surveys, demographic and environmental monitoring, and seed introductions we are investigating possible constraints on orchid recruitment, and exploring how plant and fungal distributions interact with environmental conditions. I will discuss preliminary findings on the spatiotemporal scales of variation in distributions and demographic patterns.

KEY WORDS: demography, distributions, mycorrhizae, orchid