1. The spatial distribution of plants, which is often generated by patterns of seed recruitment, is an important determinant of population dynamics, especially for orchids with seeds that must be exposed to appropriate mycorrhizal fungi. 2. We compared the distribution and abundance of target mycorrhizal fungi detected in the soil using DNA-based molecular techniques and germination in seed packets of Goodyera pubescens, Liparis liliifolia, and Tipularia discolor. 3. We further examined Tulasnella spp. associated with G. pubescens to determine whether areas with abundant host fungi resulted from multiple genets of the same species or from a single widespread fungal genet. 4. We found that target fungi were more likely to be detected using soil DNA assays than by seed germination. Based on soil DNA, fungi were more widespread than suggested by seed germination, which most often reflected the presence of abundant mycorrhizal fungi in the soil. Fungi were more likely to be abundant close to established orchids. Established plants of G. pubescens that were <50cm apart associated with a single abundant fungal genet, while those >50 cm apart associated with multiple fungal genets. 5. Synthesis. This study demonstrates the importance of using multiple methods to detect the distribution and abundance of target fungi and suggests that fungal ‘hot spots’ may be keys to the dynamics of orchid populations.
All Arrays Seed Packets and fungi_for Dryad
All Arrays Seed Packets and fungi_for Dryad.txt
This datafile includes the numbers and sizes of protocorms recovered from seedpackets placed at varying distances from conspecific plants and the abundance of fungi associated with those seedpackets. Missing data are indicated by a “.”. Data were collected by Melissa McCormick, Robert Burnett, and Dennis Whigham. Questions should be directed to Melissa McCormick.
Column headings
Species: The orchid species of seeds added to the plot in seedpacket. Goodyera=Goodyera pubescens; Liparis=Liparis liliifolia; Tipularia=Tipularia discolor
Plot: Designates which of the arrays (e.g., BPLg) seed packets were recovered from. The array names also indicate whether the array was associated with a cluster of plants, in which case it ends in ‘Lg’, or an isolated plant, in which case the name ends in ‘i’. The plots were in forest stands that ranged from 70 to 150 years old at the Smithsonian Environmental Research Center, Edgewater, Maryland, USA.
Distance: Indicates the distance (in cm) from the seedpacket to the nearest conspecific plant.
Direction: Indicates which ‘arm’ of the array the seed packet was located on. ‘Arms’ were oriented based on cardinal directions and are noted as n=north, s=south, e=east, w=west.
Protocorms: Indicates the number of protocorms recovered from each seedpacket.
Size (mm): Indicates the size in mm of the largest protocorm found in each seedpacket. A ‘.’ indicates no protocorms were recovered from a seedpacket.
Fungus Abundance: Indicates the abundance of appropriate mycorrhizal fungi in the soil associated with each seedpacket. Abundance is noted as 0=absent or 1-5=present, with 5 indicating the greatest abundance and 1 the least. Abundance was measured semi-quantitatively from the sum of ARISA peak heights for two microsatellite primers (Goodyera) or the brightness of gel bands using taxon-specific primers (Liparis, Tipularia).
