Shin-oak (Quercus havardii, Rydb.; Fagaceae) rhizome shoot production: possibilities for use in restoration
Davis, W. Jarrad
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Shin-oak (Quercus havardii Rybd.) is a slow growing, deciduous shrub found in areas of sandy soil between southeastern New Mexico and southwestern Oklahoma. Shin-oak reproduces almost exclusively via underground rhizomes. It has the ability to reproduce sexually, though it is rare in nature with infrequent acorn production. Many animal species rely on shin-oak as a habitat component, especially where it is the dominant species on the sand dunes in southeastern New Mexico. Two species of particular concern are the sand dunes lizard and the lesser prairie chicken, both listed as vulnerable by the IUCN. In many areas, shin-oak is negatively influenced by oil and gas exploration and production. These energy development activities create many disturbances with varying durations, but the habitat fragmentation caused by the construction of roadways, pipelines, and well pads may be especially problematic, since shin-oak has been slow to recolonize such sites. However, the ability of shin-oak to reproduce via rhizomes may provide a resource for restoration. Little information is available on rhizome shoot production success rates or conditions that maximize those rates, but such information is needed if restoration of shin-oak habitat is to be successful. To better understand the mechanisms and timing of shin-oak rhizome shoot production, three studies were conducted: (1) natural recovery of shin-oak at four disturbed sites was monitored; (2) the timing and ability of rhizomes to sprout under controlled conditions; and (3) the ability of rhizomes to sprout in the field was studied. Little to no expansion of shin-oak or grass species in disturbed areas was recorded. Average shin-oak cover was 14.07% and shin-oak density averaged between 0.52 and 4.06 individuals per m2. When collected in the late fall or winter, shin-oak had little ability to produce shoots in a controlled environment, though when collected at other times rhizomes sprouted more readily. Winter collection sprouting success rates averaged 6% while collections other times of the year averaged 22% or 24%. Finally, shin-oak shoot production in field environments was similar to rates occurring under controlled conditions although differences between sites were detected. Results indicate that the current restoration techniques utilized in the habitat are insufficient. The use of shin-oak rhizomes as a propagation source to re-establish the species within disturbed areas is supported. The collection of rhizomes during winter periods should be avoided unless steps are taken to overcome winter induced dormancy.