The role of sub-surface fissures on the establishment of an invasive woody shrub (Prosopis glandulosa) in grasslands.
JURENA, P.N.* and S.ARCHER
Texas A&M University, College Station, TX 77843-2126 1
We tested the hypothesis that establishment of woody plants in grasslands underlain by indurated limestone would be facilitated by `fissures' which give tree/shrub tap roots preferential access to deep stores of water and nutrients. Survival and growth of Prosopis glandulosa seedlings was monitored along ten 5 m transects perpendicular to known fissures. Soil depth along the transects ranged from 0 to 20 cm and decreased with increasing distance from the fissure. Contrary to expectations, no seedlings emerged from seeds planted directly over the fissure. Survival of Prosopis seedlings emerging 5 m from the fissure was 2x greater than that of seedlings emerging 1 m from the fissure. Survival trajectories for all seedlings were similar and reached zero within seven months of the initial planting. Seedlings farthest from the fissure were taller (3.60.8 cm vs. 3.00.2 cm) and had a greater number of leaves (4.02.0 vs. 0 leave/seedling) than those nearest the fissure. Greater production of grasses on vs. away (42.07.0 g/m2 vs. <5.0 g/m2) from fissures appeared to negate advantages that fissures might otherwise provide for shrub seedling establishment. Supporting experiments have shown that the development of disturbance `gaps' in the graminoid root layer might be required for shrub seedlings to exploit favorable microsites.
Keywords: fissure, shrub seedling, _Prosopis glandulosa_
This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS