The Effect of Quercus Douglasii Removal on Understory Yield and Composition

Abstract

The canopy of Quercus douglasii I-I. & A. (blue oak) has been variously reported to enhance or suppress understory production. The effects of canopy removal have been reported only for the northern portion of blue oak's range. We removed all blue oaks from 6 plots in the central coast of California and found no significant change in understory biomass over 3 years. Understory herb cover averaged 32.6% on cleared plots, compared to 24.3% on uncut plots, but composition changed little with the exception of an increase in Erodium cicufarium (L.) L'Her. Clearing did not produce the distinctive species composition and forage enhancement under Q. doughsiicanopy reported in other studies, all based on comparisons between unmanipulated canopy and adjacent grassland. Our results suggest that the canopy effect could instead be caused by differences in sites occupied by trees. Clearing of Q. doughiiin regions with 50 cm or less of mean annual precipitation is not recommended for increasing forage production.

Effects of soil surface disturbances after logging on plant functional types

“…Indeed, the analyses showed that perturbed areas (P) were associated more particularly with hemicryptophytes, anemochorous and ruderal species; remnant depot (R) areas with seeds dispersed by animals and competitive species; and not perturbed (N) areas with seeds dispersed by wind or animals and stress tolerant species. There was no life form which characterized in particular R or N. As in previous studies [4,20,26,28], we found that hemicryptophytes increased after logging and we specified here that they increased more particularly in perturbed places. These plant species were essentially dispersed by wind and required perturbed areas, without litter, to germinate.…”

Long-term evolution of understorey plant species composition after logging in chestnut coppice stands (Cevennes Mountains, southern France)

“…Indeed, the increase of plant species richness after logging was observed by many authors [2,10,20,30,44], as well as after other disturbances like fire and cultural abandonment. [12,37,39,45].…”

“…Therophytes and chamaephytes had very low species richness; consequently the data did not allow statistical comparisons. Two years after clear-cut, hemicryptophytes increased significantly (χ 2 (1) = 3.9; p < 0.05), while phanerophytes decreased significantly (χ 2 (1) = 10.6; p < 0.001). Between 1994 and 1998, it was the inverse, hemicryptophytes decreased (χ 2 (1) = 24.0; p < 0.001), while phanerophytes increased (χ 2 (1) = 18.23; p < 0.001).…”

“…Between 1994 and 1998, it was the inverse, hemicryptophytes decreased (χ 2 (1) = 24.0; p < 0.001), while phanerophytes increased (χ 2 (1) = 18.23; p < 0.001). After thinning (between 1998-1999), hemicryptophytes increased again (χ 2 (1) = 6.2; p < 0.05), while phanerophytes decreased (χ 2 (1) = 4.05; p < 0.05). From 1999, hemicryptophytes decreased (χ 2 (1) = 8.3; p < 0.01), and phanerophytes increased (χ 2 (1) = 5.7; p < 0.05).…”

Journal of Range Management, Volume 53, Number 2 (March 2000)

“…The ecology and management of California's annual grasslands, woodlands, and savannas have been well studied (Bartolome and Standiford 1992, Bartolome and McClaran 1992, Bartolome et al 1994, Heady et al 1992, Standiford et al 1997. However, few studies examine cold-water spring ecosystems of these rangelands, or the potential for grazing effects on them (Allen-Diaz et al 1998).…”