Sparse Ground Cover Research Articles

Use of hexazinone for understory restoration of a successionally-advanced xeric sandhill in Florida

The response of vegetation of a central Florida, USA, xeric sandhill site was tested for 0.42, 0.84, and 1.68 kg/ha active ingredient spot-grid applications of the herbicide hexazinone in a randomized complete block design (three replications of each treatment and an untreated control). The site had been excluded from fire for approximately 40 years, and the characteristically open longleaf pine ( Pinus palustris) savannah had developed a thick midstory of evergreen scrub oak species. Shading and litter accumulation had resulted in a sparse ground cover with only a weak component of the once ubiquitous wiregrass ( Aristida stricta). Our primary goal was to determine hexazinone rates suitable for releasing understory herbaceous vegetation (especially wiregrass) from midstory oak suppression. At 1 year post-treatment, proportion mortality of midstory oaks increased with increasing hexazinone rate ( P < 0.05) and decreased with increasing oak diameter. Oaks with diameters > 14 cm experienced no mortality. Proportional change in understory cover by oaks also decreased with increasing hexazinone rate, while wiregrass cover increased with increasing hexazinone rate. Wiregrass biomass responded to treatment rate in a nonlinear fashion, possibly due to differences in top-kill. Treatment responses for woody non-oak species, and forbs could not be detected.

Effects of logging and fire on small mammals in Mumbulla State Forest, near Bega, New South Wales

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery.

Development of a Distance Method for Deer Census from Pellet Groups

Estimates of deer pellet groups on 0.0001-, 0.0005-, 0.001-, and 0.01-acre plots declined from about 5,000/acre on the smallest plots to 1,000/acre on the largest plots. The relationship conforms to a log polynomial curve which is closely approximated by the hyperbola d = a' s-' (d = density, s = plot area, a and b = regression constants specific to an area). This pattern typically arises from counts in bounded plots because a pellet or other small part of a group is more likely to occur alone and be recorded as a group on small plots, whereas, when large plots are used, it is more likely that groups will be correctly defined or that clusters of groups will be described as a single group. The effect is most pronounced where rain, sparse ground cover, or steep slopes cause groups of pellets to become widely scattered. A distance method has been developed and tested for estimating pellet group density, and its application to census of a small population of red deer (Cervus elaphus) is discussed. The census model used requires estimates of pellet group density, disappearance (decay) rate, and defecation rate.

Ecological Distributin of Mice in the Medicine Bow Mountains of Wyoming

The distribution of six species of native mice with regard to plant communities, vegetative ground cover, and proximity of water was studied in the Medicine Bow Range of Southern Wyoming. The eight types of plant communities sampled were: mountain mahogany, sagebrush, aspen, subalpine meadow, willow—alder bog, lodgepole pine, spruce—fir, and alpine tundra. The western jumping mounse (Zapus princeps) and long—tailed vole (Microtus longicaudus) both reached their greatest densities in three habitats: Willow—alder, aspen forest, and subalpine meadows. Both species preferred sites adjacent to water and having dense ground cover. The montane vole (Microtus montanus) was most abundant in meadow situations as exemplified by alpine tundra and subalpine forb—sedge meadows. This species preferred moderate to dry situations and dense to intermediate ground cover. The redbacked vole (Clethrionomys gapperi) was by far the most abundant species taken in lodgepole pine and spruce—fir communities. This species occurred commonly at a distance from water and was equally abundant in areas of dense, intermediate, or sparse vegetative ground cover. The heather vole (Phenacomys intermedius) was not trapped in great numbers at any locale but was most frequently taken in subalpine meadows, spruce—fir forest, and alpine tundra, indicating the species is primarily a high altitude form. Heather voles exhibited no preferences with regard to proximity of water or density of ground cover. The deer mouse (Peromyscus maniculatus) was the most widely distributed species studied, but displayed particularly high densities in mountain mahogany and sagebrush communities. The habitats yielding the highest overall mouse production were those located at lower elevations in the mountains, i.e. the sagebrush, mountain mahogany, aspen, and subalpine meadows; while those habitats yielding the lowest number of mice were at highest elevations, i.e. lodgepole pine, spruce—fir, and alpine tundra. The proximity of water seemed to have no clearcut effect on the overall production of mice, although areas of dense cover were on the average twice as productive as those with sparse cover.

The Root System of Longleaf Pine on the Deep Sands of Western Florida

The most extensive timber type on the Choctawhatchee National Forest, 30 miles east of Pensacola, Florida, is longleaf pine, Pinus palustris. The stands consist of a sparse growth of 8 to IO mature and overmature longleaf pines to the acre with an understory of turkey oak, Quercus catesbaei, and bluejack oak, Q. cinerce. Understocking of pine, while resulting in part from past logging practice and frequent fires, may also be attributed to natural causes, among which insect attacks, drought, and poor site have played no small role. In addition to causing the gradual depletion of the veteran trees, these adverse conditions have made natural replacement inadequate, so that the present forest is on the decline (fig. i). As the Choctawhatchee region is typical of approximately five million acres in the state of Florida, and as timber growing appears to be one of the most logical means of utilizing this large acreage of sandy land, the importance of a study of reforesting these lands with desirable tree growth has been recognized. The most widespread soil of the region is classed as Norfolk sand, 'deep phase. This sterile sand, in places 6o feet deep, is 96 to 98 per cent silica. Because of the small amount of fine material present, the normal moisture holding capacity is approximately only 5 per cent. Drainage is excessive over most of the area. The average annual rainfall is 65 inches, and is fairly evenly distributed throughout the year with the exception of late spring or early summer when dry periods of 3 to 6 weeks duration may occur. That fires have been common in this region is attested by the numerous turkey oak sprouts. A sparse ground cover exists, consisting of wire grass, Aristida sp., other herbaceous plants including a variety of legumes, and the gopher apple, Chry'soblalwns obloiigifolius. Pine reproduction is rarely present in sufficient density to insure normal stocking. On abandoned fields, however, reproduction is much more abundant, indicating that climatic and edaphic factors are probably not the only ones unfavorable to the regeneration of longleaf pine. One phase of the work on the natural reproduction of longleaf pine in this region is a study of the roots of trees varying in size from seedlings to mature trees, the older trees being included as a means of judging whether root competition from these individuals is a factor in seedling survival. Although this

The Beach Pool‐Leaf Hopper Complex

The University of Michigan Biological Station is located at Douglas Lake about twenty miles south of Mackinac. Douglas Lake is one of a number of large and small lakes in the northern part of the Southern Peninsula. This region consists generally of low sandy ridges formerly covered by an extensive pine forest but, owing to repeated cutting and burning, has grown up to a mixed forest of pines and aspens with a sparse ground cover. Douglas Lake itself is roughly fish-shaped with a broad shallow margin, called the shelf, which fringes the shore all around the lake. The shelf averages about twenty feet in width with a depth of six feet at the outer margin. Beyond the shelf the bottom of the lake drops almost, perpendicularly to depths of fifty feet or more.