Browse selection by beaver: effects on riparian forest composition

1990 ◽  
Vol 20 (7) ◽  
pp. 1036-1043 ◽  
Author(s):  
Carol A. Johnston ◽  
Robert J. Naiman
Keyword(s):  
Forest Succession ◽  
Riparian Forest ◽  
Basal Area ◽  
Forest Composition ◽  
Maximum Diameter ◽  
Long Term Effects ◽  
Selective Foraging ◽  
Biomass Structure ◽  
Preferred Species

Beaver (Castorcanadensis) herbivory has both immediate and long-term effects on biomass, structure, and composition of riparian forests. Intense beaver foraging of trembling aspen (Populustremuloides Michx.) decreased tree density and basal area by as much as 43% within ~ 1-ha forage zones surrounding two beaver ponds in northern Minnesota. Maximum diameter of trees cut was 43.5 cm; average aspen stem diameter cut was 13.9 and 10.2 cm at the two ponds. Woody biomass harvested per beaver averaged 1.4 Mg•ha−1•year−1 over a 6-year foraging period. Most wood harvested was left on site or used in dam construction, rather than consumed. Selective foraging by beaver decreased the relative importance of preferred species (i.e., P. tremuloides) and increased the importance of avoided species (i.e., Alnusrugosa (Du Roi) Spreng., Piceaglauca (Moench) Voss), with long-term implications to forest succession and dynamics.

Modeling the long-term effects of disturbances on forest succession, Olympic Peninsula, Washington

1986 ◽  
Vol 16 (1) ◽  
pp. 56-67 ◽  
Author(s):  
Virginia H. Dale ◽  
Miles Hemstrom ◽  
Jerry Franklin
Keyword(s):  
Leaf Area ◽  
Pacific Northwest ◽  
Forest Succession ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Forest Composition ◽  
Silver Fir ◽  
Long Term Effects ◽  
Olympic Peninsula

A model of forest development has been adapted for the Pacific Northwest. The regeneration, growth, and death of individual trees are tracked for simulated 0.2 ha plots and tree attributes are aggregated to provide stand measures. The model includes the influence of temperature, soil moisture, light tolerance, and competition on tree growth. Long-term simulations for Douglas-fir dominated forests on the western Olympic Peninsula show that the stand is eventually dominated by western hemlock with silver fir being codominant. Even after 1200 years of subsequent stand development, silver fir fails to replace western hemlock indicating that this is a self-replicating and stable community. Fire, windthrows, insect disturbance, and clear-cut logging followed by replanting are incorporated into the model as single-event disturbances to a 500-year-old forest. For those cases where large Douglas-fir survive the disturbance, stand biomass and leaf area patterns are not significantly impacted until the death of the last large Douglas-fir. The projections were all carried out to the time when the forest is dominated by western hemlock and silver fir. At that time, the differential effect of the earlier disturbance is not apparent from the forest composition, biomass, or leaf area patterns except for the insect disturbance. Following the removal of all Douglas-fir by an insect, leaf area fluctuates regularly with a period of 600 years.

Long-Term Effects of Early Pruning and Thinning Treatments on Growth of Natural Longleaf Pine

1980 ◽  
Vol 4 (2) ◽  
pp. 77-79
Author(s):  
Robert C. Sparks ◽  
Norwin E. Linnartz ◽  
Harold E. Harris
Keyword(s):  
Longleaf Pine ◽  
Basal Area ◽  
Pinus Palustris ◽  
Diameter Growth ◽  
Stocking Rate ◽  
Long Term Effects ◽  
Natural Stand ◽  
Stocking Rates ◽  
Pruning Intensity

Abstract Pruning and thinning a young natural stand of longleaf pine (Pinus palustris Mill.) in southwest Louisiana had little influence on height. However, diameter growth was reduced substantially as pruning intensity or stocking rate increased up to 25-percent live crown and 200 stems per acre, respectively. Improved diameter growth at lower stocking rates was not sufficient to equal the total basal area increment of 200 trees per acre.

scholarly journals Stand Structure and Composition 32 Years after Precommercial Thinning Treatments in a Mixed Northern Conifer Stand in Central Maine

2011 ◽  
Vol 28 (2) ◽  
pp. 92-96 ◽  
Author(s):  
Aaron R. Weiskittel ◽  
Laura S. Kenefic ◽  
Rongxia Li ◽  
John Brissette
Keyword(s):  
Stand Structure ◽  
Abies Balsamea ◽  
Basal Area ◽  
Long Term Effects ◽  
Mixed Species ◽  
Precommercial Thinning ◽  
Large Trees ◽  
Stand Attributes ◽  
And Control

Abstract The effects of four precommercial thinning (PCT) treatments on an even-aged northern conifer stand in Maine were investigated by examining stand structure and composition 32 years after treatment. Replicated treatments applied in 1976 included: (1) control (no PCT), (2) row thinning (rowthin; 5-ft-wide row removal with 3-ft-wide residual strips), (3) row thinning with crop tree release (rowthin+CTR; 5-ft-wide row removal with crop tree release at 8-ft intervals in 3-ft-wide residual strips), and (4) crop tree release (CTR; release of selected crop trees at 8×8-ft intervals). PCT plots had more large trees and fewer small trees than the control in 2008. There were no other significant differences between the rowthin and control. The rowthin+CTR and CTR treatments had lower total and hardwood basal area (BA) and higher merchantable conifer BA than the control. CTR also resulted in more red spruce (Picea rubens [Sarg.]) and less balsam fir (Abies balsamea [L.]) than the other treatments. Although stand structures for rowthin+CTR and CTR were similar, the percentage of spruce in CTR was greater. Although the less-intensive rowthin+CTR treatment may provide many of the same benefits as CTR, the latter would be the preferred treatment if increasing the spruce component of a stand is an objective. Overall, early thinning treatments were found to have long-term effects on key stand attributes, even more than 30 years after treatment in areas with mixed species composition and moderate site potential.

scholarly journals Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 888
Author(s):  
Allison K. Rossman ◽  
Jonathan D. Bakker ◽  
David W. Peterson ◽  
Charles B. Halpern
Keyword(s):  
Prescribed Burning ◽  
Basal Area ◽  
Tree Regeneration ◽  
Dry Forest ◽  
Permanent Plots ◽  
Long Term Effects ◽  
Fuels Reduction ◽  
Forest Fuels ◽  
Fuels Treatments

The long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timeframes and simple disturbance histories of past research. Here, we present results of a 15-year fuels-reduction experiment in central Washington, including responses to planned and unplanned disturbances. We explore the changing patterns of Douglas-fir regeneration in 72 permanent plots (0.1 ha) varying in overstory abundance (a function of density and basal area) and disturbance history—the latter including thinning, prescribed burning, and/or wildfire. Plots were measured before treatment (2000/2001), soon afterwards (2004/2005), and more than a decade later (2015). Thinning combined with burning enhanced sapling recruitment (ingrowth) into the overstory, although rates of ingrowth were consistently low and greatly exceeded by mortality. Relationships between seedling frequency (proportion of quadrats within a plot) and overstory abundance shifted from weakly negative before treatment to positive after thinning, to neutral in the longer term. However, these relationships were overshadowed by more recent, higher-severity prescribed fire and wildfire that stimulated seedling establishment while killing advanced regeneration and overstory trees. Our results highlight the dependence of regeneration responses on the history of, and time since, fuels treatment and subsequent disturbance. Managers must be aware of this spatial and temporal complexity and plan for future disturbances that are inevitable but unpredictable in timing and severity.

Long-term effects of thinning and fertilization on growth of red fir in northeastern California

2005 ◽  
Vol 35 (6) ◽  
pp. 1285-1293 ◽  
Author(s):  
Jianwei Zhang ◽  
William W Oliver ◽  
Robert F Powers
Keyword(s):  
Basal Area ◽  
Basal Area Increment ◽  
Stand Development ◽  
Long Term Effects ◽  
Annual Increment ◽  
Fourth Period ◽  
Abies Magnifica ◽  
The Impact ◽  
Second Period

To determine the impact of fertilization and thinning on growth and development of red fir (Abies magnifica A. Murr.) stands, we established an experiment in a 60-year-old stand using a 2 × 3 factorial design with nitrogen-fertilized and nonfertilized treatments and three stocking levels. Plots were established in 1976 and were measured every 5 years for 26 years. The periodic annual increment in basal area was 97%, 51%, 38%, and 33% greater in fertilized trees than in nonfertilized trees during the first, second, third, and fourth 5-year periods, respectively. After 20 years, annual basal area increment was greater in nonfertilized trees. The response of annual volume increment to fertilization was not statistically significant until the fourth period. Yet, volume increases of the fertilized plots were 25%–92% greater than those of the nonfertilized plots from 1976 to 1996. Similarly, basal area increment was greater in lightly thinned plots than in unthinned plots from the second period on, until heavy mortality during 1996–2002. Basal area increment was greater in the heavily thinned plots from the fourth period on. Results indicate that red fir can respond to fertilization and thinning quickly and that both treatments speed stand development. In addition, fertilization increases the stand's carrying capacity. Therefore, forest managers can use these silvicultural practices to improve stand growth, to reduce fire fuels, and to accelerate stand development.

Loblolly pine and mixed hardwood stand dynamics for 27 years following chemical, mechanical, and manual site preparation

1993 ◽  
Vol 23 (10) ◽  
pp. 2126-2132 ◽  
Author(s):  
Glenn R. Glover ◽  
Bruce R. Zutter
Keyword(s):  
Loblolly Pine ◽  
Stand Structure ◽  
Growth Yield ◽  
Basal Area ◽  
Site Preparation ◽  
Growth And Yield ◽  
Long Term Effects ◽  
Fayette County ◽  
Stand Basal Area

A site-preparation study installed in 1959 in Fayette County, Alabama, U.S.A., provides data to evaluate long-term effects of varying densities of hardwood on loblolly pine (Pinustaeda L.) plantation growth, yield, and stand structure. Six treatments (hand girdle; bulldoze scarification; herbicide applied to axe frill, chain frill, and with an injector; and an untreated check) were installed as a randomized complete block with five replications. Periodic measurements of pine and hardwood size and density show that higher hardwood densities existing early in the pine plantation had a substantial negative effect on loblolly pine survival and basal area yield, with the bulldoze and herbicide treatments having less hardwood and higher survival and stand basal area. Pine total height and diameter at breast height were reduced by increasing hardwood density early in the life of the plantation, but size of surviving trees differed little among treatments at later ages, except on plots where most pine trees were suppressed by hardwoods. Strong relationships between pine basal area per hectare at age 27 and both number of hardwood stems at age 3 and percentage of stand basal area in hardwood at age 6 were noted. These relationships indicate promise for predicting long-term growth and yield of loblolly pine plantations from early measures of hardwood interference.

Time Series and Postglacial Forest Ecology

1981 ◽  
Vol 15 (3) ◽  
pp. 265-277 ◽  
Author(s):  
David G. Green
Keyword(s):  
Time Series ◽  
Forest Ecology ◽  
Forest Succession ◽  
Fire Frequency ◽  
Forest Composition ◽  
Mixed Composition ◽  
Individual Tree ◽  
Tree Communities ◽  
Pollen Records

AbstractForest ecology suffers from a lack of long-term community records. Preserved pollen data are richer in such information than is generally realized. By applying suitable statistical techniques to pollen records, one can learn much about competition, succession, and population dynamics in past tree communities. In this study, preserved pollen records from Everitt Lake, Nova Scotia, are analyzed as time series. Time domain studies reveal the post-fire responses of individual tree taxa. Correlograms yield models of past forest succession patterns. The models explain some effects of changing fire frequency, thus suggesting mechanisms by which fire, competition, and climate combine to produce long-term forest composition changes. Frequency domain studies suggest relationships between disturbance cycles, stand composition, and forest mosaics. Fire frequencies are seen to be highest where fire-dependent species abound and most regular where tree stands have uniform, not mixed, composition.

scholarly journals Long-Term Suppression of Hardwood Regeneration by Chinese Privet (Ligustrum sinense)

2022 ◽  
Vol 4 ◽  
Author(s):  
Taylor N. Turner ◽  
Thomas J. Dean ◽  
Jeff S. Kuehny
Keyword(s):  
Native Species ◽  
Urban Forest ◽  
Basal Area ◽  
Forest Composition ◽  
Forest Fragment ◽  
Chinese Privet ◽  
Salvage Logging ◽  
Crown Cover ◽  
Overstory Trees

Native hardwood regeneration in the southeast United States is hindered by repeat disturbance events and the presence of invasive species. Our study aimed to determine the ability of native species in an unmanaged urban forest fragment to persist following high winds from hurricane Gustav in 2008 and subsequent salvage logging. In 2009, researchers estimated the density and composition of the regeneration and overstory trees as well as percent crown cover of invasive Chinese privet. Percent Chinese privet cover was visibly high, leading them to believe it may be inhibiting native hardwood establishment. Ten years later in 2019, we returned to the plots to take repeat measurements. Forest composition remains the same and privet crown cover remains high. There has been no increase in regenerating individuals, and overstory trees per hectare and basal area remains low. These results confirm that the heavy Chinese privet presence is persistent long term and will require management to promote reproduction of native overstory tree species.

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