Hardwood Sprouts Research Articles

Differential relative bark thickness and aboveground growth discriminates fire resistance among hardwood sprouts in the southern Cascades, California

Bark thickness relative to stem diameter and radial stemwood and height growth patterns provided a more accurate discrimination of fire resistance than absolute bark thickness alone in juvenile stems. Thick bark provides thermal protection to cambial tissues and adventitious buds during fires, and thus, is a functional trait associated with more fire-resistant species and species persisting in fire-prone environments. However, bark thickness alone may not provide the best indicator of fire resistance due to differences among species-dependent growth, reproductive, and survival strategies. We measured bark thickness relative to radial stemwood and height growth among five juvenile co-occurring hardwood species following the Chips Fire (2012) in the southern Cascades, California. We found canyon live oak (Quercus chrysolepis) and Oregon white oak (Quercus garryana), the most fire-resistant, did not have the greatest bark thickness (0.7–0.4 mm; 0.8–0.3 mm), but rather had significantly greater relative (to stem diameter) bark thickness (8–18%) at all heights along the stem (p Q. garryana > Q. kelloggii > Pacific dogwood, Cornus nuttallii > A. macrophyllum). Our findings highlight the importance of considering bark thickness relative to stem diameter and aboveground growth patterns in assessing species fire resistance.

Impacts of logging and prescribed burning in longleaf pine forests managed under uneven-aged silviculture

The longleaf pine (Pinus palustris Mill.) ecosystem has historically been very important in the southeastern United States due to its extensive area and high biodiversity. Successful regeneration of longleaf pine forests requires an adequate number of well-distributed seedlings. Thus, mortality of longleaf pine seedlings during logging operations and prescribed burning appears to be important. Longleaf forests have been commonly managed using even-aged silvicultural methods, but, recently, interest in the use of uneven-aged (UEA) methods has increased in these forests. Research on the impact of UEA logging in longleaf forests is limited. In addition, the influence of overstory density on the impact of prescribed burning under UEA management has not been sufficiently studied in longleaf pine forests. In this study, impacts of UEA logging and prescribed burning (both growing and dormant seasons) on longleaf pine seedlings were observed. In addition, the impact of logging and burning on hardwood seedlings, which are detrimental for longleaf pine seedlings' survival, was also monitored. Damage of logging on longleaf pine seedlings was less than that on hardwood sprouts. A growing-season burning conducted in September 2011 killed most of the hardwood seedlings; however, most of the advance longleaf pine seedlings survived with an average survival rate of 91%. Impact of a dormant-season burning (conducted in January and February 2014) on the survival of 2-year-old longleaf seedlings increased with increasing stand density. This study shows that prescribed burning may be responsible for longleaf pine seedlings' mortality in some cases. It also suggests that damage of UEA logging on longleaf pine seedlings may be negligible.

Effect of Chemical and Manual Release on Live Oak Sprouts and Other Vegetation in a Ponderosa Pine Plantation on a Poor Site

Abstract In their quest to increase vegetation management alternatives, managers continue to test new treatments and to apply old ones to different species. In this northern California study, the new treatment was undiluted Velpar applied with a spot-gun; the old treatments were Garlon 3A, Garlon 4, and manual release; and the different species was canyon live oak (Quercus chrysolepis). Principal categories of vegetation in the new plantation were hardwoods (mostly live oak root-crown sprouts), shrubs, forbs, and grasses. Planted 2-yr-old ponderosa pine (Pinus ponderosa var. ponderosa) seedlings were part of the plant community. Eleven growing seasons after treatment (1988–1998), hardwood sprouts in the untreated control averaged 1,850/ac, combined shrubs over 3,600/ac, forbs 5,900/ac, and grasses more than 19,500/ac. Mean hardwood height in 1998 was significantly shorter when treated with Velpar and Garlon 4 than in the control. Significantly longer needles for pines in the Velpar and manual release treatments in 1989 forecast a significant difference among treatments that was realized in 1994, when mean stem diameter of pines at 12 in. above ground was significantly larger in all treatments than in the control. Stem height and diameter of pine did not differ significantly among treatments in 1998, but needle length again indicated that it would in the near future. Ten years may not be enough time to fully evaluate release treatments on poor sites with hard-to-control species. West. J. Appl, For. 18(1):22–28.

Post‐fire succession and 20th century reduction in fire frequency on xeric southern Appalachian sites

Abstract. We document post‐fire succession on xeric sites in the southern Appalachian Mountains, USA and assess effects of 20th century reduction in fire frequency on vegetation structure and composition. Successional studies over 18 yr on permanent plots that had burned in 1976–1977 indicate that tree mortality and vegetation response varied with fuel load and fire season. In the first three years after fire, hardwood sprouts dominated tree regeneration. On sites where summer and autumn fires reduced litter depth to less than 1 cm, densities of shade‐intolerant Pinus seedlings increased steadily over this period. 4 to 8 yr after fire, large numbers of newly established seedlings and sprouts had grown to 1 – 10 cm DBH. By year 18 growth of these saplings led to canopy closure on most sites. Herbaceous cover and richness peaked in the first decade after fire, then declined. On similar sites that had not burned in more than 50 yr, regeneration of shade‐intolerant Pinus spp. and mean cover and richness of herbs were considerably lower than those observed on recently burned plots. Reconstructions of landscape conditions based on observed post‐fire succession and 20th century changes in fire regime suggest that reductions in fire frequency circa 1940 led to substantial changes in forest structure and decreases in cover and richness of herbaceous species.

Effect of competition on genetically improved ponderosa pine seedlings

In northern California, ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. ponderosa) height and diameter growth were analyzed to determine if genetically improved seedlings were more competitive than other vegetation and if they outgrew nursery stock in the field. Analysis of growth during the third through sixth growing seasons (1992-1995), indicated no statistical differences for pine height or diameter among genetic classes (control pollinated, wind pollinated, nursery run) when grown with competing vegetation. In 1995, mean height of seedlings grown with competition was 2.4 m for control-pollinated seedlings, 2.3 m for wind-pollinated seedlings, and 2.2 m for nursery-run seedlings. For seedlings grown essentially without competition, control-pollinated seedlings significantly outgrew nursery-run seedlings in height each year for the first six growing seasons. In 1995, the values were 3.0 versus 2.6 m, respectively. The competition consisted of a vigorous stand of shrubs, hardwood sprouts, forbs, and grasses. Within each genetic class, mean height and diameter of pines were significantly larger without competition.

Genetically Improved Ponderosa Pine Seedlings Outgrow Nursery-Run Seedlings with and without Competition—Early Findings

Abstract Three classes of ponderosa pine (Pinus ponderosa) seedlings (nursery-run, wind-pollinated, control-pollinated) were evaluated for stem height and diameter at the USDA Forest Service's Placerville Nursery and the Georgetown Ranger District in northern California. Pines in all three classes were grown with competing vegetation or maintained in a free-to-grow condition. Control-pollinated seedlings were statistically taller (P < 0.05) than nursery-run counterparts when outplanted, and after 1 and 2 growing seasons in the field with and without competition. They also had significantly larger diameters when outplanted and after 2 growing seasons in the field when free to grow. Wind-pollinated seedlings grew taller than nursery-run seedlings when free to grow. A large amount of competing vegetation [bearclover (Chamaebatia foliolosa)—29,490 plants per acre; herbaceous vegetation—11,500; hardwood sprouts—233; and whiteleaf manzanita (Arctostaphylos viscida) seedlings—100] ensure that future pine development will be tested rigorously. West. J. Appl. For. 9(2):00-00.

Spatial and Temporal Variation in Competitive Effects on Soil Moisture and Pine Response.

The effects of different plant life-forms, including a bunch grass species, Andropogon virginicus L. (broomsedge), and a sprouting deciduous tree species, Liquidambar styraciflua L. (sweetgum), on soil moisture and competitive responses of a transplanted coniferous tree seedling, Pinus taeda L. (loblolly pine), were investigated. Addition of the bunch grass and/or hardwood sprouts either had no effect or increased soil moisture in the surface soil (0-14 cm) depending on the time, while addition of sweetgum and/or broomsedge (greatest density alone) decreased soil moisture in deeper portions of the solum during the summer months. Soil moisture available to pine seedlings at various points in time was assessed by measuring predawn xylem pressure potential. Temporal variation in predawn xylem pressure potential was accounted for through a water stress integral approach. More than half of the variation in pine size after one growing season could be accounted for by the water stress integral.

Fire regimes for pine-grassland communities in the southeastern United States

Four combinations of season and frequency of burning were applied in Coastal Plain loblolly pine stands over a 43-year period. Overstory species composition and growth were unaffected by treatment. Above-ground portions of small hardwoods (less than 12.5 cm d.b.h.) were killed and replaced by numerous sprouts under periodic summer, periodic winter, and annual winter burning regimes. With annual summer burning, small hardwoods and shrubs were killed and replaced by vegetation typical of grassland communities. Grasses and forbs also dominated the understory of annual winter burns but numerous hardwood sprouts survived. Study results emphasize that frequent burning over a long period is needed to create and maintain the pine-grassland community observed by the first European settlers of the southeast.

Nutrient cycling following whole-tree and conventional harvest in northern mixed forest

Soil and water chemistry and soil-respiration activity were studied in a mature, mixed conifer and hardwood forest and in adjacent whole-tree harvest (WTH) and conventional harvest (CH) areas dominated by hardwood sprouts. Compared with the uncut mature forest, forest floor contents of N and K were lower in the WTH area 3 years after harvest; Ca and Mg were higher in the CH area, probably owing to inputs in logging slash. Mineral soil Ca and pH were higher in the harvested areas than in the uncut area. During the 2nd year after harvest, cation concentrations in forest floor leachate varied in the order WTH > CH > uncut area, but differences largely disappeared the next year. Soil water NO3 concentrations were slightly elevated in the CH area, but only 1.6 kg N•ha−1•year−1 leached below the rooting zone. Bulk precipitation K and Mg concentrations were lower in the WTH area than in the CH area owing to the loss of canopy leaching from the residual stand. Slightly higher amounts of cations were found in the snowpack under the mature forest canopy. Midwinter rains caused movement of NO3 and H within the snowpack. Despite the higher soil-respiration rates in the harvested areas, no differences in soil organic matter pools were observed relative to the uncut area; harvest-related inputs of slash, decaying roots, and stumps may have offset respiratory carbon losses. Current high nutrient demands of rapidly growing sprouts in the WTH area greatly exceed nutrient inputs in bulk precipitation; this may lead to future growth declines.

Whole-Tree Harvesting Affects Pine Regeneration and Hardwood Competition

Abstract Mixed upland hardwood-pine stands of low quality in the Upper Piedmont of Georgia were whole-tree harvested to 1-inch and 4-inch diameter limits in both winter and summer. Natural pine regeneration and hardwood sprouting were observed two growing seasons after harvesting. Early pine establishment was generally successful after winter harvesting but not after summer harvesting. Pine regeneration was excellent following the 1-inch winter harvest and acceptable following the 4-inch winter harvest. The treatment resulting in the best pine regeneration also produced the greatest coverage of hardwood sprouts.1

Early Regeneration of a Clear‐Cut Southern Appalachian Forest

The components of hardwood forest regeneration on a southern Appalachian watershed were assessed during the 1st yr following clear—cutting. First—year net primary production (NPP) on the clear—cut was 1955 kg/ha, representing 22% of the NPP of a nearby undisturbed hardwood forest. First—year nutrient pools in NPP for N, P, K, Mg, and Ca were estimated at 29—44% of those in the NPP of the control. The greatest NPP and nutrient pools were represented in descending order by hardwood sprouts, herbs, vines, and seedlings. Woody successional species (Robinia pseudo—acacia, Liriodendron tulipifera, and Vitis aestivalis var. argentifolia) and herbs (Aster spp., Solidago spp., and Erechtites hieracifolia) were important in revegetation due to competitive advantages in growth rates, growth forms, and propagative capacities. The woody successional species had higher tissue concentrations of N and P than most other woody species. Herbs as a group had significantly higher foliar concentrations of K than woody species. Woody successional and herbaceous species collectively had higher biomass and elemental pools than other woody species. Following forest disturbance, these fast—growing species conserve substantial pools of nutrients in their biomass and initiate a rapid recovery of forest elemental cycling processes.

The Effect of Overhead Shade on the Survival of Loblolly Pine Seedlings

Loblolly pine (Pinus taeda) 1 seedlings, if they succeed in germinating under overhead shade and survive the first season or two, will almost inevitably die at some later period unless this competition is removed. This makes it impossible either to practice the single tree or pure selection system of silviculture, or to maintain successfully for an indefinite period a growing stock on the same area, from which only an amount equal to the annual growth is removed annually or even at 10-year intervals. Under such practice, conditions originally favoring the establishment of loblolly pine, caused by past cutting and fires, are gradually altered to favor the dominance of hardwoods of inferior species and quality, leading ultimately to elimination of loblolly pine. On the other hand, if loblolly pine seedlings start in the same year with competing hardwood sprouts, they have a more than even chance of outgrowing and dominating the hardwoods in spite of their lesser height growth in the first year compared with sprouts. Full sunlight or freedom from overhead shade permits loblolly pine rapidly to assume its normal rate of growth in height, which can exceed that of all competitors except red gum (Liquidambar styraciflua) by from 25 to 50 per cent. Gum, due to its narrow crown, is not always a serious competitor if the pine develops at the same time, but, with oaks and other hardwoods, it becomes so if it starts 2-3 years earlier. Observers are often confused by the fact that in a rather mature high forest of mixed pine and hardwoods, especially among the hardwoods, great numbers of young loblolly pine seedlings and small