Crop Tree Management Improved Growth and Crown Class Maintenance of Green Ash: 18-Year Results

The relationships between foliar weight/leaf area and four stem dimensions (dbh, total stem cross-sectional area, total sapwood area, and current sapwood area at breast height) were investigated in two important bottomland tree species of the southern United States, cherrybark oak (Quercus falcata var. pagodifolia Ell.) and green ash (Fraxinus pennsylvanica Marsh.). In all models tested and for both species, total sapwood area was consistently more highly correlated with foliar weight and leaf area than were the other three measures. However, there was little difference in accuracy among simple linear, multiple, and nonlinear models that used total sapwood area to predict either foliar weight or leaf area. Accuracy was improved slightly through the addition of total height and live crown ratio to the linear model. Foliar weight of both species was best described as a function of total sapwood area and live crown ratio (r2 = 0.97, n = 16 for both species). Leaf area of cherrybark oak was best described as a function of total sapwood area, total height, and live crown ratio (r2 = 0.96, n = 16), whereas leaf area of green ash was best described as a nonlinear function of total sapwood area (r2 = 0.95, n = 16). In contrast with other studies on upland oaks in relatively cool climates, we found that current sapwood area was only a fair estimator of foliar weight and leaf area in cherrybark oak and was a poor estimator in green ash. These results lead to the speculation that more of the sapwood than just the most recent one or two growth rings may be active in water conduction in bottomland species in warm climates. Specific leaf area was highest in the lower crowns of trees of both species and was highest among trees of the lower crown classes. Although based on a limited sample size of four trees per crown class per species, we found that the vertical distribution of foliage within the crown differed among crown classes in both species. Most of the foliage on dominant and codominant trees of both species was concentrated in the upper one-third of the crown, with only a very small proportion of the foliage in the lower one-third of the crown. Intermediate and overtopped cherrybark oaks and intermediate green ash trees had a more even distribution of foliage throughout their crowns, while the foliage of overtopped green ash trees was highly concentrated in the lower one-third of the crown. The leaf area:sapwood area ratio did not differ significantly among crown classes in either species, but averaged 0.67 m2 cm-2 in cherrybark oak and 0.24 m2 cm-2 in green ash. FOR. SCI. 48(1):69–76.

Five-year radial growth of red oaks in mixed bottomland hardwood stands

We measured the response of white pine (Pinus strobus L.) saplings after partial release of a hardwood overstory on three sites in central Minnesota. Both height and diameter growth increased quickly after release compared to prerelease growth. Diameter growth response was related to prerelease diameter growth, but not to initial size of the sapling (diameter at time of release). On the other hand, height growth response was strongly influenced by the initial height of all trees, but not related to prerelease height growth in the largest saplings (initial heights > 8.76 m). Increased release intensity (i.e., difference between prerelease and postrelease overstory densities) resulted in higher diameter and height growth responses. The height/diameter ratios decreased after release, indicating that stability as well as growth increased after the release. North. J. Appl. For. 17(3):89–94.

To determine the effects of intermediate silvicultural treatments on bottomland hardwoods, two types of thinning (crown thinning and low thinning) and one level of fertilizer (200 lb/ac N + 50 lb/ac P) were applied to a predominantly red oak stand in southeastern Texas. Treatments were applied in a 3 × 2 factorial arrangement as a randomized complete block design of 12 ac in size. Crop trees were selected prior to the treatments, and diameter at breast height measurements were taken pre-treatment and for three proceeding years to assess diameter growth response of all trees. Epicormic branching measurements were also taken for three years post-treatment to evaluate epicormic branching response of all crop trees to crown thinning, low thinning and fertilization. Furthermore, reproduction plots were established pre-treatment to evaluate reproduction height growth response to all intermediate treatments. First-year results showed no significant difference in current annual increment (CAI) of crop-tree diameter growth response; however, second-year results of CAI diameter growth showed that crop trees in thinned plots achieved significantly more growth than in unthinned plots. With third-year results of CAI diameter growth, crop trees in crow-thinned plots grew significantly better than in both low-thinned and unthinned plots, all regardless of fertilization. Epicormic branching was generally greater in crown-thinned and fertilized plots immediately following treatment, and reproduction height growth was generally greater in crown-thinned, and in some cases, fertilized plots.

Nine-week-old green (Fraxinus pennsylvanica Marsh.) and white (F. americana L.) ash were exposed to O3 and/or SO2 (control, 0.10 ppm O3, 0.08 ppm SO2 or 0.10 ppm O3 + 0.08 ppm SO2) for 4 h d-1, 5 d wk-1 in combination with simulated rain (pH 3.0, 4.3 or 5.6, 1 h d-1, 2 d wk-1 at 0.75 cm h-1) for 6 weeks, under controlled laboratory conditions, with rain applied either just before or after fumigation. Across all rain treatments, white ash biomass was suppressed by the application of O3 and cumulative shoot elongation of green ash exposed to O3 and/or SO2 was less than controls. The combination of O3 + SO2 did not affect the growth of either species more than the pollutants applied alone. Leaf area ratio (LAR) and root to shoot ratio (RSR) exhibited quadratic responses to rain pH in green ash, across all pollutant treatments. Significant pollutant x pH interactions occurred in leaf weight ratio (LWR) in green ash and LAR and RSR in white ash. Significant linear increases in LAR and decreases in RSR, with decreasing pH, were observed for O3 and SO2-treated white ash. These findings are discussed relative to implications of the effects of gaseous pollutants in combination with acid rain on green and white ash growth. For. Sci. 34(4):1016-1029.

Yellow-poplar (Liriodendron tulipfera L.) and black cherry (Prunus serotina Ehrh.) seedling-origin crop trees were released seven years after clearcutting. Ten years after the release, height and diameter growth, clear bole length, survival, crown class, and potential as a crop tree, were evaluated for released and unreleased trees. Based on this evaluation, the selection and releasing of young crop trees to a dominant crown-class position using the methods described here, is not recommended at this time. Because grapevines caused considerable tree damage, early treatment of grapevines is recommended.

The survival, growth, and biomass of baldcypress (Taxodium distichum (L.) Rich.), water tupelo (Nyssa aquatica L.), Chinese tallow (Sapium sebiferum (L.) Roxb.), and green ash (Fraxinus pennsylvanica Marsh.) seedlings were examined in an experiment varying water levels (watered, flooded) and salinity levels (0, 2, and 10 ppt, plus a simulated storm surge with 32 ppt saltwater). All seedlings, except for those flooded with 10 ppt saltwater, survived to the end of the experiment. In 10 ppt saltwater, flooded baldcypress, water tupelo, and green ash survived two weeks whereas Chinese tallow survived for 6 weeks. However, a second set of slightly older baldcypress, water tupelo, and Chinese tallow seedlings survived eight weeks of flooding with 10 ppt saltwater. When carried through the winter to the beginning of the second growing season, flooded baldcypress and Chinese tallow seedlings from the 0 and 2 ppt treatments leafed out, but only Chinese tallow recovered from the saltwater surge treatment. The diameter and growth (height) of each species was not affected when watered with 2 ppt saltwater, except for the effects of the height growth of baldcypress. Growth was reduced for all species when watered with 10 ppt saltwater. The diameter growth of green ash was reduced by freshwater flooding. The diameter growth of baldcypress and water tupelo was greater when flooded with fresh water. Flooding with 2 ppt saltwater caused a significant reduction in diameter growth in water tupelo, green ash, and Chinese tallow, but not in baldcypress. Root and stem biomass values were not significantly different for any species between the 0 and 2 ppt salinity watering treatments. However, seedlings watered with 10 ppt saltwater had significantly lower root and stem biomass values, except for baldcypress roots and green ash stems. Baldcypress was least affected by flooding with 0 and 2 ppt saltwater, although there were slight reductions in root biomass with increasing salinity. Because of the susceptibility of the seedlings of these four species to increases in flooding and salinity, their regeneration may be limited in the future, thereby causing shifts in species composition.

The performance of planted northern red oak (Quercus rubra L.), black walnut (Juglans nigra L.), and green ash (Fraxinus pennsylvanica Marsh.), with and without tree shelters, was evaluated 10 yr after planting. Northern red oak was planted in three harvested forest openings, and black walnut and green ash were planted in a cultivated field. Survival of northern red oak with tree shelters was significantly (P < 0.05) higher than northern red oak without shelters only for year 3. Survival differences between tree shelter treatments for black walnut and green ash were not significant. However, overall survival of green ash declined rapidly after year 5. Trees began to exit the 120-cm-tall shelters after 2 yr, but not in large numbers until the fourth year. Sheltered oaks were significantly taller than unsheltered oaks at year 10, and sheltered oaks had more height growth than unsheltered oaks at year 5, but not at year 10. Except for year 1, neither height nor height growth for black walnut was significantly different between tree shelter treatments. Green ash was taller and had more height growth with shelters than without shelters in year 1, but had more height growth without shelters than with shelters in year 5. Diameter growth at breast height did not differ between treatments for any of the three species. The greater height of sheltered northern red oaks compared to unsheltered northern red oaks could increase the opportunity of sheltered oaks to achieve dominant and codominant positions in the developing stands. North. J. Appl. For. 20(3):104–108.

Growth of white ash (Fraxinusamericana L.), green ash (Fraxinuspennsylvanica Marsh.), and velvet ash (Fraxinusvelutina Torr.) as related to infection by ash yellows mycoplasmalike organisms (MLOs) was assessed by diagnosing and grouping trees as MLO infected or healthy and comparing their previous annual radial growth over periods of 9–22 years. White ash and green ash 17–30 years old were studied on two sites per species in central New York State. Velvet ash 30–90 years old was studied in Zion National Park, Utah. MLOs were detected by fluorescence microscopy. Widths of growth rings were measured on increment cores or cross sections of main stems. Growth trends of diseased and healthy groups of white ash and green ash diverged when ash stands were 12–21 years old. In the fifth year after divergence, the unweighted average growth of diseased green ash across two plots was 70% of that of healthy trees. For white ash, the corresponding average was 61%. In white ash tested annually for MLO infection, growth reduction preceded MLO detection by an average of 1 year. Velvet ash did not sustain MLO-associated growth reduction. This species may be tolerant of infection by ash yellows MLOs.

We compared the effects of 9.5 months of a continuous flooding treatment with a drained control treatment on one year-old seedlings of green ash (Fraxinus pennsylvanica Marsh.) and water oak (Quercus nigra L.), two tree species common to the bottomland-hardwood forests of eastern North America. The internal root gas composition of the more flood tolerant species, green ash, maintained higher oxygen and lower carbon dioxide concentrations under the flooding treatment than water oak. This apparently resulted in differences in rhizosphere oxidation. The amounts of Fe and Mn and the Fe/Mn ratio of the root coating extracted from trees in reduced soil conditions were much higher for the green ash than the water oak. It is argued that this reflects differences in the ability of these two species to maintain rhizosphere oxidation under prolonged periods of flooding and to prevent the accumulation of reduced potentially phytotoxic compounds. Alcohol dehydrogenase activity increased in the green ash and decreased in the water oak in the flooded treatment. This indicated that the better adapted species was able to rely upon increased anaerobic respiration in order to compensate for the decreased root oxygen supply, but the water oak was unable to maintain previous levels of respiration, probably as the result of sulfide toxicity.

In 1988, seven study areas were established in Connecticut to examine the effects of precommercial crop tree release on development of sapling red oaks ( Quercus rubra L.) (n = 1250). Crown class at canopy closure, competition from adjacent trees for growing space and limited resources, and interaction of these factors were major determinants of survival, upper canopy persistence, and diameter growth over the 18 year period studied. Complete release from competition of neighboring trees, but not partial release, increased survival of intermediate and codominant stems. Complete release did not increase survival of oaks in the dominant crown class. Few intermediate and no suppressed oaks ascended into the upper canopy without crop tree release. Complete release doubled the proportion of codominant trees that remained in the upper canopy and increased the proportion of intermediates that ascended into the upper canopy. Complete release increased 18 year diameter growth only for dominant and codominant oaks. Because precommercial crop tree release simultaneously increases the probability that high-quality stems of desired species will be present in the mature stands and increases the diameter growth of those stems, this technique should be considered in stands with low oak densities.

The goal of this study was to develop a decision rule heuristic that would incorporate theories of forest stand dynamics and crown competition into an automatic crown detection and crown size search algorithm. Specifically, we sought to develop new multi-dimensional template matching methods fused with knowledge-based decision rules that model spatial considerations for crown competition and develop multi-scale assessment criteria for appraisal of crown detection and crown size at the stand, local neighbourhood and individual crown levels. The decision rule approach to crown detection and crown size was tested on a mature mixed coniferous and deciduous forest typical of southern New England, USA. Multi-dimensional template matching was applied to a high resolution (30 cm per pixel side) colour infrared image of the study site. The decision rule heuristic developed for this study effectively reduced 2626 potential crown detections to 568 crowns, producing a 91% rate of crown detection when compared with the 516 field-measured crowns. The automatically derived crown size class distribution was shown to be statistically similar to the distribution of field crown size classes using the Kolomogorov–Smirnov statistic. Finally, a fuzzification of classification assignments to crown classes either one above or below actual crown size class resulted in an 80% match between individual field crowns and remotely sensed crowns within a 6 m spatial lag.

Can Regeneration of Green Ash (Fraxinus pennsylvanica) be Restored in Declining Woodlands in Eastern Montana?

A comparison of five tree species for intesive fiber production

Seedling morphological quality standards are lacking for bottomland hardwood restoration plantings in the Lower Mississippi River Alluvial Valley, USA, which may contribute toward variable restoration success. We measured initial seedling morphology (shoot height, root collar diameter, number of first order lateral roots, fresh mass, and root volume), second year field heights and diameters, survival, browse, and top dieback of five species – cherrybark oak (Quercus pagoda Raf.), green ash (Fraxinus pennsylvanica Marsh.), Nuttall oak (Q. nuttallii Palmer), sweet pecan (Carya illinoensis (Wangenh.) K. Koch), and water oak (Q. nigra L.). Seedlings were obtained from three regional nurseries (Arkansas, Louisiana, and Mississippi), planted on three sites (Arkansas, Louisiana, and Mississippi), and treated with or without chemical weed control. Site×nursery interaction and weed control (without interactions) usually affected survival, whereas site×weed control interaction and nursery (without interactions) influenced second year heights and diameters. Weed control generally increased survival rates, as well as second year height and diameter. Effects of initial morphological characteristics on field survival and height and diameter growth were generally dependent on the other morphological parameters. Target morphological characteristics were identified as 99, 84, and 82 in height/diameter ratios (equal units) for cherrybark oak, green ash, and Nuttall oak, respectively; mean initial height of 40–43 cm in sweet pecan; and mean initial fresh mass/root volume of 2.7 g ml−1 in water oak. Seedlings with means above these values may be more susceptible to dieback or mortality after outplanting, likely associated with excessive shoot relative to root biomass.