Tree Crown Width Research Articles

Callery Pear Cultivars Tested As Street Trees: Final Report on a 12-year Study

Cooperators in the Municipal Tree Restoration Program planted nine Callery pear (Pyrus calleryana Decne.) cultivars in 11 Pennsylvania, U.S. communities for evaluation as street trees, comparing two cultivars (three in one case) in each community. Cooperators measured them annually with standardized methods for 3 years and then at 3-year intervals until the 12th year. The most noteworthy differences occurred in tree height and crown width. The tallest were Aristocrat™, ‘Cleveland Select’, and ‘Redspire’, attaining more than 8 m (26 ft) on average by the twelfth year and even 10.3 m (34 ft) in one community. ‘Autumn Blaze’, evaluated only at one location, was ≈1.5 to 2 m (5 to 6.6 ft) shorter in the 12th year. Heights of the other cultivars, tested at just one or two locations, were similar to the tallest ones. Crown widths differed more in the first 9 years than at the twelfth when on average most were ≈6.5 m (21.5 ft) wide. Cleveland Pride ®, ‘Cleveland Select’, Valiant ®, and ‘Whitehouse’ were narrower than the others until the ninth year, but only ‘Cleveland Select’ at ≈5.6 m (18.5 ft) remained narrower in the twelfth year and not everywhere. All cultivars were in good health during the whole period, although the foliage of ‘Whitehouse’ exhibited minor injuries in many years. As street trees, the Callery pears were not invasive and did not yet experience branch breakage, which can become a serious problem. All of the cultivars are too tall to be planted under utility wires.

Relationship between vigor of Iranian Prunus mahaleb L. selected dwarf rootstocks and some morphological characters

Prunus mahaleb L. and Prunus avium L. are the principal rootstocks used in Iran and world wide for sweet and sour cherries. This study was conducted at Khorasan Natural Resources and Agricultural Research Center with the main purpose of investigation of genetic variation and identification of mahaleb dwarf genotypes for cherry rootstock breeding. We evaluated morphological characters of 17 mahaleb populations. One-way analysis of variance was performed for determination of different regions genetic diversity, which indicated significant differences for most traits. Correlation coefficient showed significant correlation between tree vigor, crown width, and crown volume and size index. Factor analysis detected that in the first factor, crown height, size index, crown width, trunk circumference and crown volume had highest factor loading, bark to wood ratio, internode and chlorophyll content were the second most important and third factor was leaf area. These factors contained 57.9% of total variance. Results also showed that mahaleb seedlings had vigor variation.

Derivation of compatible crown width equations for some important tree species of Spain

Crown width is an important feature in describing stand density and individual tree competition. Two different approaches to using crown width in competition measures are reported in the literature: (i) crown width of open-grown trees, assumed to describe the zone of influence, and thus the potentially available stand area attributable to an individual tree and (ii) crown width of stand-grown trees, describing individual tree competition in distance-dependent individual tree growth models. The crown width measurements of the second Spanish National Inventory are used to derive (i) open-grown tree crown width equations and (ii) general tree crown width equations. The results show that the expectation that open-grown tree crown width may be derived as a special case of a general crown width equation is not met. Therefore, the authors sought a method of obtaining “compatible” tree crown width equations (modelled to a specific region and for individual tree species) that cover the range from open-grown to stand-grown trees with acceptable accuracy. As a practical example, the authors’ compatible tree crown width equations with their species-dependent coefficients are then compared for 11 major tree species in Spain in order to see if these equations give the open-grown tree crown width when open-grown tree height diameter ratio is inserted as independent variable. For conifers and for Eucalyptus globulus, the authors’ procedure does indeed provide equations valid for open-grown trees to stand-grown trees with an acceptable loss of efficiency over the range. For the other broad-leaved tree species, no recommendable compatible crown width equation could be derived.

Individual tree measurements by means of digital aerial photogrammetry

This study explores the plausibility of the use of multi-scale, CIR aerial photographs to conduct forest inventory at the individual tree level. Multiple digitised aerial photographs are used for manual and semi-automatic 3D positioning of tree tops, for species classification, and for measurements on tree height and crown width. A new tree top positioning algorithm is presented and tested. It incorporates template matching in a 3D search space. Also, a new method is presented for tree species classification. In it, a partition of the image space according to the continuously varying image-object-sun geometry of aerial views is performed. Discernibility of trees in aerial images is studied. The measurement accuracy and overall measurability of crown width by using manual image measurements is investigated. A simulation study is used to examine the combined effects of discernibility and photogrammetric measurement errors on stand variables. The study material contained large-scale colour and CIR image material and 7708 trees from 24 fully mapped plots in Southern Finland. The results of the discernibility analysis suggest that 88–100% of the total stem volume is measurable when using multiple aerial photographs. The structure and density of the forest were found to affect discernibility. The best hit-rates when using the semi-automatic tree top positioning algorithm ranged from 77 to 100% of the visually discernible trees. Systematic underestimation of the crown width was observed and the measurability of crown width was best near the image nadir. Species classification was tested in mixed stands of Scots pine, Norway spruce, and silver birch. The Kappa-coefficients ranged from 0.71 to 0.86. The results of the simulation suggest that very high accuracy at the individual tree level cannot be expected. However, if the photogrammetric measurements are unbiased, the aggregate stand variables can be very accurate. An accurate species recognition method is needed in the mixed stands in order to achieve unbiased estimates for the small strata.

Loss of oak dominance in dry-mesic deciduous forests predicted by gap capture methods

Gap capture methods predict future forest canopy species composition from the tallest trees growing in canopy gaps rather than from random samples of shaded understory trees. We used gap capture methods and a simulation approach to forecast canopy composition in three old oak forests (Quercus spp.) on dry-mesic sites in southern Wisconsin, USA. In the simulation, a gap sapling is considered successful if it exceeds a threshold height of 13–17 m (height of maximum crown width of canopy trees) before its crown center can be overtopped by lateral crown growth of mature trees. The composition of both the tallest gap trees and simulated gap captures suggests that 68–90% of the next generation of canopy trees in the stands will consist of non-Quercus species, particularly Ulmus rubra, Carya ovata and Prunus serotina. Quercus species will probably remain as a lesser stand component, with Quercus alba and Quercus rubra predicted to comprise about 19% of successful gap trees across the three stands. Several methods of predicting future canopy composition gave similar results, probably because no gap opportunist species were present in these stands and there was an even distribution of species among height strata in gaps. Gap trees of competing species already average 11–13 m tall, and mean expected time for these trees to reach full canopy height is only 19 years. For these reasons, we suggest that dominance will shift from oaks to other species, even though late successional species (e.g., Acer and Tilia) are not presently common in the understories of these stands.

Analysis of the concept of growth efficiency in Eucalyptus marginata (jarrah) in relation to thinning, fertilising and tree characteristics

Growth efficiency is the amount of stemwood produced per unit of leaf area. It is an index that accounts for the influences of both photosynthetic efficiency and carbon allocation on stemwood production. Growth efficiency is becoming popular as an index to the general vigour or disease resistance of trees and stands, and is an aid in the interpretation of silvicultural experiments. Four separate estimates of growth efficiency were compared for a thinning × fertilising experiment in an even-aged regrowth Eucalyptus marginata Donn ex Smith (jarrah) stand in the northern jarrah forest of Western Australia. Both stand growth efficiency (SGE) and average tree growth efficiency (ATGE) showed large increases in response to thinning and fertilising. The large response of SGE and ATGE to thinning was mainly due to the removal of the less efficient trees. However, when trees in each plot were ranked on their growth efficiency, i.e. ranked tree growth efficiency (RTGE), the increase in RTGE in response to thinning was found to be limited to the most efficient 50 stems ha −1, with very little response in the less efficient trees. The response of RTGE to fertilising occurred over the range of tree growth efficiency classes. Therefore, the size of the response of growth efficiency to thinning and fertilising was dependent on the basis on which growth efficiency was analysed. We recommend that analysis of the effect of cultural treatments on tree growth efficiency should be done after ranking trees on their growth efficiency, i.e. on RTGE Within a thinning × fertilising treatment, individual tree growth efficiency (ITGE) was most strongly correlated with tree basal area increment, that is, the more efficient trees were the faster growing trees. ITGE could not be reliably predicted from tree leaf area, height, crown width, crown depth or tree diameter.

An empirical evaluation of a three-dimensional crown model for predicting volume growth

A three-dimensional geometric model of crown competition was developed which can be used for empirical distance-dependent individual-tree models or biologically based process models. The crown model calculates the shape of a subject tree's crown based on the positions of its competitors' crowns and the rules of competition. It is necessary to use a crown profile equation to use the crown model. The crown profile equation was estimated from the crown width of open-grown trees at the base of the live crown. Ten replicates of a loblolly pine ( Pinus taeda L.) progeny study planted in a variable density Nelder's wheel layout re-measured annually from Ages 6 to 10 and at Age 12 were used for the analysis. The use of two different rules of competition and two different methods of calculating crown volume, surface area, and exposed surface area resulted in eight different estimates related to the geometry of each crown. The relationships of the natural logarithm of periodic annual wood volume growth of different time lengths were fit to geometric estimates generated from the crown model. These relationships were compared with crown length and wood volume relationships to evaluate the utility of the three-dimensional crown model. Exposed surface area of the crown was the best predictor of volume growth produced by the crown model. Wood volume was the single best predictor of growth until Age 9, when exposed surface area became superior. The best model of all possible models was wood volume, exposed surface area, and surface area. Wood volume, exposed surface area, and total surface area length accounted for 1–11% more of the variability than crown length and wood volume. This indicated that the crown model offered benefits over the use of the raw data. The relative performance of the crown model compared with wood volume and crown length improved as competition increased. The crown model appears to offer potential for growth and yield modeling; it must be further evaluated, however, for use in mature stands.

Adaptable stand dynamics model integrating site-specific growth for innovative silvicultural prescriptions

‘Adaptive stand dynamics models’ are presented in concept with a description of some component parts. These models are designed to predict change in gross tree dimensions (e.g. tree height, crown length and crown width) for trees in a given stand. Unlike growth and yield models, which use empirical equations fit to regional growth data, these models use available information from a specific stand and general stand dynamics theory to predict stand structure changes, and are designed to improve the predictions by utilizing remeasurement data from the subject stand. The author's current vision of an adaptive stand dynamics model has been used in two very different stands, one in the Pacific Northest USA and the other in Southern Midwest USA. This paper shows the potential of such models and explains how the model differs from traditional growth models.

Lodgepole pine and white spruce crown fuel weights predicted from height and crown width

Equations were developed to predict the ovendry weight of the total crown, live crown, foliage, and the roundwood diameter classes of <0.5, 0.5–1.0, 1.0–3.0, 3.0–5.0, 5.0–7.0, 7.0–10.0 cm for lodgepole pine (n = 27) and white spruce (n = 23) occurring in Alberta, Canada. The nonlinear allometric model using total tree height and a measure of crown width provided high R2 and low SEE values. This precision could not be duplicated when total tree height was used as the only independent variable. Our results suggest the possibility of using tree height and crown width measured from aerial photographs to estimate standing live and dead fuel loadings in undisturbed forest stands.

Estimating Weights of Tree Components of Lodgepole Pine from Large-Scale Aerial Photographs

Sixty-three lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) trees were measured on the ground, felled, and their crowns and stems were weighed. The combined independent variables of tree height and crown width gave the most precise estimate of fuel components. No significant differences were found between ground and air photo measurements of total tree height and crown width. Hence, the weight of all branchwood, entire crown, and entire tree can be estimated by the use of large-scale aerial photographs.

TRIPLOID APPLE VARIETIES OF SUMMER RIPENING SELECTION VNIISPK ON CLONAL ROOTSTOCK 54-118

For the first time in the world and in Russia, Academician of the Russian Academy of Sciences, breeder Evgeny Nikolaevich Sedov created a series of triploid apple cultivars from intervalent crosses 2х × 4х. Triploid apple cultivars bear fruit more regularly, have higher self-fruitfulness and have fruits of high marketability. The article presents data on the study of triploid apple cultivars of the summer ripening period of the VNIISPK breeding - Augusta, Daryona, Maslovskoye, Osipovskoye, Zhilinskoye, Spasskoye and Yablochny Spas as well as the control Canadian cultivar Melba on a semi-dwarf clone rootstock 54-118. Maslovskoye, Zhilinskoye, Spasskoye and Yablochny Spas have immunity to scab. The orchard was planted in 2014, the garden planting scheme was 5 x 2 m. The indicators of the growth force (tree height, crown width and stem diameter) and the yield of trees were studied. At the age of six, the trees of triploid cultivars reached a height of 2.2 m (Maslovskoye) to 3.0 m (Yablochny Spas) on a semi-dwarf rootstock 54-118. The highest indicators of crown volume (3.3-5.3 m3), crown projection area (4.2-5.3 m2) and the cross-sectional area of the stem (46.5-52.8 cm2) were in Osipovskoye, Yablochny Spas, Zhilinskoye and Spasskoye. The highest yield in an average of three years was given by triploid scab-immune apple cultivars on a semi-dwarf rootstock 54-118: Maslovskoye, Zhilinskoye, Spasskoye and Yablochny Spas.

Forest sampling with 70-mm fixed air-base photography from helicopters

Using methods described in earlier reports ( Lyons, 1961, 1964), two Hulcher 70-mm model 102 cameras were mounted, one at each end of a 15 ft. boom suspended beneath a Bell 47-G-2 helicopter. The precision of estimating flying height was comparable to the earlier studies. Photo measurements of tree heights and crown widths were used to develop species, single tree, photo volume equations and photo d.b.h. equations for six British Columbia interior coniferous species and five British Columbia coast coniferous species. Sample gross volumes were compiled using standard ground procedures, and photo measurements and photo volume tables, for 23 double samples in the interior and 24 double samples on the coast. The difference between ground and photo methods is not significant on a paired sample basis. A comparison of precision was made between a survey using ground plots only and one using photo plots only. For the same precision of estimate the cost of the photo method is 15.6% and 15.0% of ground cost for interior and coast areas respectively. In testing the costs of ground surveys to photo and ground double sample surveys, costs of the double sample schemes for the same precision of estimate were 58.0% and 55.0% of ground only schemes for interior and coast areas respectively. In preliminary tests of the photo measurement of logging residue as compared to ground methods, it was found that there was generally no significant difference between photo and ground methods for determining gross volumes of individual pieces or of areas.