Comparison of geospatial and ground-based methods for determining postharvest dispersed woody residues

Postharvest woody residues are measured to estimate billable waste, bioenergy potential, fuel loadings, and carbon budgets. In fall 2014, a waste and residue survey (WRS) established twenty-nine 0.4 ha plots in the dispersed residue stratum on two cutblocks on Vancouver Island, British Columbia, and measured woody residue “logs” ≥ 10 cm inside-bark diameter and ≥ 20 cm in length. A line-intersect sampling (LIS), in spring 2015, measured all woody debris ≥ 10 cm diameter outside bark (DOB) on 18 plots. High-resolution (2 cm) photography was acquired in summer 2015, orthophotomosaics were prepared and analyzed for residue “logs” ≥ 10 cm DOB in 29 plots using semi-automated “log” delineation (SLD) and manual heads-up “log” digitization (MLD). After adjustment for bark thickness, SLD values were still higher than WRS values, due to inclusion of non-log pieces, though MLD values were not. LIS values were not different from WRS values once adjusted for bark thickness, transect overlaps, and decayed or non-log pieces excluded. The LIS and preharvest forest cover species composition differed from the WRS. While the SLD geospatial method can census ≥ 10 cm diameter residues in entire cutblocks, it was biased. Field-based methods may be required to correct SLD bias and measure species composition to determine bark thickness and wood densities to calculate biomass from residue volumes.

Predicting green and dry mass of yellow-poplar: an integral approachWest Virginia Agriculture and Forestry Experiment Station Scientific Article 2962.

An integral approach to estimating stem green and dry masses for yellow-poplar (Liriodendron tulipifera L.) in West Virginia was compared with traditional ratio equation methods. The data were based on stem analysis of 26 trees from the Central Appalachian Broadleaf Forest province in northern West Virginia and 18 trees from the Eastern Broadleaf Forest province in west-central West Virginia. Sample disks were extracted from 0.3 m, 0.6 m, 1.37 m, 1.8 m, and then every 1.2 m to an approximate 7.6 cm top diameter outside bark. Sample trees ranged from 17.3 cm to 56.1 cm in diameter and from 18.8 m to 38.5 m in total height. The proposed equation generally performed better for the whole tree as well as for sections within the tree based on the nine relative height classes examined. A constant wood-density equation was superior to the use of a linear wood-density equation as a function of height above the ground. The proposed equation explained over 90% of the variation in stem mass and compared favorably with existing fixed merchantable top mass equations.

Growth and yield of tropical moist forest for forest planning: an inquiry through modeling

For the forest growth and yield calculations presented here, the process-based model FORMIX was applied in combination with a geographic information system. The study was carried out for the 55 084 ha of the Deramakot Forest Reserve, which consists of heavily logged and degraded lowland dipterocarp forest. FORMIX was used to assess forest development with and without timber harvesting. Three scenarios were compared: undisturbed forest growth and two reduced-impact timber harvesting scenarios ("textbook" and "borderline"). The latter differ in the number of seed trees retained after harvesting. The simulations reveal that timber harvesting is feasible, although stands are presently degraded. Achievable harvesting levels differ widely from 200 to 10 000 m3·year–1 for the next 40 years for the textbook and borderline scenario, respectively. A future increase up to 80 000 m3·year–1 is possible if all silvicultural and management standards are strictly observed. An analysis of stand development reveals that the portion of commercial dipterocarps decreases with time, while the portion of pioneer and understorey species increases. Future stands do not contain as many trees >60 cm DBH (diameter outside bark at 1.3 m height above ground), whereas they contain more trees in lower diameter classes, ensuring adequate potential for future harvests.

Comparison of relative accuracy and time requirement between the caliper, the diameter tape and an electronic tree measuring fork

This study compares the relative accuracy of diameters measured with the caliper, the diameter tape, and the electronic tree measuring fork (ETMF) Tally BoyMC with and without reflector. The time required for the measure and the data entry of diameters to computer for each instrument was also evaluated. Significant differences in mean DBH (diameter outside bark at breast height — 1.3 m above ground) generally occurred among instruments. Nevertheless, even if these differences were significant, they were less than 1 cm for five of the six species tested. For white pine (Pinus strobus L.), however, the use of the ETMF without reflector led to an important overestimation of the DBH in comparison to the caliper, the diameter tape and the ETMF with reflector. The typical fissured bark observed on white pines could probably explain that overestimation. For all species, the addition of the reflector to the ETMF decreased the differences among instruments. The measures taken with the diameter tape were slightly larger than those made with the caliper. In comparison to the diameter tape and the caliper, the ETMF reduced the time required for date collection from 35 to 45%. Key words: diameter measurement, timber inventory

Models for Estimating DBH from Stump Diameter for Southern Indiana Oaks

Nonlinear regression estimates of DBH based on stump diameter outside bark 6 in. above ground are presented for northern red oak, and the white oak-scarlet oak and black oak-chestnut oak species groups in southern Indiana. Model estimates were compared to those from models developed for other regions. DBH estimates obtained from the new models and some previously reported models can be used to recontruct preharvest volume, value, and structure of harvested oak stands in southern Indiana. North. J. Appl. For. 7:79-81, June 1990.

A Red Pine Bark Factor Equation for Michigan

A multiple linear regression equation was developed to predict bark factor for red pine in Michigan as a function of tree height. The equation was validated on independent data sets. The prediction equation yielded average relative errors less than ± 1% at all tree heights. Procedures are described for using the bark factor equation to estimate diameter inside bark from diameter outside bark and vice versa at any tree height. Specific uses of the prediction equation are also discussed. North. J. Appl. For. 5:28-30, March 1988.

An investigation of product form

Product form (P) of a tree has been defined as the product of diameter-outside-bark at midheight above breast height (d) and total height (H) (P = d × H). It is used along with diameter breast height (D) in product form volume equations (VPF = f(P,D)) for estimating individual tree volumes. It is hypothesized that for each coniferous species, there exists some optimal height at which a diameter measurement can be taken and used in a product form term to estimate the inside-bark volume with minimum error. Regression equations and simpler expressions of the form V = D2 × H × F were developed for red pine (Pinusresinosa Ait.), white pine (Pinusstrobus L.), jack pine (Pinusbanksiana Lamb.), and black spruce (Piceamariana (Mill.) B.S.P.) using six upper diameter locations. The optimal location of the upper diameter was found to be 50% of the total height for red pine and white pine and 47% of total height for jack pine and black spruce. Product form is redefined as P = d* × H where d* = diameter-outside-bark at that average relative height on the tree where d* = (2 × V)/(D × H) as determined from a small sample of scaled trees, for each species and H = total height of tree.

A geometrical tree volume model based on the location of the centre of gravity of the bole

A tree bole model describing a geometrical form in between a paraboloid and cone "paracone" has been developed. The model is based on empirical evidence that the average centre of gravity of aspen (Populustremuloides Michx.) boles without branches lies at 3/10 of the bole height from its base. Outside bark bole volume, V (cubic decimetres), can therefore be estimated nondestructively from the total height, H (metres), and the diameter outside bark, dK (centimetres), measured at a relative height, K, as follows:[Formula: see text]Based on a sample of 70 aspen stems, this equation estimates individual bole volume from total bole length or height and from a single diameter measurement, either at the 3/10 position or at the breast-height position, as accurately as Smalian's formula using seven diameter measurements. Based on the sample, the 3/10 position should be chosen over breast height wherever breast height lies below 20 or above 60% of the total height. It is important that care be taken in the measurement of the diameter due to the sensitivity of the volume equation to diameter variation. In addition to volume estimation, the paracone model provides a comparison profile around which stem form variation within and among species may be observed.

Integrated Systems for the Estimation of Tree Taper and Volume

The desirability and the advantages of deriving taper equations from existing volume equations are discussed. It is demonstrated that the most common types of volume equations can be converted to compatible taper equations. These mathematical stem profile expressions yield tree volumes for any desired stump height and top diameter outside bark from inputs of diameter breast height outside bark and total height.