Volume table

Abstract: Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) is one of the most important plantation tree species in China with good timber quality and fast growth. It covers an area of 8.54 million hectare, which corresponds to 21% of the total plantation area and 32% of total plantation volume in China. With the increasing market demand, an accurate estimation and prediction of merchantable volume at tree- and stand-level is becoming important for plantation owners. Although there are many studies on the total tree volume estimation from allometric models, these allometric models cannot predict tree- and stand-level merchantable volume at any merchantable height, and the stand-level merchantable volume model was not seen yet in Chinese fir plantations. This study aimed to develop (1) a compatible taper function for tree-level merchantable volume estimation, and (2) a stand-level merchantable volume model for Chinese fir plantations. This "taper function system" consisted in a taper function, a merchantable volume equation and a total tree volume equation. 46 Chinese fir trees were felled to develop the taper function in Shitai County, Anhui province, China. A second-order continuous autoregressive error structure corrected the inherent serial autocorrelation of different observations in one tree. The taper function and volume equations were fitted simultaneously after autocorrelation correction. The compatible taper function fitted well to our data and had very good performances in diameter and total tree volume prediction. The stand-level merchantable volume equation based on the ratio approach was developed using basal area, dominant height, quadratic mean diameter and top diameter (ranging from 0 to 30 cm) as independent variables. At last, a total stand-level volume table using stand basal area and dominant height as variables was proposed for local forest managers to simplify the stand volume estimation.

Abstract: Stem taper curves, volume tables and volume yield compartments in Sessile Oak. Since the 1970ies, efficient volume tables are available for the main broadleaved species. Nevertheless, estimates of volumes obtained this way for Sessile Oak are still considered too high by some forest managers. We address this question by analysing the volume yield of Oak stands. The analysis is done by modelling the distribution of volume between stem and branches and the geometrical shape of stems (taper curves). The robustness of the method was tested by use of several, large size samples, covering the main sources of variability (age and silviculture). The coherence with former volume tables was favourably tested. Simulations based on a growth model were done in order 1) to explore the variability of volume yield with respect to site quality and silvicultural scenarios; 2) to dispatch total yield according to different criteria (stem-branches, crown-log, bark-sapwood-heartwood); 3) to evaluate the percentage of losses during industrial processing of Oak timber. Results indicate that the disagreement between practicians and scientists on volume simply refers to the nature of the volume (commercial log vs. total volume).

Abstract: The one-way volume table for the three major useful bamboos in Japan, i.e., Phyllostachys pubescens Mazel ex Houz., Phyllostachys bambusoides Sieb. et Zucc. and Phyllostachys nigra var. henonis, was constructed based on a dataset of 920 felled culms collected from five different districts. Twenty-three models were fitted to the height–diameter relationship for each species, and their goodness of fit were compared. The height–diameter relationship for P. pubescens and P. nigra could be expressed by the reciprocal equation, whereas that for P. bambusoides was approximated by the simple allometric power equation. The culm height was predicted by substituting the measured diameter at breast height (dbh) into the determined height–diameter model. The apparent culm volume was then estimated from the measured dbh and the predicted culm height with the two-way volume equations derived in previous studies. For all species, there was no significant difference between the actual and estimated apparent culm volume. The one-way volume table for these bamboo species was constructed by combining the two-way volume equation and the height–diameter model, so that the apparent culm volume could be solely estimated from dbh. For the same dbh, P. bambusoides had the largest apparent culm volume compared to the other two species, whereas P. pubescens had the smallest one. The difference in the apparent culm volume was caused by the inter-specific variations in culm slenderness and/or taper. The volume table developed here will be useful in evaluating the amounts of resources of the three major useful bamboos in Japan.

Abstract: Tree bole volumes of 103 Scots pine (Pinus sylvestris L.) were estimated using nine methods (paracone, centroid, control-variate with one and two measurement points, Huber's formula, antithetic method using importance sampling, standard volume table, local volume table, importance sampling using one and two measurement points, and a taper equation). These estimates were compared with “true” volume of each tree bole which was determined by aggregating the volumes of measured short sections (average 1m) using Smalian's formula. The antithetic method performed well in terms of mean square error and tolerance intervals, which indicate the precision of the estimates. For both importance and control-variate sampling, better precision of the estimate may be achieved by taking measurements at two positions along a stem. The results showed that the antithetic method, importance sampling and control-variate method with two measurement points, paracone and centroid methods are useful alternatives to local v...