Growth intercept models for black spruce, jack pine and balsam fir in Quebec

Abstract

Site index has traditionally been estimated using height over age curves in the province of Quebec (e.g., Vézina and Linteau 1968, Boudoux 1978, Pothier and Savard 1998. While such curves tend to be effective tools for estimating site index in mature stands, they are unreliable for estimating site index in juvenile stands, i.e., stands that are younger than 20 years old at breast height (Nigh 1995). Conversely, variable growth intercept models are being increasingly used outside Quebec to give reliable site index estimates for young stands by relating the average annual height growth of trees to site index. These models have the advantages of being: 1) developed specifically for estimating site index, not height; 2) intended for young stands; 3) not constrained to pass through the site index at index age; and 4) less sensitive to small deviations from the mean height when compared to height-age models (Nigh 1996).Because of the commercial importance of black spruce, jack pine and balsam fir as major wood supply species in Quebec, a need existed for growth intercept models for these species. ABSTRACTThe objective of this study was to develop variable growth intercept models for coniferous species of major importance in Quebec using Nigh's (1997a) modelling technique. Eighty-three, 68, and 70 stem analysis plots of black spruce (Picea mariana [Mill.] BSP), jack pine (Pinus banksiana Lamb.) and balsam fir (Abies balsamea (L.) Mill) were used, respectively. The growth intercept models for black spruce were the most precise, followed by those for jack pine and finally by those for balsam fir, based on the root mean square errors. Results indicated that the accuracy of the models was good, relative to those previously published for other species in Canada. Interim testing of the models revealed a low mean error for all three species that may not be of practical significance for site index determination, although more data should be obtained to further test the models.

Exploring forest productivity at an early age after fire: a case study at the northern limit of commercial forests in Quebec

“…Studies by Mallik (2003) and Ruel et al (2004) and a summarizing paper by Rheault (2013) have shown that, at higher latitudes in eastern Canada (>48°N), naturally regenerating black spruce take, on average, 25 years to reach the sapling stage of 100 cm. Omitting this time period likely has important consequences for expected harvest volumes (Sims et al 1990;Mailly and Gaudreault 2005): forest productivity is usually rated with site index (SI) curves that are based on measurements taken at a stem height of 100 or 130 cm. Therefore, if a SI curve suggests a total period of ca.…”

Juvenile growth of black spruce (Picea mariana [Mill.] BSP) stands established during endemic and epidemic attacks by spruce budworm (Choristoneura fumiferana [Clemens]) in the boreal forest of Quebec, Canada

“…Methods, such as the one proposed by Mailly and Gaudreault (2005) might be more promising in predicting the long-term yield of boreal plantations on an annual basis. The paraboloid power function (Forslund and Paterson 1994) seems to be a good method for evaluating the total volume at a given age with few measurements.…”

“…The site index was calculated using the method of Nigh (1997), but setting the reference height for age at 1.0 m (Mailly and Gaudreault 2005). The site index was thus obtained by calculating the top height reached at the time of sampling and the age determined at 1.0 m. Growth intercepts were calculated using the equations presented by Mailly and Gaudreault (2005) for each age 100 from one to the last year measured in given stands. Site index values in Table 2 refer to the calculation at the age of sampling.…”

“…However, the annual height growth of black spruce is very slow during the first 10 years; therefore, the stem height is not an accurate predictor of the production potential of black spruce plantations. Mailly and Gaudreault (2005) introduced a new approach to evaluate the yield in planted stands using internodal growth measurements. This non-destructive method uses measurements of annual height growth and produces results comparable to the bud scar method.…”

Ontario's forest growth and yield modelling program: Advances resulting from the Forestry Research Partnership

“…Relationships between jack pine growth and site variables were reported for plantations in New Brunswick using the growth intercept approach (Hamilton and Krause 1985). Recently, GI models were developed for natural young stands of black spruce, jack pine, and balsam fir in Quebec (Mailly and Gaudreault 2005). In Ontario, GI models had been developed for white spruce plantations (Thrower 1987), jack pine (Guo and Wang 2006) and black spruce plantations (M. Kwaiton and J. Wang, Lakehead University, unpublished data).…”