• Journal of Forest and Environmental Science
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• 제30권4호
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• pp.315-321
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• 2014

Forest timber production potential of any site is oftentimes measured quantitatively by site index, which is defined as dominant height of a particular stand at a specified age. A site index was developed for estimating site quality of monoculture Pinus caribaea plantations in southwestern Nigeria using a base age of 25 years. Dominant height data were collected from 60 Temporary Sample Plots (TSPs) of $20{\times}20m$ in plantations of 15 to 37 years. Linear and non-linear models as been widely applied in quantitative forest measurements were fitted to dominant height-age data and the best site index equation is : $SI=Exp^{(InHd-23.495(A^{-2}-0.04)}$. The site index curves constructed for the three sites (Omo Forest Reserve - OFR (J4), Oluwa Forest Reserve - OLFR and Shasha Forest Reserve - SFR) across the southwestern Nigeria using the chosen equation revealed that a 15 year old Pinus caribaea in the study area attained average dominant heights of 25, 22 and 21 m in OFR (J4), OLFR and SFR respectively. The site index equation and curves proffer veritable insight into better silvicultural options and management practices for the future plantations suitable sites.

• Journal of Forest and Environmental Science
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• 제32권3호
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• pp.280-290
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• 2016

Stem diameter variability is an essential inventory result that provides useful information in forest management decisions. Little has been done to explore the modelling potentials of standard deviation (SDD) and coefficient of variation (CVD) of diameter at breast height (dbh). This study, therefore, was aimed at developing and testing models for predicting SDD and CVD in stands of Pinus caribaea Morelet (pine) in south west Nigeria. Sixty temporary sample plots of size $20m{\times}20m$, ranging between 15 and 37 years were sampled, covering the entire range of pine in south west Nigeria. The dbh (cm), total and merchantable heights (m), number of stems and age of trees were measured within each plot. Basal area ($m^2$), site index (m), relative spacing and percentile positions of dbh at $24^{th}$, $63^{rd}$, $76^{th}$ and $93^{rd}$ (i.e. $P_{24}$, $P_{63}$, $P_{76}$ and $P_{93}$) were computed from measured variables for each plot. Linear mixed model (LMM) was used to test the effects of locations (fixed) and plots (random). Six candidate models (3 for SDD and 3 for CVD), using three categories of explanatory variables (i.e. (i) only stand size measures, (ii) distribution measures, and (iii) combination of i and ii). The best model was chosen based on smaller relative standard error (RSE), prediction residual sum of squares (PRESS), corrected Akaike Information Criterion ($AIC_c$) and larger coefficient of determination ($R^2$). The results of the LMM indicated that location and plot effects were not significant. The CVD and SDD models having only measures of percentiles (i.e. $P_{24}$ and $P_{93}$) as predictors produced better predictions than others. However, CVD model produced the overall best predictions, because of the lower RSE and stability in measuring variability across different stand developments. The results demonstrate the potentials of CVD in modelling stem diameter variability in relationship with percentiles variables.

• Journal of Forest and Environmental Science
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• 제11권1호
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• pp.81-101
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• 1995

지표-형질의 상관은 우량 개체 선발과 유전획득량의 증대를 위해 임목 육종에서 해결되어야 할 중요한 과제 중의 하나로 최근 분자유전학적 수준에서의 임의 증폭 다형 디엔에이 (RAPD) 기술의 발달로 이의 해결이 눈 앞에 다가왔다. 호주 퀸즈랜드산림청과 퀸즈랜드대 임목생물공학연구소가 공동 연구하고 있는 슬래쉬소나무, 카리비아소나무 및 그 교잡종에 있어 이 기술을 이용한 수피 두께에 대한 연구 및 육종 계획 전략을 소개한다. 1대 잡종에서 186개의 지표를 포함한 총 길이 1641cM의 16개 연관군의 유전적 지도가 작성되었고, 이 연관군 지도에 수피 두께를 지배하는 6개의 유전자좌가 추정되었다. 또한, 유전적 지표를 이용한 조기 선발을 위해 먼저 중요 형질을 지배하는 유전자들에 대한 종 특성 유전적 지표를 결정하고, 다음 여러가지 대립유전자형에 대한 지표-대립유전자 상관을 구명하는 2단계 전략이 제시되었다. 소나무류는 발아시 양료로 쓰이는 자성배우체는 모수에서 유래하나, 접합자인 배는 양친수로부터 유래하므로 이러한 이질적 유전 조성을 갖인 종자의 발달을 이용한 RAPD 지표와 형질의 상관 연구는 배 단계에서도 우량 개체의 선발을 가능하게 하여 소나무류 육종의 장래를 밝게 하고 있다.