Height growth , diameter increment and age relationship response to sustainable volume of subtropical Chir pine ( Pinus roxburghii ) forest of Karaker Barikot forest

This study was conducted in the Karaker Barikot forest of district Swat Pakistan to measure the relation of average tree height, diameter increment and age of Pinus roxburghii to the sustainable volume production. Total forest area was 724 hectares. Systematic sampling intensity 2.5% was used for the study area. Data was collected from 119 plots (1 plot= 0.1 hectare. The tree height (m), diameter increment (cm) and age (years) were measured using Spegial Relascope, Increment borer, and Diameter tape. The maximum tree height was estimated 23 m of 70 year age, and minimum 8.5 m of 13 year age. The maximum diameter increment was found (5.4 cm for lower diameter classes (12 cm) and minimum for 2.2 cm of higher diameter classes (64 cm). The total average number of trees and volume were found 1314, 1104 m3 respectively. The R2 values were (.37, .98, .99 of tree height, increment and age with diameter classes (12-64 cm) respectively. The R2 value (.988) was found significant for age and increment. It was concluded that there was significant relationship to the average age and height of Pinus roxburghii to the volume production. It was further concluded that the maximum growth increment significantly put the forest on the way to sustainability.


Height growth, diameter increment and age relationship response to sustainable volume of subtropical Chir pine (Pinus roxburghii) forest of Karaker Barikot forest
Muhammad Sadiq khan ‫٭1‬ , Salman Khan 1 , Wisal Shah 1 , Ahmad Hussain 2 and Shah Masaud 3 Introduction Tree Diameter at Breast Height (DBH), tree height and tree density are the most important variables for forest inventory.It directly influences inventory attributes spatially the yield estimate and precision of tree growth of radiata pine [1,2].Tree density has effect on both external and internal characteristics of trees within a tree stand by varying competition among trees for nutrients, water and solar radiation [3,4].
Forest Stocking direct link to diameter growth in many studies.Tree diameters were not related to forest density (620 to 12,000 stems per ha) in young P. radiata stand up to age 4, however a minimum of diameter growth was observed with high density during the 5 th growth season [5].The effect of density on the growth of height has been estimated to be low count than diameter growth [6], although several studies reported the increase of height to have great effect by high density [7].Although in the field parameters of a single tree i.e. diameter and height can be measured directly in the field.The average maximum height of the dominant species of these forests is 45-60 m for Abies pindrow and Cedrus deodara while 30 -45 m for Pinus wallichiana [13].
The regression analysis between diameter and height was carried out it was pointed out that all the species have linear relationship with diameter (cm) with different values of co-efficient of regression (R²).The maximum average height showed by the dominant species (Fir, Kail, Deodar, and Chilgoza) of the study area to be 20.40,16.06, 12.24 and 12.12 m respectively.Moreover the average maximum volume attained by the Kail, Fir, Deodar and Chalgoza trees was 1.92, 1.57, 0.46 and 0.291 m3•tree−1 respectively.The R² value for the average height and diameter was .99,.98,.89,.99[7].

Study area
Karaker forest is located at 34 ° 36′ N, 72 ° 14′ E and 34 ° 38′N, 72 ° 17′ E coordinates, and elevation range from 800 to 1900 m from mean sea level.Present study was conducted in six compartments (724 ha) of Karaker Forest, Swat K.P. Detail map of the area is shown in Figure 1.

Method
The study was conducted to estimate the tree height age, and diameter increment relation to diameter classes of Pinus roxburghii.2.5 % sample intensity was used; total of 119 plots were taken in the study area using systematic method to equally distribute the plots in the study area to get unbiased data.The instruments Speigial relascope, increment borer, and diameter tap was used for data collection respectively.An instrument increment borer was used for the extraction of core from the standing tree and the last ten years rings were counted and measured to estimate the diameter increment and age of the tree.Speigial relascope was used for the diameter and height measurement of the trees.The data was analyzed among the diameter classes, diameter increment, height and age groups of the forest.The data was also statically analyzed through linear regression and correlation (Therrell et al., 2007) [14].

Diameter and height relationship
The result found that the maximum tree height was 23 m of 56 cm diameter class and minimum of 8.5 m of the lower diameter class 12 cm, total diameter classes ranges were 12-64 cm.The statistical results were significant of r = .609,and R²= .37 (fig.2).Similar study reported that the A. Pendrow, P. Williachina, C. Deodara and P. garardiana trees had height of 20.40, 16.06, 12.24 and 12.12 m respectively Raqeeb et al., (2014) [7].The minimum average heights for all species were 2.42, 2.58, 3.03 and 3.33 m respectively.The value of R²=.99 indicate that the relationship between the diameter (cm) and height (m) was found significant.Sheikh (1993) [13] revealed that the height range of the dominant species were found 45 -60 m for Fir and Deodar, while 30 -45 m for Kail respectively.It was concluded that the tree diameter have a significant effect (Correlation was significant at the 0.01 level (2-tailed) on the tree height of the trees in the study area.

Height and diameter increment relationship
The present study estimated that the maximum diameter increment was 5.4 cm at diameter class 12 cm, and decreases as diameter increases and found minimum 2.25 cm at 64 cm diameter class, because with the increase in age, height and diameter the average increment decreases.The correlation and regression was r = -.997, and R²= -.997 found negative (fig.3).The similar study reported that the ratios of total tree height to diameter at (DBH) for damaged trees were significantly higher than for undamaged trees for all species at a significance level of 0.05 (P-value < 0.001) (Wann 2001) [15].It was found that the present study have a strong significant (Correlation is significant at the 0.000 level (2-tailed) effect among tree height and diameter increment.

Diameter and tree age relationship
The research study found that there was strong relationship between diameter and age of the tree, the diameter have a direct proportion to the age of the stand.The lower diameter class (12 cm) has 13 years age and the high diameter class (64 cm) has 70 years age in the study area.The relation was statistically analyzed and found the value of r = .99(p>.01) and R²=.99 (fig.4).Similar study revealed that growth rates changing among individual trees in the nine study sites.The change in the total stem diameter (TSD) at (100 yr) age, between the fast and slow growing trees, at study sites and found that a slight as (10 cm)

Figure 3 .
Figure 3. Relationship of diameter classes and mean increment of study area

Figure 6 .
Figure 6.Relation between Diameter classes verses height, age and volume

Relationship between tree height and tree age of the study area (Karaker forest) Diameter, age and volume relationship
The average diameter class range (12-64 cm) and average ages (13-74 yrs) of the Karaker forest contribute to the average standing volume 1104 m³.The maximum volume was at higher diameter (30-64 cm) and age (31-74 yrs) range, and found 831 m³.the result of this study found that the age and height have a great contribution in average volume production as shown in (Fig6).