# Assessment of the Mass and Surface Area of the Scots Pine (_Pinus sylvestris_ L.) Needles
## 3 Results
### Characteristics of the Sample Trees  
This was reflected by the total mass of needles from those trees. The fresh mass of needles from a suppressed and thinning tree from the community was merely 0.9 kg (0.42 kg of dry mass). In a dominant tree, this value was 8.38 kg (3.92 kg of dry mass) (Figure 1). The coefficient of variation of the mass of needles was 47%. The median was 3.6 kg, and the mean fresh mass of needles was 3.9 kg. The collected samples of 1000 needle pairs from each sample tree were characterized by a 32% differentiation of mass. The maximum mass of 1000 needle pairs was 105 g at a low total mass of needles in the crown of that tree (2 kg) and at a length of 71 mm, which was higher than average (mean length for the population was 53 mm). The lowest mass of 1000 needle pairs was 39 g at an average length of 46 mm. Taking into account the total mass of needles in the crown of that tree, which was 5.4 kg, the number of needle pairs in that tree was calculated to be more than 137,000. Compared with the crown in which the mass of 1000 needle pairs was the highest, the difference in the number of needles in the whole crown is nearly seven fold (20,402 pcs) (Figure 1). Based on the mass of needles in the whole crown, the mass of 1000 needle pairs, and the number and length structure of needles, we calculated the assimilation surface (surface area) for each sample tree. The calculated surface area of the needles was 5.8-38.4 m\({}^{2}\) (Figure 1), making the difference between the extreme values as high as seven-fold. In one-half of the individuals, the surface area of the needles was below 17 m\({}^{2}\). The highest correlation coefficients were found for DBH and FMN (r = 0.848; \(p<0.0001\)) and SN (r = 0.727; \(p<0.001\)) (Table 1). Figure 1: Median (horizontal line in box), the 25 th percentile to the 75 th percentile (box spans) and a ’whisker’ ranging to maximum and minimum but no more than 1.5 times of the interquartile range (IQR) from the box top and bottom, respectively, (DBH—diameter breast height; H—tree height; H’—crown length; FMN—fresh mass of needles (Dry mass of needles = FMN\(\cdot\)0.468); SN—surface of the needles; FMN\({}_{1000}\)—fresh mass 1000 pairs of needles; NNP—number of needle pairs in a sample tree; LN—mean length of needles). A multidimensional analysis of variables, shown in the form of a dendrogram (Figure 2), showed that trees No. 3, 16, and 18 diverged from the other ones because of their biometric parameters. The group comprised of extreme trees, namely, a dominant tree (No. 18) with maximum biometric parameters (DBH, H, H*), and a suppressed tree (No. 16), which was self-thinning from the tree stand and had the lowest values of the parameters. The third tree in this group (No. 3) had a much-shortened crown and a low mass of needles. On the other hand, it had the highest mass of 1000 needle pairs (FMN\({}_{1000}\)) in the whole test group, which most probably was accounted for by its higher-than-average length. PCA indicated that the first three principal components (PC1-3) explained 92.6% of the total variance. Figure 3 shows the points representing data in PC1 and PC2 coordinates. The length of the arrow projection on the axes illustrates the contribution of the variable to PC1 and PC2. Similar directions of the arrows representing FMN and DBH variables indicate co-variability of the parameters. Similarly, FMN\({}_{1000}\) and LN shared the trend of