## 3 Results
### Characterization of Volatiles from Different Parts of A. altissima
Eleven volatile compounds were identified from seedling foliage, and the main compounds included \(\beta\)-copaene (41.72%), \(\beta\)-caryophyllene (26.94%), \(\alpha\)-farnesene (12.74%), and leaf acetate (11.7%), accounting for 93.1% of the total amount. Eight volatile compounds were identified from annual branches, and the main compounds included \(\beta\)-copaene (41.43%), \(\alpha\)-farnesene (22.29%), \(\beta\)-caryophyllene (21.63%), and \(\beta\)-elemene (8.24%), accounting for 93.59% of the total amount (Table 2). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Number**} & \multirow{2}{*}{**Name**} & \multirow{2}{*}{**CAS**} & \multicolumn{4}{c}{**Relative Content (in \%)**} \\ \cline{4-7}  & & & **Healthy** & **Injured** & **Seedling** & **Annual** \\  & & & **Phoem** & **Phoem** & **Foliage** & **Branches** \\ \hline
1 & (1\(R\))-(+)-\(\alpha\)-Pinene & 7785-70-8 & 2.92 & & 0.53 & \\
2 & (\(-\))-Camphene & 5794-04-7 & 8.22 & & & \\
3 & Camphene & 79-92-5 & & & 0.97 & \\
4 & \(\beta\)-Pinene & 127-91-3 & 5.49 & & & \\
5 & (15)-(\(-\))-\(\beta\)-Pinene & 18172-67-3 & & & 0.54 & \\
6 & 1-Decene & 872-05-9 & & 1.7 & & \\
7 & (+)-(4\(R\))-Limonene & 5989-27-5 & & 1.21 & & \\
8 & 1-Undecene & 821-95-4 & & 2.01 & & \\
9 & 1-Tridecene & 2437-56-1 & & 10.05 & & \\
10 & \(\alpha\)-Pinene & 3856-25-5 & & 1.44 & 0.93 & 0.74 \\
11 & \(\beta\)-Bourbonene & 5208-59-3 & & 4.33 & & \\
12 & 1-Tetradecene & 1120-36-1 & & 17.58 & & \\
13 & \(\beta\)-Elemente & 515-13-9 & & & & 8.24 \\
14 & \(\beta\)-Caryophyllene & 87-44-5 & 33.88 & & 26.94 & 21.63 \\
15 & 1-Pentadecene & 13360-61-7 & 2.54 & & & \\
16 & \(\beta\)-Copaene & & & 8.94 & 41.72 & 41.43 \\
17 & \(\alpha\)-Farnesene & 502-61-4 & & & 12.74 & 22.29 \\
18 & 1-Heptadecene & 6765-39-5 & & 2.91 & & \\
19 & 2,4-Dimethylheptane & 2213-23-2 & & 1.62 & & \\
20 & n-Hendecane & 1120-21-4 & & 6.91 & & \\
21 & Dodecane & 112-40-3 & & 1.2 & & \\
22 & n-Tridecane & 629-50-5 & 2.88 & 5.45 & & \\
23 & Tetradecane & 629-59-4 & 3.34 & 2.67 & & \\
24 & n-Pentadecane & 629-62-9 & 3.13 & 6.01 & & \\
25 & n-Heptadecane & 629-78-7 & & 1.12 & & \\
26 & 1-Dodecanol & 112-53-8 & & 11 & & \\
27 & 1-Tridecanol & 112-70-9 & 6.81 & & & \\
28 & 1-Pentadecanol & 629-76-5 & & 1.21 & & \\
29 & Ethyl 2-methylbutyrate & 7452-79-1 & & & 2.24 & \\
30 & Ethyl tglate & 5837-78-5 & & & 0.67 & \\
31 & Leaf acetate & 3681-71-8 & & & 11.7 & 1.65 \\
32 & Bis(2-ethylhexyl) adipate & 103-23-1 & & & & 0.63 \\
33 & Carvacrol & 499-75-2 & & & & 3.39 \\
34 & 2,4-Di-tert-butylphenol & 96-76-4 & 2.39 & & & \\
35 & 2-Phenylethyl-1,1,2,2-d4-amine & 876-20-0 & 17.52 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Volatile compounds of different parts of _A. altissima_ by dynamic headspace method. The number of volatile components from phloem of injured trees exceeded that from phloem of healthy tree as determined by the HS-SPME and dynamic headspace methods. The main components were alkenes (76.04%) and alcohols (56.69%) in phloem of injured and healthy tree by HS-SPME, respectively. The main volatile components of different parts of _A. altissima_ by dynamic headspace method were alkenes, especially for seedling foliage (84.37%) and annual branches (94.33%). Besides, alkenes accounted for 53.05% and 50.17% of the total volatile compounds in phloem of healthy and injured trees, respectively (Tables 1 and 2).