## 2 Results and Discussion
### Differences of Volatile Compounds in Coniferous Needles According to the Extraction Methods
The dominant compounds in the needles were (+)-\(\alpha\)-pinene (mh4), \(\beta\)-myrrene (mh6), \(\delta\)-3-carene (mh14), and (\(-\))-bornyl acetate (mo23) in CP; \(\beta\)-myrrene (mh6), (+ or \(-\))-sabinene (mh7), (+)-limonene (mh18), (\(-\))-bornyl acetate (mo23), terpinenyl acetate (mo27), and stachene (dh3) in CO; and (+)-\(\alpha\)-pinene (mh4), \(\delta\)-3-carene (mh14), (\(-\))-\(\beta\)-phellandrene (mh19), and (\(-\))-caryophyllene (sh13) in TO. The essential oils of CP, CO, and TO comprised 64, 62, and 75 volatile compounds, respectively. The SD method indicated that the most abundant volatiles in CP and TO were monoterpenes, whereas there was a greater proportion of oxygenated monoterpenes than monoterpenes in CO. The major monoterpenes were mh4, mh6, mh14, and mo23 in CP; mh7, mh18, mo23, mo27, dh3, and elemol (so2) in CO; and mh4, mh14, mh19, mo27, \(\alpha\)-humulene (sh20), and spathulenol (so5) in TO. Application of the SE method yielded 68, 75, and 70 volatile compounds in CP, CO, and TO, respectively. The most abundant volatiles were monoterpenes in both CP and CO, while the most abundant were diterpenenes in TO. The predominantly detected volatiles were mh4, mh6, mo23, dh3, eudesma-4(14),11-diene (sh40), and \(\alpha\)-phellandrene (mh13) in CP; mo27, so2, dh3, and rimuen (dh1) in CO; and mh4, mh13, mh19, sh13, sh20, and so5 in TO. The major volatile compounds in each cultivar, regardless of the method of extraction, were mh4 and mh6 in CP, mo27 and dh3 in CO, and mh4 and mh19 in TO. The other volatile components, such as acids, alcohols, benzenes, ketones, aldehydes, esters, and hydrocarbons, were determined to be minor compounds in all samples. Among these, C6 alcohols and carbonyls such as 3-hexen-1-ol (al3), 2-cyclohexen-1-ol (al4), 2-cyclohexen-2-ol (al5), hexanal (c2), 2-methyl-2-pentenal (c3), 2-hexanal (c4), and 2,4-hexadien (c5) were detected in the samples. The major constituents obtained were similar for SPME and SD, while those obtained with SE differed significantly from the other two methods. The predominant volatiles in all samples were monoterpene hydrocarbons. In addition, the compositions of sesquiterpenes varied markedly among the three needle samples, although the contents were relatively low compared with monoterpenes in all samples. In this study, the major sesquiterpenes were sh40 in CP; so2 in CO; sh13 in TO. Also, the relatively high contents of \(\beta\)-cedrene (sh9) and sh20 were determined in TO. On the other hand, (+)-\(\beta\)-caryophyllene (sh14) was detected and positively identified using an authentic standard compound in this study. According to the previous studies, this unusual (+)-\(\beta\)-caryophyllene occurred in _Pellia endviifolia_, _P. epiphylla_ and _Metzgeria conjugate_[12; 17]. In CO and TO, (+)-\(\beta\)-caryophyllene was found with its isomer, \(\alpha\)-humulene (sh20) [26]. Among oxygenated sesquiterpenes, elemol (so2) having green odor was largely detected [21; 22]. After determining the volatile compounds based on cultivars, the three different extraction methods (SPME, SD, and SE) were compared to elucidate the influence of extraction method on the volatile profiles (Tables 1-3). Prior to GC-MS analysis, it is usually necessary to prepare the samples using methods such as extraction and concentration in order to obtain more purified extracts. In addition, it is important to eliminate any interfering matrix to improve the detection limits for the specific compounds [25]. This has prompted the development of several extraction methods for sample preparation [16; 20]. The volatiles extracted by the three extraction methods differed significantly not only with respect to their profiles, but also in their contents (Tables 1-3). With regard to the extraction conditions, the profiles and contents of volatiles extracted using SD differed significantly compared to the other two methods, possibly due to the use of high temperatures.