惠蓀林場紅檜人工林與闊葉樹次生林植群監測

Monitoring Taiwan Red Cypress Plantation and Secondary Broadleaf Forest at Huisun Forest Station

本研究於1998-1999年監測惠蓀林場紅檜人工林與闊葉樹次生林，以瞭解經營施業前後對物種組成與結構的影響。發現各樣區紅檜之之分叉株數所占比率極高（概為50%以上），而隨分叉數愈多，其單株平均胸徑、樹高與材積愈低，又已有如香桂等闊葉樹種入侵，故以胸高斷面積為介量，實施30、50與60%三種疏伐度之疏伐試驗，又由於疏伐後有較大之孔隙產生，並於孔隙下混植牛樟、香楠與烏心石等樹種。另各樣區紅檜之直徑級皆在40cm以內，又以胸徑10-25cm者居多；疏伐前242號造林地之紅檜總株數，以及每公頃材積高於248號造林地，又248號造林地中各樣區的闊葉樹材積較較242號造林地高，尤以A2、B2和C2樣區為然，且高於此等樣區內紅檜之材積，然疏伐後以A1樣區之紅檜的總株數和每公頃材積高於其他疏伐樣區，而疏伐前後皆以B2樣區中紅檜之總株數和每公頃材積最低。建議未來除定期調查紅檜、木荷和臺灣杉等目的樹種，另香桂、薯豆、變葉新木薑子等23種優勢植物，以及疏伐後出現之火炭母草、昭和草、蔓芒萁等13種潛在優勢植物，可為監測之候選指標種。 The purpose of this study was to reveal the change of composition and structure of speciesafter thinning. The monitoring was conducted by vegetation inventory in the Taiwan red cypressplantation and a secondary broadleaf forest at Hue-Sun Forest Station from 1998 to 1999. The rate offorking of Taiwan red cypress was more than 50%, and the higher the number of forking, the lower theaverage diameter, height and volume per tree. Some broadleaf trees, e.g. Cinnamomum randaiense, havebeen observed to invade into the Taiwan red cypress plantation. Therefore, we performed the thinning treatment of 30, 50 and 60% thinning degree based on the parameter of basal area, and mix-plantationwith Cinnamomum kanahirai, Machilus zuihoensis and Michelia compressa under the larger gaps. Thediameter class of Taiwan red cypress was less than 40 cm, and most of them were 10 to 25 cm in theplantation. Both of the sum of individuals, and per hectare volume for Taiwan red cypress in plantationNo. 242 were larger than those in plantation No. 248 before thinning. The volume of broadleaf trees inplantation No. 248 was higher than that in plantation No. 242, especially the plot A2, B2 and C2 (thevolume of broadleaf trees was higher than the volume of Taiwan red cypress in these three plots). Thesum of individuals and per hectare volume for Taiwan red cypress of plot A1 was the highest among theother thinning plots, and the sum of individuals and per hectare volume for Taiwan red cypress of plot B2was the lowest before and after thinning. In conclusion, we suggest the periodical monitor of targetspecies, such as Taiwan red cypress, Schima superba and Taiwania cryptomerioides. 23 dominants, e.g.Cinnamomum randaiense, Elaeocarpus japonicus, Neolitsea variabillima, and 13 potentional dominants,e.g. Polygonum chinense, Crassocephalum rabens, Dicranopteris linearis var. tetraphylla, were alsoselected for the candidate indicators for monitoring.

The purpose of this study was to reveal the change of composition and structure of speciesafter thinning. The monitoring was conducted by vegetation inventory in the Taiwan red cypressplantation and a secondary broadleaf forest at Hue-Sun Forest Station from 1998 to 1999. The rate offorking of Taiwan red cypress was more than 50%, and the higher the number of forking, the lower theaverage diameter, height and volume per tree. Some broadleaf trees, e.g. Cinnamomum randaiense, havebeen observed to invade into the Taiwan red cypress plantation. Therefore, we performed the thinning treatment of 30, 50 and 60% thinning degree based on the parameter of basal area, and mix-plantationwith Cinnamomum kanahirai, Machilus zuihoensis and Michelia compressa under the larger gaps. Thediameter class of Taiwan red cypress was less than 40 cm, and most of them were 10 to 25 cm in theplantation. Both of the sum of individuals, and per hectare volume for Taiwan red cypress in plantationNo. 242 were larger than those in plantation No. 248 before thinning. The volume of broadleaf trees inplantation No. 248 was higher than that in plantation No. 242, especially the plot A2, B2 and C2 (thevolume of broadleaf trees was higher than the volume of Taiwan red cypress in these three plots). Thesum of individuals and per hectare volume for Taiwan red cypress of plot A1 was the highest among theother thinning plots, and the sum of individuals and per hectare volume for Taiwan red cypress of plot B2was the lowest before and after thinning. In conclusion, we suggest the periodical monitor of targetspecies, such as Taiwan red cypress, Schima superba and Taiwania cryptomerioides. 23 dominants, e.g.Cinnamomum randaiense, Elaeocarpus japonicus, Neolitsea variabillima, and 13 potentional dominants,e.g. Polygonum chinense, Crassocephalum rabens, Dicranopteris linearis var. tetraphylla, were alsoselected for the candidate indicators for monitoring.