1. "The structure and management of uneven-aged and mixed plantation stands (3/3)" :
This study plans to investigate formerly established multi-storied plantation sites. Through investigations on growth, mortality, and succession of upper- and lower-storied trees and analyzing structural indices, dynamics information of intra- and inter-specific tree competition and species succession in different time series can be established, which can be applied to the decisions of adequate species mixture in mixed stands, alternations in spatial and temporal allocation, and management benefits. We will also analyze the quantitative indices of horizontal and vertical structures in artificial mixed plantation stands at different management phases, which can serve as reference data for mixed stand management or transformations of pure stands into mixed or multi-storied ones. The results can also be applied to enhance carbon sequestration, productivity, and biodiversity of artificial mixed plantation stands.
2. "Early grown on mixed plantation of Michelia compressa and Calocedrus formosana" :
The purpose of this project is to investigate the effect of planting density, given the constant mixed ratio of two species, on the early growth of timber growth on mixed plantation of Michelia compressa and Calocedrus formosana in Lienhweichih Experiement Forest. Based on the yearly work in plot survey, the condtruation of microsite terrain model on plot area, crown closeure analysis, microenviroment monitoring, spatial stand structure comparison and data analysis, the results of this study can be served as the base for mixed stand management reference.
3. "Management and effectiveness evaluation on broadleaved trees mixed stand (3/3)" :
According to the abundance of native broad-leaved trees species resources in Taimalii research centre, TFRI, the study focus the interests on the biology, ecology and growth characteristics of the mixed stands and plantations in this area, planning workshop including the investigation of growth status, and the monitoring on the affections of different mixed planting models to micro condition of the site. The results will be utilized to design the strategies of establishment and the accessing management of the mixed stands. On the other side, to evaluate the benefit effect of them will be analyzed simultaneously, by the way, regulation procedures will be used to analyze the effectiveness of the carbon sink of different management model of mixed stands. The research results for the third year are as follows:
On the aspects of the forest stocks, the best combination of the core and periphery species is both Formosan Michelia separately. The average stock is 183.99 m3/ha. On the other hand, the stocks values larger than the total average are for the combination of Comphor-Formosan Michelia, Comphor- Comphor and Formosan Michelia- Comphor. The values are 162.40、143.39、151.13 m3/ha separately. The lowest value of the stock is the combination of Formosan Ash- Formosan Michelia and its value is 113.24 m3/ha. On the aspects of the carbon sinks, the largest value is the combination of Formosan Ash- Formosan Ash and the average carbon sink is 85.74 ton/ha. On the other hand, the stocks values larger than the total average are for the combination of Formosan Michelia -Formosan Michelia, Formosan Ash – Comphor, Formosan Ash- Formosan Michelia and Formosan Michelia - Formosan Ash. The values are 76.39、75.03、70.52、71.59ton/ha separately. The lowest value of the carbon sink is the combination of Comphor - Comphor and its value is 47.09 ton/ha. From the above results, the values of the stock and carbon sink for the combination of Formosan Michelia- Formosan Michelia are 183.99 m3/ha and 76.39ton/ha separately. And the values of the stock and carbon sink for the combination of Formosan Ash –Formosan Ash are 131.9 m3/ha and 85.74 ton/ha separately.
On the aspects of vegetation survey, the biodiversities for different mixed models display 1% significant difference. The combination of Formosan Ash- Formosan Michelia got the largest value (0.85) and the Comphor – Comphor the smallest (0.67). For the micro-climate aspects, the related Luminosities display 1% significant difference also. The combination of Formosan Michelia - Formosan Ash got the largest value (63.34%) and the Comphor – Comphor the smallest (15.02%) also.
For the analysis of benefit-cost effect, the largest NPV is the combination of Formosan Michelia- Formosan Michelia(119,968 NT dollars/ha) and the smallest is the Comphor – Comphor combination(-70,594 NT dollars/ha). Because the high relationships between the NPV and IRR, the IRR reveals the same tendency, i.e., the combination of Formosan Michelia- Formosan Michelia shows the largest((11%), and the Comphor – Comphor the smallest (-1%)