抄録: This study conducts a survey on the urban forest parks in Taiwan to assess the benefits and affecting factors. The results show that the larger the area of the park, the higher the degree of satisfaction with the landscape and the status of the plants, and the higher the density of trees, the lower the degree of satisfaction with the scenic view. The shading effect is positively correlated with the diameter of plants at breast height, canopy cover area, and proportion of green coverage. However, higher green coverage is associated with lower satisfaction regarding the scenic view and the uniqueness of the landscape. Most visitors are less satisfied with the area of plants and landscape attractiveness. The study results can be used to evaluate the impacts of setting up urban forest parks. The outcomes also provide guidance for the relevant authorities for sustainable management and future policy making.
抄録: Estimation of lumber yield from a forest inventory is important in determining the optimal utilization of available regional wood supply. In this study, we review existing approaches of lumber yield estimation, including knowledge-based empirical board-foot log rules used in the United States and some regions of Canada, survey-based wood conversion factors, and optimization technology-based computer simulations. Lumber yields estimated from different approaches are then compared using six datasets from a white spruce commercial thinning experiment in Alberta, Canada. Our results indicated that (1) estimated lumber yield can be significantly different when different methods are employed; (2) board-foot log rules often underestimate lumber yield; (3) wood conversion factors represent regional average of lumber yield as a constant and thus are unsuitable for forest inventory-based lumber yield estimation; and (4) optimization technology-based computer simulations can provide the best estimate of lumber yield for a given forest inventory as long as the mill conditions and lumber dimensions from market demand are specified. Forestry investment in applying computer simulation methods should be encouraged in sawmill operations to improve lumber yield and enhance environmental protection, because, for a given amount of lumber, improving lumber yield means reduced demand for harvest operations.
抄録: Fast-growing poplar plantations are considered of great benefit to both timber production and carbon (C) sequestration, and are increasingly planted for multiple purposes worldwide. Irrigation and fertilization are common management practices in plantations in semiarid regions. However, quantitative investigation of the integrative effect of surface drip irrigation and fertigation (SDIF) on biomass and C storage in poplar plantations remains limited. In this study, we conducted a field experiment on a fast-growing poplar cultivar (Populus × euramericana cv. Guariento) plantation to compare the combination of surface drip irrigation and fertigation in growing seasons with conventional management (control; CK). Experiments repeated over 2 years showed that SDIF significantly increased biomass and C storage in both trees and soil in the plantation compared with the CK. Tree biomass C in SDIF-treated and CK stands after the first year of the experiment (age 5) was 6.20 and 4.05 t C ha-1, respectively, and the difference further increased, i.e., 15.18 and 8.63 t C ha-1, respectively, after the second year of the experiment (age 6). There was 53 and 76 % higher C storage in SDIF-treated trees than in the CK trees after the first and second years of the experiment, respectively. The SDIF increased the soil C concentration, especially in the surface soil at 0- to 40-cm depth. Soil organic C at a depth of 0–60 cm under the SDIF treatment was 45.42, 50.87 and 61.32 t C ha-1 in the 1st, 2nd and 3rd years, respectively, with annual increases of 12 and 21 % between the first and second, and second and third year, respectively. The corresponding soil organic C in the CK was 43.08, 43.57 and 47.92 t C ha-1 in the 1st, 2nd and 3rd years; the annual increases were only 1 and 10 %, respectively. The results confirmed the significant effect of the combined management on C storage in poplar plantations, thus we suggest it can be applied in forestry management, even though it generally did not change C concentrations of tree components.