Báo cáo lâm nghiệp: "Optimising the management of Pinus sylvestris L stand under risk of fire in Catalonia (north-east of Spain)" ppsx

... ro- tation length (R) – Age of initial stand) / (Number of thinnings + 1)): − Year of the first thinning: (Age of initial stand, Age of initial stand + 2I); Optimal management of Pinus sylvestris in Galicia ... MATERIALS AND METHODS The stand level offers the first meaningful level of decision mak- ing, and the results obtained for the stand level managem...

Ngày tải lên: 07/08/2014, 16:21

... to selection thinning in the stand was clearly dominated by P. syl- vestris. The higher the discounting rate was, the higher was the opportunity cost of holding trees in the stand; and therefore the initial ... considerations in the optimisation problem, the effect of retaining a minimum number of very large tress in the stand was analysed. The lower p...

Ngày tải lên: 08/08/2014, 00:21

... thinning for the other thinnings; remaining basal area. For the final cutting: years since the last thinning to the first regen- erative cut. Figure 2 shows the simulation of the stand level ... rotation length by allowing part of the harvest to be collected earlier, and with a lower risk of loosing it. The used fire probabilities (0–5%) cover a realistic range of...

Ngày tải lên: 08/08/2014, 00:22

... When a thinning is simulated, half of the basal area is removed equally from all diameter classes, and the other half as a low thinning, starting with the smallest trees. In this study, the regenerative ... percent discounting rate. Optimising the management of Scots pine stands in Spain 107 2.1.3. Simulation of thinnings and regenerative cuttings The simulation sub-s...

Ngày tải lên: 08/08/2014, 01:21

... represented the data almost as well, with both behaving similarly. Thereafter, the selection of the best model focused on these four models. As previously commented, visual or graphical inspection of the ... arranged with all the possible combinations among height/age pairs for each tree and plot, including descending growth intervals. All possible growth intervals typically pro...

Ngày tải lên: 08/08/2014, 00:21

... epidermal cell walls are still incomplete and unstrengthened. In July, the incubation period needed for iso- lation of cuticles is about 7 d (20% pec- tinase, 2% cellulase) ... both the anticlinal and inner periclinal walls of the epiderm was evident, which might be one reason for the poor isolation results. Over the central periclinal...

Ngày tải lên: 09/08/2014, 04:20

... first canonical axis explains 38.8% of variability, both canonical axes explain 53% of variability (Table 2). All axes explain 100% of vari- ability. e whole model was statistically significant ... in surroundings of the studied localities since larch lacks. Model e importance of all explanatory variables, their significance and correlations with axes are presented in Fig. 1...

Ngày tải lên: 07/08/2014, 03:22

... 64 samples of size 100, 32 of size 110, and 4 of size 121. In sampling a nonrectangular area, variability of the sample size will further be increased depend- ing on the irregularity of the particular ... remark- ably reduce trends in the underlying spatial data. Systematic sampling e usual one-dimensional systematic sampling design divides the N units of the p...

Ngày tải lên: 07/08/2014, 03:22

... class below must equal the number of trees growing out from it to the next diameter class above, plus the number of trees harvested (including natural mortalities) in the class. In general, the ... investigations have shown that, although the initial establishment of seedlings is possible even in closed dense beech stands, their later development will be difficult if th...

Ngày tải lên: 07/08/2014, 16:21

... was the initial state downwards in order to model the length of the top zone. The core of the proposed data analysis methodology consists in iterating an elementary loop of model building until ... multiplied by the estimated value of the internode length. All these models require previous knowledge of the number of branches on every parent annual shoot. In g...

Ngày tải lên: 07/08/2014, 16:21