WOODLOT for Windows 2.2 - Reference Manual

Appendix 14 - 3 Yield Information 3.1 The actual volume I am receiving by polygon site is different than what VDYP predicts. How can I adjust this? Use the Volume Adjustment Factor (VAF) to scale your volume up or down by polygon. The VAF is only for use in VDYP and does not affect the TIPSY curve. 3.2 When should I use TIPSY and when should I use VDYP? Use TIPSY for new even aged forests that are managed to a free growing state. Most stands established since 1987 can use TIPSY, as well as those that have received a significant amount of management treatments to equate them to a fully managed stand. VDYP generally should only be used for the "existing yield type" if it is an unmanaged or natural stand. If you plan to manage a deciduous or a partial cut stand, then you must use VDYP for the first and subsequent cuts. Refer also to Appendix 6, and the TIPSY and VDYP user manuals. 3.3 Can I use TIPSY for an older stand that is still 20-50 yrs from harvest? Only use TIPSY for newer stands that have been managed to a free growing state, or those stands that have received a significant amount of management treatments to equate them to a fully managed stand. These stands have the added benefits of full stocking, early establishment and improved stock. Older unmanaged stands should use VDYP yields. 3.4 Can we calculate Partial Cuts using TIPSY yields? No. Because of the PC methodology, we use VDYP, primarily because a partially cut stand is assumed to grow like a naturally in-filling stand. 3.5 What should I use for the Density in TIPSY? Use the initial establishment density. Refer to history records, or make your best estimate. Note that TIPSY will reduce the density in the first few decades to simulate die back and overtopping. 3.6 What yield tables should I use for stands with a deciduous component? Use VDYP for stands with deciduous species. The VAF may be applied to increase yields if you plan to manage by spacing or other means. 3.7 What are surrogate species in TIPSY? TIPSY supports 7 species (Fdc, Fdi, Hw, Cw, Pl, Ss, and Sx) TIPSY uses yield tables from these to apply as surrogates to other species with similar characteristics. When using TIPSY, select the species you wish to use, and WOODLOT will automatically choose the correct surrogate for you. Species that use surrogates are denoted by an asterix (*) and show the surrogate species code in brackets. 3.8 Why would you adjust the OAF1 or OAF2? Do not change OAF1 or OAF2 unless you can substantiate this. OAF1 and OAF2 are set to Research Branch default parameters, which are based on broad representative average managed stands. Contact Albert Nussbaum at Research Branch if you wish to adjust OAF1 or 2. 3.9 Does Crown Closure (CC) keep increasing over time? No. VDYP measures a yield for a given point in time. If your stand is less than 50 years you will need to predict yields using a projected CC for the mature stand. You can do this by using VDYP default CCs (refer to the appendices), or have VDYP provide the default CC for you by entering a SI (tot) Age. Note that TIPSY does not use CC. 3.10 I have a young open grown stand with a low CC. What CC should I use? See the above question. Use the CC that you can expect at harvest, or the default CC from VDYP. 3.11 Can I enter the Crown Closure Class? No. Use the CC %. WOODLOT should warn you if you have a CC below 10%. 3.12 What is the accuracy of FIP data? FIP data is based on a TSA level of accuracy. Therefore, errors over a large piece of land will even out. When TSA level inventory data is brought down to a woodlot level, the accuracy of the data could be out significantly. Therefore, you should do at least a few check plots to measure actual volumes on your woodlot and compare to VDYP or TIPSY.

by Enfor Consultants Ltd. Last Updated March 1999