In addition to conducting your own site assessment, it is also appropriate to draw on the experience of others. The history of local successful and unsuccessful plantations is relevant. The common stock types used on similar sites in a biogeoclimatic zone will often be acceptable for the planting site being prescribed. Remember when making comparisons, that nursery cultural methods and stock morphological specifications may have changed over the years and that certain stock types used in the past may no longer be comparable to those being grown today.
There are many stock types being requested
Stock type trends
It is also useful to consider what silviculturists are using in other areas. There was a bewildering array of 44 different stock types requested in 1997 there will be more! Considering the number of species and delivery dates used, there are over a thousand different stock types that could be created. Obviously many of these combinations are inappropriate or obsolete.
Enormous changes in stock type selection have occurred during the past several years. In 1987, bareroot, 211A, and 313A styroplugs accounted for more than 70% of the stock sown in British Columbia (see Figure 8). These same stock types accounted for less than 12% in 1993. During the same period, the larger B-sized container types grew in popularity (see Figure 9), approaching close to 70% of total orders in 1993, up from 55% in 1990.
Figure 8. Percentage of stock group sown in B.C. by year, 1987 to 1993.
Figure 9. Percentage of stock group requested by year, 1990 to 1993.
From 1993 to 1997 the predominant shift in the sowing profile has been an increase in the PSB 410 to 20% of the total sowing, with a proportionate decline in the sowing of PSB 313B (see Figure 10). The combination of 211A/313B stock types comprised 47% of the sowing in 1993, compared to 32% in 1997. The combination of 410/415B/415D/412A was only 34% of the sowing in 1993, but had increased to 61% by 1997. It should be noted however, that these provincial trends are dominated by what is sown for lodgepole pine and interior spruce. Additional information regarding trends by individual species is provided in the section on "Current Stock Types by Species".
Figure 10. Percentage of stock group sown by year, 1993 to 1997.
There have been several conspicuous trends in the development of stock types and nursery culture:
The trends illustrate the continuing development of stock types and nursery culture. Many factors have contributed to this development but the most important are:
Many developments in stock types, morphological specifications, and nursery culture can be expected, as nurseries continue to improve on seedling quality. The eventual acceptance or rejection of a stock type or morphological specification for silviculture purposes will depend on the outcome of assessments of field productivity, reliability, and feasibility.
Be sure that only a small percentage
There are a number of experimental stock types that have been proposed for use in British Columbia (e.g., PSB 1015, PSB 1005). These stock types should be selected according to the suitability criteria discussed above. The morphological attributes of the seedlings should be used to match these stock types to appropriate site conditions.
The use of experimental stock types will require the purchase of new blocks at the nursery -- an expensive undertaking for what could be a dead-end stock type. Be sure that only a small percentage of your request is composed of new stock. This will help minimize the cost at the nursery. In addition to cost considerations, the nursery also has to have time to develop acceptable cultural techniques and schedules for new stock types.
The reliability of an experimental stock type needs to be evaluated in the field and nursery for a number of years. In particular, field performance needs to be determined for a wide range of site conditions and weather, and morphological specifications.
Any new stock type must prove