Sampling
One of the most important issues related to conducting a non-timber forest inventory is the question of how thorough it
should be. Should you take a complete census of each tree and non- woody plant that occurs in your forest? If you have more
than an acre or two of forest that would be impossible, or at least impractical. If you are not going to include every plant in
your inventory then how should you choose which to include?
The best approach is to intensively and thoroughly sample one or more smaller areas (plots) of uniform size that are typical
of the biodiversity on your entire site. Most likely your site is not uniform in terms of elevation, aspect, soil type,
vegetation community, etc.. Therefore you should sample one or more representative plots from each different ecological niche
within your heterogeneous forest. This sampling strategy can be “seat of the pants” – what seems to you to be representative
of the whole or some subdivision. Or, it can involve a systematic, randomized plot selection methodology. The former may
involve simply recording what you already know about vegetation types and associations on your land, especially if it is
relatively small and you know it well. The latter is particularly well suited for large blocks of forested land that have a
great deal of plant variation and a wide range of slopes, elevations, aspects, and microclimates.
- Blank Site Assessment Workbook [PDF Version] [MS Word Version]
Notice that the workbook table is designed for recording the vegetation of zones by sampling points 1-3 within each zone. You may choose your points randomly, but it is probably more constructive to choose several points representative of different microclimates or soil types on your site. Or simply look for several areas with obviously different plant communities and sample within each area. As stated above, you choose how extensively to sample and which species you will record and consider. The next section [5.1] provides useful sources for botanical identification.
- MNG Case Study Workbook provides example trees & shrubs and understory inventories.
- Conducting a Non-timber Forest Crop Inventory, Chapter 10 and Appendix A in the Guide to Agroforesty In British Colombia.
This section of the BC guide is a particularly helpful resource for instruction on how to develop a formal plot selection strategy This chapter presents a systematic approach (including sampling strategy) to undertaking a thorough non-timber forest crop inventory. Appendix 5: Inventory Information, in the same guide, describes associated methods such as measuring tree height, and other useful information.
- Rope Method For Non Timber Vegetation Inventory (pdf)
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