steps to sustainable and community-based ntfp management

APPENDIX Imeasurement of size for the younger, stemless plants. Once a stem is apparent, however,stem height or length is used.Other plant conditions. Other observations and measurements should be made, if desired, ofother conditions such as a plant’s age, sex, any evidence of poor reproduction or health,or any signs of previous harvesting (see Section E.3.4).Plant seed production rates. The seed production rates of a plant population can be estimatedby collecting seeds from seed-bank soil cores or seed traps, as described below (Sutherland,1996):• Seed-bank soil cores. Soil cores are useful for estimating the density of seeds in the seedbank. If placed under canopies, they can also be used to estimate the seed productionof individual trees. Soil cores are taken using a soil corer, or a sheet-metal cylinder ofdiameter 2 to 20 cm (depending upon seed size) with one sharpened rim. This corer ispushed into the soil at a specified depth that can range from 5 to 20 cm. Care must betaken in sampling soil cores because of variation in space and time. Seed traps shouldtherefore be sampled objectively, and taken at the appropriate time or times over theseason of seed production. Usually, many samples are needed. The soil core should beseparated into layers (e.g. 0-2, 2-5, >5 cm depth) and the number of seeds in each layercounted. This is done by wet sieving, or running each soil layer under a running tapthrough stacked layers of mesh to sort seeds from soil. The layers of mesh should beof different sizes, starting with the largest size as the top layer. The seeds should thenbe sorted, identified and counted. To identify seeds, it may be necessary to germinatethem.• Seed traps. These are useful for estimating the density per unit time of seeds arrivingat the soil surface. Seed traps are placed on the soil surface. The traps can be madein a number of ways, but sticky traps are most popular. A sticky trap is a petri dishwith a circle of sticky paper inside; this allows removal and replacement of the stickypaper. As with soil cores, care should be taken with sampling because of variation inspace and time. Seed traps should therefore be sampled objectively, and taken at theappropriate time or times over the season of seed production. Usually many samplesare needed. The seeds should be sorted, identified and counted. To identify seeds, itmay be necessary to germinate them.Plant germination rates. The germination rate of a population of seeds (or the proportionof living seeds out of the total number of seeds sampled in the seed production studiesdescribed above) can be estimated using either seed viability tests or germination tests, asdescribed below (Sutherland, 1996):• Seed viability tests. Two types of dye, tetrazolium or indigocarmine, can be used todetermine whether seeds are dead or alive. Tetrazolium (triphenyltetrazolium chloride)stains living tissue red and remains colourless if the seed is dead. Indigocarmineremains blue if the seed is dead but goes colourless in living tissue.186