In situ and Ex situ Conservation of Commercial Tropical Trees - ITTO

157the samples depend on the breeding systems. In self-fertilized species, wildingsor seeds will genetically resemble the parent tree. But for out-crossing species,wildings or seeds will differ to a greater or lesser degree from the parent, andexhibit within-family diversity.In general, Dipterocarps produce fruits only at irregular intervals, andhave recalcitrant seed. During the duration of our project, no fruit of Shorealeprosula was available. Therefore, it was decided to collect wildlings, in situ.For Lophopetalum multinervium, we were able to collect seeds,however.Collection of genetic materials of Shorea leprosulaSince preserving genetic diversity is essential, the project needed to give carefulconsideration to developing and conducting a sampling strategy in eachpopulation. Conservation of genetic resources of trees requires an understandingof the biological dynamics of the population in which they exist. Especiallyimportant is knowledge of the diversity and distribution of genes in a treepopulation.Basic sampling strategyIn collecting genetic materials we decided to use two-stage sampling (Brown& Marshall 1995, Brown & Brigg 1991). The population was divided into 5 to10 sub-populations, then each sub-population was divided into 5 to 10 blocks orcompartments. The size of each block was about 100 hectares. In eachpopulation we planned to have about 50 blocks or compartments. Samplingpoints were chosen randomly within each block and there are 10 points in eachblock. At each point we selected 5 “best” and 5 “average” trees, so that ineach population we will have 2,500 best trees and 2,500 average trees. Wildingswere collected under these selected trees.Number and location of sampling points (sites) per populationIn each population we selected 50 sampling units. These sampling units werelocated systematically in each sub-population. Each sampling unit encompasses100 hectares of forest area and sampling points were chosen randomly withineach sampling unit. Ten sampling points per sampling unit were chosen so thatthere are 500 sampling points per population.