Inventory of plant material in forest nurseries by combining an ocular estimate and sampling measurements
Ľ. Šmelkováhttps://doi.org/10.17221/11869-JFSCitation:Šmelková Ľ. (2002): Inventory of plant material in forest nurseries by combining an ocular estimate and sampling measurements. J. For. Sci., 48: 156-165.
Two procedures of the plant material inventories in forest nurseries, used until now, are evaluated: ocular estimate and sampling. A new two-phase sampling procedure has been proposed on the basis of a suitable combination of estimation and counting and/or measurement of seedlings and plants. The optimum size of the sampling unit (length of bed segment) has been defined. The necessary number of bed segments on which the ocular estimation should be performed in the first phase (n1), and subsequently a more exact assessment of the number of individuals and/or their other qualitative and quantitative traits should be done in the second phase (n2), to achieve the required precision of results of ± 2 to 10% with reliability of 95%. A theoretical justification of the proposal as well as a detailed procedure of the accomplishment is presented. The frames have been specified where the proposed method is economically twice as beneficial as the classic sampling method.
forest nurseries; plant material inventory; two-phase sampling method; combination of ocular estimate and exact assessment