Accuracy assessment of a small-area method for estimating the spatial distribution of the degree of tree damage.
Tree damage, gauged by the amount of defoliation, is one of the basic criteria used to determine treatments for protected and economic forests. Monitoring should include an assessment of the degree of tree damage in different spatial scales. Therefore, in addition to the commonly applied large-area methods, small-area methods should be used. The aim of the paper is to present the results of the accuracy assessment of a small-area method, proposed by Podlaski (2005) [Podlaski, R. (2005). Inventory of the degree of tree defoliation in small areas. Forest Ecology and Management, 215, 361-377], for monitoring the degree of tree damage. The degree of tree damage was shown in sub-blocks P(3) of the system of information on natural environment (SINUS). To estimate the spatial distribution of the degree of tree defoliation, survey sampling, based on simple random sampling with replacement (SRSWR), was used. The degree of damage to fir (Abies alba Mill.) and beech (Fagus sylvatica L.) was analysed in the Swiety Krzyz forest section in the Swietokrzyski National Park. The maximum total estimation errors for the proportion of trees with a degree zero of damage, and with second and third degrees of damage together (for alpha = 0.05) were at most 30.8% for fir and 24.3% for beech trees. For standard, small-area evaluations, these are satisfactory values. In the Swiety Krzyz forest section, the number of P(3) sub-blocks with 0.00-5.00% of undamaged trees and with 80.01-100.00% of moderately- or severely-damaged trees was significantly greater for fir than for beech. These results indicate that the fir population was unhealthier than the beech group in the study area. P(3) sub-blocks of the SINUS system, in which the proportion of the healthiest trees was highest, were situated at the forest margin, bordering on meadows and arable fields (in the case of fir) and forming dense patches consisting of several sub-blocks, or occurring singly in the whole study area (in the case of beech). The results show the significant differentiation of forest tree health in small areas.
Podlaski
Rafał
R
Department of General Biology and Nature Protection, Institute of Biology, Pedagogical University of Kielce, ul. Swietokrzyska 15, 25-406, Kielce, Poland. r_podlaski@pro.onet.pl
D044822:Biodiversity; D003625:Data Collection; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D004787:Environmental Pollution / Q000009:adverse effects*; D016468:Forestry; D005843:Geography; D018515:Plant Leaves / Q000187:drug effects* / Q000254:growth & development; D011044:Poland; D011157:Population Dynamics; D018570:Risk Assessment; D014197:Trees / Q000187:drug effects* / Q000254:growth & development