Ocena zdrowotno?ci d?bu na podstawie stopnia ubytku aparatu asymilacyjnego wybranych drzewostanów d?bowych Nadle?nictwa Wo?ów

摘要

D?b szypu?kowy (Quercus robur L.) to najcenniejszy pod wzgl?dem gospodarczym i przyrodniczym li?ciasty gatunek lasotwórczy w Polsce. Drzewostany d?bowe stanowi;) ok. 6% ogólnej powierzchni le?nej kraju [Ceitel 2006]. W ostatnich latach na terenie ca?ego kraju obserwujemy masowe zamieranie drzewostanów d?bowych. Pierwsze doniesienia dotycz?ce z?ej kondycji zdrowotnej d?bów pochodz? z pocz?tku XVIII wieku z terenów Westfalii. Przyjmuje si? jednak, ?e do pocz?tku XX wieku d?by by?y gatunkami niezagro?onymi [Wachter 1999].%Distinct symptoms of oak decline, which occurred in the year 2004 on the area of the Wotdw Forest District, prompted to determine the health condition of this species stands according to the European criteria i.e. on the basis of the defoliation degree. Oak stands in that area are exposed to the activity the Legnicko--Glogowski Copper Industry Region. Besides, the lowering of Odra riverbed, which in that area reaches 3 m, also exerts a significant effect on the functioning of the ecosystems. An estimation of the assimilation apparatus losses was carried out at the turn of July and August in 2005 and 2007 on the basis of an atlas elaborated by Borecki and Keczynski [1992]. Data obtained in this way permitted to classify each tree into four defoliation classes from 0 to 3. In case of a dead tree, it was classified into the fifth class encoded as 4. In the first year of observation, the highest frequency (35.0%) was observed in defoliation class #2 i.e. in stands with medium damages. Class #1 included 33.6% of trees. The assessment was repeated two years later. The number of trees without defoliation symptoms decreased four times, while the number of trees with a strong defoliation and of dead trees increased.