تحقیقات جنگل و صنوبر ایران (Dec 2004)
Site demands of False walnut (Pterocarya fraxinifolia (Lam.) Spach) in ((Vaz)) Experimental Forest of Mazandaran province
Abstract
((Vaz)) research forest, one of the most important sites of False walnut in Noor Township and Chamestan District was selected for the study. The distribution areas of False walnut at Vaz forests were marked on a topographical map. False walnut grows usually with other species such as Alder, Persimmom, Caspian poplar, iron wood, mape and hornbeam. with regards to False walnut site condition and its distribution in special parts of the forests, selection of sample plots was not done randomly, but was made manually through recognition of areas, where the False walnut was dominant. The quantitative and qualitative characteristics of the individual trees were measured and recorded within the sample plots with an area of 1000 m2. The results show that False walnut grows often on clay – deep soils, northern slops of 5 – 10% gradient, altitudes of 500 – 1000 m.a.s.l. and river banks and valley sides with low gradient slope. Vaz forest contains the upper distribution limit of this species in the Caspian region, where it appears up to 1330 m.a.s.l. Mean stock volume of the studied stands was 415 silve per ha, which 55.6 and 22.9% of it belong to False walnut and Alder species, respectively. In view points of species composition, the False walnut, Persimmom and Alder contributions were 56.4, 14.5 and 8.0%, respectively. The average annual diameter and height growth rate differed at different age stages. For instance, the maximum height growth was at age of 20 year and over 55 year. The False walnut density was 142 stem number per ha, which increased up to diameter class of 35 cm and then decreased over this class. More than 80% of the False walnut trees contain diameter of l0 to 45 cm. Despite of the high density of False walnut seedlings, regeneration was not satisfactory and was generally asexual (root sucker). False walnut trees grow as over as over storey form in most of its sites of the Caspian Forests with Alnus subcordata C.A.M., Alnus glutinosa Gaetn, Acer velutinum Boiss, Carpinus betulus L., Populus Caspica Bornm., Fraxinus excelsior L. and Juglans regia L., but in the investigated sites grow as two storey from. The False walnut qualitative characteristics (stem straightness, natural prunning and crown symmetry) were not desirable. Sixteen percent of the studied trees were attacked by pests and diseases, decayed or had crown breakage.
