Site demands and life habitat of Maple "Acer velutinum Boiss." in northern forests of Iran

The present investigation is carried out in deciduous mixed forests of Caspian region in north Iran. 18 sample plots each with three and more Maple trees were established from 100 m. a. s. l. up to 2000 m. a. s. l. Moreover, 12 soil profils were studied in the Maple stands of the research area. Totally 248 Maple trees were studied quantitavely and qualitatively. The results showed that Acer velutinum Boiss. (very similar to Acer pesudoplatanus L.) is a light demand tree species which normally appears as groups in the young stage. In adult stage Maple appear as individual trees in the upper layer of mature stands. Nevertheless, Maple individuels and groups were distributed to a variety of soil types ranging from caly soils with poor drainage (marmorized brown soil) to well drained loam/sandy soils (calcic brown soil). The root system of this species is deep with maximum root density between 40 cm and 65 cm of soil depth. Although Maple grows in Oak-Hornbeam (Querceto-carpinetum betuli) stands with campact and heavy soil, but it founds its optimal growth conditions in beech stands (Fagetum hyrcanum) on gentle slopes with well drained soils reach in skelet. Here were the rate of annual diameter and height increment of Maples with mean age of 33 years, 10.1 mm/year and 84 cm/year respectively. Seed fall and regeneration of Maple occurs every year and easily. One year old Maple seedlings are very common on the forest ground flora. Due to light demands of Maple seedlings and ground flora competition, the survival of the seedlings is not very high. Generally, the plant number were reduced by decreased canopy density. In areas with>0.7 crown canopy density, the mean number of Maple seedlings decreased from 5.3/m2 to 0.4/m2, during one year. In areas with < 0.7 crown canopy density, the mean number of Maple seedlings were higher than the first one and decreased from 13.9/m2 to 0.7/m2.