Abstract
Hyrcanian or Caspian forests follow a profile along the northern slopes of the Alborz mountain range, located in the provinces of Gilan, Mazandaran and Golestan in northern Iran. The area is approximately 800 km long and 110 km wide and a covers ca 1.84 million hectare. There are few protected forest patches across this extended area in northern Iran, but Kheyrud forest is one of these reserves, which has been under the direct supervision and protection by the University of Tehran for an extended period of time. The area includes three elevational classes, lowland (50-500 m), submountain (501-1000 m) and mountain (1001-2200 m). It lies seven km east of Now-Shahr and covers an area of 10,000 hectare. Based on floristic collecting during spring, summer and autumn of 2008 and 2009, three plots were made, each with a 100 m elevational interval. Floristic data were collected in 234 plots. Data related to elevation, slope and direction were also noted. A total of 295 plant taxa were encountered, out of which 29 taxa (10%) are endemic to Iran and 16 taxa (5.5%) are only found in the Hyrcanian provinces. Classification based on life form indicates that geophytes (with 110 taxa, 37.5%) constitute the largest proportion. Chorologically, the largest proportion of the flora is constituted of Euro-Siberian elements (72 taxa, 24.7%). In addition to general assessments, variation of life forms between the study area and other similar areas are discussed. A comparison was made between the floristic data of the three elevational belts. The result of this investigation indicates that the species diversity increases with the increase of elevation. Likewise, the proportion of hemicryptophytes and geophytes are more prominent in the montane belt above 1000 m.
