Evaluation the Effect of Climatic Factors on the Development of Medicinal Species Nepeta cataria Habitats in Northwestern of Iran

Medicinal plant is defined as a plant with at least a part having medicinal and healing properties for living organisms. Iran has a rich collection of medicinal plants and is known as one of the best places in the world in terms of climatic, geographical and growth condition for such valuable plants. Population growth and emergence of pharmaceuticals companies that produce medicines from herbs has led to an increasing rate of harvesting of these plants on their natural habitats, intensifying the pressure, habitat destruction and the extinction of some plant species of the country. An alternative option to prevent this problem is to plant and crop wild species. The present research aims to update information and develop insights on climatic characteristics of habitats of species Nepeta cataria in the northwest of Iran. This species is the most famous species of Nepeta in the world which widely grown in large parts of Europe and Asia such as Iraq, Iran, Afghanistan, Pakistan and India but in the US it is widely cultivated. Nepeta cataria has been used as a medicinal plant to urination, pulmonary vasodilatation and blocked uterus opening and disposal of body worms. Essential oil is main constituents extracted from its flowering branches and inflorescence.

Study area: Natural habitats in northwest of Iran in three provinces of West Azarbaijan, East Azarbaijan and Ardebil with an area exceeding 100000km2 (about 6% of the country), were considered as study area. The spatial distribution of the species and ecological variety in the northwestern of the country, is one of the reasons for choosing this study population.Data: Preliminary data, used in this study, were included meteorological data at 29 synoptic stations in three provinces of Ardabil, East Azerbaijan and West and neighboring provinces (including in southern Kurdistan, Zanjan and Gilan provinces in the South East in study area) in point-data format with the period from the beginning of the recorded date to the end of 2005, were measured and recorded. Annual and monthly climatic variables included 30 variables in temperature, 6 in humidity, 12 in precipitation, 6 in wind and 6 variables in sunshine group.

In this study, a kriging interpolation method was used to generalize the data and mapping the spatial distribution. As a result, grids with dimensions of 10 × 10 km within the study area was established and finally matrix with 75 columns and 1055 rows (the intersection of grid lines) for the entire study area was prepared. Factor analysis was used for reduction of data matrix dimensions. Before using factor analysis, KMO (Kaiser-Mayer-Olkin) index and Bartlett's test of sphericity, were tested. Principal Components Analysis with correlation matrix type and up to 25 rotations was performed to extract the maximum operating frequency for convergence model. A Varimax method was used to improve relationship between variables and initial factors and apply special transformations on the factors, one of the most common methods is orthogonal to maintain independence between extracted factors. In this study, regression analysis was used to calculate the factor scores where, regardless of rotations, the number of related factors are estimated. The factor loadings with values greater than 0.6 were considered.

The climate type of northwest of Iran is resulted from the interaction of five different factors. They cover 88.5 % of total variance including thermal temperature (30.9), temporal rainfall pattern (19.2%), temperature of the cold season (19.2%), wind (11.4%), and rainfall (7.8%). The results of cluster analysis demonstrated that six climatic zones were detected in the study area as follows: temperate high rainfall, temperate semi-arid, cold semi-arid, temperate and windy semi-arid, and humid temperate. According to the results obtained from the adaptation of species distribution and obtained climate maps, thermal temperature, with an average value of -0.83, was identified as the most negative influential factor affecting the species distribution. The average height in the areas of medical plants is about 2000 meters from sea level with annual precipitation of 381 mm. The number of rainy day is 96 days per year in this area.