INTRODUCTION

A sustainable ecosystem might be defined as one that continuously provides its services needed by the current and future generations of humans and other life forms (Vavra, 1996). The suitable species selection for afforestation is one of the most important factors in afforestationin order to development and interplanting of forest. The miss-selection of suitable species according to edaphically climate and site conditions had not been producing desired issue or mostly the species would be destroyed. Given the importance of the afforestation in different grounds, planting species out and forest interplanting should be given priority, according to environmental capability of each region. Changes in species diversity, structural diversity and the abundance of non-native species are common concerns that are part of the international criteria for assessing sustainability of forestry practices. Because vegetation is the source of primary production for habitat, changes in the distribution of vegetation can be affected on many elements of an ecosystem (Kerns and Ohmann, 2004). Accordingly, given the important of ensuring the protection and continuation of this valuable heritage for future generation, afforestation should be accompanied by a careful selection. If a careful selection was not involved, the afforestation would not be efficient, the death of the planted saplings would not be likely and the potential of the land would not be fully explanted. Therefore, a region should be afforestated with suitable species and it should finally fulfill the intended purposes. Zeng et al. (2007) proposed decision support system for the evaluation of long and short term dangerous of wind destruction at Boreal forests. Liu et al. (2006) used a method based on Geographic information system for the evaluation of optimal allocation of land at Qinling mountains of China and they demonstrated that it must be classified into five applied classes in the studied site including agriculture, forest, rangeland, wood culture- agriculture and desert. Wakeel et al. (2005) show that the forest covers varied with population increase and agriculture development in central India at during 30 years and can replaced by afforestation with native species. Shahadat and Kwei (2003) used geographic information system for the suitable areas selection for the afforestation of Mangrove species in coastal areas of Bangladesh. They showed that the Mangrove forests could have existed in Bangladesh under both natural and artificial situations. Dilek et al. (2007) investigated on the Golbasi specially protected area in Ankara in order to afforestation using geographic information system. They concluded that it should be investigated the hydrological landscape and erodibility in studied sites in order to determination of the afforestation area and rapid reaction for special area protection. Lie et al. (2002) used the geographic information system as a targeting system for creating of new woodland in association with existing ancient woodland in the Chiltern Hills area of England. Gilliams et al. (2005) reported capable of providing advice for policy and planning decisions for agriculture land afforestation at European north-west. Monitoring of changes in the plant species distribution can serve as indicators of undesirable impacts to ecosystem (Vitousek et al., 1996), ecosystem stability, the status of other organisms and ecosystem dynamics that are more difficult for measurement (Daubenmire, 1976; Gray and Azuma, 2005). In this reason, the suitable selection of species has been lack to scientific criterions in the area and it result that waste of time for suitable increment, soil erosion and economical losses. Thus, the Aim of this research were selection of suitable species for afforestation in southern forest of Caspian sea at 25 watershed based on nature of species, suitable places in respect of edaphic, climatic and site for planting and interplanting using geographic information system, Arc GIS software and definition layers. Until, it used into suitable model for afforestation in the other sites.

MATERIALS AND METHODS

Site of Study
Shemroud 25 watershed is one of the basins which ended to Caspian sea. It is located 47 km far from province center (Rasht) and located in Eastern longitude 49 50’ 9” to 49 50’22”and Northern latitude 36 55’21” to 37 09’21”. It is connected to Siahkal city. The whole watershed perimeter was 72.10 square kilometer that has been allocated about 18961.81 ha. Shemroud basin surrounded by plain land and Siahkal from north’s side, Polroud watershed basin from south’s side and Shalmanroud watershed basin from the West’s side. This basin has been combined 13 hydrological sub basins and 3 non-hydrological sub basins. The lowest height of the basin was 30 meter and highest height was 2100 m and average height was 775 m (Fig. 1).

Method
In Shemroud basins, first of all the maps of 1: 25000 are related to this basin received of Iran survey organization and so have been figured. Information of local station and power ministration has been used to drawing the isohytal and isothermal maps. For preparing information of polygons with cover plant, design forestry has been used in the site of study.

Fig. 1:	Location of study area

The ecological needs of species has been used base on consultation and specialized judgment from forest experts and topological studies of local species. Then interplanted area determined without plants on the map in the form of information layer as polygons. These maps was prepared in order to specifying of the interplanted areas and suitable species in afforestation based on the site conditions which was the main aim of this research.

Afterwards, it was monitored the forests using GPS and controlled the ground and then were analyzed the locations of Polygons especially the largest’ polygon. Then, it was dominated ecological conditions of the site including climatic, geology, pedology, height far from sea level, slope and aspect. The available rural maps in the area serving were prepared as biotech factors through different information layers. On the other side, ecological requirement of 16 forest plants (that they had the verge of extinction or had the most extent of production in forest Nursery was extracted) which these parameters included temperature, precipitation, soil type, height far from sea level, slope and appropriate aspect of each species. The data were collected between April 2008 and June 2009. Firstly, for performance, required layers of vector format transformed to Raster, then in order to categories into layers, they classified with range of 0 to 9, based on ecological different requirements of species. So, suitable conditions of species settlement assigned the 9 value and gradually assigned lower values for unsuitable area and finally unsuitable area take 0 or 1 values that actually do not interference in selected area. Then it was performed the action of reclassification, in order to determination of a suitable model for each species under spatial analyst (Longley et al., 2005; Stillwell and Clarke, 2005) and it was selected the Raster calculator choice and influential five layers along to selection of those species which provided suitable model for each species by using Analytical Hierarchy Process (AHP) method, the maps were weighted with regard to mentioned affecting factors. A map provided with range of 1 to 9 by several categories, according to previous expression, for any effective factors in selection of species. It’s natural that the role and effect of these factors is not alike in selection of species. So, these factors should be weighted. The among of weighting methods utilized the method of pair comparison, because of having strong theory, high accuracy and facility for application base. In this method, is formed a Metris comparison method and contrast as pair and their weights are computed.

Fig. 2:	Flow chart of the study stages

In order to decreasing effect of personal ideas in weighting options of experts were utilized regarding to proportional important effective factors. Contrasting pair factors did using of Expert choice soft ware. At the end in order to make the final model, the previous models were collected and the syntactic model species were prepared as a single map (Fig. 2). In this study the software Arc GIS 9.3 featuring high capability in information processing.

RESULTS AND DISCUSSION

Given attention to provided maps, the effective factors in selection of species (Fig. 3a-f, Table 1) is classified based on ecological requirement of successful settlement after reclassify of a given species which exist in Table 1. For example, 0-30% slope of Alnus glutionsa take place in upper class (9) and slope with higher than 100% in lowest class (1), aspect, N, NE, flat and NW in highest class and rest of the aspect class take place in lowest class, 0-250 m height of sea level in upper class and the height of more than 1800 m in lower class (1). Also in the Isohyets map, rainfall of 800-1200 mm cited at upper class and rainfall of 1500 mm the lowest class. At the end, types of soil, brown non calcareous with Clay horizon and acid brown forest soil take place at upper and ranker soils in lowest class. This classify was accomplished about other 15 suggested species. The result of weighting the effective factors on the selection of species show those effective factors in planting is different for each species. For example, slope, aspect, height, precipitation and type of soil factors about, Alnus glutionsa with proportional weight was effective in order 0.1, 0.25, 0.2, 0.3, 0.15 but mention factors for Zelkova carpinifolia was in order to 0.25, 0.1, 0.3, 0.1,0.25 in settlement of species. Therefore, share of each environmental conditions queried as an effective weight in settlement of each species at Fig. 4a-f as maps that each of them is showing ecological range model (for example 6 species show at map).

It is possible structure the desired ecological conditions of many species settlement in a place. This indicates the common role of ecological particularities and appearance of species together and creating mixed forests. Finally, for introducing of several species that have capable of settlement at a given place, the final model is the sum of 16 species offered models based on the below equation.

(1)

Fig. 3:	Continued

Fig. 3:	Continued

Fig. 3:	(a) Isohyets’ map, (b) isotherm map, (c) soil map, (d) aspect map, (e) slope map and (f) without plant space map and rural points in site of study

Fig. 4:	Continued

Fig. 4:	Continued

Fig. 4:	(a) Model of ecological range for planting Alnus glutionsa specie, (b) Zelkova carpinifolia (pall) Dipp, (c) Fraxinus excelsior L., (d) Acer cappadocicum Gled, (e) Juglans regia L. and (f) Tilia begonifolia Stev

Table 1:	Ecological requirements of species

Table 2:	Type, code and abbreviation signs of species to final model

Fig. 5:	Query of tree species planting in gap space by using of geographic information system

Which T is related to code for each species and n is varies from 2 to 16. Based on the above equation, the sum of various codes would not be equal. Obtained numbers is shown in Table 2. As a result 255 composite states can be offered that are between 1to 63356. The final model has been shown in Fig. 5.

Due to afforestation, selection of suitable species is one of the most fundamental factors in the species growth at vacant lands. The obtained results regarding species selection lead us for irreparable economical loss, since it was not taking into consideration the natural factors role such as height, slope, aspect, climate and soil and also site conditions. The primary reason for this conclusion is lack of attention into the ecological requirements of the species and geographic information system. In fact, different species have different ecological requirements. Successful settlement of a species in a given region is dependent on the availability of desired conditions or environment optimization, so these species have the best growth. It is possible a species is not settled in a given region but it doesn’t have the suitable growth. The species selection for a forested area should be based on all environmental conditions and the availability of one condition is not enough to species planting. For example, suitable height or soil for a specific species cannot be the primary criterion for species planting. In fact, all environmental conditions, taking into consideration the effect of these factors should be considered in species settlement. The effect of the environmental factors are different for various species usually, determining of suitable species for afforestation is not accomplished based on exact scientific studies. To resolving of this problem, the new technologies, e.g., Geographic Information System (GIS) can be used for processing and integration of information and are suitable models for species (ecologic range). In this research, suitable places for planting and interplanting are determined and suggested with respect to edaphic, climate and site using Geographic Information System (GIS). Using identify tools in Arc GIS 9.3 software, the composite presented based on the sum of the models is observable for presentation of several species. Each of them can be recognized with abbreviations. The suggestion of species for a region, based on the ecological conditions provides specific possibility. It also provides a possibility for experts who select the most desirable species from the presented species based on their own experiences. It should be stated that the presented models in this research were not presented any species for some without-plant regions which are required more consideration. Meanwhile, the obtained results are supported by the conducted researchers by Shahdat and Kwei (2003), Dilek et al. (2007) and Lie et al. (2002). That all of them emphasized on significant geographic information system as the best instrument for determination of afforestation suitable species and probable dangers investigation of disappear species. Investigating the possibility of planting 16 species and extracting of Eq. 1 the sum of suggested models (the presented model is to improve per species) was the characteristic of our research that was not reported in previous studies.

But it should be taken into account that the best teacher is nature. Cammoner (1971), the American ecologist, in his well-known book closing circle Nature, Man and Technology rightly propones that Nature knows best. We applied this approach i.e. and compared our obtained results with selected species in nature by forest’s monitoring. We specified those conditions that existing species was sampled and specified as land control points by GPS at more than 50 points in the studied site. Obtained results are showed that in some regions, proposed species were similar to the nature species. Some proposed species existed in the past decades that is extinct or under danger of extinction and their planting should be embarked upon in the nearest time. Also it can examine growth possibility of new presented species in limited areas and then they recommend for planting in the large surfaces. Finally, it can be found the biogeoclimate for each region using specifying of the biotic influences i.e., far and proximity of village (the information layers exist) and with taking into consideration social and economical factors that are important factors of long-term duration at afforestation after the correct selection of species for a region and specification of rapid growth species to increasing of the income of people who inhabit in forests in order to prevention of the destruction of forest land. With attention to availability and production of information concerning suitable species, we can suggested geographic information system technique can provide compatibility with plantation environment, the protection of landscape and the maximum growth at the minimum time. Ultimately, in this research, the select of suitable specie for afforestation was implementing with data gathering in other to preparation of natural factors map (climate, soil and planet), ecological requirement s of species and overlay of layers by use of GIS Soft wares. So, it is suitable tool in determining and targeting sites in other to existing new and ancient woodland (Lie et al., 2002). we suggest it is use other water-shed basins to prevention of heavy expenses and time waste.

ACKNOWLEDGMENTS

Thanks to research Assistance of Islamic Azad university,Rasht branch,for the financial support.