Land suitability evaluation for poplar plantation

The implementation of the forest restoration plan in the northern region of Iran has led to an increase in efforts to enhance wood production through the cultivation of poplar seedling. Particularly, poplar trees hold a significant position among wood producers due to their distinctive features. The key consideration revolves around identifying suitable and cost-effective lands for planting fast-growing species. Purpose of this study focuses on assessing the land suitability for poplar (Populus nigra L.), a prevalent forest species in the country, through a quantitative land evaluation method based on the FAO approach.
The research gathered and classified the edaphic and climatic requirements of poplar tree by utilizing various library resources, data from the soil laboratory of the Research Institute of Forests and Ranglands, and field survey (Soil Profiles). The climatic and soil characteristics were quantitatively classified into five categories: highly suitable (S1), moderately suitable (S2), low/critically suitable (S3), The Quantitative Classification of soil and climate properties was done in five classes: suitable (S1), moderate suitability (S2), low or critical suitability (S3), currently not suitable (N1) and permanent not suitable (N2). For validation, a quantitative assessment of land suitability for poplar cultivation was performed across six soil types, including Nowshahr forest brown, Nowshahr gray brown pedzolic rich in organic matter, Chamestan alluvial regosol, Chamestan Rendezina, Chalous  Pseudogley , and Karaj alluvial cambisol, using a parametric method (second root).
Results indicate that spruce thrives in wet and semi-humid regions in a dry-type manner, with ideal conditions found in areas receiving 1500-1800 mm of rainfall. In drier, semi-arid zones, irrigation is essential for meeting water requirements. Optimal growth temperatures for spruce range from 11-16 degrees Celsius in moderate climates. Poplar flourishes in soils with a light to medium texture, granular or cubic structure, good to fast drainage, and low underground water levels with adequate calcium and magnesium cations.
The study showed that the most suitable soils for poplars have a light to medium texture with a granular or crumb structure, with adequate drainage, the absence of high groundwater and the sufficient amount of calcium and magnesium cations in the soil. Soils with incomplete drainage and heavy texture do not provide suitable conditions for poplar plantations. In terms of quantitative evaluation, Mollic Udifluvents soils with medium texture had the highest score for poplar plantations.