Development of a forest land suitability model for Lebanon reforestation under climate change conditions

In the heart of the Mediterranean Basin, the world’s most threatened biodiversity hotspot, at the Eastern end of the Mediterranean Sea (33°50’ North and 35°50’ East), falls the small country of Lebanon, covering a total of 10,452 km² of surface area. Lebanon’s topography is characterized by the high mountains of the Mount Lebanon and the Anti-Lebanon ranges, separated by the Beqaa Valley. Along its territory, Lebanon witnesses an extreme variability in altitude, exposition and topography, defining a diversity of climatic conditions from Mediterranean climate along the coast and the mid altitude of the mountain ranges, from sub alpine and mountain Mediterranean climate on the highest slopes to arid/sub-desert in the northern plains. This geographic and climatic diversity is reflected trough a set of ecological systems largely varying from one region to another, generating, over a small scaled country, a unique biodiversity and hence, a true biological hotspot. So far, in Lebanon, the land suitability tools are limited, and research for an effective and active suitability map for forest species is in process. Previous works analyze the range of species distribution according to altitude, vegetation levels or bedrock type for some key species and examine the relationship between the distribution of the Lebanese forest types and the conditions of climatic indicators and soil characteristics. These studies did not consider the introduction of pioneer species, which have a pivotal role in increasing the forest cover in the country to mitigate the negative effects of climate change. The present study aims to perform a holistic evaluation of forest land potentialities of Lebanon under present and future climatic conditions, including the introduction of pioneer species in degraded land. This study will provide an important reference to limit the loss of forest in Lebanon and to guide a development of a suitable and productive forestry system, under climate changes. For this purpose, a GIS-model was developed to combine forest species requirements, in terms of soil and climate conditions, into land suitability classes. Existing geographic database of climate and soil information were used to produce the land suitability maps for a selection of native and autochthonous forest species in Lebanon. Highly suitable or Optimal (S1), moderately suitable (S2), marginally suitable (S3) and not suitable classes (N) were created, according to altitude and soil type and present and projected values of temperature and precipitation. The preliminary results of land suitability analysis show a general critical situation in terms of forests species distribution under future climate change scenarios compared to the current situation. In fact, the distribution of thermophile species, which growth best in high temperature is projected to expand in higher locations respect to the current situation and the non-suitable classes are expected to disappear. On the contrary, the expansion of cold adapted species may be limited by Climate related impacts on natural and human systemsfuture climate change conditions. The results of land suitability analysis show not only the level of suitability for forestry land use but also the limitations for forest distribution, providing useful information to optimize the reforestation of the study area.