In 2004, RSCN established its latest nature reserve in Dibeen Forest northern Jordan. Dibeen Forest Reserve extends over 8.5 km² of mountainous terrain, covering an area of pristine pine-oak habitat (Pinus halipensis-Quercus calliprinos). These Aleppo pines are some of the oldest and largest in the Kingdom, and are the defining characteristic of this landscape, representing the southeastern geographical limit of this forest type. Dibeen is the driest part of the world in which the Aleppo pines are known to grow naturally, with an average rainfall of around 400mm per year.

Dibeen was ranked as the top priority site for conservation in the 1998 Protected Areas review, after being overlooked in the original 1979 review, as studies have revealed that Dibeen is one of the best remaining examples of the original pine-oak forest cover in the region and supports at least 17 threatened species, like the Persian Squirrel, and other globally significant biodiversity.

The entire forest of Dibeen extends over an area of 60 km², varying in altitude from 500m to 1000m above sea level. The forest is spread over steep to very steep slopes of limestone or chalky limestone rock types. The physical and age structure of the forest as a whole is remarkably varied with trees of widely different ages and sizes and a distinct under-canopy in many areas. This variety is aided by the presence of wadis, which provide different aspects, moisture levels and soil conditions throughout the forest.

The reserve is positioned in the core of this forest, encompassing three main stand types in the core area, distributed according to altitude. In the lower elevations, Aleppo pine (Pinus halepensis) is dominant and there are some pure stands with large mature trees. In the middle elevations, a pine-oak (Pinus halepensis / Quercus calliprinos) association is dominant and this extends over the majority of the area. In the upper elevations, the oak succeeds as the dominant species with small stands of deciduous oak (Quercus infectoria) on the upper most slopes. Other trees present in the forest include Strawberry tree (Arbutus andrachine), pistachio (Pistachia palestina) and wild olive (Olea europea); while the ground flora is exceptionally rich and includes several orchid species and other forest related plant species. According to the latest study of vegetation cover, the ecosystem of the Dibeen Forest Reserve supports 517 plant species.