Impact of forest fragmentation on flora, life forms, and chorology of plant species (case study: Zagros forests, Chardavol county, Ilam province)

Forest degradation is one of the major environmental challenges leading to fragmentation of forest ecosystems and disruption of their structure, functioning, and natural processes. In the Zagros region, forest fragmentation has been intensified particularly by overgrazing, land-use conversion of forest lands, infrastructure development, and unsustainable exploitation of forest resources. Understanding the impacts of these changes on vegetation can provide a scientific basis for forest management and restoration. Therefore, this study aimed to assess the effects of forest fragmentation caused by conversion to rainfed agriculture on floristic composition, life-form spectra, and chorological distribution of plant species in the Zagros forests.



Two categories of forest patches resulting from fragmentation were considered: small (1–3 ha) and large (8–12 ha) patches. Three patches were randomly selected for each size class. Within each patch, four sampling points were randomly established in the core area and four at the edge. Similar sampling was conducted in three agricultural fields (rainfed wheat cultivation) and in a contiguous forest stand (~150 ha) as a reference site. At each sampling point, one main plot of 400 m² (20 × 20 m) was established to record tree and shrub species. Herbaceous understory species were surveyed in two 1 m² subplots randomly located within the main plot. Following species identification using standard floristic references, life-form classification, chorotype determination, and floristic analyses were performed.



In total, 61 plant species belonging to 20 families were recorded. Species richness was highest in the reference forest (43 species) and lowest in the agricultural fields (19 species). Richness in large patch cores was 32 species, while large patch edges and small patch cores each contained 30 species, and small patch edges harbored 28 species. Asteraceae had the highest species representation across most habitats, whereas Fabaceae was dominant in the reference forest and large patch cores (8 species). Therophytes were the prevailing life form in all habitats. Life-form diversity was highest in the reference forest and lowest in the agricultural fields. Irano-Turanian and Irano-Turanian–Mediterranean elements were the dominant chorotypes. Comparison of floristic composition between the reference forest and patch interiors and edges indicated that, in both patch sizes, core areas exhibited greater similarity to the reference forest than edges (19 shared species in large patch cores and 4 in small patch cores).



Overall, fragmentation and land-use conversion reduced species richness, increased the proportion of opportunistic species, and consequently weakened the ecological stability of the Zagros forests. Conservation and restoration of forest ecosystems, preservation of large forest patches, prevention of further subdivision into small patches, and long-term habitat rehabilitation planning are essential for maintaining biodiversity, ecological stability, and resilience in the Zagros region.