Dear Belul Gixhari,

It depends on what do you want to focus your study... because the different diversity indices allow to answer to diferent questions. You can check these references on the topic (diversity and altitudinal gradient):

- Amit Chawla, S. Rajkumar, K.N. Singh, Brij Lal, and R.D. Singh. 2008. Plant Species Diversity along an Altitudinal Gradient of Bhabha Valley in Western Himalaya. J. Mt. Sci., 5: 157–177.

- Wenxin Zhang, Dizhou Huang, Renqing Wang, Jian Liu, Ning Du. 2016.

Altitudinal Patterns of Species Diversity and Phylogenetic Diversity across Temperate Mountain Forests of Northern China. PlosOne

- Md Rawi Che Salmah & Salman Abdo Al-Shami & Ahmad Abu Hassan & Madziatul Rosemahanie Madrus & Abdul Nurul Huda. 2014. Distribution of detritivores in tropical forest streams of peninsular Malaysia: role of temperature, canopy cover and altitude variability. Int J Biometeorol 58:679–690

- Arturo Sánchez-González & Lauro López-Mata. 2005. Plant species richness and diversity along an altitudinal gradient in the Sierra Nevada, Mexico. Diversity and distributions.

- D.E.Gurvicha, S.R.Zeballosa and P.H.Demaio. 2014. Diversity and composition of cactus species along an altitudinal gradient in the Sierras del Norte Mountains (Córdoba, Argentina). South African Journal of Botany

Hope this can help,

BF

Please have look at our article from high mountains at the other side of the Adria (Gils et al. 2012) on an altitudinal distribution of endemic plant diversity and related ecological paradigms: Mid-Altitudinal Peak and Island Theory/Species Area Relationship.