Vegetation surveys in the Indian Trans-Himalaya: a report on the surveys conducted during summer 2000

Abstract

Ladakh and adjacent trans-Himalayan ranges harbor a typical vegetation characterized by steppe formations, sedge-grass meadows and herbaceous communities. A few attempts have been made to classify and describe the major plant communities of the trans-Himalaya in the past. However, most of the descriptions are based on local information from a few pockets. A complete account of life form distribution and ecological characteristics from the entire range is not available. Keeping this in view, we conducted an extensive survey of vegetation in the trans-Himalaya with a view to address the following questions: (i) how similar or dissimilar are the vegetation communities found within various trans-Himalayan ranges viz., north of Pir-Panjal (Lahul), Zanskar, Changthang, Ladakh mountains, and Karakoram region, (ii) what are the proportions of various growth forms (lichens, mosses, graminoids, forbs and shrubs) within the communities of these ranges, and (iii) which are the unique, rare or endemic species within each range and what are the possible threats to such species ? We sampled the vegetation and related abiotic variables systematically along the Rohtang - Leh - Nubra road following a `Rapid GRADSECT’ approach. Data on various parameters were collected at four levels, viz., (i) General physiognomy, cover types and landscape features within 100 m x 2 km belts, (ii) Community composition of woody species and cover abundance of different life forms at a regular intervals of 2 kms, (iii) Species composition at and around 5 high passes covering various aspects and landforms, and (iv) Species composition and cover abundance around a high altitude brackish water lake. The preliminary findings of the survey include: (i) 10 distinct physiognomic units viz., Herbaceous meadow (HM), Sedge meadow (SM), Mixed scrub or steppe (MS), Riverine scrub (RS), Sparse vegetation including degraded slopes (SV), Woodland/Plantation (WP), Cultivation/Habitation (CH), Grasslands i.e., area dominated by grasses (GR) and cushionoid vegetation including mosses and lichens (CV). were identified along with their percent coverage within various sectors and also along the GRADSECT, (ii) 9 major woody communities along the Gradsect were identified, viz., Juniper woodland, Artemisia dracunculus - A. maritima, Caragana, Eurotia, Caragana - Eurotia, Artemisia gmelinii - A. salsoloides, Hippophae - Myricaria, Salix lindleyana, Lysium ruthinicum, and Ephedra gerardiana, (iii) High passes (Rohtang, Baralacha La, Lachulung La, Tanglang La, and Khardung La ranging from 3900-5500 m asl) represented different geological formations and therefore distinct plant communities. General vegetation cover, species richness, density and diversity decreased with increasing altitude and latitude, and (iv) The banks of Tso Moriri (brackish water lake) were dominated by Carex melanantha, Carex nivalis and a few other herbs which was quite different from the banks of fresh water lakes and other marsh meadows of the alpine regions.