S. K. Barik

Liana diversity and abundance as related to microenvironment in three forest types located in different elevational ranges of the Eastern Himalayas

Background: Liana diversity and abundance in forests along an elevational range is poorly understood. Aims: To study the diversity and abundance of lianas in three forest types located in different elevational belts of the Eastern Himalayas, and to explore the role of microenvironmental factors in relation to liana abundance. Methods: Adult (≥ 0.2cm diameter at breast height) and juvenile lianas were enumerated in 0.1ha and 1m2 plots in lower montane, montane and upper montane forests between 1200 and 3000m above sea level. Ten microenvironmental variables were related to liana density within each forest type using stepwise forward multiple regression analysis, and across the forest types by using Canonical Correspondence Analysis (CCA). Results: Liana species richness followed the order: lower montane > montane > upper montane forest. Light and soil phosphorus (P) concentration were related to adult liana density. Soil pH, P, light and relative humidity were related to seedling density. The positioning of 43 liana species with respect to light, soil pH, nitrogen and P gradients in CCA plots indicated species-specific microenvironmental preferences. Conclusions : Liana diversity and abundance decreased with increasing elevation, and at each elevation were related to specific microenvironmental variables and differential species response.

Molecular characterization of novel Bradyrhizobium strains nodulating Eriosema chinense and Flemingia vestita, important unexplored native legumes of the sub-Himalayan region (Meghalaya) of India

Root nodule bacterial strains were isolated from the little-studied legumes Eriosema chinense and Flemingia vestita (both in tribe Phaseoleae, Papilionoideae) growing in acidic soil of the sub-Himalayan region of the Indian state of Meghalaya (ME), and were identified as novel strains of Bradyrhizobium on the basis of their 16S rRNA sequences. Seven isolates selected on the basis of phenotypic characters and assessment of ARDRA and RAPD patterns were subjected to multilocus sequence analysis (MLSA) using four protein-coding housekeeping genes (glnII, recA, dnaK and gyrB). On the basis of 16S rRNA phylogeny as well as a concatenated MLSA five strains clustered in a single separate clade and two strains formed novel lineages within the genus Bradyrhizobium. The phylogenies of the symbiotic genes (nodA and nifH) were in agreement with the core gene phylogenies. It appears that genetically diverse Bradyrhizobium strains are the principal microsymbionts of these two important native legumes. The novel genotypes of Bradyrhizobium strains isolated in the present study efficiently nodulate the Phaseoloid crop species Glycine max, Vigna radiata and Vigna umbellata. These strains are genetically different from strains of Bradyrhizobium isolated earlier from a different agro-climatic region of India suggesting that the acidic nature of the soil, high precipitation and other local environmental conditions are responsible for the evolution of these newly-described Bradyrhizobium strains. In global terms, the sub-Himalayan region of India is geographically and climatically distinct and the Bradyrhizobium strains nodulating its legumes appear to be novel and potentially unique to the region.

Pterocymbium tinctorium (Merrill, 1901) (Magnoliophyta: Malvales: Sterculiaceae: Sterculioideae): new record from mainland India and extension of geographic distribution

We present a new record of the winged-boot tree ( Pterocymbium tinctorium ) discovered in the Khasi Hills of Meghalaya on the Indian mainland. With this record, the known geographical distribution of P . tinctorium is now extended up to the foothills of the Eastern Himalayas in Southeast Asia. The species was recorded from the tropical moist deciduous forests of Meghalaya. The habitat of P. tinctorium was characterized by the presence of surface lime-stone with karst topography. Future investigations should aim at identifying the factors responsible for the restricted distribution of this species so that appropriate conservation measures can be taken.

Selection of Bradyrhizobium or Ensifer symbionts by the native Indian caesalpinioid legume Chamaecrista pumila depends on soil pH and other edaphic and climatic factors

Nodules of Chamaecrista pumila growing in several locations in India were sampled for anatomical studies and for characterization of their rhizobial microsymbionts. Regardless of their region of origin, the nodules were indeterminate with their bacteroids contained within symbiosomes which were surrounded by pectin. More than 150 strains were isolated from alkaline soils from the Thar Desert (Rajasthan), wet-acidic soils of Shillong (Meghalaya), and from trap experiments using soils from four other states with different agro-ecological regions. Molecular phylogenetic analysis based on five housekeeping (rrs, recA, glnII, dnaK andatpD) and two symbiotic (nodA and nifH) genes was performed for selected strains. Chamaecrista pumila was shown to be nodulated by niche-specific diverse strains of either Ensifer or Bradyrhizobium in alkaline (Thar Desert) to neutral (Tamil Nadu) soils and only Bradyrhizobium strains in acidic (Shillong) soils. Concatenated core gene phylogenies showed four novel Ensifer-MLSA types and nine Bradyrhizobium-MLSA types. Genetically diverse Ensifer strains harbored similar sym genes which were novel. In contrast, significant symbiotic diversity was observed in the Bradyrhizobium strains. The C. pumila strains cross-nodulated Vigna radiata and some wild papilionoid and mimosoid legumes. It is suggested that soil pH and moisture level played important roles in structuring the C. pumila microsymbiont community.

Diversity of Lianas in Eastern Himalayas and North-Eastern India

Lianas constitute an important component of plant diversity in a wide range of ecosystems. The liana diversity has been reported to have critical role in maintaining ecosystem structure and function, with a predicted greater role to play under changing climate conditions. However, our understanding on the diversity pattern of lianas in different forest ecosystems along an elevation gradient is limited. Studies on lianas in the Eastern Himalayas and North-eastern region of India are very few. In this paper, we review the status of liana research in the two biodiversity hotspots viz., the Himalayas and Indo-Myanmar, and conducted primary studies in selected high diversity forests of the region to understand the patterns of liana diversity along elevation gradient in the Himalayas. The diversity and distribution of lianas in three major forest types representing the dominant ecological zones of the region viz. tropical, montane-subtropical and temperate were studied using liana census protocol of Gerwing et al. (2006). We recorded 196 liana species in three forest types in the states of Arunachal Pradesh, Sikkim and Meghalaya in north-eastern India through plot-based field survey. The diversity and abundance of lianas were greater in sub-tropical and tropical forests than temperate forests. Threat assessment for liana conservation was suggested for their in situ conservation.

Plantae, Magnoliophyta, Gentianales, Apocynaceae, Asclepiadoideae, Ceropegia hookeri : distribution and rediscovery in eastern Himalayas, Sikkim, India

The Eastern Himalayan region is home to several rare flora (Rao 1994). Floristically the region acts as a gateway for the migration of flora from the adjacent countries such as China, Japan, Nepal and Bhutan. The Khangchendzonga Biosphere Reserve (KBR) in Sikkim is an important phytodiversity centre in Eastern Himalayas due to its unique geographical position. During the floristic exploration of KBR, Ceropegia hookeri (Figure 1) was collected. The genus Ceropegia L. comprises 200 species distributed from southern Africa to Australia (Bruyns 2003). In India, the genus is represented by 48 species and three varieties (Malpure et al. 2006). From north-eastern India including the eastern Himalayas, nine species have so far been reported (Jagtap and Singh 1999).