Effect of abiotic factors on understory community structures in moist deciduous forests of northern India

Understory vegetation controls, in a significant way, the regeneration of overstory trees, carbon sequestration and nutrient retention in tropical forests. Development and organization of understory vegetation depend on climate, edaphic and biotic factors which are not well correlated with plant community structures. This study aimed to explore the relationships between understory vegetation and abiotic factors in natural and planted forest ecosystems. A non-metric multidimensional scaling(NMS) ordination technique was applied to represent forest understory vegetation among five forest communities, i.e., a dry miscellaneous forest(DMF), a sal mixed forest(SMF), a teak plantation(TP), a low-land miscellaneous forest(LMF) and a savanna area(SAV) of the Katerniaghat Wildlife Sanctuary, located in northern India. Microclimatic variables, such as photosynthetically active radiation(PAR), air temperature(AT), soil temperature(ST), ambient atmospheric CO 2 concentration, absolute air humidity(AH), physical and chemical soil properties as well as biological properties were measured. Understory species were assessed via 100 random quadrats(5 m × 5 m) in each of the five forests in which a total of 75 species were recorded encompassing 67 genera from 37 families, consisting of 32 shrubs and 43 plant saplings. DMF was the most dense forest with 34,068 understory individuals per ha of different species, whereas the lowest understory population(13,900 per ha) was observed in the savanna. Ordination and correlation revealed that microclimate factors are most important in their effect compared to edaphic factors, on the development of understory vegetation in the various forest communities in the north of India.

Community Structure, Diversity, Biomass and Net Production in a Rehabilitated Subtropical Forest in North India

Gangetic alluvial plain in north India constitutes significant proportions of barren sodic lands. A representative site, where afforestation was carried out during 1960s to rehabilitate the site under forest ecosystem, was selected to assess the restoration success. Three stands (S1, S2, and S3) were selected in a semi-natural subtropical forest at Banthra, Lucknow (26°45’ N, 80°53’ E) on the basis of different vegetation morphology and basal area gradient. Species composition and their growth forms were studied in overstory, understory and ground layer vegetation, in which dominants were assorted. Among the dominants few species were common in the three stands as also in different strata, which perhaps indicate their natural regeneration. Classification of individuals among the different size classes indicated ‘L’ shape distribution in which most of the individuals remained confined in younger groups. Biomass increased from the stand S1 to S3 stand in overstory, and vise versa for understory. Stand S2 consisted of predominance of ground layer biomass over the other stands. Biomass allocation in different plant components differed significantly between the overstory and understory for aerial woody components (stem and branch). Annual litter fall did not differ significantly among the stands, where as fine root biomass (up to 45 cm soil depth) decreased from S1 to S3 stands. Rainy and summer seasons contributed to two-third proportion of total annual fine root production. The state of this rehabilitated forest when compared with the degraded and reference forest of the region indicated that structural complexity, biomass and production levels have been achieved to 70% of the reference forest site even after having a different species composition.