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.

Forest encroachment in Eastern European forest-steppes at a decadal time scale

In the Eurasian forest-steppe,with increasing aridity,the balance between naturally co-existing forest and grassland patches is expected to shift towards grassland dominance in the long run,although feedback mechanisms and changes in land-use may alter this process.In this study,we compared old and recent aerial photographs of Hungarian forest-steppes to find out whether and how the forest proportion and the number of forest patches change at the decadal time scale.The percentage area covered by forest significantly increased in all study sites.The observed forest encroachment may be a legacy from earlier land-use:due to ceased or reduced grazing pressure,forests are invading grasslands until the potential forest cover allowed by climate and soil is reached.The number of forest patches significantly increased at one site(Fülöpháza),while it decreased at two sites(Bugac and Orgovány)and showed no significant change at the fourth site(Tázlár).This indicates that forest encroachment can happen at least in two different ways:through the emergence of new forest patches in the grassland,and through the extension and coalescence of already existing forest patches.Though the present work revealed increasing tree cover at a decadal time scale,the dynamic process should be monitored in the future to see how the vegetation reacts to further aridification.This could help devise a conservation strategy,as the woody/non-woody balance has a profound influence on basic ecosystem properties.