EFFECT OF INDUS RIVER FLOODS ON DYNAMICS OF RIVERINE FLORA OF LOW RIPARIAN ZONE

Abstract

The riparian zone refers to biotic communities on the banks of rivers, streams and lakes. Riparian zones are an unusually diverse mosaic of landforms, communities and environments within the larger landscape and they serve as a framework for understanding the organization, diversity and dynamics of the communities associated with fluvial ecosystems. A variety of natural disturbances create a spatial and temporal environmental mosaic with few parallels in other systems. Pakistan riparian zone mostly belongs to Sindh and Punjab provinces and prone to varieties of climatical problems and anthropogenic activities. The research was conducted to estimate and compare the effects of 2010 floods on the structure and composition of riverine floral diversity in low riparian zone of River Indus. To estimate the impact, data was collected from two sites along River Indus in low riparian zone i.e. Keti Shah Forest (Sukkur, Sindh province) and Taunsa Wildlife Sanctuary (Muzaffargarh, Punjab province). The study evaluates the phytosociological parameters of floral diversity in low riparian zone of River Indus. The impact of 2010 floods on floral diversity was calculated using BioDiversity Professional Statistical Software. The results of the study shows that the Taunsa Wildlife Sanctuary is rich in floral diversity with total 30 species in pre-monsoon season and 20 species in post-monsoon season, in comparison to the Keti Shah Forest. In Keti Shah Forest 22 species found in pre-monsoon and 16 in post-monsoon season. Different biodiversity parameters (Shannon Index, Simpson’s Index, Margalef’s lndex, SHE analysis and cluster analysis) shows that pre-flooded vegetation was more rich with total 39 families in Taunsa Wildlife xxiii Sanctuary and 18 families in Keti Shah Forest. The edaphic parameters proved less fertility in post-monsoon season in comparison to pre-monsoon season. The outcome of this study revealed that floods and heavy rains have destructive effects on vegetation of the study area. These adverse effects eliminate 23 and 7 families from the Taunsa and Keti Shah Forest, respectively. The results concluded that in upstream areas about 60% plant families eliminated after 2010 floods, with 75% species lost. In comparison to downstream about 40% plant families eliminated due to floods, with 37% species lost. The more lost in plant biodiversity in upstream was due to high intensity of floods as compared to downstream. The outcome of this study benefits in future in forest management, planning, floral diversity conservation and in mitigating adverse effect of the floods in studied areas. In future, illicit cutting and conversion of forest area to agricultural land should be controlled by implementing the proper management plan of the forest area. Regeneration and replanting activities of the native species should be carried out on regular basis and species gene bank should be established to conserve the species which are growing well in the area. Planting woody plant species on the banks of the river helps in reducing the velocity of the flood water and serves as the barrier for the whole forest area by preventing it from adverse impacts of the regular floods.