Effect of floods on the growth of Phragmites japonica on the sediment bar of regulated rivers: a modelling approach

Rashid

Bakar

2014

River Research & Apps

Intensive forestation widely occurs in East Asian rivers. It deteriorates the ecosystem of gravelly or sandy bars, affects flood protection, and changes the landscape of the river. For the regulation of forestation and vegetative succession on the bars, a suitable tool, through either a numerical simulation model or through empirical knowledge that will predict the future process after treatment, is required. With this background, a dynamic model is developed based on the empirical knowledge obtained by field observations in order to simulate the vegetative growth process on the bars. Observations were conducted at several Japanese rivers in order to better understand tree growth and biomass, herbaceous plant biomass, and soil nitrogen content. The model is composed of four modules: a hydrological module, which provides for flood inundation, flushing and sedimentation processes, a tree module, which describes the recruitment, growth and thinning of tree densities, and a herbaceous plant module, which describes the biomass of herbs as a function of environmental conditions. Finally, there is a soil module, which mostly describes nitrogen budgets. The model was successfully applied to the Arakawa River in central Japan in order to simulate a 30-year process after a major flood. Simulations were conducted for several cases related to the processes of two tree species: Robinia pseudoacacia and Salix spp. The model was then applied in order to elucidate the forestation mechanism of the bar, which indicated a possible reason for the effect of decreasing the supply of coarse sediment. The impact of the tree and herbaceous plants by different hydrological processes is also discussed.

Section: Model Developmentmentioning

confidence: 99%

Dynamic Modelling of Soil Nitrogen Budget and Vegetation Colonization in Sediment Bars of a Regulated River

Rashid

Bakar

2014

River Research & Apps

“…In such areas, however, the levels of colonised plant species have a wide range. Certain species, such as Phragmites japonica and Miscanthus sacchariflorus, grow in stony sterile as well as low nutrient conditions, [5] whereas other species prefer relatively *Corresponding author. Email: asaeda@mail.saitama.u-ac.jp fine sediment with nutrient-rich conditions.…”

Section: Introductionmentioning

confidence: 99%

Role of arbuscular mycorrhizal fungi on the performance of floodplainPhragmites japonicaunder nutrient stress condition

Sarkar

Wang

et al. 2015

Chemistry and Ecology

Self Cite

A pot experiment was conducted to evaluate the potential effects of arbuscular mycorrhizal fungi (AMF) on growth, nutrient uptake, and inoculation effectiveness on Phragmites japonica. Spores of AMF strains (Gigaspora margarita Becker & Hall) were collected from the commercial product 'Serakinkon'. Four treatments, namely, natural soil (NS), natural soil inoculated by AM fungi, sterilised soil (SS) inoculated by AM fungi, and SS without AM fungi inoculation were selected to determine the effects of applied and indigenous AMF on P. japonica. The average colonisation level of P. japonica was 24-33%, whereas no colonisation was found in the SS. AMF colonisation increased the chlorophyll content (r = 0.84, p < .01), plant dry mass (r = 0.89, p < .01), and N, P, K, Mg, and Fe concentration of the plant's roots, stems, and leaves when AMF was applied with natural and SS. In all cases, maximum values were found when the plants were applied with NS in combination with AMF, but Ca concentration decreased as the colonisation level increased. Mn concentration decreased in the roots, but increased in the leaves. Cu concentration was not significantly affected by treatments. N-loss minimisation from the soil was significant when the colonisation level was high.

“…Recently, several numerical models have been proposed in order to predict the colonization of vegetation on the floodplain (Asaeda et al 2011a, Benjankar et al 2011. However, in all of those cases, the condition of the vegetation was given as a function of disturbance, not as the result of a dynamic process of plant growth.…”

Section: Introductionmentioning

confidence: 99%

Modelling of nutrient dynamics and vegetation succession in midstream sediment bars of a regulated river

International Journal of River Basin Management

Rashid

2014

Self Cite

In the floodplain of a regulated river with an intermittent flood disturbance, nutrient dynamics is mainly dependent on the successional stage of vegetation, types of flora and initial substrate conditions brought about by a previous large flood. In this study, we collected data on plant and substrate parameters from a gravelly bar of a regulated river in Japan and developed nutrient dynamic and vegetative succession models on the basis of allometric relationships between observed data. The models were validated with field observed data from the Ara and Kurobe Rivers of Japan. We obtained satisfactory agreements between observed and simulated results. The developed models can predict the progressive vegetative biomass and amount of nutrients processed by herbaceous plants and trees on a sediment bar during large flood intervals.