Spatial and temporal heterogeneity ofEragrostis curvulain the downstream flood meadow of a regulated river

Abstract

-We studied the spatiotemporal trends of Eragrostis curvula (Schrad.) Nees in a flood meadow of a regulated river. The response variables, including the abundance of colonies, colony sizes, flowering spikes, biomass and root structure were checked against a set of environmental variables. These variables included distance from the river, substrate conditions (stony to sandy), soil nutrients (total nitrogen, phosphorous and calcium) and soil moisture. Relationships were evidenced using redundancy analysis. Response variables were found to be distinctive and based on substrate conditions (i.e. stony or sandy). The variables 'distance from the river' and 'soil phosphorous' contributed significantly to the overall variance. Stony habitats were observed to have lower soil nutrient levels and were characterised by monospecific stands of E. curvula, while the high nutrient levels of sandy habitats promoted heterogeneous herbaceous vegetation growth. Primary production, especially belowground, was measured to be significantly higher (t-test, P<0.05) in stony habitats. Spatiotemporal trends suggested that, irrespective of the number of colonies, E. curvula demonstrated significant levels of adaptation to micro-environments through biomass allocation and the morphological plasticity of its roots. The study results suggest that river regulation and the subsequent reduction in the frequency of inundation, in addition to the reduction of nutrients and fine sediment supply downstream, give a competitive edge to E. curvula over other herbaceous species.

Tree colonization trends on a sediment bar after a major flood

“…The erosion of the surface layer and subsequent exposure of the underlying coarse and/or boulder sediment layers is commonly observed in Japanese rivers (Nakai and Kisanuki, 2007;Asaeda et al, 2009a). This reduces the moisture and nutrient level of the habitat (Gomes and Asaeda, 2009). In contrast, floods transport and accumulate sediments on the riparian zone (Baker and Kochel, 1988).…”

Nanometer-scale elongation rate fluctuations in theMyriophyllum aquaticum(Parrot feather) stem were altered by radio-frequency electromagnetic radiation

“…[46][47][48] Plants may thus have adapted to EMR exposure as they are continuously exposed to EMR in the natural environment due to the continuous operation of communication transmitters. Therefore, it is important to study plants exposed to EMR for long periods of time to understand any mechanisms used by plants to adapt to EMR exposure.…”

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

“…Relationship between soil TN (%) and herb biomass: (circle) Ara River—low sky‐view factor (SKV), (black circle) Ara River (Gomes and Asaeda, ) (black triangle) P. japonica in Ara River (Asaeda et al , ), (lozenge) Kurobe River—coarse soil (Asaeda and Rashid, ), (triangle) Tama River (Asaeda et al , ; Rashid et al , ), (black square) Tone River (unpublished data), and (black diamond) Kurobe River (Asaeda and Rashid, ). Asterisk symbols are data points extracted from several works (Tilman and Cowan, ; Nams et al ., ; Day, ; Schenk et al ., ; Davidson et al ., ).…”