The role of soil characteristics in the succession of two herbaceous lianas in a modified river floodplain

Abstract

The Tamagawa floodplain of Japan experienced a series of changes in the structure of its plant community after 1960. Today, two dominant lianas -Pueraria lobata and Sicyos angulatus -have colonized the area and are competing for space. This study explores their competitive abilities in relation to soil factors and flooding disturbance downstream of the Tama River. Several colonies of these species were selected in three spots of the Tamagawa floodplain having different soil characteristics and flooding frequencies. Our results revealed that S. angulatus can only grow on fine sediment, whereas P. lobata can grow on soil with a wide range of particle sizes. Soil moisture and nitrogen requirements are higher for S. angulatus. S. angulatus grows only on fine sediment for two reasons: first, fine sediment stores a higher concentration of nitrogen and moisture; second, S. angulatus has a very shallow root system. P. lobata has an extensive root system with nodules, with which it can thrive on coarse and relatively dry soil with lower nitrogen. However, P. lobata requires higher soil phosphorus than S. angulatus does. The earlier patchy colonization of S. angulatus on the Tamagawa floodplain was provoked by flooding, when the perennial Miscanthus sacchariflorus and other species trapped fine sediments. Gradually, sediments became finer and nutrient-rich due to vegetative decomposition, and S. angulatus invaded the area. The soil at that time was not deep enough for the root system of P. lobata. Subsequently, P. lobata outcompeted S. angulatus on the various types of soil that developed. Severe washing of fine substrates by floodwaters makes the area unsuitable for S. angulatus, whereas P. lobata continues to thrive.

The impact of tourists on Antarctic tardigrades: an ordination-based model

“…CCA (Fig. 5) does however imply that tardigrades are influenced by vegetation and habitat correlating with, for example, small to medium particle soils, which provide stable rooting media for higher plants, rather than larger, more mobile pebbles and stones (Denef and Six 2005;Barni et al, 2007;Asaeda et al, 2011). There is however little evidence of any other larger-scale congruent patterns with, for example, only Pt.…”

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

“…The construction of dams in upstream sites reduces the magnitude of flooding and limits the transport of suspended sediments into downstream areas (Asaeda et al 2011c). While such constructions have reportedly inhibited the colonization of flora in most cases (van Oorschot et al 1998, Steiger et al 2001, there are many incidences where intensive vegetation has occurred downstream due to upstream river regulations (Uddin et al 2010).…”

“…In recent years, the sediment bars of many rivers have become thickly vegetated and their stony characteristics are lost (Müller 2000, Asaeda andRashid 2012). This kind of vegetative development usually starts with the colonization of annual herbaceous species followed by perennial ones that have a larger biomass turnover (Asaeda and Rajapakse 2008, 2011c of bushes, where they are then finally colonized by tree species. The forestation process continues unless it is disturbed by a large catastrophic flood.…”

“…In many cases, the occurrence of relatively high riparian zones or bars limits the frequency of larger scale flooding. Between larger flood intervals, the riparian vegetation gradually recovers, following a process of primary vegetation succession (Asaeda et al 2011c). In recent years, the sediment bars of many rivers have become thickly vegetated and their stony characteristics are lost (Müller 2000, Asaeda andRashid 2012).…”

The Riparian Vegetation Disturbed by Two Invasive Alien Plants, Sicyos angulatus and Paspalum distichum var. indutum in South Korea

“…따라서 침입외래종이 번성하는 하안역은 고유의 전형적인 구조와 기능에 서 벗어난 특성을 보이게 된다. 무엇보다 먼저 침입 외래종에 의하여 하안 고유 생물군집의 구조가 변화 되는데 특히 하천 고유 개척자 식물종이 피해를 받 아서 생물다양성이 변형된다 (Shin and Cho 2001, Asaeda et al 2011). 이러한 식물군집의 조성과 구조 의 변화는 생태계 기능을 다양하게 변화시킬 수 있다 (Richardson et al 2007).…”