Invasion of the cosmopolitan species Echinochloa colona into herbaceous vegetation of a tropical wetland system
No Thumbnail Available
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ecological Society of Japan 2014
Abstract
Description
Ecological research,2014; 29: 969-979
The negative effects of alien plant species on ecosystem structure and functions are increasingly recognised, and efforts to control these species are vital to restore degraded ecosystems and preserve biodiver- sity. However, we lack a full understanding of factors that determine alien species invasions along spatial gradients in herbaceous vegetation of tropical systems. We therefore examined the effects of community prop- erties, environmental variables and human-related dis- turbance factors on the invasion of the alien grass Echinochloa colona (L.) Link at small- and large scales in the Kilombero Valley wetland, Tanzania. Generalized additive mixed models showed that E. colona abundance on a small scale was negatively related to above-ground biomass and evenness of resident species, whereas E. colona abundance was positively related to grazing intensity. On a large scale, biomass (negatively related to E. colona abundance) and distance to river (positive) were important in explaining E. colona abundance. These findings support the assertion that different fac- tors may contribute to the invasion of alien plant species at different spatial scales, as also reported in many temperate systems. Overall, our results show that suc- cessful invasion of alien species is a function of plant community properties, human-related disturbance and favourable environmental conditions. Effective man- agement strategies should consider mitigations that can increase the biomass and evenness of native species and a reduction of grazing pressure to restore the wetland and conserve biodiversity.
The negative effects of alien plant species on ecosystem structure and functions are increasingly recognised, and efforts to control these species are vital to restore degraded ecosystems and preserve biodiver- sity. However, we lack a full understanding of factors that determine alien species invasions along spatial gradients in herbaceous vegetation of tropical systems. We therefore examined the effects of community prop- erties, environmental variables and human-related dis- turbance factors on the invasion of the alien grass Echinochloa colona (L.) Link at small- and large scales in the Kilombero Valley wetland, Tanzania. Generalized additive mixed models showed that E. colona abundance on a small scale was negatively related to above-ground biomass and evenness of resident species, whereas E. colona abundance was positively related to grazing intensity. On a large scale, biomass (negatively related to E. colona abundance) and distance to river (positive) were important in explaining E. colona abundance. These findings support the assertion that different fac- tors may contribute to the invasion of alien plant species at different spatial scales, as also reported in many temperate systems. Overall, our results show that suc- cessful invasion of alien species is a function of plant community properties, human-related disturbance and favourable environmental conditions. Effective man- agement strategies should consider mitigations that can increase the biomass and evenness of native species and a reduction of grazing pressure to restore the wetland and conserve biodiversity.
Keywords
Biomass, Diversity, Evenness, Alien species, Spatial scales, Human-related disturbance