Abstract
Forest gaps and margins of sub-montane forests in the Knuckles Forest Reserve (KFR) are invaded by Ageratina riparia. It creates a dense cover and prevents the penetration of sunlight to the ground, which may affect the seedling establishment of indigenous species in invaded areas. Six forest gaps and four footpaths inside sub-montane forests were sampled for A. riparia cover, density of forest species, soil moisture, soil root density, and canopy openness. Soil seed bank experiments were conducted during wet and dry seasons. The percentage cover of A. riparia decreased significantly when moving from the center of gaps/footpaths into the forest interior. Mean density and species diversity of forest species decreased with the increase of percentage cover of A. riparia. Low root density of forest species was observed in areas with high density of this invasive species. Higher seedling emergence of A. riparia from soil seed bank was observed along footpaths (~1500 seedlings m-2) than in forest gaps (~750 seedlings m-2) during the wet season. A. riparia seedling emergence was higher during the dry season (~22%) than the wet season (7-11%). Lower number of forest seedlings emerged in locations with higher percentage of A. riparia seedlings. Availability of light affects the establishment of A. riparia inside forests. Native species, Psychotria zeylanica and Symplocos cochinchinensis can be used to restore forests invaded by A. riparia.
Highlights
Sri Lanka is a small tropical island, a wide range of topographic and climatic variations in the country have led to evolution of many types of ecosystems, with high level of biodiversity per unit area, that is higher than most of other countries in the region (Bambaradeniya, 2002)
The objectives of the study were to determine the distribution of A. riparia in submontane forests, the effect of A. riparia on regeneration of sub-montane forests species, the seasonal effect on the soil seed bank composition in sub-monatne forests infested by A. riparia, estimate the root density of native tree seedlings and A. riparia, and determine soil moisture content and canopy openness in areas infested by A. riparia
The lowest seedling density of the forest species was observed at the center of the forest gaps and 0 m distance of the footpaths, where the highest percentage cover of A. riparia was recorded [Figure 3 (b)]
Summary
Sri Lanka is a small tropical island, a wide range of topographic and climatic variations in the country have led to evolution of many types of ecosystems, with high level of biodiversity per unit area, that is higher than most of other countries in the region (Bambaradeniya, 2002). Sub-montane forests are located at 1,000-1,500 m elevation above the mean sea level and cover 1.1% of the total land area (Bastiaanssen and Chandrapala, 2003). These forests with high biodiveristy are important due to many ecosystem services provided by them including protecting of important watersheds and providing habitats for many endemic flora and fauna (Doumenge et al, 1995; Weerawardane, 2005). Invasive species that have escaped from the cultivations have infested lawns as pests, displaced native plant species, reduced wildlife habitats, clogged important water ways and have
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
