Lantana camara L. invasions in dry rainforest ‐ open forest ecotones: The role of disturbances associated with fire and cattle grazing

Abstract

A field experiment was used to evaluate the effects of fire and cattle grazing on the initiation oi Lantana camara invasions in dry rainforest-open forest ecotones in the gorges of the Macleay River, NSW. A factorial combination of four factors (burning, biomass removal, soil scarification, and fertilization) at two levels (presence and absence) was established to assess the suitability of disturbed patches for germination, survival, and growth in association with changes in microclimate and resource availability. Burning, biomass removal and soil scarification, either singularly or in any combination, significantly increased germination, on average, by 19%, from 50.2% to 59.7%. Survival increased on average 26% across all treatments while mortality decreased by 26% when compared with the control. The differences between treatment combinations were not significant. Seedling growth was significantly enhanced by all disturbances, except by soil scarification alone. Treatment combinations that reduced vegetation cover (burning and/or biomass removal) and, therefore reduced shading, significantly increased L. camara biomass production by an average of 140% for all treatments. The control yielded 14.0 g m"', while fertilizer alone and biomass removal alone yielded 27.6 g m" -and 40.5 g m~', respectively. Other treatment combinations averaged 35.2 gm~" and were not significantly different from each other. Consequendy, successful invasions are likely to occur whenever canopy disturbances create patches of greatly decreased competition and/or increased resource availability. Shading plays a greater role as a limiting factor than any other, while surface soil macronutrient levels are also important, particularly when combined with canopy disturbances that increase light availability. The effects of biomass reduction and soil disturbance associated with fire and cattle grazing are significant in the successful invasion of L. camara. Management strategies to reduce weed encroachment and community degradation must identify and maintain ecological barriers to L. camara invasion in order to promote rainforest conservation and biodiversity.

Lantana Camara L. Invasion and Impact on Herb Layer Diversity and Soil Properties in a Dry Deciduous Forest of India

“…The presence of disturbance in the form of canopy openings increases resource availability and also modifies the microclimate, which is consistent with the disturbance patch invasion model (Gentle and Duggin, 1997). The model state that the removal of competitive biomass and disruption of inter specific competitive interactions creates patches of increased resources.…”

Disturbance affects short-term facilitation, but not long-term saturation, of exotic plant invasion in New Zealand forest

“…This corroborates the widely recognized role of disturbance as an important driving force of exotic plant invasion [2][3][4], and our results suggest that natural disturbance events such as wind-throw, landslides and insect damage, promote the colonization of invasive species in a similar way to human-caused disturbance such as clear-felling and fire [4,38].…”

Factors influencing the local scale colonisation and change in density of a widespread invasive plant species, Lantana camara, in South India

“…Published information (Day et al 2003, Sharma et al 2005, Gentle and Duggin 2006 and observations from our study area suggest that L. camara is present in high densities in dry-and moist-deciduous environments compared to wet evergreen environments . Thus, habitat suitability for L. camara may be related to canopy deciduousness.…”