WELLINGTON, Sept. 9 (Xinhua) -- Farming at the edges of nature reserves is facilitating invasions by exotic plants, according to a study published on Monday.
The study found that exotic plants are invading native shrubland reserves in the Canterbury Plains of New Zealand's South Island, which are being sped along by nutrient and water spillover from adjacent intensive agriculture.
Researchers from Landcare Research found spillover of water and nitrogen enrichment, which is likely from animal effluent, 10 meters inside reserve boundaries, allows exotics to outcompete natives up to 40 meters inside the boundary.
The study published in the New Zealand Journal of Ecology called for future reserves to be made larger from the start, as some small reserves are only 100 meters wide.
"These distances are significant as some of these reserves are only 100 m across, meaning that more than 60 percent of these reserves can be affected," said co-author Gretchen Brownstein, adding that irrigation and effluent buffers around these reserves would help to limit further degradation of these reserves.
Native shrublands were once common across the Canterbury Plains, but over time, conversion of land to other uses including irrigated pasture has contributed to their gradual decline, said the researchers.
Co-author Adrian Monks said the ongoing effects of more intensive land use adjacent to the reserves could be managed with better rules around buffers. ■
