Pasture with rainforest behind in the Lacandon rainforest. Photo by: Alejandro Linares Garcia.
Tropical reforestation is not easy, especially in abandoned pasturelands. But a new study in mongabay.com’s open access journal Tropical Conservation Science finds that removing grasses prior to and after planting native tree seeds significantly improves the chances of forests to take root. The study site, located in Mexico’s Lacandon rainforest, was covered in an invasive African grass (Cynodon plectostachyus).
“Across the tropics, millions of hectares of forest have been converted to cattle pasture and then abandoned. Invasive alien grass species such as Cynodon plectostachyus, and many others originally introduced as pasture plants, commonly form dense, monospecific stands in tropical pastures […] As a consequence, vast areas of the tropics are now characterized by agricultural mosaics of pastures and fields interrupted by occasional forest remnants, a scenario that presents significant new challenges to conservation and restoration,” the researchers write.
After burning the field site, researchers planted 960 seedlings of 16 species, including a broad range of tropical tree types. Eighteen months later, they found that removing grass before and after planting significantly improved the chances of many of the species.
“Survival and growth rates of tree species always increased significantly with more intense grass removal treatments, and trees receiving less frequent treatments suffered greater mortality and lower growth,” the researchers write.
However, even though the tree seedling had greater success after grass removal, the scientists caution that the process makes reforestation more expensive. The Lacandon reforestation project cost $1,260 per hectare.
“For the time being, it is clear that legal incentives and economic support will be needed to assist restoration interventions, starting with seed collecting and nursery costs, and extending right though to planting and post-planting site maintenance such as the grass removals described here,” the researchers write.
CITATION: Román-Dañobeytia, F. J., Castellanos-Albores, J., Levy-Tacher, S. I., Aronson, J., Ramírez-Marcial, N., Rodrigues , R. R. 2012. Responses of transplanted native tree species to invasive alien grass removals in an abandoned cattle pasture in the Lacandon region, Mexico. Tropical Conservation Science Vol. 5(2):192-207.
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