Management Information
Preventative measures: A Risk assessment of Imperata cylindrica for the Pacific region was prepared by Pacific Island Ecosystems at Risk (PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score of 19 and a recommendation of: reject the plant for import (Australia) or species likely to be a pest (Pacific).
Physical: Hand pulling is an option but is extremely labor intensive. Integrated management: Burning alone is not an option, as burning only will stimulate growth an extra 50-100% per year. An integrated approach is best, utilizing burning to remove thatch layer, follow with mowing or dicing, and late season (fall 3-4 weeks prior to any frost) applications of a broad spectrum herbicide such as imazapyr or glyphosate using the labelled rate for spot treatments. The Pacific Islands of Palau and Yap are effectively controlling I. cylindrica with applications of the herbicide Roundup-Pro, followed by establishment of shade providing trees. The initial application greatly reduces the stand of I. cylindrica, but in most cases several herbicide applications are needed. Trees can be planted in scalped patches within the herbicided plots. Follow-up herbicide treatments at 4-6 month intervals are needed to clean up newly emerging I. cylindrica. Care should be taken to avoid the planted trees which eventually provide shade that should effectively prevent re-establishment (Duane Nelson, USDA- Forest Service, Hawaii). Click here for more Information about management of Imperata cylindrica.
Location Specific Management InformationRiam Kiwa trial area (Indonesia)
In 1983 the Reforestation and Natural Forest Management Project, part of the Indonesian-Finland Forestry Programme, established a trial area in Riam Kiwa in order to study methods of reforestation. Today, 60% of the 1000 hectare trial area in Riam Kiwa has been reforested. 10 to 15 species were found promising for grassland restoration and different plantation methods have been tested (Otsamo et al in press, in Jussi et al 1995). Problems of reforestation have been studied for over ten years in the area (as of 1995) and both fast-growing exotics and indigenous species have been planted and evaluated including dipterocarps such as Schorea spp., Hopea spp. and Vatica spp (Jussi et al 1995). Several exotics have shown promising results in terms of growth and suppressing I. cylindrica. Successful establishment of these species requires heavy site preparation, which turns over the rhizomes of I cylindrica and improves the rooting of tree seedlings (Otsamo et al in press, in Jussi et al 1995). The plantations create microclimate and soil conditions that improve the germination and survival rates of species unable to germinate in the open or within I. cylindrica grass cover. Most of the tree species spread naturally to the plantation and are fruit-bearing plants with animal vectors (notably birds and bats) as the principle dispersal mechanism. This suggests that plantation canopy promotes the regeneration process by providing roosting habitats for seed-dispersing animals. The majority of tree species dispersed into the plantations belong to the pioneer or secondary forest species characterised by effective means of rapid dispersal. Royal Bardia National Park (Nepal)
Grasslands (or phantas) may occur as a result of anthropogenic disturbance (Pokharel 1993, in Peet et al. 1999). The I. cylindrica grassland is important for biodiversity. Cutting and fire have been promoted to prevent succession from grassland to forest or taller grassland (dominated by Erianthus, Narenga and Saccharum species (which are less favourable to ungulates). However traditional cutting and burning has been deleterious to less mobile species such as the pygmy hog and hispid hare (Oliver 1980, Bell, Oliver and Ghose 1990, in Peet et al. 1999).
A study by Peet and colleagues (1999) was designed to investigate best management practices for preserving cover-dependant species such as the hispid hare, in particular whether rotational patches of unmanaged grassland could provide refugees for these species. The experimental site was located in Baghoura Phanta, the second largest Imperata dominated grassland (covering approximately 80 hectares). A randomised block experiment (with four treatments: cutting, burning, cutting and burning, and no management) was used to examine species abundance, richness and grassland structure. In all managed plots there was in increase in species richness of forbs, a decrease in D. bipinnata and an increase in I. cylindrica. The authors concluded that rotational cutting and burning of the grassland would provide suitable habitat for the population persistence of small mammals, herpetofauna and invertebrates. In Bardia the total area of I. cylindrica grassland is small (less than 340 hectares) so the total area removed by cutting and burning should not be more than 25 to 50 hectares. United States (USA)
In areas other than closed-canopy forests or plantations, where cogon grass survives poorly due to shading, and heavily cultivated lands, where it is kept in check mechanically, infestations are treated by relatively costly, laborious, and repetitive control measures. Currently the most effective management strategies in the United States have involved integrating mechanical (e.g., discing, mowing), cultural (e.g., burning), chemical (e.g., herbicide applications of glyphosate and imazapyr), and revegetation methods (Shilling and Gaffney, 1995; Dozier et al., 1998, in Van Loan Meeker and Minno 2002). However, a single herbicide application can cost as much as $400/ha. Impacts on non-target species from herbicide application are often severe, creating disturbances that allow for the re-invasion by cogon grass or secondary invasion by other weedy species (Gaffney and Shilling, 1996, in Van Loan Meeker and Minno 2002). For both economical and environmental reasons, the currently recommended control strategies often are unacceptable, necessitating consideration of some form of classical biological control (Shilling and Gaffney, 1995; Dozier et al., 1998, in Van Loan Meeker and Minno 2002).
Management Resources/Links
1. Chikoye, David., 2003. Characteristics and management of Imperata cylindrica (L.) Raeuschel in smallholder farms in developing countries. In Weed Management for Developing Countries Addendum 1 (Ed) by R. Labrada. Food And Agriculture Organisation Of The United Nations (FAO) Rome 3. Jussi, K., Goran, A., Yusuf, J., Antti, O., Kari, T. and Risto, V. 1995. Restoration of Natural Vegetation in Degraded Imperata cylindrica Grassland: Understorey Development in Forest Plantations, Journal of Vegetation Science 6. [Accessed 13 March 2006, from Jstor (online database)]
Summary: Paper on the restoration of I. cylindrica wastelands in an Indonesian site via secondary exotics. 4. Peet, N.B., Watkinson, A.R., Bell, D.J. and Sharma, U.R. 1999. The Conservation Management of Imperata cylindrica Grassland in Nepal With Fire and Cutting: An Experimental Approach, Journal of Applied Ecology 36. [Accessed 13 March 2006, from Jstor (online database)]
Summary: Rationale behind cutting and fire practises in Imperata grasslands in Nepal. 5. Van Loan, A.N. Meeker, J.R. and Minno, M.C. Cogon Grass In: Van Driesche, R. et al., 2002, Biological Control of Invasive Plants in the Eastern United States, USDA Forest Service Publication FHTET-2002-04. [Accessed 13 March 2006, from http://www.invasive.org/eastern/biocontrol/28CogonGrass.html]
Summary: Overview of the biology and status of I. cylindrica in the USA. 6. Wilson, Colin, Wildlife Management Officer, Department of Infrastructure, Planning and Environment, Parks & Wildlife Service, Northern Territory, Australia.
Summary: Compilor of original GISD profile of Chromoleana odorata. Results Page: 1
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