The Editor’s Choice for issue 55:1 is written by Associate Editor, Paul Kardol. The article chosen is Integrating local knowledge and research to refine the management of an invasive non-native grass in critically endangered grassy woodlands by Firn et al.
Elucidating patterns of species invasions and the underlying mechanisms are key challenges for present-day ecologists. They are also of utmost importance in developing effective management strategies. How could we effectively combat negative effects of invasive plants on native ecosystems? Ask the locals!
When travelling generally, asking the locals is a good start for discovering new places in unfamiliar surroundings, beyond what the mainstream travel guides have to offer. The same might be true for ecological research on invasive plants. Here, the locals are landholders who share historical knowledge, long-term experiences with dealing with invasive species, and anecdotal stories of changes in the ecosystems they manage. The mainstream travel guides then are ecological researchers (and the journal pages they fill) who focus on theories, concepts, and more general patterns of species invasions and their drivers. Ecologists generally design their research based on their previous work and on work by other researchers. Local knowledge is rarely embedded in ecological research. This creates some sort of an ivory tower situation, where management recommendations are ineffective at the local level or are not implemented at all because they are perceived as ineffective. Also, possible management options may be overlooked simply because we cannot keep up to pace with the spread and impact of invasive species, and by that, miss out on important local phenomena. This is where locals could help with finding the way.
But, are local perceptions always right? In this Editor’s Choice article, Firn et al. put theory to the test and developed a ‘landholder first’ philosophical approach for research on drivers and impacts of invasion of African lovegrass (Eragrostis cuvula) in endangered Lowland Grassy Woodlands in New South Wales, Australia. The C4-grass, African lovegrass, has been intentionally introduced and planted across Australia for pasture improvement and as a soil stabiliser to control erosion. But, the species has not met the expectations. It has spread throughout large parts of Australia and now is a major concern as it can outcompete native species, thus reducing plant diversity and negatively affecting the native ecosystems. African lovegrass can also pose a fire hazard because of its high biomass production.
Their ‘landholder first’ approach consisted of interviews with landholders asking them questions about the patterns of African lovegrass invasion, the factors they perceived to influence the invasion as well as the control strategies (success or fail) they have used in combating the invasion. Firn et al. then used the local knowledge elicited from these interviews to develop a series of landholder-derived hypotheses, which were tested using field surveys of vegetation and soils at the farms of the landholders and complementary greenhouse and lab studies. The burning question: were the local perceptions about African lovegrass invasions right? In other words, did Firn et al. find support for the landholder-derived hypotheses? Not in all cases. The landholders were right in their perception that African lovegrass is associated with a decrease in plant diversity, is lower in abundance where there is canopy cover from woodland trees, and when other native or exotic C4 grasses are abundant. However, they were (partly) wrong in their perception that African lovegrass is lower in abundance on high-fertile sites, that African lovegrass leaves are palatable to grazing livestock and native grazers (kangaroos and wombats) at high soil fertility levels, and that spot spraying with herbicides is ineffective and increases the abundance of African lovegrass. One other landholder-derived hypothesis – African lovegrass is favoured by drought and overgrazing – could not be evaluated within the scope of their study but provides a basic for long-term monitoring.
Why is it important to use local knowledge as the basis for scientific, ecological research? First, supported perceptions of landholders can lead to management recommendations that would not be easily obtained from traditional research approaches. For example, in this case a possible management strategy could be the sowing of native C4-grasses, or the re-establishment of woodland tree cover. Second, and certainly not less important, landholder perceptions that were not supported can halt ineffective and potentially harmful management practices. For example, in this case, using fertilizers seems pointless and would only lead to further degradation of the native ecosystems through negative effects of eutrophication on species diversity and other ecosystem values. On the other hand, the use of spot spraying with herbicides appears more effective than perceived by the landholders, and could actually be useful in management of African lovegrass invasions. So, the study by Firn et al. provides a powerful case of the importance of local knowledge as a basis for scientific research and the design of field experiments. Their study also is a great example of how better communication and mutual-learning between researchers and the public (in this case landholders, but in other case could be foresters, conservationists, and other land-users) could lead to improved, science-supported and publicly accepted ecosystem management strategies.
The full article, Integrating local knowledge and research to refine the management of an invasive non-native grass in critically endangered grassy woodlands is available in issue 55:1 of Journal of Applied Ecology.
Read Senior Editor, Marc Cadotte’s thoughts on the article here.