Ideally, ecological restoration will help heal a habitat, but when you bring back plants to a location, what else are you bringing along? According to researcher Ruth Mitchell’s study published in Restoration Ecology, the well-intended act of introducing flora might also inadvertently spread plant pests or pathogens, potentially causing more harm to the ecosystem and biodiversity than anticipated. Results from a survey show that those active in habitat restoration in the UK greatly underestimate some risks in bringing plants to a new location. More alarmingly, though 70% had biosecurity guidance – a framework to prevent such biological hazards – 22% of them did not check its implementation, leaving the ecosystem vulnerable to unanticipated dangers. Mitchell argues that standardising risk assessments for plant pests/pathogens in ecological restoration is vital.
Anyone who has tried to garden knows that along with your beautiful new rose bush, you might unwittingly bring a host of unwanted pests into your garden. The same applies to ecological restoration but on a much larger scale. However, according to a study by Ruth Mitchell, those leading the charge in habitat restoration consistently underestimate the danger these parasites pose.
One example she gives is the use of mature plants. Mitchell found that many workers believe there is not a lot of difference in risk between using seeds and using mature plants to restore habitats. However, mature plants act as a “biological package”, housing not just the plant itself but any organisms living on it or within the surrounding soil. So, we might unintentionally reintroduce pests and pathogens into these habitats. These unwelcome guests could then establish themselves in the new environment, undermining restoration efforts. Yet often, neighbours are perceived as a greater source of pests than anything the restoration workers are doing. In her article, she writes:
If neighbors are perceived as the most likely source of infection of pests rather than any activity carried out by the participants, this raises the question of how much participants are prepared to alter their activities. For example, they may feel it is not worth changing their activities to reduce the risk if the greatest risk is from their neighbors. This is similar to the attitudes of those involved in large scale-landscaping projects (Karlsdóttir et al. 2021). In that study participants often expected biosecurity expertise to come from elsewhere, mainly the landscape contractor or the supplier to source plants responsibly.Mitchell 2023.
Mitchell also asks if ecologists give all habitats are given the same consideration. She argues there’s a tendency to focus on those with the most publicity, such as woodlands and freshwater habitats. This focus might leave other equally vulnerable habitats, like moorlands and heathlands, at risk.
A solution she proposes is the development of standardized risk assessments and biosecurity procedures during ecological restoration. Currently, these critical protocol checks are neglected, with many organizations either lacking a risk assessment for plant pests or ignoring if biosecurity measures are being followed. Ironically, a single approach to biosecurity could help tackle the diverse risks restoration projects face. She writes:
There are multiple types of ecological restoration, and some will be riskier than others. There is thus a balance to be achieved between ensuring greater awareness of the plant health risks and not burdening low-risk ecological restoration projects with unnecessary biosecurity measures, which become a barrier to “bending the curve for biodiversity” and mitigating the biodiversity crisis.Mitchel 2023.
Mitchell’s findings are based on a questionnaire she devised to understand people’s role in ecological restoration, their knowledge of plant health risks, and their use of risk assessments and biosecurity measures. To gather this information, She asked 19 questions in four sections.
The first section aimed to learn more about the participant’s involvement in ecological restoration, while the second focused on the participants’ perceptions about the greatest threats from plant pests. In the third section, participants disclosed which risk assessments they utilised and their adherence to biosecurity guidelines. The last section of the questionnaire sought to identify any gaps in their understanding of plant health risks and biosecurity practices.
The questionnaire was shared with 333 individuals and organisations across the United Kingdom. These respondents were all involved in the creation or restoration of habitats. The aim was to reach out to this diverse connection of professionals working at different scales – from local to national. The responses totalled 224.
What was intriguing was how participants perceived the potential impact of plant pests on biodiversity to differ between habitats. They believed that the effect of plant pests on biodiversity in woodlands was significantly higher than in all other habitats; contrastingly, alpine/montane habitats were ranked significantly lower. There was also a powerful positive correlation between the participant’s perceptions of the likelihood of a pest establishing in a habitat and its potential impact on biodiversity.
Interestingly, the establishment of plant diseases was seen as a lower threat to biodiversity than agricultural practices, habitat loss, and land management. In comparison, plant pests were perceived to be about the same level of threat to biodiversity as climate change and factors like nitrogen pollution and urban development.
Regarding risk assessments and biosecurity practices, more than half of the participants were unsure or did not know if they had a risk assessment for plant pests. The numbers were slightly better for biosecurity guidance, but 22% of participants admitted to not checking if this guidance was followed. Even more concerning, 40% of participants either did not know or were unsure if anyone was responsible for biosecurity within their organization.
Only about a third of participants monitored the ecological restoration for plant pests following the completion of work, while 37% did no monitoring whatsoever. Many participants admitted that they did not do any specific monitoring for pests but assumed the presence of pests would be picked up in general habitat condition surveys.
Regarding sources of information and further guidance, quite a number of participants (26%) felt the guidance they had about plant health risks was sufficient. In contrast, almost half of the participants wanted more advice on biosecurity for staff and contractors, understanding the current legislation on plant pests and movements of plants/soil/equipment, and biosecurity for the general public.
Mitchell emphasizes that the exchange of knowledge among colleagues plays a crucial role in pest management. Enhancing the community’s understanding of potential risks can help practitioners assess situations more accurately and take relevant actions without inadvertently making matters worse. In a nutshell, caution and education are our best weapons against the unintended consequence of exacerbating plant diseases.
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Mitchell, R.J. (2023) “The amplification of plant disease risk through ecological restoration,” Restoration Ecology, 31(5). Available at: https://doi.org/10.1111/rec.13937.