A Dynamic Modeling Framework to Evaluate the Efficacy of Control Actions for a Woody Invasive Plant, Hakea sericea

Abstract

Invasive alien species (IAS) are a significant component of global changes, causing severe economic and biodiversity damage. In this regard, Hakea sericea is one of the most widespread IAS throughout the Mediterranean region, including Portugal. The difficulty surrounding its management is exacerbated by post-fire situations, signifying a challenging task for managers. To assist in this effort, we used a system dynamic approach to model the population dynamics of Hakea sericea regarding the combinations of wildfire risk and control scenarios, which differ in periodicity, type of interventions, and cohort age. The ultimate goal of this study was to assess the effectiveness and costs of control efforts at reducing the abundance of this IAS. A Natura 2000 site Alvão/Marão (code PTCON0003) in northern Portugal, severely invaded by Hakea sericea, served as the study site. The modeling results demonstrate that Hakea sericea is likely to continue spreading if left uncontrolled. Although it may not be possible to ensure eradication of Hakea sericea from the study, repeated control actions aimed at the entire IAS population could be very effective in reducing its area. From a practical standpoint, removing all plants 24 months after each fire event followed by subsequent monitoring appears to be the most cost-effective strategy for managing Hakea sericea. Considering the modeling results, the dynamic modeling framework developed is a versatile, instructive tool that can support decision-making aimed at effective management of Hakea sericea.

Developing an Integrated Capitals Approach to Understanding Wildfire Vulnerability: Preliminary Considerations from a Literature Review

“…Within the first group of studies focusing on impacts of fire on natural assets, ecological values and ecosystem services, a preeminent role was played by papers addressing damages and disturbances to forest ecosystem dynamics (Wu & Kim, 2013;Aleksić et al, 2009), direct changes to dominant vegetation and biodiversity (Adams, 2013) and indirect shifts caused by grass invasion (Morais et al, 2021;Kerns et al, 2020), higher impacts of pest and diseases on plant survival, variations in traits expression (Lerch et al 2016;Bélanger et al, 2013;Salazar et al, 2020), and reduction in forest resilience (Wu & Kin, 2013, Mouillot et al, 2005. Less investigated are impacts on water and soils.…”

Invasiveness, Monitoring and Control of Hakea sericea: A Systematic Review

“…In Portugal, H. sericea presents better performance than resident species, such as Pinus pinaster [ 5 ], increasing in abundance after intense fires [ 129 ]. Currently, dense (>75% cover) stands of H. sericea negatively affect several ecosystem functions and services, such as recreation and animal production, due to difficulty or impossibility of access to humans and wild and domesticated animals [ 5 , 12 , 130 ].…”

“…However, knowledge and expertise in control, monitoring, and management methods have evolved significantly [ 32 , 46 , 51 , 149 ]. More recently, New Zealand and Portugal have conducted research on the control, monitoring and management of H. sericea populations impacting the scientific community [ 11 , 127 , 129 , 130 , 150 , 151 , 152 ]. In this section, we structured the main findings of the literature review on control methods (mechanical and prescribed fire, chemical, biological and integrated control management), modeling and monitoring, and the management and of H. sericea invasions.…”

“…Morais et al developed a H. sericea population dynamics model combining several fire risk and control scenarios, differing in periodicity of fire occurrence, control intervention type, and plant cohort age. The results indicated that in the absence of control actions, H. sericea populations will continue to expand and that periodic control actions can decrease plant population levels [ 129 ].…”