Invasion landscapes as social-ecological systems: role of social factors in invasive plant species control.
Biological invasions are a major threat to biodiversity and human well-being. Scientists and environmental managers typically seek ecological solutions to the biological invasion problem. However, micro-scale social factors, such as landowner attitudes and social interactions that underlie landowners' willingness to control invasive species, may provide an important lever for controlling biological invasions. Yet, compared to our ecological understanding of invasion dynamics, little is known about the effect of micro-level social factors on the efficiency of invasive species control. Here, we determine how landowners' micro-scale social factors contribute to the efficiency of invasive species control, that is, landowners' ability to contain or eradicate invasion at landscape level. First, we survey landowners across New Zealand to gain an understanding of the social factors that affect their willingness and ability to control invasive conifers. Then, we disentangle how micro-scale social factors influence landscape-level patterns of conifer invasion using a social-ecological simulation model. We estimate the influence of social factors individually and through their aggregated effects. We found that micro-scale social factors can determine the efficiency of invasion control to the extent that higher level management strategies, such as early detection of the invasion, become irrelevant. Our experiments support a management strategy for New Zealand conifer invasion that is based on targeting both social and ecological factors. Combining establishment of shared rules for control participation that target socially conditioned behaviour with coordination of control action based on the aggressiveness of the invasion can amplify the efficiency of control at landscape level. Our survey shows that New Zealand landowners are generally highly motivated to control the invasion, but they also adapt their control behaviour to that of others and are limited by the cost of control. The results indicate that integrating such adaptive landowner behaviour with ecological invasion dynamics can, over time, create feedbacks that decrease landowners' ability to control the invasion. This study demonstrates that failure to consider how social and ecological factors interact in invasion landscapes can lead to suboptimal control programs and irreversible environmental change. A social-ecological perspective on biological invasions will significantly improve our ability to explain and manage invasion dynamics.