Recent research on public land production in the broader region highlights similarities and differences between public and private land production. For example, both seem to be located relatively close to rivers and streams, with ~50% canopy cover, and in relatively young stands . However, while we may presume that all production on public lands represents new clearing for production, our results indicate that 32% of farms are on already developed and unforested parcels. Additionally, public lands provide critical refuges for many of the region’s carnivores, which may help explain why public land production appears to overlap more with carnivore habitat than our results for private land production . Perhaps most importantly at a landscape scale, farm size and total extent appear to be much smaller for legacy pathway private land cannabis mapped in this study compared to estimates of public land production practices . Despite the differences between public and private land cannabis production, private land cannabis farming still has characteristics that warrant continued research and planning. Our results suggest that legacy pathway cannabis farming could be compatible and comparable with existing rural land use in Josephine County. In order to ensure this continues to be the case, however, further attention should be given to conservation outreach, policies to support small scale farming, and attention to land use practices on farms, particularly those that may affect carnivores and coho salmon. As the industry continues to expand, policymakers and conservationists need to clarify landscape level strategies to ensure a sustainable future. Care should be taken when interpreting these results, since cannabis agriculture takes many forms and often exhibits regional differences in production practices that may influence its ecological impact . Our study, by nature of our mapping approach, evaluated outdoor production on private lands. We were unable to quantify whether the farms we mapped were illegal or licensed medically or recreationally, nor how many farms we may have missed by farmers effectively concealing their crop. Given our mapped sites included 2,227 farms in 2016 compared to the 43 recreationally licensed locations in 2016 , plant grow trays it is likely that most of the farms we georeferenced were not licensed. If this is the case, the lack of effort to conceal crops is notable.

We suspect because cannabis was pervasive , that enforcement would not have been feasible . Therefore, we were confident that our study accurately quantified the distribution of private-land cannabis production because of the visibility of both licensed and unlicensed farms from aerial imagery. Further, our data likely does not capture all of the cannabis being grown in Josephine County as we were unable to quantify concealed farms on public land or indoor cannabis production. Instead, our study offers critical insights into the ecological consequences of the growing industry in legacy production regions. The overall cultivated area of private land cannabis agriculture at the landscape scale in Josephine County in 2016 appears to be similar to small-scale rural development already occurring regionally. For example, in a county of 4,250 km2 , the total cannabis cultivation area was only 1.34 km2 . This small size is similar to other agricultural production in the county: in 2017, Josephine County produced 2.98 km2 of grapes and 0.48 km2 of vegetables . Cannabis in Josephine County was also considerably smaller in scale than other legacy cannabis-producing regions in Northern California in 2016, where averages ranged from 53-119 plants per site, compared with the median of 21 found in our study . While we do not have comparative research on the ecological effects of other agriculture in the study area, small-scale agriculture in rural areas often creates a landscape mosaic that supports species richness . The ability of small-scale cannabis farming to function like agriculture in other working lands systems, however, requires a deeper understanding of land use practices associated with cannabis production. Specifically, to be ecologically sustainable, small scale private land cannabis farms would need to create a significantly smaller ecological footprint than public land cannabis . Although the area of cultivation for cannabis in Josephine County was small, this study did not evaluate the edge effects of cannabis cultivation, nor take into account other forms of disturbance associated with the sites, such as clearing beyond the cultivated area, road construction, or water storage development. Therefore, the actual overlap and potential ecological effect from cannabis farming in the region is likely to be larger than what was documented in this study. Our understanding of these broad scale impacts would be enhanced in future studies that may be able to assess the fine scale response of wildlife on and surrounding cannabis farms.

While our study does not address direct effects of cannabis production, we did identify spatial relations of cannabis development that could pose unique risks to terrestrial and freshwater ecosystems. We found that cannabis production was clustered in its distribution, which is consistent with research from northern California . Similarly, the proliferation of fences associated with cannabis could be a concern for habitat fragmentation as the industry expands . The overlap results indicate that cannabis may be grown disproportionately in forests and at higher elevations, which suggests cannabis could be associated with greater land clearing than other development on private parcels. However, the forests where cannabis was grown did not appear to be denser or older than comparable parcels. Our results indicate a large overlap of cannabis farms with areas of high projected fisher occupancy. This overlap was greater on cannabis farms than private land generally, but could be due to a higher proportion of cannabis farms located at higher elevations . However, elevation alone doesn’t explain this overlap. Fisher occupancy was projected to be higher on cannabis farms than the areas immediately surrounding them . This suggests that even at fine scales, farms are appearing in areas of potential for high quality habitat for fisher. What this overlap may mean for fisher populations is unclear, given the lack of research on the impacts of private land cannabis production. Private land cannabis has not been documented to have the same negative effects on fishers as public land production, and in particular pesticide and toxicant use appears to be lower on private land farms, according to self-reported farmer surveys . However, anecdotal reports and local news stories raise concerns for these private land farms as well, and many grower organizations have emphasized a need for stronger environmental norms among farmers. Given the remaining uncertainty, these results emphasize the potential need for conservation attention to private land farms as well. Surprisingly, the individual species differences did not add up to differences in overall carnivore richness, which was relatively consistent across the study area. This raises the possibility that the differences in carnivore distributions might be driven by competitive interactions , though finer scale research would be needed to disentangle the drivers of these species distribution patterns in relation to cannabis production. Regarding potential interactions between cannabis production and freshwater ecosystems, the picture was also somewhat mixed. There were a number of farms within 15 m of rivers and streams, but this was not surprising given the high density of rivers and streams in the study area. On average, most farms were only slightly closer to rivers and streams than the surrounding context of all private land parcels. Cannabis was located on average 273 m closer to coho salmon habitat than private parcels overall, 387 m closer to fall run chinook, and 132 m closer to winter run steel head, though the IQR intervals overlap. This proximity to freshwater in Josephine County was also generally closer than observed in other legacy cannabis regions . For example, the proportion of sites in Josephine County within 500 m of coho habitat was more than twice the proportion in northern California . Butsic et al. used intrinsic potential data rather than direct fish population data, custom grow rooms which may overestimate fish populations , so this difference could be even more extreme. Coho salmon spawn in smaller upstream tributaries that may be particularly susceptible to drought or water withdrawals . This proximity to coho may be explained by the large number of cannabis sites in proximity to small, head water streams , which could further indicate potential threat to other species that depend on these habitats, such as headwaters-dwelling amphibians. Therefore, this proximity to fish habitat could be an ecological concern if farms are drawing water from small rivers or shallow wells during the dry season .

Whether or not metrics summarizing the proximity of farms and sensitive habitats result in actual ecological harm largely depends on the individual land use practices occurring on cannabis farms. There is a rich history of different approaches to cultivating cannabis , which could lead to variation in how cannabis affects ecosystems. Unfortunately, we still do not have a complete picture of cannabis land use practices, nor their mechanisms underlying their ecological effects. So far, available published research suggests that much of small-scale private land cannabis production may not be as ecologically damaging as previously believed , though a consensus has not been reached, and effects may vary over time. Given our current knowledge, therefore, the snapshot of private land cannabis in 2016 in Josephine County does not on its own indicate widespread ecological effects. There could however be an increased concern for local biodiversity if cannabis development expands in size or intensity while remaining in the same spatial configuration—located in forested vegetation, and in proximity to a few key sensitive carnivore and fish species. Certainly, the large number of new farms in the first year of legalization suggest a rapidly expanding industry. This concern suggests a need to consider development pathways and future trajectories that sustain conservation values. The recent boom in outdoor cannabis farming has created a rapid development frontier in the 19 US states that have legalized cannabis production . For decades, outdoor cannabis was grown illegally, often in rural, remote areas, but with state-level legalization, production in those same “legacy” regions has rapidly expanded . In some of these rural, legacy-production regions, cannabis production on private lands can transform development patterns at a regional scale . This development frontier can foster new cultural, economic and demographic dynamics . Importantly, these new patterns of land use also incite concerns for ecological impact related to habitat fragmentation or degradation, potential effects on freshwater quality/availability, and direct or indirect effects on wildlife populations . To understand, reduce, or mitigate these potential impacts, it is important to identify the social and ecological factors that drive cannabis development on private lands across space and time. For example, understanding why farmers choose to cultivate at particular sites may help lawmakers craft and prioritize appropriate regulations for licensed cannabis. Additionally, spatial distribution and socio-cultural drivers are important for understanding where risks of environmental impact or human-wildlife conflict may arise, and for predicting the future trajectory of the cannabis industry. However, there remain many challenges to understanding drivers of cannabis development in these complex systems. Outdoor cannabis production in legacy regions is unique from other forms of traditional agriculture and functions as a closely tied social-ecological system. In these small-scale cannabis systems, the history of illicit farming lays a foundation for production practices that are vastly different from crops that did not have to be concealed, or that were grown following standardized agricultural practices across an industry . Given the continued barriers to bringing legacy farmers into legalized cannabis systems and the existence and persistence of illegal markets, historical context is likely to influence current growing patterns, even as they move into licit markets and expand on private lands . In addition to historical practices that initiated the industry, there are other factors that likely influence whether, where, and how cannabis is produced, including federal, state, and local regulation and enforcement, social acceptance of cannabis within a region, access to education and communication of production practices among growing communities, short- and long-term economic tradeoffs, and others. These factors will influence the spatial distribution and predominant production practices of cannabis over time, which could shift the proximity of cannabis to terrestrial and aquatic wildlife habitats, or alter cannabis impacts on the local environment. These perceived or actual environmental impacts from cannabis can feed back into cannabis land use via shifts in attitudes that could lead to voluntary changes of production practices, increased enforcement, regulatory changes, or shifts in community acceptance for local production .