The predominance of cannabis in forest and undeveloped land covers was also supported by the Gradient Nearest Neighbor data on forest structure. Although the GNN dataset uses a broader categorization for forest, it also indicated that cannabis was disproportionately grown in forested areas . Nevertheless, the forest structure of farms was similar to that on all available private parcels . Cannabis farms occurred in areas with intermediate carnivore richness, similar to all available private parcels . However, at the individual species level, cannabis farms overlapped with higher projected fisher and ring tail occupancy, and lower gray fox occupancy . These differences were consistent across land cover, forest structure, and zoning. However, median fisher occupancy values were larger on high elevation parcels, and a greater proportion of cannabis farms were at higher elevations compared with private parcels. There was no difference in richness between existing or new cannabis farms, and no difference at the species level except for gray fox, which had a slightly higher median occupancy on existing farms compared with new farms .Cannabis was located slightly closer to rivers compared with all available private parcels, though the interquartile range intervals overlap . There were also a higher proportion of cannabis farms located within 15 m of a river or stream, compared to private parcels . However, the proximity of farms to threatened fish species was mixed. For example, although there was a large variation in distances and overlap of IQR intervals, on average cannabis was nearly 1.5 times closer to coho salmon habitat than all private parcels, yet more than 5 times farther from spring chinook habitat. The variation in proximity to fish habitat may be in part due to the proximity of cannabis to smaller streams by order . This study is one of the first landscape-scale assessments of small-scale outdoor cannabis farming and its potential broad-scale ecological effects in a rural biodiversity hotspot. Our results suggest two main conclusions. First, private land cannabis farming in Josephine County, Oregon in 2016 was common and spatially clustered, expanded post-recreational legalization , and yet only covered a small portion of the total land area.

This supports our expectation that cannabis farming in Josephine County would exhibit characteristics typical of the legacy development pathway, but that these farms would largely be new post legalization. Second, our spatial proximity results highlighted areas of overlap or proximity of cannabis farms and sensitive habitats and species. Compared to the surrounding context of all available private land parcels, cannabis was more frequently located in forested areas and undeveloped land, closer to rivers/streams and coho salmon habitat, and in areas of high value as fisher habitat. These results provided mixed support for our expectation that cannabis production would be in areas that increase its potential ecological impact. 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 , it is likely that most of the farms we georeferenced were not licensed. If this is the case,planting table 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 . This clustering could be an ecological concern if cannabis is occurring disproportionately in sensitive ecological areas. 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.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.