Marijuana farming hurts environment

October 31, 2017

Science Daily/Ithaca College

Planting cannabis for commercial production in remote locations is creating forest fragmentation, stream modification, soil erosion and landslides. Without land-use policies to limit its environmental footprint, the impacts of cannabis farming could get worse, according to a new study published in the November issue of Frontiers in Ecology and the Environment.

Earlier studies have shown that cannabis production causes environmental damage, including rodenticide poisoning of forest mammals and dewatering of streams due to improper irrigation.

Cannabis, as either a medicinal or recreational drug, is now legal in more than 30 U.S. states and in several countries. In California, where medicinal marijuana has been legal since 1996, voters in November approved the sale and possession of one ounce of marijuana for recreational use. As a result, cannabis production is ramping up.

"Cannabis leaves a small spatial footprint but has potentially significant environmental impacts," said co-author Jake Brenner, associate professor in the Department of Environmental Studies and Sciences at Ithaca College. "To mitigate these impacts, policymakers and planners need to enact specific environmental and land-use regulations to control cannabis crop expansion during this early stage in its development."

Scale matters Effective policymaking for a new crop can be challenging without scientific data. In this study, Brenner, along with Van Butsic, a University of California Cooperative Extension specialist in UC Agriculture and Natural Resources and the UC Berkeley Department of Environmental Science, Policy and Management, and Ian J. Wang, assistant professor in the UC Berkeley Department of Environmental Science, Policy and Management, present an approach for early assessment of landscape changes resulting from new agricultural activities.

Their approach uses per-unit-area analysis of landscape change. To study forest fragmentation in northern California, the scientists compared the effects of cannabis cultivation to those of timber harvest from 2000 to 2013 in Humboldt County.

Based on the size, shape and placement of the cannabis grows among 62 randomly selected watersheds, they quantified the impacts relative to those of timber harvest.

"We found that although timber has greater landscape impacts overall, cannabis causes far greater changes in key metrics on a per-unit-area basis," said Butsic.

On a per-unit-area basis, the cannabis grows resulted in 1.5 times more forest loss and 2.5 times greater fragmentation of the landscape, breaking up large, contiguous forest into smaller patches and reducing wildlife habitat.

"The results show how important it is to consider environmental impacts at different scales," said Brenner.

Current California law caps the size of outdoor cannabis production to 1 acre per parcel, to prohibit the development of industrial-scale cannabis operations outdoors. An unintended consequence of this law may be small dispersed cannabis grows that edge out wildlife.

While the long-term effects of cannabis cultivation on the environment are unknown, the researchers concluded that land management and agricultural policy informed by further research may reduce these threats in California and in other states and countries where cannabis production can be regulated.

"Studies like this one have the potential to directly inform local land-use policy and state environmental regulation," said Brenner. "It's exciting to be a part of this research because it is capturing a human-environment phenomenon at the moment of its emergence."

https://www.sciencedaily.com/releases/2017/10/171031202705.htm

Marijuana's hidden price: Environmental impact

October 19, 2016

Science Daily/Ithaca College

A new survey of marijuana grow sites in California demonstrates the potential environmental impact of marijuana farming and provides an example of the survey and analysis needed as farming expands.

"It's just a plant" is a common refrain from those who want to legalize the leaf, but a recent study of cannabis production argues that the environmental impact of marijuana farming must be considered -- especially as more states move toward further legalization this election season.

The study was conducted by Jake Brenner, an assistant professor in the Department of Environmental Studies and Sciences at Ithaca College, and Van Bustic, a specialist at the University of California Cooperative Extension. It was published earlier this year in the journal Environmental Research Letters.

The study also highlights the lack of published, peer-reviewed empirical research on all aspects of cannabis agriculture, which is already a multi-billion dollar industry in the United States despite still being listed as a Schedule 1 drug by the federal government.

Location, location

The amount of land and water used for growing cannabis has not traditionally been a concern, especially when compared to other agricultural products grown in California. But where the cannabis is grown has potential ecological consequences.

Brenner and Bustic examined grow sites in three northern California counties and found that their usual placement had potentially negative impacts on two threatened fish species.

That's because the sites are typically placed on remote plots of land in forested areas, many on steep slopes. Access roads need to be created and swaths of land cleared for production, regardless of whether the cannabis is grown outdoors or in a greenhouse; that increases potential for soil erosion and chemical run-off into streams in which the Chinook salmon and steelhead trout live.

The fish are also susceptible to harm from a decrease in water flow as a result of the cannabis agriculture.

"Siting grows in areas with better access to roads, gentler slopes, and ample water resources could significantly reduce threats to the environment," Brenner and Bustic write. "Future cannabis policy should take into consideration the potential for mitigating environmental impacts through land-use planning."

Know before you grow

Brenner and Bustic say their study, which covers the watersheds of northern California's Humbolt County, is an example of the sort of survey and analysis that could be done -- and is necessary -- anywhere cannabis agriculture takes place.

And while California is taking efforts to encourage local governments to create land-use policies for cannabis agriculture, they argue that more research on marijuana farming needs to be done.

"Land-use science on cannabis agriculture lags behind research on other crops, but advances in the field will be crucial for predicting future cannabis expansion and moderating its impacts," they write.

That multi-billion marijuana production industry is only going to grow: This November, voters in Arizona, California, Maine, Massachusetts and Nevada will decide whether to allow their states to legalize and tax recreational marijuana; while voters in Arkansas, Florida, Montana and North Dakota will head to the polls to determine whether their states will allow medicinal uses of marijuana, joining the 25 other states that already do so.

https://www.sciencedaily.com/releases/2016/10/161019173110.htm