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.
“Despite its small current footprint, the boom in cannabis agriculture poses a significant threat to our environment,” said co-author Van Butsic, a UC Cooperative Extension specialist in UC Agriculture and Natural Resources and the UC Berkeley Department of Environmental Science, Policy and Management. “To mitigate the anticipated environmental impacts, now is the time for policymakers and land-use planners to set regulations to manage the spatial pattern of cannabis expansion before crop production becomes established.”
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.
Effective policymaking for a new crop can be challenging without scientific data. In this study, Butsic and Ian J. Wang, assistant professor in the Department of Environmental Science, Policy and Management at UC Berkeley, and Jacob C. Brenner, associate professor in the Department of Environmental Studies and Sciences at Ithaca College in New York, 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,” Butsic said.
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,” Brenner said.
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,” Brenner said. “It's exciting to be a part of this research because it is capturing a human-environment phenomenon at the moment of its emergence.”
Given California's changing climate, should Sierra Nevada residents replant pine trees after so many died during the 2010-2016 drought? The short answer is yes, says Susie Kocher, UC Cooperative Extension forestry advisor.
“We have every reason to believe that pines will continue to be an important part of mixed conifer forests in the Sierras,” Kocher said.
Kocher spoke at a meeting for UC Master Gardeners, volunteers who provide landscape advice to the public in California. Questions have been coming in to Master Gardener hotlines from mountain residents wondering what to do after unprecedented tree loses in the last few years.
Most California forests are suffering from severe overcrowding due to 100 years of aggressive fire suppression and selective harvesting of the largest and most resilient trees. They were then subjected to five years of drought.
“There were just too many stems in the ground,” Kocher said. “The drought was very warm, so trees needed more water, but got less. These were optimal conditions for bark beetles.”
Western pine beetle is a native pest that attacks larger ponderosa pine and Coulter pine trees weakened by disease, fire, injury or water stress. Bark beetles are tree species specific, so other beetles target other species of trees in California's mixed conifer forests. Typically, bark beetles bore through tree bark and create long winding tunnels in the phloem. An aggregating pheromone attracts additional bark beetles to the tree, and heavily attacked trees invariably die.
During the drought, 102 million Sierra Nevada trees died from bark beetle attack or simply lack of water; 68 million of those died in 2016 alone. But after the abundant rainfall in the 2016-17 season, the bark beetle population seems to have crashed.
Landowners with 20 acres or more may be eligible for a state cost-sharing program to remove trees, reduce the fire hazard and replant new seedlings. Landowners in mountain communities who wish to revitalize their properties can contact local UC Master Gardeners for recovery advice.
UC Master Gardeners are plant enthusiasts who have passed an intense training program presented by UC academics. They participate in continuing education annually to update and maintain their knowledge. More than 60 Master Gardeners from Mariposa, Madera and Fresno counties gathered in Oakhurst in October to learn from UC scientists how to work with mountain homeowners whose towering trees have died. Similar training sessions, all funded by a grant from UC Agriculture and Natural Resources, were held in El Dorado and Tuolumne counties in June.
“There is life after beetles,” said Jodi Axelson, UC Cooperative Extension forestry specialist at UC Berkeley.
“Eco systems are stretched, and then they come back,” she said. “You must remember the time scale of forest change is long and pines have been a major species in the Sierra Nevada for at least 28,000 years. As long as there have been pines, there have been bark beetles.”
The scientists suggest that people who own forestland take a step back and assess the landscape after their dead trees have been removed.
“We're seeing a lot of young cedar and white fir surviving the drought. Oaks seem to be doing really well,” Kocher said.
She suggests landowners thin young trees so available sun and soil moisture are focused on the healthiest trees. Water seedlings that are receiving more sun than before to reduce stress. Planting native conifers is the best option. Due to climate change, she recommends choosing trees from a slightly lower elevation to hedge against warmer temperatures in the future.
Pines are adapted to the California forest, but may need help to regenerate. When the ground is moist in the late fall or spring, plant seedlings 10 to 14 feet apart. New trees should be planted well away from homes to maintain defensible space and at least 10 feet from power lines.
“Please don't set them up for future torture,” Kocher said. “That's just sad.”
To help the new trees become established, cover the ground around the tree, but not touching the bark, with two or three inches of mulch and irrigate weekly during the dry season for the first few years.
Questions about special circumstances may be directed to local UC Master Gardeners. Find the local program here: http://mg.ucanr.edu/FindUs/
It's Deja Vu all over again
- Yogi Berra
Once again I'm asked to provide some perspective on yet another catastrophic situation affecting the North Coast. In 2015, it was the Valley Fire. In 2016, it was the Clayton Fire. This year there are so many fires I'm having difficulty recalling their names...14 at last count.
The cause for these 2017 conflagrations will be apparent once the elements of the fires are assessed. Tornadic winds hitting 50 mph Sunday, October 8, will most likely have started most if not all. Winds of this intensity can ignite fires by impacting electrical infrastructure by breaking lines and causing transformers to explode. The cause of the fires will come out in time. Thick stands of vegetation, the result of mid-20th century land management practices, years of fire suppression, homes built in rural locations in steep terrain, old legacy roads too small to accommodate modern fire-fighting equipment, and exurban development without the necessary resources to address fire prevention. All this leads to almost impossible conditions to arrest a fire being pushed by wind.
I would argue there is no better fire-fighting force in the world than those found in California. What these men and women do is nothing short of extraordinary. But they are faced with an impossible task in the absence of an equally focused program of fire prevention.
What have I learned from Lake County as a result of the Valley and Clayton fires?
The Lake County fires have provided insights that can help with the recovery and reconstruction of the most recent events. Specifically, resources must be secured to assist landowners and communities in better incorporating fire resilience into local rural and suburban planning and projects, to prepare for the eventuality of another fire by creating and maintaining conditions that allow the fire to be controlled before getting out of hand. Admittedly, the recent fires were wind-driven events that became uncontrollable. However, these fires are the exception to the rule. There are hundreds of fires a year in California that are quickly controlled and extinguished. Fire resiliency must incorporate plans and projects that can address less catastrophic conditions, in the hopes of arresting a fire before it becomes a conflagration.
Other aspects for communities to consider when addressing fire resiliency may include fire-fighting equipment scaled to accommodate old, rural roads, resources to retrofit old roads to accommodate evacuees and first responders, and rural lands with poor or non-existent internet service need to re-establish fire sirens to alert residents of impending danger. Local statutes need to establish and enforce vegetation management standards on absentee parcels. And, finally, a sustained dialogue addressing fire resiliency must be incorporated into all land-use planning discussions to help landowners recognize and implement actions to help reduce the risk of catastrophic fire.
None of this will be easy or inexpensive. But neither is fighting hundreds of thousand acres of wildland fires every year.
Admittedly, the weather conditions responsible for these fires may negate the best plans and efforts. But again, those conditions are the exception to the rule.
For every acre burned this year there are ten more, in the same condition, that didn't, providing next year's opportunity for a conflagration. The road forward to address California's wildland fire threat is long, and full of twists and turns. But as with all long journeys, each begins with the first step.
Greg Giusti is a UC Cooperative Extension advisor emeritus specializing in forests and wildlands ecology.
Art is an expression of creativity, a conveyance of beauty, and for naturalists, it is a way to process, remember and interpret nature.
Many branches of nature art are popular, such as photography, painting and sketching. The UC California Naturalist Regional Rendezvous in October introduced an old but uncommon method for documenting natural objects – cyanotype.
At the CalNat Rendezvous at the Pepperwood Preserve, Santa Rosa artist Jessica Layton taught the cyanotype process to volunteers certified by the UC California Naturalist program, giving them a new tool to use in educating and engaging children and adults in conservation organizations they work with around the state.
The cyanotype process begins by mixing two chemicals - ferric ammonium citrate and potassium ferricyanide – to create the blue photo reactive solution. The chemicals may be purchased at art stores and online by searching for cyanotype solutions.
Once blended, the chemicals are painted on paper or cotton cloth and allowed to dry. Leaves, grasses, seeds, pine cones, flowers, stones – any number of natural objects collected outside may be artfully arranged on the blue background and, if needed, held in place with a pane of glass.
The project is then set out in bright sunlight for 5 to 7 minutes, brought back inside to be washed in clean water and allowed to dry. The areas of the paper or cloth exposed to the sun are a radiant lapis blue; the areas that were shaded by the natural objects appear in silhouette.
“I have come to appreciate art as a way to improve observation skills and deepen an appreciation for nature,” Merenlender said. “We offered this session to our volunteers for them to improve their capacity and become better naturalists.”
Knowing the names of trees is a point of pride for many California Naturalists. So a walk among the diversity of oaks at the Pepperwood Preserve left many feeling humbled.
The three-hour excursion was part of the UC California Naturalist Regional Rendezvous in October at the 3,200-acre nature preserve nestled in the foothills between Napa Valley and Santa Rosa.
Excursion leader Steve Barnhart, academic director emeritus at Pepperwood, said there are 500 oak species in the world; 21 in California. But cohabitating on the rolling hills and valleys of the Golden State, many oaks have produced hybrids that combine characteristics, making identification challenging.
Doctoral candidate Phrahlada Papper, who is studying oak tree genetics, said, “I'm of the mind that you shouldn't ever name an oak.”
Even the tan oak, long thought to be misnamed, is coming under new scrutiny.
“It's not an oak,” Barnhart said. “It has acorns, male and female flowers on the same stalk, but tan oaks are insect pollinated. True oaks are wind pollinated. Tan oaks are closer to chestnuts.”
But Papper raised his hand. “Genetically, it might be an oak,” he said.
Barnhart laughed. “So tan oak is up in the air. That's why it's so much fun to be in science,” he said. “I learned something today.”
In popular culture, oaks are thought to be majestic, towering trees, with wide spreading branches. However, Barnhart said, most California oaks are shrubs, including the leather oak.
Leather oaks grow in serpentine soils and have the ability to produce two types of flowers, one in the spring and another quite different in the fall. Leather oaks are monoecious, they have both male and female flowers on the same plant. On a particular leather oak at Pepperwood, Papper was surprised to find male and female flower parts in one bract and surmised that weather patterns may be responsible.
“California has weird weather and with climate change, it's getting even more weird,” Papper said.
Papper believes tracking phenology, the cyclic and seasonal changes in plants, is an ideal citizen science project for California Naturalists. One such project underway at Pepperwood is led by Wendy Herniman. A University of Edinburgh, Scotland, master's student, Heniman is documenting the phenology of 10 Pepperwood oak trees: 2 blue oaks, 3 coast live oaks, 2 black oaks and 3 Oregon oaks.
“Pepperwood is looking at climate change. It's a designated sentinel site. We're monitoring fog, we have soil probes, and we're collecting all weather and climate information. We can tie that to phenology,” she said. “We're trying to find out if phenophases are changing.”
Understanding the changing phenophases is important, Barnhart said.
“Everything is connected,” he said. “If acorns are produced early, animals species that depend on the food source will be disrupted. You have imbalances in the timing of the natural world. With climate change, what are the effects we'll be seeing?”