BOISE — The Boise foothills are one of the region's most protected jewels in the Gem State; so why is there a large-scale project going on to take down trees in the Lower Hulls Gulch area?
It is the start of a major effort to remove invasive species. This is the first time the City of Boise Parks and Recreation Department's open space management has tackled a large-scale restoration project in that area to protect an ecosystem they say is under attack.
The area where trees are being removed this week is up 8th Street in Lower Hulls Gulch, behind Camel's Back Park. You can quickly access the area from The Grove parking lot by heading west on the Red-winged Blackbird trail. Once atop a ridge, you can view the grove of trees crews are tackling first.
For those of you who use that area: Lower Hulls Gulch is open and users can still hike, run and bike on trails while tree removal and restoration are underway.
Our cherished foothills have been invaded by non-native trees, brushes and shrubs.
“When people look at the foothills they talk about how beautiful and natural these areas are. And while there are many great native plants in the foothills, there are also a lot of invasive species,” City of Boise Parks and Recreation Foothills Restoration Specialist Martha Brabec said.
To loosen those species' grasp, City of Boise foothills management is restoring a popular area.
“Getting control of invasive species to allow native plants to compete is a really large part of restoration and a major challenge for ecologists today,” Brabec said.
The first step of the multi-phased approach is getting rid of Russian Olive trees, taking over the riparian Lower Hulls Gulch stormwater retention ponds. This week, an arborist is chopping down 75 percent of the Russian Olive trees and spraying herbicide on the stumps; Brabec says they are notorious for re-sprouting quickly and if they do not apply herbicide they will be seeing this same issue again in a few years.
"This is a really important riparian area because there is water available here year-round. We live in a desert ecosystem - wherever there is water, there is wildlife. However, this area is under attack. As you can see all the silver foliage is Russian Olive which is a non-native tree that came over in the 1800's from Western Asia and is now monopolizing all these wet riparian areas in southwest Idaho as well as the Great Basin desert," Brabec told KTVB.
Brabec says Russian Olive trees are detrimental to the ecosystem for a number of reasons: they out-compete the native plants that are meant to be in the foothills, they remove a large quantity of water from the ecosystem, and when their fallen leaves are "biological garbage" because decomposers and insects in the ground can't readily consume the leaves, which in turn reduces insect populations as well as bird populations over time.
The invasive trees will be replaced with native trees soon. Foothills managers will be collecting willow and cottonwood this fall to plant back on the site and plant a variety of upland shrubs come spring. They will continue controlling invasive species through mechanical and chemical means, as necessary.
For those concerned about bird habitat, Brabec says there is still plenty of habitat in the Boise foothills for birds:
"While birds will be displaced in the short term, in the long term there is going to be much better native riparian vegetation, which will support more robust diverse bird populations in the future," Brabec told KTVB.
“Hulls Gulch is a beloved location because of its shade as well as its ability to view wildlife, like birds. So we want to keep that going and we want to foster more sustainable long-term habitat for wildlife,” she added.
Taking control of the landscape is no small feat.
"These systems need to be managed. Weeds are a major problem and you can't just do a one and done and walk away. We're going to manage these weeds into the foreseeable future," Brabec said. "What we're doing is selective surgical restoration. Weeds are everywhere; to do restoration we have to select a spot we think we can make a difference then work our way outwards."
This is thanks, in large part, to Zoo Boise and their visitors. The zoo has a conservation fee tacked onto their admission tickets and they pledged $50,000 for the next five years to the city to complete conservation and restoration projects in the lower Boise foothills.
"You can expect to see other selective projects like this over the next five years,” Brabec said.
People are great vectors for invasive species, so to help prevent them from spreading, be conscientious of what's on your shoes when you're on trails and always check the bottom of your pants for seeds, such as cheatgrass and Medusa Head because they are easy to transport.
There are a number of different restoration projects you can help with this fall and there will be opportunities when the Hulls Gulch area is re-vegetated in the coming months. Learn how to volunteer here.
Trails in Lower Hulls Gulch are also getting some needed TLC. Ridge to Rivers is adding all-weather surface material to about half a mile of trails spread out over 10 different sections; they are primarily focusing on Red Fox, Grove and Goldfinch trails. The goal is to provide a handful of all-weather opportunities on the system and give people options to head to when trails are muddy in the fall, winter and spring.
Over the last couple weeks, they've concentrated on areas they identified as persistently muddy last winter. It looks like native surface on the trails, but has road mix in it and is slightly raised from the normal tread. The material is expected to last a very long time.
“When we did our trail plan in 2016 folks asked for more all-weather trails. They wanted to have trail opportunities in the winter when things are muddy,” Ridge to Rivers Program Manager David Gordon said, “We are constantly telling people to stay off the muddy trails. And so now it benefits those trails because we can say go and ride or walk or run on these trails, you're not going to hurt anything, they're ready for you under muddy conditions, and stay off the trails that are muddy.”
The problem is the trail tread gets destroyed and uneven and the drainage structures they put in place to divert water off the trails become flatted and essentially ineffective, all leading to trail erosion. Or, when people want to avoid mud, they often walk or bike along the sides of paths, killing plants and making trails wider.