This year Borderlands Restoration Network’s (BRN) native plant program has secured two different grants to help control invasive species in our region.
Grasslands are among the world’s most endangered ecosystems. Unfortunately, they are also among the most unappreciated, partially because of what we can’t see, since up to 80% of the biomass of a grassland is underground! Grasses have deep fibrous roots which store carbon and help make these ecosystems resilient to fire and grazing. Here in the Sky Islands our grasslands support hundreds of species, from endemic plants and migratory birds to threatened mammals like pronghorn and black-tailed prairie dogs. Invasive plants pose one of the biggest threats to our Sky Island grasslands and the species that call them home.
Invasive species are introduced non-native species that can take over ecosystems, reducing the diversity of native plant and animal species. A particularly aggressive species of invasive grass called Yellow bluestem has started spreading throughout Southeastern AZ along roadsides and across rangelands, converting diverse grasslands to invasive monocultures. This species has been documented in small populations in the Sonoita-Elgin grasslands.
With support from the Arizona Department of Forest and Fire Management, BRN will lead an effort in collaboration with the Appleton-Whittell Research Ranch, the Babacomari Ranch and the Tucson Audubon Society. This cooperative effort is aimed at controlling this invasive grass on 21,000 acres of mixed grassland habitat directly adjacent to the Las Cienegas National Conservation Area and Coronado National Forest.
While this species has been found in small, relatively controllable patches for over a decade, it has recently begun to spread to new places and can be seen along many roads and within the grasslands. With our partners we will monitor and map the extent of invasive grass species across the 21,000 acres, repeatedly treat invaded areas and facilitate the establishment of native species in treated areas.
Another, smaller project BRN is working on over the next two years is located at the Wild Chile Botanical Area (WCBA) in the Tumacacori highlands. The Forest Service surveyed the area and found multiple areas of buffelgrass, an invasive weed more commonly found invading the lower deserts. BRN will partner with the
Tucson Audubon Society to eradicate the invasive buffelgrass and will revegetate with native species.
The WCBA is a 2,836-acre area under management of the Forest Service. It was designated in 1999 to protect the northernmost natural population of the chiltepin pepper (Capsicum annuum), the wild ancestor of many cultivated peppers. This special area was also created to provide protection and research opportunities for both the wild chile and other plants of economic importance or conservation concern.
At least 45 species of crop wild relatives (CWR) occur in the watershed containing the WCBA within the east side of the Tumacacori Mountains on the Nogales Ranger District. Many of these CWR species have proven or potential uses as crop genetic resources for improvement of domesticated crops already being grown commercially in Arizona and the rest of the U.S. and the world. The WCBA is also one of the most botanically interesting areas in southern Arizona, providing a fantastic snapshot of the unique biotic community of the Tumacacori Highlands, which is home to numerous plant species that are at the northern extent of their range and grow in few other locations in the United States. For this reason in and of itself, the WCBA deserves protective measures.
Revegetating treated areas with native plants helps keep invasive species from returning and speeds the recovery of the grassland. To improve the success of the reseeding efforts we will use pelletized seeds, seeds added to a mixture of clay, high-nutrient soil or compost and water. Seed pellets are formed mechanically, in the cement mixer and by hand, and dried. Because seeds embedded in pellets have high soil contact and are protected from seed predation by insects and rodents, they require minimal soil disturbance. Also, these seeds remain on site until heavy rains arrive with the monsoon, which wets up the clay and allow seeds to germinate while the soil is moist.
We are grateful for the support of AZ Forest and Fire Management as well as support from Title II Special Projects of the Secure Rural Schools grant and look forward to working with our nonprofit and private partners to control these invasive grasses and restore diverse native species to our local Sky Island grasslands. You can find out more about what BRN is up to at www.borderlandsrestoration.org