What type of revegetation techniques do Water Funds typically use?
Assisted revegetation typically involves one or more of the following techniques: tubestock planting, direct seeding, and natural regeneration.
What is tubestock planting?
Tubestock planting involves the raising of seedlings in small nursery tubes for later transport to the project site. These seedlings may be planted by hand or through mechanical seedling planters. As with direct seeding, this technique requires site preparation, weed control, and fencing.
What is direct seeding?
Direct seeding is an active process in which seeds from native species are selectively sowed, and/or cuttings from perennial shrubs are planted onto disturbed areas to accelerate the rate of plant coverage. While the selection of species will be driven by the goals and objectives of the water fund, the goal is typically to develop self-supporting vegetation with similar structure, function and plant communities that were found in the original environment. This is preferable as native species will be better adapted to the surrounding environment. Nonetheless, in some cases, it may be difficult to obtain seeds and plant material in sufficient quantities to revegetate large areas, thereby requiring more innovative approaches to meet conservation goals. When compared to tubestock planting, direct seeding is generally more efficient in terms of time, cost and labor. It also allows for a more diverse seed mix, which can lead to greater plant diversity at the project site. However, direct seeding may have some drawbacks that include reduced control over spacing and stocking, predation of seed by birds and small mammals, and seed lost by washing away by rain. Also, seedlings may not effectively compete with other vegetation and hence may have lower survival and slower growth compared to tubestock planting.
What is natural regeneration?
Natural regeneration is the term used to describe the growth of plants from seed naturally distributed to the site. Accordingly, this technique relies on existing seed sources, such as soil, canopy stored seed, or seed transported to the site by water, wind, or animals transiting through the area that is being revegetated. While natural regeneration is considered to be a passive technique, it still commonly requires some level of management (e.g. fencing to exclude livestock and weeding). and limited site preparation). This technique is particularly worthwhile for individuals and groups with limited resources.
Natural Regeneration in Practice:
An Example from the Western U.S.
Engelmann spruce, the most common native spruce tree in America, is one of the most important trees in the Rocky Mountain ecosystem, supporting healthy forest structure and providing important wildlife habitat. However, widespread outbreaks of spruce beetle, a native insect, threaten trees across the west. Uncompahgre Plateau project in Western Colorado brings community members and partners together to work with the USDA Forest Service to enhance the resiliency, diversity, and productivity of this 572,000 acre landscape. Part of the strategy to achieve this goal is to promote spruce regeneration and tree age class diversity on the landscape.
Engelmann spruce is notoriously difficult to regenerate, and after a history of failures, the group undertook a monitoring project, working with a local university, to better understand what factors promote successful establishment. The researchers mimicked natural seed fall and planted seedlings in different conditions on the forest to simulate natural regeneration and observed the success rate of the plants over 2 growing seasons. They found that coarse, woody debris and the shade from adjacent trees provided microsite conditions to retain soil moisture and keep the maximum soil temperatures low enough to avoid killing the establishing trees. The spruce regeneration study will continue over the following 5-10 years to track longer term trends. The group can now use this information to help guide future management actions and may expand the study to include other tree species.