|Zvirzdin, D -|
|Petersen, S -|
|Hopkins, B -|
|Roundy, B -|
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2012
Publication Date: N/A
Interpretive Summary: Land managers will typically broadcast seeds of desired species across burned landscapes to promote recovery. Unfortunately, the success rate of these restoration efforts is notoriously low. Anchor chaining can improve the success of these seeding efforts. For burned piñon and juniper woodlands, the success of this treatment may in part be linked to its ability to disrupt soil water repellency. Our objectives were to determine the effect of anchor chaining on soil water repellency and the response of seeded and invasive species. At one of the two sites measured, anchor chaining dramatically reduced soil water repellency and the establishment of invasive species, while greatly improving water movement through the soil and the establishment of seeded species. At the other site, anchor chaining had a small effect on soil water repellency; invasive species dominated both the anchor chained and non-anchor chained sites. These results suggest that when anchor chaining or other treatments effectively disrupt soil water repellency in post-fire piñon-juniper woodlands, the probability of treatment success increases. While anchor chaining may not always be successful, forgoing effective post-fire treatments in piñon-juniper woodlands greatly increases the risk that recovery will be poor.
Technical Abstract: Broadcast seeding is one of the most commonly used rehabilitation treatments for the restoration of burned piñon (Pinus ssp.) and juniper (Juniperus spp.) woodlands, but the success rate of this treatment is notoriously low. In piñon-juniper woodlands, post-fire soil water repellency can impair reseeding success by reducing soil water content and enhancing runoff and erosion. Anchor chaining directly after seeding can improve establishment of seeded species. In addition to enhancing seed soil contact, anchor chaining may improve restoration success by disrupting the water repellent layer through the tilling action of the chain. The objectives of this research were to 1) quantify the extent that anchor chaining overcomes post-fire soil water repellency, and 2) establish meaningful relationships between soil water repellency, unsaturated hydraulic conductivity (K(h)), and the establishment of seeded and invasive species. Plots at two burned piñon-juniper woodland sites with severe water repellency were aerially seeded and either anchor chained or left untreated. At one location, anchor chaining considerably improved soil hydrologic properties, reducing the severity and thickness of the water repellent layer, and increasing soil K(h) 2-4 fold in the first two years following treatment. At this same location, anchor chaining increased perennial grass cover 16-fold and decreased annual grass and forb cover by 5 and 7-fold, respectively. Results from the second site did not provide conclusive evidence that anchor chaining improves soil hydrologic properties or perennial grass establishment. At this site, annual grasses dominated both treatments. These results suggest that when soil disturbance from anchoring chaining is sufficient to overcome soil water repellency, the establishment of perennial grasses from seed is dramatically improved. While there is a probability that anchor chaining may not improve reseeding success on some sites, our results and those derived from other similar studies in degraded rangeland systems imply that there is a considerably higher risk that the site will transition into an annual dominated system without effective restoration efforts.