Martin Hutten | Geology Reports

USGS2017

Short-term response of Holcus lanatus L. (Common Velvetgrass) to chemical and manual control at Yosemite National Park, USA

One of the highest priority invasive species at both Yosemite and Sequoia and Kings Canyon national parks is Holcus lanatus L. (common velvetgrass), a perennial bunchgrass that invades mid-elevation montane meadows. Despite velvetgrass being a high priority species, there is little information available on control techniques. The goal of this project was to evaluate the short-term response of a single application of common chemical and manual velvetgrass control techniques. The study was conducted at three montane sites in Yosemite National Park. Glyphosate spot-spray treatments were applied at 0.5, 1.0, 1.5, and 2.0% concentrations, and compared with hand pulling to evaluate effects on cover of common velvetgrass, cover of other plant species, and community species richness. Posttreatment year 1 cover of common velvetgrass was 12.1% ± 1.6 in control plots, 6.3% ± 1.5 averaged over the four chemical treatments (all chemical treatments performed similarly), and 13.6% ± 1.7 for handpulled plots. This represents an approximately 50% reduction in common velvetgrass cover in chemically- treated plots recoded posttreatment year 1 and no statistically significant reduction in hand pulled plots compared with controls. However, there was no treatment effect in posttreatment year 2, and all herbicide application rates performed similarly. In addition, there were no significant treatment effects on nontarget species or species richness. These results suggest that for this level of infestation and habitat type, (1) one year of hand pulling is not an effective control method and (2) glyphosate provides some level of control in the short-term without impact to nontarget plant species, but the effect is temporary as a single year of glyphosate treatment is ineffective over a two-year period.

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USGS2002

Bryophytes and lichens: Small but indispensable forest dwellers

* What is a Bryophyte? * Bryophytes are the small green plants commonly known as mosses, liverworts and hornworts. Compared to plants, they have primitive tissues for conducting food and water, and they lack a protective outer surface to maintain water balance. Most bryophytes, because they lack tissues such as roots, obtain their water through direct surface contact with their environment. During dry weather they have the capacity to withstand complete dehydration. Bryophytes that are dry may appear dead but will regain normal function when moisture is available. Instead of producing seeds, bryophytes can either reproduce sexually by means of spores, or asexually when small pieces break off and grow into new individuals. * What is a Lichen? * Lichens are dual organisms consisting of a fungus and an alga or a cyanobacterium. The fungus provides the alga with structure, protection, nutrients, and water absorbed from the atmosphere and the substrate (e.g., soil, rotten logs, tree branches). In return, the alga provides carbohydrates from photosynthesis to the fungus. Algae from some lichens grow independently of the fungus, but in lichen form, the algae can inhabit more challenging environments than when growing alone. Most lichens can reproduce asexually. They either produce specialized propagules containing both partners, or parts of the lichen simply break, allowing both the fungus and the alga to disperse together. In some lichens, the fungal partner reproduces sexually by releasing spores, but the partner alga must be present in order for a lichen to reform.

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