Forest Pests, Invasive Plants, and Air Quality

Invasive, non-native plants ("weeds") can spread rapidly and extensively in many ecosystems, including California forest and rangelands. This indicator reports on the number of weed species and area of cover. Reporting units may include by ownership, forest type, type of weed, and area affected.

Native and non-native insects and diseases can both cause high rates of mortality during an outbreak. Although native insects and diseases have their place in forest ecology, non-native insects and diseases are unlikely to benefit native forest ecosystems. Reporting units for this indicator could include by ownership, forest type, type of insect/disease, or volume and area affected.

Air pollution can have noteworthy cumulative impacts on forested ecosystems by affecting regeneration, productivity, and species composition (U.S. EPA, 2006). In the U.S., ozone in the lower atmosphere is one of the pollutants of primary concern. Ozone injury to forest plants can be diagnosed by examination of plant leaves. Foliar injury is usually the first visible sign of injury to plants from ozone exposure and indicates impaired physiological processes in the leaves. U.S. EPA (United States Environmental Protection Agency). 2006. Air quality criteria for ozone and related photochemical oxidants. EPA/600/R-05/004aF-cF. Research Triangle Park, NC.

Area and volume of ozone damaged trees. This evaluates effects of air pollution on ecosystem health in forest and rangelands. Known impacts occur from several processes including ozone damage to pine and other plant species in areas with chronic air pollution , and the deposition of fertilizing or acidifying substances in clear mountain waters and on mountain desert and soils.

Defoliation can be caused by disease, physical force (extreme storms), and pest insects. Most trees can recover from defoliation, but it can be a serious source of stress and will reduce photosynthetic activity and growth.

Number and area of exotic invasive plants that occur in California. Invasive, non-native plants damage California ecosystems by displacing native species, out-competing native plants, changing plant communities, and reducing the value of habitat for wildlife and stock.

High impact NIPS species are capable of having significant impacts on biological diversity, productive capacity, soil and water, and social well being. These impacts include out-competing native species, slowing timber regeneration and forage production, altering riparian shading and streambank morphology, and altering fire regimes affecting public heath and safety. (from the 2003 Forest and Rangeland Assessment)

Number of native and exotic pests that occur in California. Movement of native forest pests into new areas, and migration of non-native forest pests into California increase risks to forest land from forest pest damage. Non-native pests are of particular concern to ecosystem health due to the lack of natural enemies and built-in defenses for local host species.

Efficient and effective weed control programs and strategies are characterized by efforts that prevent invasions and quickly detect new occurrences so the species may be removed or contained before spreading. The California Department of Food and Agriculture’s (CDFA) Noxious Weed Prevention and Control Program works under the assumption that it is more cost effective to keep pests out of California than to address potentially widespread and ongoing infestations. The strategy for pest prevention is similar for all kinds of pests. There are four major parts: 1) keep a foreign pest from getting into California in the first place (exclusion); 2) if a pest does get in, find it while the population is still small (detection); 3) when such a population is found, remove it so California is once again free of the pest (eradication); and 4) inform the public of the importance of keeping California free of new pests. (from the 2003 Forest and Rangeland Assessment)

American agricultural policy has long recognized the threat to domestic farming and ranching from diseases introduced from other countries. Concerns over homeland security have heightened efforts to monitor the food supply chain. California’s livestock industry has undergone a variety of changes making it more susceptible to the spread of diseases such as foot-and-mouth disease and anthrax. These changes include factors such as greater concentrations of cattle in feedlots and nearby areas, and use of dairy related by-products as cattle feed. (fromt eh 2003 Forest and Rangeland Assessment)