Cooperative Extension San Joaquin County
University of California
Cooperative Extension San Joaquin County

UC Blogs

Do California spotted owls prefer to nest near forest edges? SNAMP scientists say no.


Adult and juvenile California spotted owl

During a Sierra Nevada Adaptive Management Project (SNAMP) public meeting, a participant brought up the idea that California spotted owls preferred to nest near forest edges to be closer to foraging habitat and their prey. Principal investigator for the SNAMP Owl Team, Dr. Rocky Gutierrez, charged research fellow Casey Phillips and SNAMP Owl Team project leader Doug Tempel to research this question at SNAMP study sites in the Tahoe and Eldorado National Forests to see if this was true.

Owl researchers used field data that consisted of current vegetation maps derived from aerial photos and owl nest site location data gathered during their annual surveys. One nest tree site within a forest stand was randomly selected from each owl territory and one comparison location within those stands was randomly selected by a computer program. The distances between these two locations, relative to the nearest edge of the forest stand, were then compared statistically. A forest edge could be either a hard edge, such as an adjacent clear-cut; or a soft edge, such as a young, mixed-conifer forest. Elevation at each nest site was also considered because owls living at higher elevations prey on flying squirrels that typically inhabit forests with greater canopy cover. So, one might expect owl nest sites to be further from forest edges at higher elevations.

Researchers found no evidence that owls chose nest sites closer to forest edges than one would expect by chance, even though an edge location might bring them closer to a prey source. Results also showed that owls nested further from hard edges than expected. These results were consistent regardless of the elevation at a nest site.

It is possible that some timber harvest may have occurred after owls used a particular nest site, and before the vegetation maps were made. This scenario would have only lessened the distance to the nearest edge at these sites. This would also apply to the randomly selected points. Therefore, habitat alteration should not have affected the findings. Researchers speculate that limited availability of suitable nest trees within the stand may be as important of a determinant in the location of a nest site as any physical characteristics associated with its location.


Banded female California spotted owl

Where owls choose to nest has implications for forest managers and their management plans. This research suggests that creating forest edges would not enhance owl nest site choices and that other factors would likely influence owl nest site selection, such as the availability of large trees appropriate for nesting (i.e., those with cavities, broken tops, and mistletoe broom).

Information for this article comes from the following: Phillips, C.E., D.J. Tempel, and R.J. Gutierrez. 2010. Do California spotted owls select nest trees close to forest edges? Journal of Raptor Research 44:311-314.

Posted on Wednesday, February 23, 2011 at 8:04 AM

Study to examine giant sequoia groves

The giant sequoias of the Sierra Nevada are the biggest and among the oldest trees on the planet. Some are 2,000 to 3,000 years old. Forestry scientists from the University of California and Cal Poly, San Luis Obispo,  want to learn more about how disturbance factors affect the health of these aging behemoths.

Growth-response studies to date show that tree vigor can increase following moderate intensity disturbances such as prescribed fire or mechanical fire-hazard reduction treatments. Less certain, however, is how giant sequoias respond to lower and higher intensity disturbances. This information is of critical importance to identify the tradeoffs involved in fire prevention treatments or evaluating management options.

This summer scientists will visit native groves within Giant Sequoia National Monument, where high-intensity disturbances occurred 20 years ago. Harvests conducted at that time removed all trees except for large giant sequoia, creating a forest structure similar to what you’d expect after a high-intensity wildfire. Following the harvests, there was considerable public concern over the fate of the giant sequoias remaining. Mortality and growth in these areas has not been assessed until now.

The primary investigator on the project is Robert York, station manager of the UC Center for Forestry and an adjunct professor in the UC Berkeley Department of Environmental Science, Policy and Management. York is an expert in giant sequoia ecology.  His co-investigator on the project is Scott Sink, a professor in the Department of Natural Resources at Cal Poly, San Luis Obispo. He has investigated differences between old growth and secondary forests and developed expertise in measurements of tree ring growth. The researchers will partner with forest ecologist Steve Hanna of Giant Sequoia National Monument in Porterville.

The scientists will also study tree ring widths taken from 33 giant sequoias at the UC-Whitaker Forest, where light burns and small tree removal occurred in 1967. York previously conducted field work on growth response in a giant sequoia forest subjected to a moderate-intensity disturbance. In addition to publishing a journal article on this work, researchers will hold a field trip for managers of giant sequoia groves, involve UC and CSU students in field and laboratory work, and develop a lab module for coursework at UC Berkeley.

The project is funded by a $10,000 grant intended to foster collaboration in higher education in California on issues affecting agriculture, natural resources or human sciences. In their grant proposal, the researchers said: “We have a unique opportunity to measure growth response in giant sequoia to these different levels of disturbance intensity, and therefore improve our understanding of this species’ complex life-history strategy, while informing management within giant sequoia groves.”

Posted on Wednesday, February 16, 2011 at 8:30 AM
Tags: forest (12), giant sequoia (1), Sierra Nevada (8), wildfire (34)

Alternatives to fumigation and improving fumigant efficacy

Synthetic soil fumigants such as chloropicrin and 1,3-D are used by some commercial growers to control soilborne pathogens, weeds and nematodes prior to planting strawberries, onions, tomatoes, eggplant, peppers and spinach. These fumigants and all other biocidal products with the potential to harm the environment and human health are highly-regulated by the federal Environmental Protection Agency, the state Department of Pesticide Regulation, and county agricultural commissioner's offices.

UC Cooperative Extension farm advisor Oleg Daugovish and his collaborators work hard to find effective, environmentally-safe and economically-viable ways to improve efficacy of fumigants and to investigate alternatives to soil fumigation. The Ventura County Cooperative Extension website has archived audio and visual presentations, which includes the following topics:

  • Assessment of permeability of commercial tarps under a variety of cultural practices and in various soil and environmental conditions is expected to lead to better understanding of maximizing fumigant effectiveness while reducing emissions.
  • Growing in substrate (soil-less culture) allows growers to produce crops with minimal plant disease and weeds without using fumigants.
  • Heating soil using steam is a successful way to disinfest it. However, the process to generate steam in a field can be slow and very expensive. Researchers are working to find ways to improve speed while reducing cost.
  • Most organisms, including plant pathogens, cannot survive without oxygen. Researchers are investigating an organic method to create anaerobic (oxygen-free) conditions to treat soil before planting.
  • Planting mustard as a cover crop can provide many positive benefits, one of which is allelochemical compounds. These compounds found in mustard are similar to those found in fumigants. Current research shows it is possible to use this green biomass to prepare fields for production.

More environmentally-responsible research from Dr. Daugovish can be found here.

Injecting steam may be one way to disinfest soil without chemical fumigants.
Injecting steam may be one way to disinfest soil without chemical fumigants.

Posted on Wednesday, February 2, 2011 at 8:14 AM
  • Author: Chris M. Webb

How does climate change impact plants?

All bets are off in terms of what will happen with plant species migration and crop production as the climate changes globally.

A common assumption has been that native plants and animals would “move,” or migrate, to higher elevations as temperatures rise, to maintain their “preferred” temperatures, but a new report by Jonathan Greenberg at UC Davis, shows that many California plant species moved downhill over the past 70 years.

According to Greenberg, “While the climate warmed significantly in this period, there was also more precipitation. These wetter conditions are allowing plants to exist in warmer locations than they were previously capable of.”

According to the news release summary:

“Many forecasts say climate change will cause a number of plants and animals to migrate to new ranges or become extinct. That research has largely been based on the assumption that temperature is the dominant driver of species distributions. However, Greenberg said the new study reveals that other factors, such as precipitation, may be more important than temperature in defining the habitable range of these species.

“The findings could have global relevance, because many locations . . . have had increased precipitation in the past century, and global climate models generally predict that trend will continue, the authors said.”

Many studies are showing that climate change is impacting plant and animal species, but because of the overlapping influence of so many factors, including temperature, precipitation, and elevation, and even factors such as increases in smog and carbon dioxide, it is too early to predict precisely how climate change will impact native species . . . and agricultural crop production.

Here are some UC Davis news summaries in just the last year on the impact of climate change on plant and animals species:

  • Plants moved downhill, not up, in warming world – news summary
  • Climate change impact on mountain plants at low elevations – news summary
  • Warmer ocean waters favor aliens over natives – news summary
  • Warming climate means harsher smog – news summary
  • Rising CO2 levels threaten crops – news summary
  • Changes in agriculture needed as world warms – news summary
  • Climate tipping points may give no warning – news summary
  • Butterflies reeling from impact of climate – news summary
Posted on Friday, January 21, 2011 at 4:51 PM

Green energy may generate more greenbacks for farmers

California’s role as an emerging world leader in the development of green energy technologies offers the state’s farmers the opportunity to diversify their cropping systems and increase their income.

Sacramento lawmakers have given the California Energy Commission an annual budget of $100 million to support the development of alternative and renewable low-carbon fuels. In addition, the State Alternative Fuels Plan set goals of reducing petroleum dependence by 15 percent and increasing alternative fuels use by 20 percent by 2020. These efforts are meant to help meet the growing fuel demands of the world population while reducing greenhouse gas emissions in California to 1990 levels.

“With the new mandates, there are new opportunities for using agricultural waste and dedicated energy crops for biofuels, but we’re not yet sure exactly what form it will take,” said UC Cooperative Extension alfalfa specialist Dan Putnam. “I would always encourage growers to experiment with the crop, but I wouldn’t jump in whole hog unless I had a buyer lined up.”

Switchgrass is a potential biofuel crop.

U.S. ethanol production in January 2010 was 818,000 barrels per day, according to the U.S. Energy Information Administration. The United States uses about 20 million barrels of oil per day. If the EPA allows up to 15 percent ethanol blends for all vehicles, then the 10 million barrels per day of oil used by cars and trucks could allow ethanol and biofuels to make up 1.5 million barrels per day.

Cellulosic biomass is the only known resource for the sustainable production of liquid transportation fuels on a large scale and at low costs, according to UC Riverside environmental engineer C. W. Wyman.  Cellulosic biomass includes agricultural residues such as corn stems and leaves, forestry residues such as sawdust and paper, landscape waste, herbaceous plants such as switchgrass and sorghum, and woody plants such as poplar trees.

Since a dry ton of cellulosic biomass could provide about three times as much energy as a barrel of petroleum, the cellulosic biomass would have three times the value as a barrel of petroleum. That means cellulosic biomass would be worth about $200 per dry ton when crude oil sells at $65 per barrel.

“To utilize this abundant resource, we must develop low-cost technologies for transforming biomass into fuels that can compete with petroleum,” Wyman wrote in a California Agriculture article “Cellulosic biomass could meet California’s transportation fuel needs.”

Current and potential biomass crops include the grasses switchgrass and miscanthus, other perennial grasses, plus high biomass sorghum, alfalfa and other crops.

Across California, University of California scientists are studying potential biofuel crops. Putnam has four research trials under way, testing varieties from Ceres and Mendel Biotechnology, Inc.  He said switchgrass and miscanthus the top contenders so far in his trials.

“The yields of switchgrass under irrigation have been quite high,” Putnam said. “It is an efficient crop for converting solar energy into biomass under warm weather condition.”

Switchgrass does have relatively high water needs. Putname said scientists are looking into whether the crop can be grown under deficit irrigation to save water and still produce the biomass.

“The key issue with biofuels is not necessarily the total water requirement, but the water use efficiency and amount of biomass produced per unit of water,” Putnam said. “Even if a crop has high water use, if it produces a large amount of biomass, it may still be the best option.”

Steve Kaffka and UC Cooperative Extension advisors are involved in research on winter annual oilseeds such as canola, camelina and meadowfoam as potential biofuel feedstock crops.

“Recent economic modeling we have done suggests that at current market prices, canola is a competitive crop in California, but outlets have not yet developed for the seed,” Kaffka said. “Currently, petroleum prices are too low to support the use of canola for biofuel feedstocks, but that is changing rapidly. “

The director of the UC Kearney Research and Extension Center, Jeff Dahlberg, sees opportunities for California production of sorghum as a biofuel crop.

"Sorghum is one of the few crops that span all the different renewable fuel options," he said. "You can use the grain to convert into ethanol. We have sweet sorghum, a specialty sorghum which is very similar to sugar cane. You can press the juice out and convert it into ethanol. And, we can produce a lot of biomass."

Dahlberg previously served as research director for the National Sorghum Producers and the research director for the United Sorghum Checkoff Program in Lubbock, Tex. He currently is lead investigator on a $984,000 U.S. Department of Energy grant to study the composition of sorghum and its potential for cellulosic conversion to biofuel. In addition to continuing this research at Kearney, Dahlberg is interested in developing a center for on-farm green technologies at the Central California research station.

Posted on Wednesday, January 19, 2011 at 7:05 AM
Tags: biofuel (6), canola (1), Dan Putnam (4), energy (5), green (2), Jeff Dahlberg (7), sorghum (3), Steve Kaffka (2), switchgrass (2)

First storyPrevious 5 stories  |  Next 5 stories | Last story

 
E-mail
 
Webmaster Email: mdhachman@ucdavis.edu