Sustainable Method of Protecting Western Redcedar from Deer Browsing

View the project final report

• 2016 annual report

Commodities

• Additional Plants: trees, ornamentals

Practices

• Education and Training: demonstration, extension, farmer to farmer, networking, on-farm/ranch research, workshop
• Farm Business Management: feasibility study, agricultural finance
• Pest Management: biological control, field monitoring/scouting, prevention
• Sustainable Communities: sustainability measures

No other tree in the Pacific Northwest has such a tremendous cultural value as the Western Redcedar (WRC) (Thuja plicata). Coastal Washington, Oregon, Northern California, and Alaska used to be covered with WRC forests, and Native American tribes used cedar wood and other products from this magnificent tree for a wide range of applications, from building canoes to making totem poles. This sacred tree was an indispensable participant in the life of many Native American tribes.

Currently, tree farmers in the PNW, whether small landowners like Tree Fever or industry giants like Weyerhaeuser, grow primarily Douglas fir and almost no WRC. This is despite the fact that cedar logs bring a 60% higher selling price than Douglas fir, and that the rate of WRC growth on high-class sites can be as high as that of Douglas fir. The main obstacle to the wide-scale adoption of WRC by tree farmers is the tree’s susceptibility to damage by deer, elk, and other wildlife. WRC seedlings are very high on the list of preferred foods for both deer and elk (“deer candy”).  Deer and elk browsing on newly planted WRC seedlings results in delayed regeneration and often in total plantation failure.

We propose to test a sustainable method for preventing deer and elk damage to a new plantation of WRC. This method is based on the idea of planting a WRC seedling (candy) together – in the same hole – with a seedling of Sitka spruce (Picea sitchensi), “guardian.” The sharp needles of Sitka will act as a deterrent for browsers – reaching for the candy may not be worth being pricked by the guardian’s needles in the snout and eyes!

A potential shortcoming of this method is that the candy and the guardian compete with each other for resources, and that this competition slows down the growth of both. However, as both seedlings grow, the guardian Sitka often becomes less and less competitive. A large percentage of Sitka trees growing at low elevations are attacked by a curculionid weevil (Pissodes sitchensis), which is prominently present on our farm. This weevil is the most serious enemy of young Sitka in the PNW, but it does not affect the WRC. The weevil kills the terminal shoots of Sitka, and the trees become shrub-like, easy to be overtopped by neighboring trees, in our case WRC. When the WRC reaches six fee in height, it no longer needs protection, even from elk. At that time, Sitka trees will be clipped, allowing WRC to grow freely.

This method is described on some Internet blogs, and some small landowners and large companies have allegedly used it with various degrees of success, but it has never been tested in a fully controlled experiment, and no results have been published in peer-reviewed literature. We have carefully planned and proposed to execute a research project to test the feasibility of this method, publish its results, and disseminate the obtained new knowledge among timber growers in the PNW.

The PI on this project is the owner of Tree Fever, a 136 acre tree farm that grows trees for timber. He is also a career biomedical researcher and Full Professor with 30 years of research experience (unrelated to farming). He has recruited Dr. Georg Ziegltrum, an expert in animal damage and forest protection, to serve as Technical Advisor. Dr. Ziegltrum will consult on the wildlife biology and pest control aspects of this research and help the PI prepare the results for publication. Being employed by the Washington Forest Protection Association, Dr. Ziegltrum is in a position to disseminate the results of this project among large growers in the State of Washington. The PI has also recruited Mr. Chuck Chambers, one of the most experienced foresters and tree farmers in the PNW, to serve as consultant on the tree farming aspects of the project and to help manage the project on the ground. Mr. Chambers is also an expert biometrician and the author of many articles on measuring trees; he will be helping the PI with data processing and results interpretation.

Our main educational activities will include the following:

1) Because at least one forestry extension program has already expressed interest in the proposed research, we will inform extension programs at universities throughout the PNW about our study. We will seek their feedback and invite them to visit the project.
2) During year 2, we will host a Field Day for the members of WFFA. We will discuss with tree farmers the obstacles to growing WRC and the measures available to them to protect their crops from wildlife. Dr. Ziegltrum will host a Q&A session (workshop) on preventing animal damage to tree crops. Mr. Chambers, who often gives tours and talks for WFFA, will show our project to the farmers.
3) During years 2 and 3, as the project starts producing results, we will inform extension programs and tree farmers (WFFA e-mail list) about our current progress.
4) At the end of the three-year period, we will prepare an abstract or a full-length research article on our results and send it to a peer-reviewed, open-access journal, such as Public Library of Science One (PLoS One).

1. Summer 2014. We will inform forestry extension programs in the PNW and Washington tree farmers (WFFA members) about our project. We will seek feedback and be open to ideas about fine-tuning the design of our study.

2. Winter 2014-15. We will plant 6,223 WRC seedlings in three different browsing protection modes (three experimental groups): 1) protected by the new method (co-planted with Sitka spruce; n = 2,075); 2) protected by a traditional method ("Vexar" tube; n = 2,074); and 3) unprotected (n = 2,074). WRC seedlings of the three groups will be uniformly intermixed throughout the entire plantation (seven acres). To increase the study population, we will plant 889 WRC seedlings per acre (7 x 7 feet spacing) instead of the regular 436 stems per acre (10 x 10 feet). Tree Fever will pay for the regular number of WRC seedlings, Vexar tubes, and regular labor costs.

3. 2014-16. This study can fail if there is a high rate of browsing-independent mortality. (As an extreme example, if all trees are killed by weeds, we will not learn whether the proposed method protects WRC from deer.) To minimize nonspecific mortality, we will include an extra round (beyond regular practices) of site preparation (fall 2014) and an extra round of weed and brush control (winter 2015-16). All regular practices will be paid for by Tree Fever.

4. Winter 2015-16. We will determine whether the new protection method increases the proportions of one-year survivors and of one-year non-damaged survivors among WRC seedlings, as compared to the traditional method and to no protection.

5. Spring 2016. After we process the data, we will prepare a brief report on the one-year results and send it to extension programs and WFFA members.

6. 2016-17. If the results are promising, we will apply for funding to extend this study beyond the original time frame.

7. Summer 2016. We will invite WFFA members for a Field Day, during which we will showcase our project. Dr. Ziegltrum will lead an educational workshop on preventing animal damage to trees and answer producers’ questions.

8. Winter 2016-17. We will determine whether the new protection method increases the proportions of two-year survivors and of two-year non-damaged survivors among WRC seedlings. We will also collect data on the extent of browsing-associated damage and on tree growth.

9. Spring 2017. We will prepare a brief report about our study and send it to extension programs and WFFA members. We will also make a decision on how to publish our results. Either an abstract and presentation at a forestry-related conference or a research article for publication in an open-access journal will be prepared.