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The Global Invasive Species Team | |
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Global Invasive Species Team listserve digest #013 Wed, 20 Jan 1999 16:53:19 -0800 (PST) --CONTENTS-- 1. Dangers of Photomonitoring Results of Leafy Spurge Biocontrol --------------------------------------- 1. Dangers of Photomonitoring Results of Leafy Spurge Biocontrol From: David Hanna (dhanna(at)3rivers.net) After 5 years, we are seeing significant results from our biocontrol releases for leafy spurge. The quantitative data from our release sites clearly shows that the beetles are impacting the spurge. However, the photomonitoring portion of our monitoring has turned out to be somewhat problematic. The phenology of spurge affected by the flea beetles is very different from non-affected spurge. At our sites, spurge affected by the flea beetles flowers 4-6 weeks later than spurge in non affected areas. Thus, the visual impact of the beetles impact in photos varies by season. Photos taken in late June show non-affected spurge in bright yellow flower while with affected spurge just coming up, producing fairly stiking visual evidence the beetles are working. However, photos taken in late July show non-affected spurge senescing, with affected spurge in peak flower, making the impact of the beetles appear much less dramatic. So, if releases at other sites use only photomonitoring, we recommend taking these differences in phenology casued by the flea beetles into account when setting up the monitoring protocol. If photos are taken only once in a season, the full picture of the beetles' impact will not be captured--the impact will likely be over or under represented. David Hanna Pine Butte Swamp Preserve HC 58 Box 34B Choteau MT 59422 406-466-5526 --------------------------------------------------------------- |
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