Good News on the Waiwi Front:<\/b> One of the most pestiferous plants in Hawaiian forests is strawberry guava (also known as waiwi or Psidium cattleianum<\/i>). Seeds from its toothsome fruits are easily spread by pigs, birds, and other animals, and when the seeds sprout, the resulting plants form dense, impenetrable thickets that crowd out natives.<\/p>\n
\tYet there is a bright spot in all this: unlike many other forest pest species whose seeds can remain viable in soil for years, strawberry guava seeds have a short half-life. If they don\u2019t germinate within six months, they probably never will, according to research by Amanda Uowolo and Julie Denslow, scientists with the U.S. Forest Service whose writeup of their work appears in the January 2008 edition of Pacific Science<\/i>.<\/p>\n
\tThe findings, they note, have important implications for foresters trying to control strawberry guava: \u201cBecause most P. cattleianum<\/i> seeds do not live beyond 3 months in the soil, chemical or mechanical control efforts would be most efficient and effective if conducted at least 3 months after the fruiting season.\u201d<\/p>\n
\tAnd those efforts could be even more effective if combined with a leaf gall that has been proposed for use in Hawai`i and which suppresses fruit and seed production. \u201cOur results suggest that a biocontrol agent that reduced \u2026 seed production would also rapidly deplete soil seed stocks, therefore increasing effectiveness of chemical and mechanical control,\u201d they conclude.<\/p>\n
\t\u201cOf course strawberry guava also sprouts like crazy so the seed bank isn’t the whole story, but it’s certainly a big part of it,\u201d Denslow told Environment Hawai`i.<\/i><\/p>\n
Kaunakakai Wetland Study:<\/b> Elsewhere in this issue, we discuss water disputes in Moloka`i, where many folks are concerned that increased well withdrawals will impact the health of fish and seaweed that have been an important part of residents\u2019 lifestyles for centuries. Because so many of Moloka`i\u2019s leeward streams are fed almost exclusively by springs, taking more water from upstream wells will inevitably reduce freshwater flowing into the nearshore areas.<\/p>\n
\tBut how much impact will there be?<\/p>\n
\tThe U.S. Geological Survey was asked this question, in connection with plans of Maui County and the U.S. Corps of Engineers to construct about 3 acres of wetlands near the mouth of Kaunakakai Stream as habitat for the endangered Hawaiian stilt (Himantopus mexicanus knudseni<\/i>). Late last year, it released the results of its investigations, led by hydrologist Delwyn S. Oki, examining groundwater withdrawals under six different scenarios, ranging from the base case (with 2.123 million gallons a day taken from water sources feeding the stream) to 3.921 mgd, which would occur if all proposed withdrawals were permitted and developed.<\/p>\n
Using computer simulations, Oki found that withdrawals under scenarios 2 through 6 could reduce discharge in the area proposed for restoration by amounts ranging from 98,000 to 170,000 gallons a day. Actual reductions might well be less than that, he said, noting limitations of the modeling program used.<\/p>\n
\t\u201cThe reduction of groundwater level near the habitat-restoration site also may reduce the wetted habitat area available to the native species,\u201d he wrote, depending on the slope of the ponds near their edges. \u201cThe salinity of groundwater discharging into the wetland area likely will increase by an unknown amount in response to increased withdrawals upgradient from the site,\u201d he said, adding that further work was needed to evaluate effects of this.<\/p>\n
\tThe study is online at: [url=http:\/\/pubs.usgs.gov\/sir\/2007\/5128\/]http:\/\/pubs.usgs.gov\/sir\/2007\/5128\/[\/url]<\/p>\n
Volume 18, Number 8 February 2008<\/p>\n","protected":false},"excerpt":{"rendered":"
Good News on the Waiwi Front: One of the most pestiferous plants in Hawaiian forests is strawberry guava (also known as waiwi or Psidium cattleianum). Seeds from its toothsome fruits are easily spread by pigs, birds, and other animals, and … Continued<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[166],"tags":[],"class_list":["post-1244","post","type-post","status-publish","format-standard","hentry","category-february-2008"],"_links":{"self":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/1244","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1244"}],"version-history":[{"count":0,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/1244\/revisions"}],"wp:attachment":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1244"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1244"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1244"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}