GEOSTATISTICS FOR MAPPING WEEDS, WITH A CANADA THISTLE (CIRSIUM-ARVENSE) PATCH AS A CASE-STUDY

Geostatistical methods were used to describe and map nonrandom distribution and variation (standard deviation) of shoot density and root growth across a well-established patch of Canada thistle, a perennial weed. Semivariogram functions and kriging, an interpolation method, were used to prepare isoarithmic contour maps and associated error maps. Maps consisted of interpolated contours of uniform weed density and other measured or calculated regionalized variables between measured X-Y control points, as well as maps of error (standard deviation) associated with contour estimation. Mapped regions of greatest shoot density across a patch not only had the greatest underlying root biomass and, often, greatest density of adventitious root buds, but also had more deeply growing root biomass. Nomenclature: Canada thistle, Cirsium arvense (L.) Scop. # CIRAR3.