| This study documents both stress-tolerant and ruderal strategies in Eastern red cedar (Juniperus virginiana) in southern Wisconsin. I investigated the changes in cedar glades over the last fifty years and identified the conditions that determine red cedar occurrence on the modern landscape, which allowed the development of an estimated distribution. Prior to European settlement, fire restricted red cedar to protected sites that are often extremely dry and nutrient poor. Fire suppression led to the decline of cedar glade communities, but, in conjunction with disturbance associated with agriculture, has allowed the red cedar population to expand.; Having resampled six cedar glades first sampled in the 1950s by John Curtis, I found that red cedar remains the dominant tree and these savannas have succeeded to closed-canopy red cedar forests. The prairie and savanna plants that dominated the herb layer in the 1950s have largely been replaced with shade-tolerant species, but species density remains unchanged at 1m 2 and 20m2 scales. While non-native species number and non-native plant abundance have significantly increased, the increased abundance of a few native herb species had the greatest impact on changes in understory composition.; To identify the conditions that determine red cedar occurrence on the modern landscape, I sampled a 180km2 area within GIS using 400 randomly located, non-overlapping circular plots (100m radii). Red cedar and road occurrence was recorded from an aerial photomosaic; data on land cover, slope and aspect were collected from digital raster layers. Most red cedar grows in deciduous forest gaps on ridges and, to a lesser degree, on edges and abandoned agricultural fields. Analysis of the GIS data through logistic regression indicates that the variety of land cover types and the range in slope within a plot significantly predict red cedar occurrence. The model correctly predicts red cedar occurrence approximately 80% of the time and, when applied to the full extent of southern Wisconsin, the model yields an estimated distribution of the species. Comparison of the distribution to pre-settlement vegetation records shows that red cedar has gone from very rare to widespread, particularly in the western half of southern Wisconsin. |
