Edge effects in mixed conifer group selection openings: tree height response to resource gradients

摘要: Replicated circular openings ranging in size from 0.1 to 1 ha were cleared on a Sierran mixed conifer forest 1996 at the Blodgett Forest Research Station, California and planted with seedlings of six native species. After 3 years growth, heights all trees measured analyzed according species, opening size, location within opening. To determine cause edge influence height, we differences along north‐south transects extension pre-dawn water potential, light availability for three species trees: giant sequoia (Sequoiadendron giganteum), ponderosa pine (Pinus ponderosa), Douglas-fir (Ptseudotsuga menziesii var. menziesii). The sequence mean height tallest shortest based was: > incense cedar white fir sugar pine. For combined, ten-fold increase area corresponded 34% height. Trees average north rows south rows. There was no difference between east west As expected, resource greatest near center least edges receiving significantly more than southern edges. In general, observed effects sapling growth correlated supply. However there important nature co-limitation. Giant most sensitive availability. Together they explained 47% variation contrast, only significant predictor performance. related both but unexplained variability model compared other These highly controlled experimental group provide standard reference silviculturalists using selection method regeneration. # 2002 Elsevier Science B.V. All rights reserved.