tailieunhanh - Báo cáo lâm nghiệp: "Canopy structure and spatial heterogeneity of understory light in an abandoned Holm oak woodland"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Canopy structure and spatial heterogeneity of understory light in an abandoned Holm oak woodland. | Ann. For. Sci. 63 2006 749-761 INRA EDP Sciences 2006 DOI forest 2006056 749 Original article Canopy structure and spatial heterogeneity of understory light in an abandoned Holm oak woodland Fernando VALLADARESa Beatriz GuZMANb a Institute de Recursos Naturales Centro de Ciencias Medioambientales . Serrano 115 dpdo. 28006 Madrid Spain Area de Biodiversidad y Conservation ESCET Universidad Rey Juan Carlos 28933 Mostoles Madrid Spain b Real Jardin Botánico de Madrid . Pza. de Murillo 2 28014 Madrid Spain Received 31 May 2005 accepted 27 January 2006 Abstract - Understory light is crucial to understand forest ecology but there is scant information for Mediterranean forests. Understory light of an abandoned Holm oak Quercus ilex L. woodland was studied in central Spain by means of hemispherical photographies in a 30 X 30 grid of 1-m2 points. Canopy height stem density and basal area had a significant influence on understory light. Height exhibited the most significant correlation with indirect light. However its potential as a predictor of understory light was low due to the large fraction of unexplained variance. Sunflecks contributed to half of the understory light they were intense and long 25 min and 10 min shorter at the herb than at the shrub layer. Mean light availability in the understory was half of that in the open and it exhibited a significant spatial heterogeneity. Spatial grain was significantly coarser for indirect than for direct light it was also coarser at the herb than at the shrub layer indicating that while a single individual shrub exploits light heterogeneity via phenotypic plasticity at the shrub layer different individuals or micropopulations exploit it at the herb layer. Abandonment of traditional management of Holm oak woodlands leads to a decrease in both the availability and the spatial heterogeneity of understory light. hemispherical photography Holm oak understory light Mediterranean forests spatial heterogeneity .