tailieunhanh - Báo cáo lâm nghiệp: "Spatial dynamics of late successional species under Pinus nigra stands in the northern Apennines (Italy)"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:"Spatial dynamics of late successional species under Pinus nigra stands in the northern Apennines (Italy)" | Ann. For. Sci. 62 2005 669-679 INRA EDP Sciences 2005 DOI forest 2005059 669 Original article Spatial dynamics of late successional species under Pinus nigra stands in the northern Apennines Italy Giustino TONONa Pietro PANZACCHIa Giacomo GRASSIa Minotta GIANFRANCOb Lucia CANTONIa Umberto BAGNARESIa a Dipartimento di Colture Arboree Università di Bologna Via Fanin 46 40127 Bologna Italy b Dipartimento AGROSELVITER Università di Torino Via Leonardo da Vinci 44 10095 Grugliasco TO Italy Received 18 October 2004 accepted 8 April 2005 Abstract - The present study was carried out in three plots 20 X 50 m established in even-aged Pinus nigra Austrian black pine stands located at approximately the same altitude characterised by a similar age but showing different growth rate. Spatial distribution of natural regeneration NR were examined for each species by calculating Ripley s K and Moran index and by analysing their age- and size structure. Although the species mixture of NR differed among the plots Abies alba was always the most frequent. Results showed that the clumped distribution of NR prevails over the random one. The spatial autocorrelation analysis indicated at least two modes of space colonisation in line with clumped distribution of NR. In the first the seedlings occupy different micro-areas in different times whereas in the second the colonisation process occurs in the same micro-area for a more extended time. The resulting structure of NR is constituted by several small patches of different age in the first case or by patches with a similar uneven-aged structure in the second. These different colonisation patterns could be ascribed respectively to short-term disturbances such as sudden opening in the canopy and litter removal in the first case and to longterm disturbances or the presence of scarcely modifiable environmental factors such as soil characteristics and micro-morphology in the second. However the colonisation process was always temporally .