Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài: "Local variations of ecosystem functions in Mediterranean evergreen oak woodland. | 561 Ann Sci For 1996 53 561 -570 Elsevier INRA Original article Local variations of ecosystem functions in Mediterranean evergreen oak woodland R Joffre s Rambal F Romane Centre d ecologle fonctionelle et evolutive CNRS BP 5051 34033 Montpellier cedex France Received 9 December 1994 accepted 10 November 1995 Summary The spatial variation of ecosystem function was studied in a Quercus excoppice growing on hard limestone with low soil water availability. Spatial structures obtained from data on I leaf area index ii leaf litterfall and III leaf litter decay rate were compared. All these variables were sampled on 26 points located within a 30 X 30 m plot. Mean average leaf litterfall over 10 years 1984-1993 was 254 . For each year the semivariograms of leaf litterfall have been fitted using a spherical model. The values of the range parameter indicating the limit of the spatial dependence ranged from to m very close to the value m of the range parameter obtained when fitting the semivari-ogram of mean leaf litterfall over 10 years. This result indicates the temporal persistence of the spatial pattern of leaf litterfall. The leaf area index LAI was estimated at the same points with a plant canopy analyzer. The mean value was . The limit of spatial dependence for LAI was very close to that obtained for leaf litterfall range m . The litter decomposition pattern was obtained through analysis of litter samples taken at the same points. The percentage of ash-free litter mass remaining LMR estimated using near-infrared reflectance spectroscopy indicates the stage of decomposition. It decreased strongly between the surface mean value and the subsurface layers mean value . The two semivariograms can be described by spherical models the sill being reached at a range of and m for the surface and subsurface layers respectively. The two variables directly related to the structure of the canopy LAI and leaf litterfall exhibited .
