Spatial variability and estimation of tree attributes in a plantation forest in the Caspian region of Iran using geostatistical analysis

This research was conducted to investigate spatial variability and estimate tree attributes in a plantation forest in the Caspian region of Iran using geostatistical analysis. Sampling was performed based on a ۵۰m?۱۲۵m systematic grid in a maple stand (Acer velutinum Boiss) ۱۸ years of age using circular samples of ۲۰۰m۲ area. Totally, ۹۶ sample plots were measured in ۶۳ hectares and ۱۴.۲۵ hectare was inventoried as full census area. Experimental variograms for forest stem basal area, stem density and tree height attributes were calculated and plotted using the geo-referenced inventory plots. The calculated variograms of basal area and height showed a high spatial auto-correlation, which is fitted by spherical model. However, stem density showed a large nugget effect. Estimations for basal area and height interpolated by ordinary block kriging and cross validation results showed that all the estimations were accurate. Furthermore, the estimated kriged mean of basal area showed no significant difference to the real mean in the full census area. Therefore, geostatistical analysis is able to capture and explain the spatial variability as well as estimate tree attributes (not stem density) in this kind of plantation forest, accurately.   REFERENCES Akhavan, R., Zahedi Amiri, Gh. and Zobeiri, M. (۲۰۱۰) Spatial variability of forest growing stock using geostatistics in the Caspian region of Iran. Caspian J. Env. Sci, ۸ (۱), In Press. Bellehumeur, C. and Legendre, P. (۱۹۹۸) Multiscale sources of variation in ecological variables: modeling spatial dispersion, elaborating sampling designs. Landsc. Ecol., ۱۳, ۱۵-۲۵. Biondi, F., Myers D.E. and Avery, C.C. (۱۹۹۴) Geostatistically modeling stem size and increment in an old-growth forest. Can. J. For. Res., ۲۴, ۱۳۵۴-۱۳۶۸. Cressie, N.A.C. (۱۹۹۳) Statistics for spatial data. John Willy and Sons Inc., New York. pp. ۹۰۰. Dale, M.R.T. (۲۰۰۰) Spatial pattern analysis in plant ecology. Cambridge University press, Cambridge, United Kingdom, ۳۲۶ p. Freeman, E.A. and Moisen, G.G. (۲۰۰۷) Evaluating kriging as a tool to improve moderate resolution maps of forest biomass. Environ. Monit. Assess. ۱۲۸, ۳۹۵- ۴۱۰. Goovaerts, P. (۱۹۹۷) Geostatistics for natural resources evaluation. Oxford University Press, New York,  ۴۸۳ p. Gunnarsson, F., Holm, S. Holmgren, P. and Thuresson, T. (۱۹۹۸) On the potential of kriging for forest management planning. Scan. J. For. Res., ۱۳, ۲۳۷- ۲۴۵. Hernández, J. and Emery, X. (۲۰۰۹) A geostatistical approach to optimize sampling designs for local forest inventories. Can. J. For. Res., ۳۹, ۱۴۶۵-۱۴۷۴. Husch, B., Miller C.I. and Beers, T.W. (۱۹۸۲) Forest mensuration. ۳rd ed. John Wiley and Sons, inc., New York. pp. ۴۴۳. Isaaks, E.H. and Srivastava, R.M. (۱۹۸۹) An introduction to applied geostatistics. Oxford University Press, New York, ۵۶۱ p. Jeffers, J.N.R. (۱۹۸۲) Modeling. Chapman and Hall, London, ۸۰ p. Kint, V., Meirvenne, M.V. Nachtergale, L. Geudens G. and Lust, N. (۲۰۰۳) Spatial methods for quantifying forest stand structure development: a comparison between nearest neighbor indices and variogram analysis. Forest science, ۴۹, ۳۶-۴۹. Mandallaz, D. (۱۹۹۱) A unified approach to sampling theory for forest inventory based on infinite population model. PhD. Dissertation, Academic Press, ETH Zürich, Switzerland, Chair of Forest Inventory and Planning. http://www. e-collection.ethb.ethz.ch/. Mandallaz, D. (۱۹۹۳) Geostatistical methods for double sampling schemes: application to combined forest inventory. Technical report, ETH Zürich, Chair of Forest Inventory and Planning, ۱۳۳ p. Montes, F., Hernandez M.J. and Canellas, I. (۲۰۰۵) A geostatistical approach to cork production sampling in Quercus suber forests. Can. J. For. Res., ۳۵, ۲۷۸۷-۲۷۹۶. Pierce Jr., K.B., J.L. Ohmann, M.C. Wimberly, M.J. Gregory and J.S. Fried, (۲۰۰۹) Mapping wildland fuels and forest structure for land management: a comparison of nearest neighbor imputation and other methods. Can. J. For. Res., ۳۹, ۱۹۰۱-۱۹۱۶. Samra, J.S., Gill H.S. and Bhatia, V.K. (۱۹۸۹) Spatial stochastic modeling of growth and forest resource evaluation. Forest Science, ۳۵, ۶۶۳-۶۷۶. Tuominen, S. Fish S. and Poso, S. (۲۰۰۳) Combining remote sensing, data from earlier inventories, and geostatistical interpolation in multi-source forest inventory. Can. J. For. Res., ۳۳, ۶۲۴- ۶۳۴. Webster, R. and Oliver, M.A. (۲۰۰۰) Geostatistics for environmental scientists, Wiley Press, ۲۷۱ p.

کلیدواژه ها:

Geostatistics ، Spatial variability ، Plantation forest ، Tree attribute ، Caspian region