برآورد و پهنه‌بندی موجودی یک جنگل مدیریت‌نشده خزری به‌روش زمین‌آمار (پژوهش موردی: بخش چلیر جنگل خیرود نوشهر)

نوع مقاله : علمی- پژوهشی

نویسندگان

1 استادیار موسسه تحقیقات جنگلها و مراتع کشور

2 استادیار دانشگاه آزاد، واحد علوم و تحقیقات تهران

3 استادیار دانشگاه تهران

4 پژوهشگر، موسسه تحقیقات جنگلها و مراتع کشور

5 مربی، موسسه تحقیقات جنگلها و مراتع کشور

چکیده

برآورد و پهنه‌بندی موجودی در مدیریت و برنامه‌ریزی جنگل امری اجتنابناپذیر است. در این تحقیق از شیوه درون‌یابی کریجینگ روش زمین‌آمار به‌منظور برآورد و پهنه‌بندی متغیرهای موجودی در یک جنگل طبیعی و ناهمسال مدیریتنشده (فاقد طرح جنگلداری) استفاده شد. منطقه موردبررسی در بخش چلیر جنگل آموزشی- پژوهشی خیرود نوشهر و در ارتفاع 1100 تا 1450 متر بالاتر از سطح دریا واقع شده است و مساحتی برابر 516 هکتار دارد. آماربرداری زمینی با استفاده از قطعاتنمونه 10 آری دایره‌ای شکل و براساس شبکه‌ای به ‌ابعاد 200×75 متر به‌روش منظم- تصادفی انجام و درمجموع 309 قطعهنمونه اندازه‌گیری شد. سپس واریوگرام‌های تجربی با استفاده از داده‌های زمین‌‌مرجع برداشت شده برای متغیرهای موجودی جنگل شامل تراکم (تعداد در هکتار)، رویه‌زمینی (سطحمقطع برابرسینه) و موجودی حجمی جنگل محاسبه شدند. نتایج واریوگرافی نشان داد که دو متغیر رویه‌زمینی و موجودی حجمی جنگل از هیچ‌گونه ساختار مکانی مناسب به‌منظور استفاده در درون‌یابی کریجینگ برخوردار نیستند، به‌جز زمانیکه براساس طبقههای قطری یا گونه‌های غالب درختی طبقه‌بندی شوند، اما متغیر تراکم جنگل از خود ساختار مکانی متوسط نشان داد که در نتیجه با استفاده از مدل کروی برازش شد. در مرحله بعد برآورد و پهنه‌بندی تراکم جنگل به‌روش کریجینگ معمولی- بلوکی انجام شد که نتایج ارزیابی متقابل نشان داد که برآوردها از صحت لازم برخوردارند. نتیجه این پژوهش نشان داد که زمین‌آمار قادر به تبیین تغییرات مکانی تراکم در این جنگل مدیریتنشده بود و می‌تواند نقشه پهنه‌بندی آن را با صحت مناسب تولید نماید که براساس آن می‌توان متغیرهای رویه‌زمینی و موجودی حجمی جنگل را که مستقیماً به این روش قابلبرآورد نیستند، به‌صورت غیرمستقیم برآورد نمود. 

کلیدواژه‌ها


عنوان مقاله [English]

Geostatistically estimation and mapping of forest stock in a natural unmanaged forest in the Caspian region of Iran (Case study: Keyroud forest, Nowshahr)

نویسندگان [English]

  • Reza Akhavan 1
  • Hadi Kia Daliri 2
  • Vahid Etemad 3
  • Majid Hassani 4
  • Khosro Mirakhorlou 5
1 Assistant Prof., Forest Research Division, Research Institute of Forests and Rangelands, Tehran, I.R. Iran
2 Assistant Prof., Science and Research Branch, Islamic Azad University, Tehran, I.R. Iran.
3 Assistant Prof., Faculty of Natural Resources, University of Tehran, Karadj, I.R. Iran.
4 Research Expert, Forest Research Division, Research Institute of Forests and Rangelands, Tehran, I.R. Iran.
5 Senior Research Expert, Forest Research Division, Research Institute of Forests and Rangelands, Tehran, I.R. Iran.
چکیده [English]

Estimation and mapping of forest resources is a prerequisite for research, management, and planning. In this study, we applied kriging geostatistical interpolation for estimation and mapping of forest stock attributes in a natural, uneven-aged and unmanaged forest in the Caspian region of northern Iran. The elevation across the 516-ha study area ranged from 1100 to 1450 m a.s.l. Field sampling was performed using 1000 m2 circular sample plots in a 75 m × 200 m systematic grid. Total numbers of 309 plots were sampled. Experimental variograms were fitted for stem basal area (BA), volume stock (V) and stem density (N) using geo-referenced plots. The variograms of BA and V exhibited no spatial autocorrelation, except for the stratified data based on diameter classes and tree species. The N showed yet a medium spatial structure which was fitted by a spherical model. The stem density was estimated by ordinary block kriging. The cross-validated results showed high estimation accuracy. The applied geostatistical methods were concluded to be advantageous for accurately capture the spatial variability of stem density which was reflected in the stem density maps. The methods can be applied to similar unmanaged, uneven-aged stands in the north of Iran, and thereby support the estimation of forest growing stock.

کلیدواژه‌ها [English]

  • Geostatistics
  • Mapping
  • forest stock
  • unmanaged forest
  • spatial structure
- Akhavan, R. 2004. Application of Geostatistics for forest stock estimation in comparison to classical statistics in the Caspian region of Iran. Ph.D. thesis, University of Tehran, 64p (In Persian).
- Akhavan, R., Zobeiri, M., Zahedi Amiri, Gh., Namiranian, M. and Mandallaz., D. 2006. Spatial structure and estimation of forest growing stock using geostatistics in the Caspian region of Iran. Iranian Journal of Natural Resources, 59(1): 89-102 (In Persian).
- Akhavan, R. and Kleinn, C. 2009. On the potential of kriging for estimation and mapping of forest plantation stock. Iranian Journal of Forest and Poplar Research, 17(2): 303-318 (In Persian).
- Akhavan, R., Sagheb Talebi, Kh., Zenner, E.K. and Safavimanesh, F. 2012. Spatial patterns in different forest development stages of an intact old-growth Oriental beech forest in the Caspian region of Iran. European Journal of Forest Research, 131(5): 1355-1366.
- Anonymous, 1995. Volume table of Beech for Mazandaran forests. Forests, Ranges and Watersehed Management Organization of Iran, 366p (In Persian).
- Anonymous, 2002. Volume table of tree species of northern forests of Iran. Forests, Ranges and Watersehed Management Organization of Iran, 255p (In Persian).
- Biondi, F., Myers, D.E. and Avery, C.C. 1994. Geostatistically modeling stem size and increment in an old-growth forest. Canadian Journal of Forest Research, 24: 1354-1368.
- Brus, D.J., Hengeveld, G.M., Walvoort, D.J.J., Goedhart, P.W., Heidema, A.H., Nabuurs, G.J. and Gunia, K. 2012. Statistical mapping of tree species over Europe. European Journal of Forest Research, 131: 145-157.
- Cambardella, C.A., Moorman, T.B., Parkin, T.B., Karlen, D.L., Turco, R.F. and Konopka, A.E. 1994. Field scale variability of soil properties in Central Iowa soil. Soil Science Society of America Journal, 58: 1501-1511.
- Cressie, N.A.C. 1993. Statistics for Spatial Data. John Willy and Sons, Inc., New York, 900p.
- Dale, M.R.T. 2000. Spatial Pattern Analysis in Plant Ecology. Cambridge University Press, Cambridge, United Kingdom, 326p. 
- Eslami, A., Sagheb-Talebi, Kh. and Namiranian, M. 2007. Determining of equilibrium state in uneven- aged Oriental beech forests of northern Iran. Iranian Journal of Forest and Poplar Research, 15(2): 92-104 (In Persian).
- Freeman, E.A. and Moisen, G.G. 2007. Evaluating kriging as a tool to improve moderate resolution maps of forest biomass. Environmental Monitoring and Assessment, 128: 395-410.
- Ghanbari, F. 2008. Prediction of spatial distribution of forest alometric characteristics using geostatistics and GIS in Dr. Bahramnia’s forest. M.Sc. thesis, Agricultural Sciences and Natural Resources University of Gorgan, 155p (In Persian).
- Goovaerts, P. 1997. Geostatistics for Natural Resources Evaluation. Oxford University Press, New York. 483p.
- Gunnarsson, F., Holm, S., Holmgren, P. and Thuresson, T. 1998. On the potential of kriging for forest management planning. Scandinavian Journal of Forest Research, 13: 237- 245.
- Isaak, E.H. and Srivastava, R.M. 1989. An Introduction to Applied Geostatistics. Oxford University Press, New York, 561p.
- Kia-Daliri, H., Akhavan, R. and Anissi, I. 2011. Timber marking and its impact on forest stand. Iranian Journal of Forest, 3(1): 49-59 (In Persian).
- Kint, V., Meirvenne, M.V., Nachtergale, L., Geudens, G. and Lust, N. 2003. Spatial methods for quantifying forest stand structure development: a comparison between nearest neighbour indices and variogram analysis. Forest Science, 49(1): 36-49.
- Mandallaz, D. 1991. A unified approach to sampling theory for forest inventory based on infinite population model. Ph.D. thesis, Academic Press, ETH Zürich, Switzerland, Chair of Forest Inventory and Planning, 257p.
- Mandallaz, D. 1993. Geostatistical methods for double sampling schemes: Application to combined forest inventory. Technical Report, ETH Zürich, Chair of Forest Inventory and Planning, 33p.
- Moeur, M. 1993. Characterizing spatial patterns of trees using stem- mapped data. Forest Science, 39(4): 756-775.
- Mohammadi, J., Shataee, Sh., Habashi, H. and Yaghmaee, F. 2008. Comparison of remote sensing and geostatistics techniques in forest tree density estimation. Journal of Agricultural Sciences and Natural Resources, 15(1): 10-21 (In Persian).
- Montes, F., Hernandez, M.J. and Canellas, I. 2005. A geostatistical approach to cork production sampling in Quercus suber forests. Canadian Journal of Forest Research, 35: 2787-2796.
- Sagheb-Talebi, Kh. and Schütz, J-Ph. 2002. The structure of natural Oriental beech (Fagus orientalis) in the Caspian region of Iran and potential for the application of the group selection system. Forestry, 75(4): 465-472.
- Sagheb-Talebi, Kh., Sajedi, T. and Yazdian, F. 2004. Forests of Iran. Published by Research Institute of Forests and Rangelands, No. 339, 28p.
- Sarmadian, F. and Jafari, M. 2001. Study of educational- experimental Kheyroud forest soils. Iranian Journal of Natural Resources, Special Issue (54), 111p (In Persian).
- Samra, J.S., Gill, H.S. and Bhatia, V.K. 1989. Spatial stochastic modeling of growth and forest resource evaluation. Forest Science, 35: 663-676.
- Tröltzsch, K., van Brusselen, J. and Schuch, A. 2009. Spatial occurrence of major tree species groups in Europe derived from multiple data sources. Forest Ecology and Management, 257: 294-302.
- Tuominen, S., Fish, S. and Poso, S. 2003. Combining remote sensing, data from earlier inventories, and geostatistical interpolation in multi-source forest inventory. Canadian Journal of Forest Research, 33: 624- 634.
- Webster, R. and Oliver, M.A. 2000. Geostatistics for Environmental Scientists. Wiley Press, 271p.
- Zobeiri, M. 1994. Forest Inventory. Tehran University Press, 401p (In Persian).