Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [WP-3 FOREST INVENTORY APPLICATIONS]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: REMOTE SENSING-AIDED SURVEY OE RENEWABLE RESOURCES WITH EMPHASIS ON FORESTRY IN THE TROPICS. Simo Poso

Document type:: Multivolume work

Structure type:: Chapter

The stratification of the first phase units can be repeated using different kinds of auxiliary data for as many times as required. Each stra tification produces a new set of ground vari able estimates for each first phase sample plot The result is illustrated in Figure 2. 1,2 1,2 1,2 1,- 1,- 3,4 3,4 3,4 3,4 3,- 1,2 1,2 1,2 1,- 1,- 3,4 3,4 3,4 3,- 3,- 1,2 1,2 1,- 1,- 1,- 3,4 3,4 3,- 3,- 3,- 1,2 1,2 1,- 1,- 1,- 3,- 3,- 3,- 3,- 1,- 1,- 1,- 1,- 1,- 3,- 3,- 3,- “ У ~ Figure 2. Estimate vectors for the first phase sample units The numbers in the Fig. 2 refer to the strati fications. Each of the 25 first phase plots may obtain four different sets of estimates when all stratifications are represented. Some plots are represented only in one stratification and hence receive only one set of estimates. If no auxil iary data exist for a first phase plot it can not be included in any stratum and it does not receive any estimate directly. In this case nearest neighbour techniques, i.e., taking the estimates from the geographicly nearest neigh bor plots, may be applied. In order to estimate the final ground variable values for a specific first phase plot, the con cept of the reliability of the estimates has to be introduced. The final estimates for the ground variables, e.g. site, mean height, basal area, volume, tree species distribution, volume increment, and technical quality of the growing stock, is calculated by weighting the separate estimates by the reliability of the estimate. 3. DISCUSSION The method, based on one stratification using a combination of satellite imagery and map data, has been tested in Finnish conditions on several occasions with positive results. These experi ences include an inventory of two communes with forest areas of 18 000 and 120 000 hectares. The field sample plots were usually relascope points with a basal area factor of 2 nr/ha. A study of the relevant possibilities and prob lems in estimating final ground truth variable values on the basis of more than one stratifi cation has been started at the University of Helsinki as a part of a thesis for a FI.Sc. deg ree. The study deals with updating of old inven tory data using remote sensing, forest growth models, and maps. The applicability of the approach to the tropics has not been attempted. The methodology describ ed may, however, be simple enough for forest re source assessment and monitoring. In the most extreme cases only N0AA and some basic map in formation may be used for stratification. Land- sat TM or corresponding data can be used when ever accessible. The major problem would be the availability of good quality ground truth data as field inventories in tropical conditions are very difficult to perform. The need for ground measurements may be especially demanding in the tropics if much weight is allocated for tree species estimation. A single hectare of closed tropical forest, for example, may include more than 100 tree species each with its own indepen dent colony of plants and animals. According to Birdsey et al. (1986) tropical species tend to have a clustered distribution. The use of clus ters as sampling units is recommended (e.g. Vazquez Soto 1987). Another general recommenda tion for the tropics is the use of permanent sampling units (e.g. Schreuder and Singh 1987). It is important that all data: plots, pixels, air photos, maps, etc., can be located at the same coordinate and time system. The correspon dence of different data should thus be tested. Studies with satellite imagery have shown that dislocation of some 20 m may cause a severe de crease in the usability of remote sensing in conditions where the average stand size is small. Problems may also originate from unreli able maps. Sometimes, it may be advisable to substitute maps for satellite imagery in the tropics. The date of the first and second phase data may differ and procedures for updating se cond phase data are thus required. Forest data updating often requires the application of growth models. The lack of reliable volume and biomass growth models and change models in land use emphasizes the need for permanent sample plots, especially in the tropics. REFERENCES Bickford, C.A. 1952. The sampling design used in the forest survey of the Northeast. Journal of Forestry 50(4), 290-293. Birdsey, R.A., Weaver, P.L. and Nicholls, C.F. 1986. The forest resources of St. Vincent, West Indies. SO. 229. LA: New Orleans. 25 p. Frayer, W.E. 1979. Multi-level sampling designs for resource inventories. Department of Fo rest and Wood Sciences, Colorado State Univ., Rocky Mountain Forest and Range Exp. Sta., USDA, Forest Service. Harma, P. 1988. Interpretation of satellite ima geries at the department of forest mensura tion and management. Proc. of IUFR0 S4.02.05 Meeting. Research Notes 21. Department of Forest Mensuration and Management, University of Helsinki. LaBau, V. and Winterberger, K. 1988. Use of four-phase sampling design in Alaska multi- resource vegetation inventories. IUFR0 S4.02. 05 Meeting, Aug. 29 - Sept. 2, 1988. Research Notes 21. Department of Forest Mensuration and Management, University of Helsinki. Mattila, E. 1985. The combined use of systematic field and photo samples in a large-scale fo rest inventory in North Finland. Communica tiones Instituti Forestalis Fenniae 131. Neyman, J. 1938. Contribution to the theory of sampling human populations. Journal Amer. Stat. Assoc. 33: 101-116. Peng, S. 1987. On the combination of Multitem poral Image and Field Data for Forest Inven tories. Acta Forestalia Fennica 200. 435

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