Urban timber volume estimation How to measure forests in urban areas with limited resources Technische Universität München

Content 1.Need of forest measurements 2.Single tree volume measurement 3.Measuring forest stands 4.Methodological background 5.Urban forest cover 6.Application in Dar es Salaam 7.Draft results 8.Considerations 9.References Technische Universität München 2

Need of forest measurements Three principle reasons (WEST, 2004): 1.To help with decisions about how to manage forest at different scales (timber import/export; source of employment/water supply; contribution to income) 2.To assist their management (level of change over time; timber supply in the long term) 3.Research (factors determining forest growth; climate impacts; etc.) Technische Universität München 3

Single tree volume measurement Technische Universität München FunctionSpecies and location Vu=0,298*D²*HEucalyptus regnans, New Zealand Vu=0,005+0,330*D²*HPinus taeda, southern USA Vo=0,450*D 1.92 *H 0.90 Juniperus procera, Ethiopia Pictures from AVERY & BURKHARD, 2002; table below adapted from WEST,

Measuring forest stands 1.Using stand volume tables: limited to monocultures, no dynamics Technische Universität München Stand volume table for Scots Pine in north eastern Germany (LEMBCKE, KNAPP & DITTMAR, 2000) 5

Measuring forest stands 2.Conduct a complete survey, i.e. measuring all trees of a single forest stand: limited to small stands (time and cost intense) 3.Conduct an inventory, i.e. measuring samples of the forest stand: different inventory designs Random sampling Block sampling Stratified sampling Systematic sampling … Technische Universität München Problem: they all need ground measurements… 6

Methodological background How to measure forest where resources (time, money, persons, access rights etc.) are limited? Idea: To adapt the statement: “…FAO estimated total growing stock by taking subregional averages of growing stock per hectare and multiplying these by the forest area for the respective years.“ (FAO 2010) for our UMT and LC Analysis Technische Universität München 7

Urban forest cover  Part of the LC-analysis  Tree cover classes according to FAO landcover classes have to be defined  Def. of forest (FAO 2010): land spanning more than 0.5 ha with a minimum tree height of 5m and at least 10% tree cover  Def. of OWL: …5-10% tree cover or accumulated cover of trees, shrubs and bushes above 10% UMTs with tree cover Land cover analysis UMTs Technische Universität München 8

Application in Dar es Salaam  Case study: Dar es Salaam (area of whole city according to UMT map approximately 1500 km²?)  Inputs: aerial image of 2008 (pixel size approximately 0,45m*0,45m), Urban Morphology Type Map (extent covering approximately 390 km²)  first land cover analyses for UMTs „1.3 Mixed farming“ and „2.5 Bushland“  Differentiated tree cover by tree/crown size  for Dar 2 classes distinguished by crown diameter (threshold 6m diameter): –Large trees –Small trees/shrubs Technische Universität München 9 UMT CodeUMT Class Polygon count Area_Sum [sq_km]Area [ha] # Sample points 1.3Mixed farming1249, , Bushland168, ,11100

Draft results Technische Universität München 10 LC-type Land cover within UMT 1.3 Growing Stock per ha (FAO 2010, Tab 10) [m³/ha] Growing stock in UMT [m³] Large trees 2,75% 10 (OWL) Small trees/ shrubs 12,75% LC-type Land cover within UMT 2.5 Growing Stock per ha (FAO 2010, Tab 10) [m³/ha] Growing stock in UMT [m³] Large trees 2,00% 10 (OWL) Small trees/ shrubs 39,00%

Considerations  Calculated volumes are intended to act as general overview/orientation  Range of tree species might differ from rural areas  Ground truthing to validate  Method is applicable to each case study city with an UMT mapping and LC-analysis  Single trees grow different compared to trees in forest stands  Forest growth calculation is dependant from standing volumes  Can be the basis for estimation of the biomass and carbon sequestration Technische Universität München 11

References  Avery, T.E., Burkhart, H.E., 2002: Forest Measurements, Fifth Edition; McGraw-Hill Series in Forest Resources  FAO 2010: Global Forest Resources Assessment 2010 – Main Report; FAO Forestry Paper 163; Food and Agricultural Organisation of the United Nations, Rome  Lembcke, Knapp, Dittmar, 2000: Ertragstafel für die Kiefer (Pinus sylvestris L.) im nordostdeutschen Tiefland; Landesforstanstalt Eberswald  West, P.W., 2004: Tree and Forest Measurement; Springer-Verlag, Berlin  Zöhrer, F., 1980: Forstinventur, ein Leitfaden für Studium und Praxis; Pareys Studientexte 26; Verlag Paul Parey, Hamburg und Berlin Technische Universität München