Remote sensing assessment of tree size inequality

Transcription

1 Remote sensing assessment of tree size inequality Rubén Valbuena Marie S. Curie Research Fellow Department of Plant Sciences. Forest Ecology and Conservation

2 In the long term ( ): Pan-European Indicators of Forest Structural Complexity from Airborne Laser Scanning at European Forest Institute (EFI). Grant awarded by Foundation for European Forest Research (FEFR). ( ): Doctoral thesis + PostDoc at University of Eastern Finland (Joensuu). Most relevant related publications: Forest Ecology Management 276 (2012): Canadian Journal of Forest Research 43 ( ): Ecological Indicators 60 (2016) Remote Sensing of Environment (2016) in press ( ): LorenzLiDAR: Classification of Forest Structural Types with LiDAR Remote Sensing Applied to Study Tree Size-Density Scaling Theories at University of Cambridge (UK). Marie Skłodowska-Curie Actions (MSCA) Individual Fellowship (IF).

3 Outline What is tree size inequality? Tree size inequality as an important element of forest structure Potential applications How tree size inequality is measured and evaluated in the forest? Tree diameter distributions Indicators of tree size inequality How tree size inequality can be assessed using remote sensing? Inductive: statistical relationships for production of estimation maps Deductive: supporting theories in relation to tree size inequality

4 Outline What is tree size inequality? Tree size inequality as an important element of forest structure Potential applications How tree size inequality is measured and evaluated in the forest? Tree diameter distributions Indicators of tree size inequality How tree size inequality can be assessed using remote sensing? Inductive: statistical relationships for production of estimation maps Deductive: supporting theories in relation to tree size inequality

5 Forest Structure & Tree Size Inequality Elements of Forest Complexity (McElhinny et al. 2005): Structure Abundance (a.k.a. stand parameters: density, basal area, mean quadratic diameter, dominant height, above-ground biomass) Spatially explicit indicators (neighbourhood) horizontal structure Non-spatial indicators size differentiation Indicators of structural diversity / tree size inequality Composition (species richness and abundances) Function (nutrient cycling, species interactions; e.g. competition)

6 Forest Structural Diversity or Tree Size Inequality Structural Diversity? Tree size inequality

7 Applications of RS Indicators of Tree Size Inequality Monitoring forest conservation status Provision of ecosystem services Habitat suitability for fauna / flora Incorporation conservation objectives in forest management? Supporting increasingly complex management systems Fire spread 31/10/2016

8 Applications of RS Indicators of Tree Size Inequality Forest Structure Indicators from LIDAR The forest is surveyed with a device called LIDAR: a laser scanner mounted onboard a plane. Developing the use of Lorenz curve to describe tree dominance and diameter distributions. Indicators: The Gini coefficent of tree size inequality + asymmetry. Developing methods for assessing these indicators and classifying forest areas into structural types. 31/10/2016

9 Applications of RS Indicators of Tree Size Inequality Gini Coefficient: Conservation vs. Commercial Forests 31/10/2016 Valbuena R., Eerikäinen K., Packalen P. & Maltamo M. (2016) Gini Coefficient Predictions from Airborne Lidar Remote Sensing Display the Effect of Management Intensity on Forest Structure. Ecological Indicators 60:

10 Applications of RS Indicators of Tree Size Inequality Forest development Forest disturbance Even-sized Even-sized Even-sized Senescence of mature trees Seed regeneration Ingrowth Self-thinning Bimodal Reverse J Reverse J 31/10/ /10/2016 Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43:

11 Applications of RS Indicators of Tree Size Inequality From Indicators to Forest Structural Types 31/10/2016

12 Outline What is tree size inequality? Tree size inequality as an important element of forest structure Potential applications How tree size inequality is measured and evaluated in the forest? Tree diameter distributions Indicators of tree size inequality How tree size inequality can be assessed using remote sensing? Inductive: statistical relationships for production of estimation maps Deductive: supporting theories in relation to tree size inequality

13 Forest Indicators of Tree Size Inequality Forest simulation.

14 Forest Indicators of Tree Size Inequality Theoretical distribution functions. Weibul distribution

15 Forest Indicators of Tree Size Inequality Concise Indicators

16 Forest Structure & Tree Size Inequality Forest structural diversity / Tree size inequality Richness: number of different size classes Equitability: relative abundances (evenness) Diversity (entropy): Shannon, etc. Diameter class diversity / evenness Foliage height diversity (McArthur & McArthur, 1961) Homogeneity (size variation): Size class diversity Tree size inequality Dispersion (spread): Diameter standard deviation Concentration: Diameter coefficient of variation / Gini coefficient Dominance or rarity: Asymmetry / Skewness?

17 Forest Structural Diversity

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19 Intrinsic Diversity Ordering Some attention on the definition of Diversity. What means to be more/less diverse? An initial situation in the structure of a forest plot (F1) can develop into an intrinsically more diverse state (F2) by a finite sequence of either of these events (Patil & Taillie 1982): (a) introducing new size classes (b) transferring abundances between two classes to make them more identical (c) permuting the components of its abundance vector (should remain equal) Proof: Testing Intrinsic Diversity Ordering

20 Intrinsic Diversity Ordering Intrinsic Diversity Ordering Curve Ranked Abundance Vector: Arranging the components of p in descending order k is the rank of each size class (1 st most dominant size class, 2 nd, ) Curve of Cumulated Dominance Majorization method (Solomon 1979): Solomon (1979) A comparative approach to species diversity. In: Grassle, Patil, Smith, & Taillie (Eds.), Ecological Diversity in Theory and Practice. International Cooperative Publishing House, Fairland, Maryland, USA, pp

21 Intrinsic Equitability (Lorenz Ordering) Diversity = Richness + Equitability (relative abundance) Intrinsic Equitability Ordering Curve Ranked Abundance Vector: Curve of Cumulated Dominance Majorization method (Solomon 1979): Cumulative Richness Proportions

22 Evenness among Size Classes......or Inequality among Individual Tree Sizes? Valbuena R., Packalén P., Martín-Fernández S. & Maltamo M. (2012) Diversity and Equitability Ordering Profiles Applied to the Study of Forest Structure. Forest Ecology and Management 276:

23 Forest Structural Diversity or Tree Size Inequality Structural Diversity? Tree size inequality

24 The Lorenz curve of Tree Size Inequality

25 The Lorenz curve of Tree Size Inequality

26 The Lorenz curve of Tree Size Inequality

27 Applications of RS Indicators of Tree Size Inequality Forest development Forest disturbance Even-sized Even-sized Even-sized Senescence of mature trees Seed regeneration Ingrowth Self-thinning Bimodal Reverse J Reverse J 31/10/ /10/2016 Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43:

28 Applications of RS Indicators of Tree Size Inequality Forest development Forest disturbance Senescence of mature trees Even-sized Even-sized Seed regeneration Even-sized Ingrowth Self-thinning 31/10/ /10/2016 Bimodal Reverse J Reverse J Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43:

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30 Applications of RS Indicators of Tree Size Inequality Forest development Forest disturbance Senescence of mature trees Even-sized Even-sized Seed regeneration Even-sized Ingrowth Self-thinning 03/11/ /11/2016 Bimodal Reverse J Reverse J Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43:

31 Forest structure & Tree Size Inequality Tree Size Inequality (Gini Coefficient) + Tree Size Dominance (Lorenz Asymmetry, Basal Area larger than mean) 31/10/2016 Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43:

32 Outline What is tree size inequality? Tree size inequality as an important element of forest structure Potential applications How tree size inequality is measured and evaluated in the forest? Tree diameter distributions Indicators of tree size inequality How tree size inequality can be assessed using remote sensing? Inductive: statistical relationships for production of estimation maps Deductive: supporting theories in relation to tree size inequality

33 Remote Sensing Assessment of Tree Size Inequality

34 Remote Sensing Assessment of Tree Size Inequality

35 RS Assessment of Tree Size Inequality Individual Tree Detection Methods Semi ITD (Beidenbach et al. (2010) Remote Sensing of Environment 114: ) Valbuena R., Vauhkonen J., Packalen P., Pitkänen J. & Maltamo M. (2014) Comparison of Airborne Laser Scanning Methods for Estimating Forest Structure Indicators Based on Lorenz Curves. ISPRS Journal of Photogrammetry & Remote Sensing 95:

36 Remote Sensing Assessment of Tree Size Inequality Area-based approach X Predictors (ALS metrics)

37 Remote Sensing Assessment of Tree Size Inequality Area-based approach

38 Remote Sensing Assessment of Tree Size Inequality

39 Remote Sensing Assessment of Tree Size Inequality

40 Remote Sensing Assessment of Tree Size Inequality

41 Remote Sensing Assessment of Tree Size Inequality Regression Trees Random Forest GC < 0.28

42 Remote Sensing Assessment of Tree Size Inequality Nearest neighbour methods Many types of distance metrics (Hudak et al Remote Sensing of Environment 112: 2232): Euclidean (k-nn) Mahalanobis Canonical Correlation Projectors (Most Similar Neighbour) Gradient nearest neighbour Random Forest proximity matrix Can be used for multivariate responses too. Tree list estimation (Packalen & Maltamo 2008 Canadian Journal of Forest Research 38: 1750)

43 Remote Sensing Assessment of Tree Size Inequality

44 Remote Sensing Assessment of Tree Size Inequality Modelling Quantitative variables Classification of Qualitative variables

45 Remote Sensing Assessment of Tree Size Inequality Valbuena R., Packalen P., García-Abril A., Mehtätalo L. & Maltamo M. (2013) Characterizing Forest Structural Types and Shelterwood Dynamics from Lorenz-based Indicators Predicted by Airborne Laser Scanning. Canadian Journal of Forest Research 43: Valbuena R., Maltamo M. & Packalen P. (2016) Classification of multi-layered forest development stages from low-density national airborne datasets. Forestry 89:

46 Remote Sensing Assessment of Tree Size Inequality Valbuena R., Maltamo M. & Packalen P. (2016) Classification of multi-layered forest development stages from low-density national airborne datasets. Forestry 89: A comparison of machine learning methods. Revista de Teledetección 45:

47 Remote Sensing Assessment of Tree Size Inequality Deductive Approaches: Conceptual models Asner, G.P., & Mascaro J. (2014). Mapping tropical forest carbon: Calibrating plot estimates to a simple LiDAR metric. Remote Sensing of Environment 140, Bouvier, M., Durrieu, S., Fournier, R.A., & Renaud, J.P. (2015). Generalizing predictive models of forest inventory attributes using an area-based approach with airborne LiDAR data. Remote Sensing of Environment, 156,

48 Remote Sensing Assessment of Tree Size Inequality Deductive Approaches: Conceptual models Asner, G.P., & Mascaro J. (2014). Bouvier, et al. (2015).

49 Remote Sensing Assessment of Tree Size Inequality Valbuena R., Maltamo M. Mehtätalo L., & Packalen P. (2016) Key Structural Features of Boreal Forests may be Detected Directly using L-moments from Airborne Lidar Data. Remote Sensing of Environment (in press)

50 Remote Sensing Assessment of Tree Size Inequality Valbuena R., Maltamo M. Mehtätalo L., & Packalen P. (2016) Key Structural Features of Boreal Forests may be Detected Directly using L-moments from Airborne Lidar Data. Remote Sensing of Environment (in press)

51 Remote Sensing Assessment of Tree Size Inequality Forest Indicators Using ALS predictors only Valbuena R., Maltamo M. Mehtätalo L., & Packalen P. (2016) Key Structural Features of Boreal Forests may be Detected Directly using L-moments from Airborne Lidar Data. Remote Sensing of Environment (in press)

52 Applications of RS Indicators of Tree Size Inequality The Opportunity: National Laser Survey Programmes Lidar datasets from National Land Survey Agencies are being surveyed and made largely available (under INSPIRE directive): Finland (NLS) Netherlands (AHN2) United Kingdom (ARSF) Poland (ISOK) Spain (PNOA) Switzerland (DOM) Denmark (Kortforsyningen) Sweden (Lantmateriet) and also others like Germany, France, Italy, Norway, Austria, etc. Challenges to obtaining a trans-national monitoring tool: Research on the relevance of technical and survey configurations of Lidar systems, and how changes affect the indicators. Differences between surveys: point density, season of acquisition, and instruments used. Effects of site characteristics. Water / light limitations to growth. 31/10/2016

53 Thank you Rubén Valbuena Marie S. Curie Research Fellow Department of Plant Sciences. Forest Ecology and Conservation