Comparison and Analysis of Small Area Estimation Methods for Improving Estimates of Selected Forest Attributes

Comparison and Analysis of Small Area Estimation Methods for Improving Estimates of Selected Forest Attributes
Author: Michael E. Goerndt
Publisher:
Total Pages: 274
Release: 2010
Genre: Estimation theory
ISBN:

One of the most common practices regarding estimation of forest attributes is the partitioning of large forested subpopulations into smaller areas of interest to coincide with specific objectives of present and future forest management. New estimators are needed to improve estimation of selected forest attributes in small areas where the existing sample is insufficient to obtain precise estimates. This dissertation assessed the strength of light detection and ranging (LiDAR) as auxiliary information for estimating plot-level forest attributes (trees/ha, basal area/ha, volume/ha, quadratic mean diameter, Lorey's height) using intensity and nonintensity area-level LiDAR metrics and single tree remote sensing (STRS). LiDAR intensity metrics were useful for increasing precision for trees/ha. With the exception of Lorey's height, STRS did not significantly improve precision for most of the attributes. Small area estimation (SAE) techniques were assessed for precision and bias in estimating stand-level forest attributes (trees/ha, basal area/ha, volume/ha, quadratic mean diameter, mean height of 100 largest trees/ha) assuming a localized subpopulation using LiDAR auxiliary information. Selected estimation methods included area-level regression-based composite estimators and indirect estimators based on synthetic prediction and nearest neighbor imputation. The composite estimators produced lower bias and higher precision than synthetic prediction and imputation. The traditional composite estimator outperformed empirical best linear unbiased prediction for bias but not for precision. SAE methods were compared for precision and bias in estimating county-level forest attributes (trees/ha, basal area/ha, volume/ha, quadratic mean diameter, mean height of 100 largest trees/ha) assuming a regional subpopulation using Landsat auxiliary information. Selected estimation methods included unit-level mixed regression-based indirect and composite estimators, and imputation-based indirect and composite estimators. The indirect and composite estimators based on linear mixed effects models generally outperformed those based on imputation. The composite estimators performed the best in terms of bias for all attributes.

Small Area Estimation of County-level Forest Attributes Using Forest Inventory Data and Remotely Sensed Auxiliary Information

Small Area Estimation of County-level Forest Attributes Using Forest Inventory Data and Remotely Sensed Auxiliary Information
Author: Okikiola Michael Alegbeleye
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:

The Forest Inventory and Analysis (FIA) program of the United States Department of Agriculture Forest Service collects forest inventory data that provide estimates with reasonable accuracy at the national scale. However, for smaller domains, these estimates are often not as accurate due to the small sample size. Small area estimation improves the accuracy of the estimates at smaller domains by relying on auxiliary information. This study compared direct (FIA estimates), indirect (multiple linear regression), and composite estimators (Fay-Herriot) using auxiliary information derived from Landsat and Global Ecosystem Dynamics Investigation (GEDI) to obtain county-level estimates of forest attributes namely total and merchantable volume (m3 ha-1), aboveground biomass (Mg ha-1), basal area (m2 ha-1), and Lorey's mean height (m). Compared with FIA estimates, the composite estimator reduced error by 75-78% for all the variables of interest. This shows that a reasonable amount of precision can be achieved with auxiliary information from Landsat and GEDI, improving FIA estimates at the county level.

Introduction to Small Area Estimation Techniques

Introduction to Small Area Estimation Techniques
Author: Asian Development Bank
Publisher: Asian Development Bank
Total Pages: 152
Release: 2020-05-01
Genre: Business & Economics
ISBN: 9292622234

This guide to small area estimation aims to help users compile more reliable granular or disaggregated data in cost-effective ways. It explains small area estimation techniques with examples of how the easily accessible R analytical platform can be used to implement them, particularly to estimate indicators on poverty, employment, and health outcomes. The guide is intended for staff of national statistics offices and for other development practitioners. It aims to help them to develop and implement targeted socioeconomic policies to ensure that the vulnerable segments of societies are not left behind, and to monitor progress toward the Sustainable Development Goals.

Examination of Imputation Methods to Estimate Status and Change of Forest Attributes from Paneled Inventory Data

Examination of Imputation Methods to Estimate Status and Change of Forest Attributes from Paneled Inventory Data
Author: Bianca N. I. Eskelson
Publisher:
Total Pages: 280
Release: 2009
Genre: Forest monitoring
ISBN:

The Forest Inventory and Analysis (FIA) program conducts an annual inventory throughout the United States. In the western United States, 10% of all plots (one panel) are measured annually, and a moving average is used for estimating current condition and change of forest attributes while alternative methods are sought in all regions of the United States. This dissertation explored alternatives to the moving average in the Pacific Northwest using Current Vegetation Survey data collected in Oregon and Washington. Several nearest neighbor imputation methods were examined for their suitability to update plot-level forest attributes (basal area/ha, stems/ha, volume/ha, biomass/ha) to the current point in time. The results were compared to estimates obtained using a moving average and a weighted moving average. In terms of bias and accuracy, the weighted moving average performed better than the moving average. When the most recent measurements of the variables of interest were used as ancillary data, randomForest imputation outperformed both the moving average and the weighted moving average. For estimating current basal area/ha, stems/ha, volume/ha, and biomass/ha, tree-level imputation outperformed plot-level imputation. The difference in bias and accuracy between tree- and plot-level imputation was more pronounced when the variables of interest were summarized by species groups. Nearest neighbor imputation methods were also investigated for estimating mean annual change in selected forest attributes. The imputed mean annual change was used to update unmeasured panels to the current point in time. In terms of bias and accuracy, the resulting estimates of current basal area/ha, stems/ha, volume/ha, and biomass/ha outperformed the results obtained using plot-level imputation. Information on hard to estimate forest attributes such as cavity tree and snag abundance are important for wildlife management plans. Using FIA data collected in Washington, Oregon, and California, nearest neighbor imputation approaches and negative binomial regression models were examined for their suitability in estimating cavity tree and snag abundance. The negative binomial models were preferred to the nearest neighbor imputation approaches.

Spatial Microsimulation: A Reference Guide for Users

Spatial Microsimulation: A Reference Guide for Users
Author: Robert Tanton
Publisher: Springer Science & Business Media
Total Pages: 272
Release: 2012-11-13
Genre: Social Science
ISBN: 9400746237

This book is a practical guide on how to design, create and validate a spatial microsimulation model. These models are becoming more popular as academics and policy makers recognise the value of place in research and policy making. Recent spatial microsimulation models have been used to analyse health and social disadvantage for small areas; and to look at the effect of policy change for small areas. This provides a powerful analysis tool for researchers and policy makers. This book covers preparing the data for spatial microsimulation; a number of methods for both static and dynamic spatial microsimulation models; validation of the models to ensure the outputs are reasonable; and the future of spatial microsimulation. The book will be an essential handbook for any researcher or policy maker looking to design and create a spatial microsimulation model. This book will also be useful to those policy makers who are commissioning a spatial microsimulation model, or looking to commission work using a spatial microsimulation model, as it provides information on the different methods in a non-technical way.

Forest Measurements

Forest Measurements
Author: Thomas Eugene Avery
Publisher:
Total Pages: 0
Release: 2015
Genre: Forests and forestry
ISBN: 9781478629085

Timber measurement techniques applicable to any tree inventory project regardless of management objectives are covered by this text. Thorough coverage of sampling designs, land measurements, tree measurements, forest inventory field methods, and growth projections ensures utility for all foresters. Included are chapters on aerial photographs, GIS, and using similar techniques to measure other natural resources such as rangelands, wildlife, and water.

Statistical Methods and Applications in Forestry and Environmental Sciences

Statistical Methods and Applications in Forestry and Environmental Sciences
Author: Girish Chandra
Publisher: Springer Nature
Total Pages: 290
Release: 2020-01-04
Genre: Medical
ISBN: 9811514763

This book presents recent developments in statistical methodologies with particular relevance to applications in forestry and environmental sciences. It discusses important methodologies like ranked set sampling, adaptive cluster sampling, small area estimation, calibration approach-based estimators, design of experiments, multivariate techniques, Internet of Things, and ridge regression methods. It also covers the history of the implementation of statistical techniques in Indian forestry and the National Forest Inventory of India. The book is a valuable resource for applied statisticians, students, researchers, and practitioners in the forestry and environment sector. It includes real-world examples and case studies to help readers apply the techniques discussed. It also motivates academicians and researchers to use new technologies in the areas of forestry and environmental sciences with the help of software like R, MATLAB, Statistica, and Mathematica.

Estimation and Modeling of Selected Forest Metrics with Lidar and Landsat

Estimation and Modeling of Selected Forest Metrics with Lidar and Landsat
Author: Jacob L. Strunk
Publisher:
Total Pages: 145
Release: 2012
Genre: Artificial satellites in forestry
ISBN:

Lidar is able to provide height and cover information which can be used to estimate selected forest attributes precisely. However, for users to evaluate whether the additional cost and complication associated with using Lidar merits adoption requires that the protocol to use lidar be thoroughly described and that a basis for selection of design parameters such as number of field plots and lidar pulse density be described. In our first analysis, we examine these issues by looking at the effects of pulse density and sample size on estimation when wall-to-wall lidar is used with a regression estimator. The effects were explored using resampling simulations. We examine both the effects on precision, and on the validity of inference. Pulse density had almost no effect on precision for the range examined, from 3 to .0625 pulses / m2. The effect of sample size on estimator precision was roughly in accordance with the behavior indicated by the variance estimator, except that for small samples the variance estimator had positive bias (the variance estimates were too small), compromising the validity of inference. In future analyses we plan to provide further context for wall-to-wall lidar-assisted estimation. While there is a lot of literature on modeling, there is limited information on how lidar-assisted approaches compare to existing methods, and what variables can or cannot be acquired, or may be acquired with reduced confidence. We expand our investigation of estimation in our second analysis by examining lidar obtained in a sampling mode in combination with Landsat. In this case we make inference about the feasibility of a lidar-assisted estimation strategy by contrasting its variance estimate with variance estimates from a variety of other sampling designs and estimators. Of key interest was how the precision of a two-stage estimator with lidar strips compared with a plot-only estimator from a simple random sampling design. We found that because the long and narrow lidar strips incorporate much of the landscape variability, if the number of lidar strips was increased from 7 to 15 strips, the precision of estimators with lidar can exceed that of estimators applied to plot-only SRS data for a much larger number of plots. Increasing the number of lidar strips is considered to be highly viable since the costs of field plots can be quite expensive in Alaska, often exceeding the cost of a lidar strip. A Landsat-assisted approach used for either an SRS or a two-stage sample was also found to perform well relative to estimators for plot-only SRS data. This proved beneficial when we combined lidar and Landsat-assisted regression estimators for two-stage designs using a composite estimator. The composite estimator yielded much better results than either estimator used alone. We did not assess the effects of changing the number of lidar strips in combination with using a composite estimator, but this is an important analysis we plan to perform in a future study. In our final analysis we leverage the synergy between lidar and Landsat to improve the explanatory power of auxiliary Landsat using a multilevel modeling strategy. We also incorporate a more sophisticated approach to processing Landsat which reflects temporal trends in individual pixels values. Our approach used lidar as an intermediary step to better match the spatial resolution of Landsat and increase the proportion of area overlapped between measurement units for the different sources of data. We developed two separate approaches for two different resolutions of data (30 m and 90 m) using multiple modeling alternatives including OLS and k nearest neighbors (KNN), and found that both resolution and the modeling approach affected estimates of residual variability, although there was no combination of model types which was a clear winner for all responses. The modeling strategies generally fared better for the 90 m approaches, and future analyses will examine a broader range of resolutions. Fortunately the approaches used are fairly flexible and there is nothing prohibiting a 1000 m implementation. In the future we also plan to look at using a more sophisticated Landsat time-series approach. The current approach essentially dampened the noise in the temporal trend for a pixel, but did not make use of information in the trend such as slope or indications of disturbance - which may provide additional explanatory power. In a future study we will also incorporate a multilevel modeling into estimation or mapping strategies and evaluate the contribution of the multilevel modeling strategy relative to alternate approaches.