Relative Efficiency of ALS and InSAR for Biomass Estimation in a Tanzanian Rainforest

Hansen, Endre Hofstad; Gobakken, Terje; Solberg, Svein; Kangas, Annika; Ene, Liviu Theodor; Mauya, Ernest William; Næsset, Erik

doi:10.3390/rs70809865

Cited by 23 publications

(13 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is well known that maximum annual biomass growth (ABG) is reached earlier in dense plantings because the trees occupy the site more quickly than in less dense plantings. However, less dense plantings quickly catch up and maintain high ABG longer than their dense counterparts because inter-tree competition is less severe [57,58].…”

Section: Planting Density Responsementioning

confidence: 99%

Willow Short Rotation Coppice Trial in a Former Mining Area in Northern Spain: Effects of Clone, Fertilization and Planting Density on Yield after Five Years

Castaño-Díaz

Barrio-Anta

Afif-Khouri

et al. 2018

Forests

View full text Add to dashboard Cite

Abstract:A willow short rotation coppice (SRC) trial was conducted on former mining land in northern Spain over a period of five years, with the purpose of evaluating the effects on yield of two planting densities (9876 and 14,815 cuttings ha −1 ), three treatments (control, two levels of nitrogen, phosphorus and potassium compound fertilizer (NPK) plus weed control) and three willow clones (Björn, Inger, Olof). The area was subsoiled, ploughed, harrowed and fertilized with NPK before trial establishment. A randomized block design was applied, with three replications of each treatment in a total of 54 plots, each of an area of 400 m 2 . The effects of the interactions between the various factors on yield and other growth parameters were also studied. The clone factor significantly affected the number of shoots per stool (greatest for the Inger clone) and the Olof clone, which showed the lowest mortality rate and produced the largest trees and largest quantity of biomass. The combined application of fertilizer and herbicide also significantly increased the values of all response variables considered, except the mortality rate. The planting density did not significantly affect the response variables. Clone × treatment interactions were significant for the shoots per stool, height, diameter and biomass variables, and the Olof clone displayed the highest height and diameter growth and yield. The results obtained in the first rotation indicate that the Olof clone adapted well to the trial conditions and therefore would be appropriate for producing biomass in abandoned mine land in Asturias. These findings will help in the development of strategies for the establishment and management of SRC on marginal land.

show abstract

Section: Planting Density Responsementioning

confidence: 99%

Willow Short Rotation Coppice Trial in a Former Mining Area in Northern Spain: Effects of Clone, Fertilization and Planting Density on Yield after Five Years

Castaño-Díaz

Barrio-Anta

Afif-Khouri

et al. 2018

Forests

View full text Add to dashboard Cite

show abstract

“…Larger plots will also tend to reduce the plot boundary effects [39]. Several authors have studied the effects of sample plot sizes on biomass estimates and other forest attributes in inventories assisted by remotely sensed data in tropical wet forests [15,[40][41][42][43][44], temperate forests [38,45] and a boreal forest [46,47], among others. To the best of our knowledge, no studies on the influence of sample plot sizes on efficiency of biomass estimates have been conducted in UAS-assisted sample inventories, i.e., using design-based and model assisted inferential framework, in miombo woodlands.…”

Section: Study Areamentioning

confidence: 99%

Influence of Plot Size on Efficiency of Biomass Estimates in Inventories of Dry Tropical Forests Assisted by Photogrammetric Data from an Unmanned Aircraft System

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract:Applications of unmanned aircraft systems (UASs) to assist in forest inventories have provided promising results in biomass estimation for different forest types. Recent studies demonstrating use of different types of remotely sensed data to assist in biomass estimation have shown that accuracy and precision of estimates are influenced by the size of field sample plots used to obtain reference values for biomass. The objective of this case study was to assess the influence of sample plot size on efficiency of UAS-assisted biomass estimates in the dry tropical miombo woodlands of Malawi. The results of a design-based field sample inventory assisted by three-dimensional point clouds obtained from aerial imagery acquired with a UAS showed that the root mean square errors as well as the standard error estimates of mean biomass decreased as sample plot sizes increased. Furthermore, relative efficiency values over different sample plot sizes were above 1.0 in a design-based and model-assisted inferential framework, indicating that UAS-assisted inventories were more efficient than purely field-based inventories. The results on relative costs for UAS-assisted and pure field-based sample plot inventories revealed that there is a trade-off between inventory costs and required precision. For example, in our study if a standard error of less than approximately 3 Mg ha −1 was targeted, then a UAS-assisted forest inventory should be applied to ensure more cost effective and precise estimates. Future studies should therefore focus on finding optimum plot sizes for particular applications, like for example in projects under the Reducing Emissions from Deforestation and Forest Degradation, plus forest conservation, sustainable management of forest and enhancement of carbon stocks (REDD+) mechanism with different geographical scales.

show abstract

“…While plot data are often regarded as 'ground truth', they also have many uncertainties-location, measurements [8,9] size of plots [10], and extrapolation models (i.e., allometric equations) [11][12][13][14].…”

Section: Background To the Study-the Redd+ Initiativementioning

confidence: 99%

“…This would allow more countries to rapidly provide data on AGB for REDD+ reporting [51]. The measure of the improvement of the combined approach compared to the field plots alone is provided by the relative efficiency [10,52], which gives the improvement in precision (i.e., reduction in variance). A relative efficiency of two would mean that a ground survey of X plots with remote sensing correction would give the same precision as a ground survey of 2X plots without remote sensing data.…”

Section: The Current Studymentioning

confidence: 99%

The Potential of High Resolution (5 m) RapidEye Optical Data to Estimate Above Ground Biomass at the National Level over Tanzania

Gascon

Ceccherini

Garcı́a-Haro

et al. 2019

Forests

View full text Add to dashboard Cite

In this paper, we review the potential of high resolution optical satellite data to reduce the significant investment in resources required for a national field survey for producing estimates of above ground biomass (AGB). We use 5 m resolution RapidEye optical data to support a country wide biomass inventory with the objective of bringing to the attention of the traditional forestry sector the advantages of integrating remote sensing data in the planning and execution of field data acquisition. We analysed the relationship between AGB estimates from a subset of the national survey field plot data collected by the Tanzania Forest Service, with a set of remote sensing biophysical parameters extracted from a sample of fine spatial (5 m) resolution RapidEye images using a regression estimator. We processed RapidEye data using image segmentation for 76 sample sites each of 20 km by 20 km (covering 2.3% of the land area of the country) to image objects of 1 ha. We extracted reflectance and texture information from those objects which overlapped with the field plot data and tested correlations between the two using four different models: Two models from inferential statistics and two models from machine learning. The best results were found using the random forests algorithm (R2 = 0.69). The most important explicative factor extracted from the remote sensing data was the shadow index, measuring the absorption of light in the visible bands. The model was then applied to all image objects on the RapidEye images to obtain AGB for each of the 76 sample sites, which were then interpolated to estimate the AGB stock at the national scale. Using the relative efficiency measure, we assessed the improvement that the introduction of remote sensing data brings to obtain an AGB estimate at the national level, with the same precision as the full survey. The improvement in the precision of the estimate (by reducing its variance) resulted in a relative efficiency of 3.2. This demonstrates that the introduction of remote sensing data at this fine resolution can substantially reduce the number of field plots required, in this case threefold.

show abstract

Relative Efficiency of ALS and InSAR for Biomass Estimation in a Tanzanian Rainforest

Cited by 23 publications

References 45 publications

Willow Short Rotation Coppice Trial in a Former Mining Area in Northern Spain: Effects of Clone, Fertilization and Planting Density on Yield after Five Years

Willow Short Rotation Coppice Trial in a Former Mining Area in Northern Spain: Effects of Clone, Fertilization and Planting Density on Yield after Five Years

Influence of Plot Size on Efficiency of Biomass Estimates in Inventories of Dry Tropical Forests Assisted by Photogrammetric Data from an Unmanned Aircraft System

The Potential of High Resolution (5 m) RapidEye Optical Data to Estimate Above Ground Biomass at the National Level over Tanzania

Contact Info

Product

Resources

About