scholarly journals Retrieving Secondary Forest Aboveground Biomass from Polarimetric ALOS-2 PALSAR-2 Data in the Brazilian Amazon

2018 ◽  
Vol 11 (1) ◽  
pp. 59 ◽  
Author(s):  
Henrique Luis Godinho Cassol ◽  
João Manuel de Brito Carreiras ◽  
Elisabete Caria Moraes ◽  
Luiz Eduardo Oliveira e Cruz de Aragão ◽  
Camila Valéria de Jesus Silva ◽  
...  
Keyword(s):  
Land Use ◽  
Forest Structure ◽  
Secondary Forest ◽  
Structural Parameters ◽  
Basal Area ◽  
Tree Height ◽  
P Value ◽  
The Past ◽  
The Mean ◽  
Past Land Use

Secondary forests (SF) are important carbon sinks, removing CO2 from the atmosphere through the photosynthesis process and storing photosynthates in their aboveground live biomass (AGB). This process occurring at large-scales partially counteracts C emissions from land-use change, playing, hence, an important role in the global carbon cycle. The absorption rates of carbon in these forests depend on forest physiology, controlled by environmental and climatic conditions, as well as on the past land use, which is rarely considered for retrieving AGB from remotely sensed data. In this context, the main goal of this study is to evaluate the potential of polarimetric (quad-pol) ALOS-2 PALSAR-2 data for estimating AGB in a SF area. Land-use was assessed through Landsat time-series to extract the SF age, period of active land-use (PALU), and frequency of clear cuts (FC) to randomly select the SF plots. A chronosequence of 42 SF plots ranging 3–28 years (20 ha) near the Tapajós National Forest in Pará state was surveyed to quantifying AGB growth. The quad-pol data was explored by testing two regression methods, including non-linear (NL) and multiple linear regression models (MLR). We also evaluated the influence of the past land-use in the retrieving AGB through correlation analysis. The results showed that the biophysical variables were positively correlated with the volumetric scattering, meaning that SF areas presented greater volumetric scattering contribution with increasing forest age. Mean diameter, mean tree height, basal area, species density, and AGB were significant and had the highest Pearson coefficients with the Cloude decomposition (λ3), which in turn, refers to the volumetric contribution backscattering from cross-polarization (HV) (ρ = 0.57–0.66, p-value < 0.001). On the other hand, the historical use (PALU and FC) showed the highest correlation with angular decompositions, being the Touzi target phase angle the highest correlation (Φs) (ρ = 0.37 and ρ = 0.38, respectively). The combination of multiple prediction variables with MLR improved the AGB estimation by 70% comparing to the NL model (R2 adj. = 0.51; RMSE = 38.7 Mg ha−1) bias = 2.1 ± 37.9 Mg ha−1 by incorporate the angular decompositions, related to historical use, and the contribution volumetric scattering, related to forest structure, in the model. The MLR uses six variables, whose selected polarimetric attributes were strongly related with different structural parameters such as the mean forest diameter, basal area, and the mean forest tree height, and not with the AGB as was expected. The uncertainty was estimated to be 18.6% considered all methodological steps of the MLR model. This approach helped us to better understand the relationship between parameters derived from SAR data and the forest structure and its relation to the growth of the secondary forest after deforestation events.

scholarly journals Retrieving Secondary Forest Aboveground Biomass from Polarimetric ALOS-2 PALSAR-2 Data in the Brazilian Amazon

2018 ◽  
Author(s):  
Henrique Luis Godinho Cassol ◽  
Yosio Edemir Shimabukuro ◽  
Elisabete Caria Moraes ◽  
João Manuel de Brito Carreiras ◽  
Luiz Eduardo de Oliveira Cruz e Aragão ◽  
...  
Keyword(s):  
Land Use ◽  
Secondary Forest ◽  
Cloud Model ◽  
Brazilian Amazon ◽  
Climatic Conditions ◽  
Secondary Forests ◽  
Remotely Sensed Data ◽  
The Past ◽  
Multiple Prediction ◽  
Past Land Use

Secondary forests (SF) are important carbon sinks, removing CO2 from the atmosphere through the photosynthesis process and storing photosynthates in their aboveground live biomass (AGB). This process occurring at large-scales partially counteracts C emissions from land-use change, playing, hence, an important role in the global carbon cycle. The absorption rates of carbon in these forests depend on forest physiology, controlled by environmental and climatic conditions as well as on the past land use, which is rarely considered for retrieving AGB from remotely sensed data. In this context, the main goal of this study is to evaluate the potential of full polarimetric ALOS-2 PALSAR-2 data for estimating AGB by taking into account the past-land use of SF areas in the Brazilian Amazon. We surveyed a chronosequence of 42 SF plots (20 ha) near the Tapaj&oacute;s National Forest in Par&aacute; state to quantifying AGB growth rates. We explored the full polarimetric data testing three regression models including non-linear (NL), multiple linear regressions models (MLR), and the semi-empirical extended water cloud model (EWCM). The results showed that the intensity of previous use has affected the structure of SF by reducing the AGB accumulation and being noticeable by several polarimetric attributes. The combination of multiple prediction variables with MLR improved the AGB estimation by 70% comparing amongst other models (R&sup2; adj. = 0.51; RMSE = 13.2 Mg ha-1) bias = 2.1 &plusmn; 37.9 Mg ha-1. The error propagation of the MLR model was estimated to be 15%.

scholarly journals Estimating historical land use patterns in Amazonia for hydrological studies

2017 ◽  
Vol 8 (4) ◽  
pp. 189-197
Author(s):  
Christiane Cavalcante Leite ◽  
Marcos Heil Costa ◽  
Ranieri Carlos Ferreira de Amorim
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Land Use Change ◽  
Census Data ◽  
Land Use Patterns ◽  
Use Patterns ◽  
The Past ◽  
The World ◽  
Historical Land Use ◽  
Past Land Use

The evaluation of the impacts of land-use change on the water resources has been, many times, limited by the knowledge of past land use conditions. Most publications on this field present only a vague description of the past land use, which is usually insufficient for more comprehensive studies. This study presents the first reconstruction of the historical land use patterns in Amazonia, that includes both croplands and pasturelands, for the period 1940-1995. During this period, Amazonia experienced the fastest rates of land use change in the world, growing 4-fold from 193,269 km2 in 1940 to 724,899 km2 in 1995. This reconstruction is based on a merging of satellite imagery and census data, and provides a 5'x5' yearly dataset of land use in three different categories (cropland, natural pastureland and planted pastureland) for Amazonia. This dataset will be an important step towards understanding the impacts of changes in land use on the water resources in Amazonia.

scholarly journals Predicting Growing Stock Volume of Eucalyptus Plantations Using 3-D Point Clouds Derived from UAV Imagery and ALS Data

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 905 ◽  
Author(s):  
Guerra-Hernández ◽  
Cosenza ◽  
Cardil ◽  
Silva ◽  
Botequim ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Basal Area ◽  
Remote Sensing Data ◽  
Tree Height ◽  
Point Clouds ◽  
Volume Estimation ◽  
P Value ◽  
Test Statistic ◽  
Individual Tree ◽  
Significant Difference

Estimating forest inventory variables is important in monitoring forest resources and mitigating climate change. In this respect, forest managers require flexible, non-destructive methods for estimating volume and biomass. High-resolution and low-cost remote sensing data are increasingly available to measure three-dimensional (3D) canopy structure and to model forest structural attributes. The main objective of this study was to evaluate and compare the individual tree volume estimates derived from high-density point clouds obtained from airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) in Eucalyptus spp. plantations. Object-based image analysis (OBIA) techniques were applied for individual tree crown (ITC) delineation. The ITC algorithm applied correctly detected and delineated 199 trees from ALS-derived data, while 192 trees were correctly identified using DAP-based point clouds acquired from Unmanned Aerial Vehicles (UAV), representing accuracy levels of respectively 62% and 60%. Addressing volume modelling, non-linear regression fit based on individual tree height and individual crown area derived from the ITC provided the following results: Model Efficiency (Mef) = 0.43 and 0.46, Root Mean Square Error (RMSE) = 0.030 m3 and 0.026 m3, rRMSE = 20.31% and 19.97%, and an approximately unbiased results (0.025 m3 and 0.0004 m3) using DAP and ALS-based estimations, respectively. No significant difference was found between the observed value (field data) and volume estimation from ALS and DAP (p-value from t-test statistic = 0.99 and 0.98, respectively). The proposed approaches could also be used to estimate basal area or biomass stocks in Eucalyptus spp. plantations.

scholarly journals Comparing precipitation and temperature trends between inland and coastal locations

2019 ◽  
Vol 60 ◽  
pp. C109-C126 ◽  
Author(s):  
Joshua Hartigan ◽  
Shev MacNamara ◽  
Lance M Leslie
Keyword(s):  
Climate Change ◽  
Minimum Temperature ◽  
Southern Oscillation ◽  
Power Spectra ◽  
Maximum Temperature ◽  
P Value ◽  
Wet Season ◽  
Intergovernmental Panel ◽  
The Past ◽  
The Mean

Motivated by the Millennium Drought and the current drought over much of southern and eastern Australia, this detailed statistical study compares trends in annual wet season precipitation and temperature between a coastal site (Newcastle) and an inland site (Scone). Bootstrap permutation tests reveal Scone precipitation has decreased significantly over the past 40 years (p-value=0.070) whereas Newcastle has recorded little to no change (p-value=0.800). Mean maximum and minimum temperatures for Newcastle have increased over the past 40 years (p-values of 0.002 and 0.015, respectively) while the mean maximum temperature for Scone has increased (p-value = 0.058) and the mean minimum temperature has remained stable. This suggests mean temperatures during the wet season for both locations are increasing. Considering these trends along with those for precipitation, water resources in the Hunter region will be increasingly strained as a result of increased evaporation with either similar or less precipitation falling in the region. Wavelet analysis reveals that both sites have similar power spectra for precipitation and mean maximum temperature with a statistically significant signal in the two to seven year period, typically indicative of the El-Nino Southern Oscillation climate driver. The El-Nino Southern Oscillation also drives the Newcastle mean minimum temperature, whereas the Scone power spectra has no indication of a definitive driver for mean minimum temperature. References R. A., R. L. Kitching, F. Chiew, L. Hughes, P. C. D. Newton, S. S. Schuster, A. Tait, and P. Whetton. Climate change 2014: Impacts, adaptation, and vulnerability. Part B: Regional aspects. Contribution of Working Group II to the Fifth Assessment of the Intergovernmental Panel on Climate Change. Technical report, Intergovernmental Panel on Climate Change, 2014. URL https://www.ipcc.ch/report/ar5/wg2/. Bureau of Meteorology. Climate Glossary-Drought. URL http://www.bom.gov.au/climate/glossary/drought.shtml. K. M. Lau and H. Weng. Climate signal detection using wavelet transform: How to make a time series sing. B. Am. Meteorol. Soc., 76:23912402, 1995. doi:10.1175/1520-0477(1995)0762391:CSDUWT>2.0.CO;2. M. B. Richman and L. M. Leslie. Uniqueness and causes of the California drought. Procedia Comput. Sci., 61:428435, 2015. doi:10.1016/j.procs.2015.09.181. M. B. Richman and L. M. Leslie. The 20152017 Cape Town drought: Attribution and prediction using machine learning. Procedia Comput. Sci., 140:248257, 2018. doi:10.1016/j.procs.2018.10.323.

Goal and products of PAGES LandCover6k 2018-2020: Past Global Land Cover and Land Use for Climate Modelling

2020 ◽  
Author(s):  
Marie-Jose Gaillard ◽  
Andria Dawson ◽  
Ralph Fyfe ◽  
Esther Githumbi ◽  
Emily Hammer ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Carbon Cycle ◽  
Climate Model ◽  
Climate Modelling ◽  
Model Simulations ◽  
Lulc Changes ◽  
The Past ◽  
Per Capita ◽  
Past Land Use

&lt;p&gt;The question of whether prehistoric human impacts on land cover (i.e. anthropogenic land cover change due to land use, LULC) were sufficiently large to have a major impact on regional cli-mates is still a matter of debate. Climate model simulations have shown that LULC datasets can have large regional impacts on climate in recent and prehistoric time&lt;sup&gt; (1)&lt;/sup&gt;. But there are major differences between the available LULC scenarios/datasets such as HYDE (History Database of the Global En-vironment) and Kaplan&amp;#8217;s KK10 &lt;sup&gt;(2)&lt;/sup&gt;, and diagnoses of inferred carbon-cycle impacts show that none of the scenarios are realistic &lt;sup&gt;(3)&lt;/sup&gt;. The only way to provide a useful assessment of the potential for LULC changes to affect climate in the past, is to provide more realistic LULC data based on palaeovegetation and archaeological evidence to improve the LULC datasets used in climate modelling&lt;sup&gt;(4)&lt;/sup&gt;. We use the REVEALS model to reconstruct LC from pollen data at a regional scale, and archaeological data to map LU types and distribution, and estimate per capita LU. The archaeology-based LU maps and per-capita LU estimates are used to improve LULC datasets. Pollen-based REVEALS LC estimates are then used to evaluate/validate the new, improved LULC datasets. These new datasets will be used to implement past land use in palaeoclimate and carbon cycle model simulations. Such simulations are necessary to assess the impact of LULC changes in the past and understand the effect of ecosys-tem management on future climate. We present results from five years of PAGES LandCover6k activities.&amp;#160;&lt;/p&gt;&lt;p&gt;(1) Strandberg G, Kjellstr&amp;#246;m E, Poska A, Wagner S, Gaillard M-J et al. (2014) Regional climate model sim-ulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation. Clim. Past 10, 661&amp;#8211;680.&lt;br&gt;(2) Gaillard M-J, Sugita S, Mazier F et al (2010) Holocene land-cover reconstructions for studies on land cover-climate feedbacks. Clim. Past 6, 483-499.&lt;br&gt;(3) Stocker B, Yud Z, Massae C, Joos F (2017) Holocene peatland and ice-core data constraints on the tim-ing and magnitude of CO2 emissions from past land use. www.pnas.org/cgi/doi/10.1073/ pnas.1613889114.&lt;br&gt;(4) Harrison S P, Gaillard M-J, Stocker B D, Vander Linden M, Klein Goldewijk K, Boles O, Braconnot P, Dawson A, Fluet-Chouinard E, Kaplan J O, Kastner T, Pausata F S R, Robinson E, Whitehouse N J, Madella M, and Morrison K D (2019) Development and testing of scenarios for implementing Holocene LULC in Earth Sys-tem Model Experiments, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2019-125, in review, 2019.&lt;/p&gt;&lt;p&gt;&lt;sup&gt;&amp;#160;&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals The importance of forest structure to biodiversity–productivity relationships

2017 ◽  
Vol 4 (1) ◽  
pp. 160521 ◽  
Author(s):  
Friedrich J. Bohn ◽  
Andreas Huth
Keyword(s):  
Species Distribution ◽  
Forest Structure ◽  
Basal Area ◽  
Tree Height ◽  
National Forest Inventory ◽  
National Forest ◽  
Forest Stands ◽  
Annual Productivity ◽  
Structure Indices ◽  
Modelling Approach

While various relationships between productivity and biodiversity are found in forests, the processes underlying these relationships remain unclear and theory struggles to coherently explain them. In this work, we analyse diversity–productivity relationships through an examination of forest structure (described by basal area and tree height heterogeneity). We use a new modelling approach, called ‘forest factory’, which generates various forest stands and calculates their annual productivity (above-ground wood increment). Analysing approximately 300 000 forest stands, we find that mean forest productivity does not increase with species diversity. Instead forest structure emerges as the key variable. Similar patterns can be observed by analysing 5054 forest plots of the German National Forest Inventory. Furthermore, we group the forest stands into nine forest structure classes, in which we find increasing, decreasing, invariant and even bell-shaped relationships between productivity and diversity. In addition, we introduce a new index, called optimal species distribution, which describes the ratio of realized to the maximal possible productivity (by shuffling species identities). The optimal species distribution and forest structure indices explain the obtained productivity values quite well ( R 2 between 0.7 and 0.95), whereby the influence of these attributes varies within the nine forest structure classes.

scholarly journals Growth Relationships in Silver Fir Stands at Their Lower-Altitude Limit in Romania

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 439
Author(s):  
Gheorghe-Marian Tudoran ◽  
Avram Cicșa ◽  
Albert Ciceu ◽  
Alexandru-Claudiu Dobre
Keyword(s):  
Basal Area ◽  
Tree Height ◽  
Silver Fir ◽  
Radial Increment ◽  
Height Increment ◽  
Lower Altitude ◽  
Volume Increment ◽  
The Mean ◽  
Annual Volume ◽  
Mean Current

This study presents the biometric relationships among various increments that is useful in both scientific and practical terms for the silvicultural of silver fir. The increments recorded in the biometric characteristics of trees are a faithful indicator of the effect of silvicultural work measures and of environmental conditions. Knowing these increments, and the relationships among them, can contribute to adaptations in silvicultural work on these stands with the purpose of reducing risks generated by environmental factors. We carried an inventory based on tree increment cores. The sample size was determined based on both radial increment and height increment variability of the trees. The sample trees were selected in proportion to their basal area on diameter categories. Current annual height increment (CAIh) was measured on felled trees from mean tree category. For CAIh we generated models based on the mean tree height. Percentages of the basal area increment and of form-height increment were used to compute the current annual volume increment percentage (PCAIv). For the mean tree, the CAIh estimated through the used models had a root-mean-square error (RMSE) of 0.8749 and for the current annual volume increment (CAIv) the RMSE value was 0.1295. In even-aged stands, the mean current volume increment tree is a hypothetical tree that may have the mean basal area of all the trees and the form-height of the stand. Conclusions: The diameter, height, and volume increments of trees are influenced by structural conditions and natural factors. The structures comprising several generations of fir mixed with beech and other deciduous trees, which have been obtained by the natural regeneration of local provenances, are stable and must become management targets. Stable structures are a condition for the sustainable management of stands.

scholarly journals Culturally modified trees and forest structure at a Kawésqar ancient settlement at Río Batchelor, western Patagonia

Human Ecology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 585-597
Author(s):  
Lars Östlund ◽  
Gabriel Zegers ◽  
Benjamin Cáceres Murrie ◽  
Macarena Fernández ◽  
Robert Carracedo-Recasens ◽  
...  
Keyword(s):  
Land Use ◽  
Indigenous People ◽  
Forest Structure ◽  
Environmental Conditions ◽  
Forest Ecosystems ◽  
Temporal Information ◽  
Culturally Modified Trees ◽  
Settlement Site ◽  
Past Land Use ◽  
Indigenous Land

AbstractIndigenous land use occurring on temporal scales over centuries or millennia shapes forests in specific ways and influences the dynamics of forest ecosystems. It is challenging to study such land use, but analysis of “culturally modified trees” (CMTs) can give precise spatial and temporal information on past land use by indigenous people. The aim of this study was to increase our knowledge of indigenous use of land and resources in Nothofagus forests by identifying CMTs and analyzing the forest structure dynamics in an ancient Kawésqar settlement site in western Patagonia. Our results show that there are CMTs at Río Batchelor and that the forest structure varies significantly within the site, indicating that Kawésqar people altered the forest by extracting various resources. We conclude that CMT studies have great potential in Nothofagus forests in southernmost America, but also face specific challenges due to environmental conditions and lack of corroborating historical information.

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