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

Author(s):  
Henrique Luis Godinho Cassol ◽  
Yosio Edemir Shimabukuro ◽  
Elisabete Caria Moraes ◽  
João Manuel de Brito Carreiras ◽  
Luiz Eduardo de Oliveira Cruz e Aragão ◽  
...  

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 Tapajós National Forest in Pará 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 (R² adj. = 0.51; RMSE = 13.2 Mg ha-1) bias = 2.1 ± 37.9 Mg ha-1. The error propagation of the MLR model was estimated to be 15%.

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 ◽  
...  

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.


2002 ◽  
Vol 46 (1) ◽  
Author(s):  
Dietrich Schmidt-Vogt

AbstractManagement of secondary tropical forests: a new perspective for sustainable use of forests in Asia. The decline of primary forests in the tropics is leading to a reassessment of the role secondary forests might play within the context of tropical forest management. Recent research has shown that secondary forests in the tropics can be both rich in species and complex in terms of stand structure. There is, moreover, a growing recognition of the importance of secondary forests for traditional subsistence economies in the tropics and of their economic potential for land use systems in the future. Management of secondary forests in Asia as an alternative to the extraction of timber from primary forests but also as one among other options to intensify traditional land use systems has a potential for the future especially because of the existence of vast tracts of valuable secondary forest cover, and because of the store of traditional knowledge that can still be found in tropical Asia.


2017 ◽  
Vol 8 (4) ◽  
pp. 189-197
Author(s):  
Christiane Cavalcante Leite ◽  
Marcos Heil Costa ◽  
Ranieri Carlos Ferreira de Amorim

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.


2008 ◽  
Vol 38 (12) ◽  
pp. 3033-3046 ◽  
Author(s):  
Thomas Knoke ◽  
Patrick Hildebrandt ◽  
Daniel Klein ◽  
Rodrigo Mujica ◽  
Martin Moog ◽  
...  

The expected opportunity costs of conserving a specific land use are usually considered adequate as financial compensation. However, a “conservation premium” is sometimes proposed as an added incentive, i.e., compensation greater than the expected opportunity costs. This paper discusses various methodological opportunities for deriving effective compensation under uncertainty. Based on cumulative distribution functions of possible opportunity costs (a Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plantation was considered the alternative to conserving a Chilean secondary forest), generated through Monte Carlo simulations, we derived an inclusive range of possible compensations from 77 up to 375 US$·ha–1·year–1. If we assumed that the two land-use alternatives were mutually exclusive and independent from other risky investments, a compensation of 375 US$·ha–1·year–1 was necessary to convince every decision maker to maintain the secondary forest. However, only 77 US$·ha–1·year–1 was enough for a risk-averse decision maker (given average opportunity costs of 113 US$·ha–1·year–1). Yet, it turned out that the greatest possible opportunity costs would already be compensated for with 199 US$·ha–1·year–1, given an error probability of 0.05. Compensating for the last 5% of possible opportunity costs would thus require an additional 176 US$·ha–1·year–1. Our approach had two main limitations, namely we did not consider portfolio effects, which would allow diversifying away unsystematic risks, and we did not take into account the different systematic risks of the compared alternatives. These limitations may have led to an overestimation of effective compensation.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Katie M. McGee ◽  
Teresita M. Porter ◽  
Michael Wright ◽  
Mehrdad Hajibabaei

Abstract Tropical forests are fundamental ecosystems, essential for providing terrestrial primary productivity, global nutrient cycling, and biodiversity. Despite their importance, tropical forests are currently threatened by deforestation and associated activities. Moreover, tropical regions are now mostly represented by secondary forest regrowth, with half of the remaining tropical forests as secondary forest. Soil invertebrates are an important component to the functioning and biodiversity of these soil ecosystems. However, it remains unclear how these past land-use activities and subsequent secondary forest developments have altered the soil invertebrate communities and any potential ecological consequences associated with this. DNA metabarcoding offers an effective approach to rapidly monitor soil invertebrate communities under different land-use practices and within secondary forests. In this study, we used DNA metabarcoding to detect community-based patterns of soil invertebrate composition across a primary forest, a 23-year-old secondary forest, and a 33-year-old secondary forest and the associated soil environmental drivers of the soil invertebrate community structure in the Maquenque National Wildlife Refuge of Costa Rica (MNWR). We also used a species contribution analysis (SIMPER) to determine which soil invertebrate groups may be an indication of these soils reaching a pre-disturbed state such as a primary forest. We found that the soil invertebrate community composition at class, order, family, and ESV level were mostly significantly different across that habitats. We also found that the primary forest had a greater richness of soil invertebrates compared to the 23-year-old and 33-year-old secondary forest. Moreover, a redundancy analysis indicated that soil moisture influenced soil invertebrate community structure and explained up to 22% of the total variation observed in the community composition across the habitats; whereas soil invertebrate richness was structured by soil microbial biomass carbon (C) (Cmic) and explained up to 52% of the invertebrate richness across the primary and secondary forests. Lastly, the SIMPER analysis revealed that Naididae, Entomobryidae, and Elateridae could be important indicators of soil and forest recuperation in the MNWR. This study adds to the increasing evidence that soil invertebrates are intimately linked with the soil microbial biomass carbon (Cmic) and that even after 33 years of natural regrowth of a forest, these land use activities can still have persisting effects on the overall composition and richness of the soil invertebrate communities.


2021 ◽  
Author(s):  
Viola Heinrich ◽  
Ricardo Dalagnol ◽  
Henrique Cassol ◽  
Thais Rosan ◽  
Catherine Torres de Almeida ◽  
...  

&lt;p&gt;Overall, global forests are expected to contribute about a quarter of pledged mitigation under the Paris Agreement, by limiting deforestation and by encouraging forest regrowth.&lt;/p&gt;&lt;p&gt;Secondary Forests in the Neo-tropics have a large climate mitigation potential, given their ability to sequester carbon up to 20 times faster than old-growth forests. However, this rate does not account for the spatial patterns in secondary forest regrowth influenced by regional and local-scale environmental and anthropogenic disturbance drivers.&lt;/p&gt;&lt;p&gt;Secondary Forests in the Brazilian Amazon are expected to play a key role in achieving the goals of the Paris Agreement, however, the Amazon is a large and geographically complex region such that regrowth rates are not uniform across the biome.&lt;/p&gt;&lt;p&gt;To understand the impact of key drivers we used a multi-satellite data approach with the aim of understanding the spatial variations in secondary forest regrowth in the Brazilian Amazon. We mapped secondary forest area and age using a land-use-land-cover dataset &amp;#8211; MapBiomas &amp;#8211; and, combined with the European Space Agency Aboveground Carbon dataset, constructed regional regrowth curves for the year 2017.&lt;/p&gt;&lt;p&gt;We found large variations in the regrowth rates across the Brazilian Amazon due to large-scale environmental drivers such as rainfall and shortwave-radiation. Regrowth rates are similar to previous pan-Amazonian estimates in the North-West (3 &amp;#177;1.0 MgC ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;), which are double than those in the North-East Amazon (1.3 &amp;#177;0.3 MgC ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;). The impact of anthropogenic disturbances, namely fire and repeated deforestation prior to the most recent regrowth only reduces the regrowth by 20% in the North-West (2.4 &amp;#177;0.8 MgC ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;) compared to 55% in the North-East (0.8 &amp;#177;0.8 MgC ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;). Overall, secondary forest carbon stock of 294 TgC in the year 2017, could have been 8% higher with avoided fires and repeat deforestation.&lt;strong&gt; &lt;/strong&gt;We found that the 2017 area of secondary forest, which occupies only ~4% of the Brazilian Amazon biome, can contribute significantly (~5.5%) to Brazil&amp;#8217;s net emissions reduction targets, accumulating ~19.0 TgC yr&lt;sup&gt;-1&lt;/sup&gt;until 2030 if the current area of secondary forest is maintained (13.8 Mha). However,this value reduces rapidly to less than 1% if only secondary forests older than 20 years are preserved (2.2 Mha).&lt;/p&gt;&lt;p&gt;Preserving the remaining old-growth forest carbon stock and implementing legal mechanisms to protect and expand secondary forest areas are key to realising the potential of secondary forest as a nature-based climate change mitigation solution.&lt;/p&gt;


2020 ◽  
Author(s):  
Marie-Jose Gaillard ◽  
Andria Dawson ◽  
Ralph Fyfe ◽  
Esther Githumbi ◽  
Emily Hammer ◽  
...  

&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;


2010 ◽  
Vol 14 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Arlete Silva de Almeida ◽  
Thomas A. Stone ◽  
Ima Célia G. Vieira ◽  
Eric A. Davidson

Abstract While interest in Amazonian deforestation mostly focuses on frontier areas, the amount of forest cover in areas already dominated by human settlement is also changing. Secondary forests play an increasingly important role for maintaining genetic diversity, hydrological functioning, and greenhouse gas emissions of altered landscapes, but secondary forests are also being converted to more intensive agricultural uses. Five dates of Landsat imagery from 1984 to 2002 were analyzed, covering 8000 km2 of the Zona Bragantina of the eastern part of the Brazilian state of Pará, which underwent its most intensive wave of deforestation several decades ago. However, even in this area of relatively long-term human occupation, ongoing decreases of forest cover were found, both in the small remaining areas of mature forest and in the more widespread areas of secondary forests, as human population increased and land use intensified. Although there was an initial increase in the area of secondary forest from 1984 to 1994, there has been a steady decline since then, from 75% secondary forest cover in 1994 to 54% in 2002. The amount of pasture was relatively stable from 1984 to 1994 but more recently has shown a steady increase, reaching 37% cover in 2002. The average rate of carbon loss over the 18-yr study period was 0.9 Mg C ha−1 yr−1 for the 8000 km2 study area. Forests in this long-settled region of eastern Amazonia continue to be degraded, resulting in the loss of ecosystem services and carbon stocks due to continued land-use change.


2019 ◽  
Author(s):  
Nidhi Jha ◽  
Nitin Kumar Tripathi ◽  
Wirong Chanthorn ◽  
Warren Brockelman ◽  
Anuttara Nathalang ◽  
...  

Abstract. Half of Asian tropical forests were disturbed in the last century resulting in the dominance of secondary forests in Southeast Asia. However, the rate at which biomass accumulates during the recovery process in these forests is poorly understood. We studied a forest landscape located in Khao Yai National Park (Thailand) that experienced strong disturbances in the last century due to clearance by swidden farmers. Combining recent field and airborne laser scanning (ALS) data, we first built a high-resolution aboveground biomass (AGB) map over 60 km2 of the forest landscape. We then used the random forest algorithm and Landsat time-series (LTS) data to classify landscape patches as non-forested versus forested on an almost annual basis from 1972 to 2017. The resulting chronosequence was then used in combination with the AGB map to estimate forest carbon recovery rates in secondary forest patches during the first 42 years of succession. The ALS-AGB model predicted AGB with an error of 14 % at 0.5-ha resolution (RMSE = 45 Mg ha−1) using the mean top-of-canopy height as a single predictor. The mean AGB over the landscape was of 291 Mg ha−1 showing a high level of carbon storage despite past disturbance history. We found that AGB recovery varies non-linearly in the first 42 years of the succession, with an increasing rate of accumulation through time. We predicted a mean AGB recovery rate of 6.9 Mg ha−1 yr−1, with a mean AGB gain of 143 and 273 Mg ha−1 after 20 and 40 years, respectively. These estimates are within the range of those reported for the well-studied Latin American secondary forests under similar climatic conditions. This study illustrates the potential of ALS data not only for scaling up field AGB measurements but also for predicting AGB recovery dynamics when combined with long-term satellite data. It also illustrates that tropical forest landscapes that were disturbed in the past are of utmost importance for the regional carbon budget and thus for implementing international programs such as REDD+.


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