12 research outputs found
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
Alometria de Árvores e Biomassa Florestal na Amazônia Sul-Ocidental
The world’s tropical forests, and the Amazonian Forest in particular, play an important
role because they store between 193 ± 58 Pg and 228 ± 12 Pg of carbon and are facing
intensive conversion to other land uses. There is a high level of uncertainty related to the
quantification of this carbon reservoir and its emissions, in part due to the low density
of field samples to characterize the natural variability. This research aimed to develop
allometric equations for estimating total above and below-ground dry biomass for both
trees and bamboo, apply these equations on forest inventory data, and test methods
of extrapolation of the estimates to the landscape through remote sensing information.
In order to adjust the allometric equations, we used the direct compartment method,
roots (thin 2 mm < ∅ < 5 cm and thick ∅ ≥ 5 cm), trunks, branches (thin ∅ < 10 cm
and thick ∅ ≥ 10 cm) and leaves of 190 trees with diameters varying between 5 and
92 cm; and 206 bamboo individuals (Guadua weberbaueri), subdivided in below- (roots)
and above-ground (stems, branches and leaves) biomass. The basic wood density was
determined in three trunk positions and in thick branches (∅ ≥ 10 cm) in 81 trees of
different species with diameters varying between 11 and 90 cm. To determine forest biomass
from remote sensing data, methods and density of LiDAR points were tested. The results
showed that the allometrics patterns for estimating tree biomass in the Southwestern
Amazon are different from other sampled regions in the Amazon. This fact may be related
to lower tree height and wood density and higher water content in the fresh biomass. Were
tested eight allometric models to estimate below-ground, above-ground and total biomass
of individual trees in primary forest. Considering accuracy, practicality and costs, the use
of the simple power equation involving only diameter (AGB tree = a × D b ) presented the
best performance to estimate forest biomass. Bamboo biomass is an important component
of the forest carbon cycle in a considerable part of the Southwestern Amazon. Were
found a low allometric relation between bamboo dried biomass and its stalk diameter and
height, a result distinct to those found by other authors, suggesting that there are different
allometric patterns among the bamboo populations in this part of the Amazon. For the
Amazon rainforest, an environment of low topographic variability, it is recommended the
use of LiDAR point clouds with a density ≥ 2 m −2 to generate forest structure metrics and
biomass estimation. To increase sample density is fundamental to improve the accuracy
of forest biomass estimates. However, in order to contemplate spatial variability and
access a large territorial extensions ecosystem such as the Amazonia, it is necessary to
combine field data with remote sensing data as LiDAR. Open forests (+200,000 km 2 )
in the southwestern Amazonia are significantly different from forests in other regions of
the Amazon. These differences can lead to disparities of up to 35 % in estimated forest
biomass and consequently in carbon stocks and fluxes between forests and the atmosphere.
To improve the accuracy of forest biomass estimates via LiDAR, consideration should
be given to: (1) The quantity and size of the calibration plots; (2) the density of LiDAR
points; and (3) the computation method.
Keywords: forest biomass. allometric equations. LiDAR. Acre.As florestas tropicais do mundo, em especial a Floresta Amazônica, têm um papel im-
portante, pois armazenam entre 193 ± 58 Pg – 228 ± 12 Pg de carbono e estão sofrendo
processos intensivos de conversão em outros usos. A incerteza associada à quantificação
desse reservatório de carbono e suas emissões, é grande. Em parte, pela baixa densidade de
amostras de campo para caracterizar a variabilidade natural. O objetivo deste trabalho foi
desenvolver para a Amazônia Sul-Ocidental, equações alométricas para estimar biomassa
seca total, abaixo e acima do solo em árvores e bambu, como também, aplicar a dados
de inventário florestal e testar métodos de extrapolação das estimavas para a paisagem
usando informações de sensoriamento remoto. Para ajustar as equações alométricas foi
realizada estimativa de biomassa, pelo método direto dos compartimentos, raiz (fina 2 mm
< ∅ < 5 cm e grossa ∅ ≥ 5 cm), tronco, galhos (fino ∅ < 10 cm e grosso ∅ ≥ 10 cm)
e folhas de 190 árvores com diâmetro variando entre 5 e 92 cm; e de 206 indivíduos de
bambu (Guadua weberbaueri), subdividindo em biomassa abaixo (raízes) e acima (colmos,
galhos e folhas) do solo. Foi determinada, também, a densidade básica da madeira em três
posições no tronco e galho grosso (∅ ≥ 10 cm) em 81 árvores de diferentes espécies com
diâmetro variando entre 11 e 90 cm. Para estimar biomassa florestal a partir de dados de
sensoriamento remoto foram testados métodos e densidade de pontos LiDAR. Os resultados
mostram que os padrões das relações alométricas para estimar biomassa de árvores na
Amazônia Sul-Ocidental são distintos de outras regiões amostradas na Amazônia. Este
fato pode estar relacionado a menor altura e densidade da madeira e maior teor de água da
biomassa fresca. Foram testados oito modelos alométricos para estimar biomassa abaixo
do solo, acima do solo e total de árvores individuais em floresta primária. Considerando os
parâmetros de qualidade, praticidade de uso e custo, a equação de simples entrada em
potência, envolvendo somente diâmetro (AGB tree = a × D b ) teve melhor desempenho na
estimativa da biomassa florestal, sendo preferível a utilização da mesma. A biomassa de
bambu é um importante componente do ciclo do carbono florestal em uma porção conside-
rável da Amazônia Sul-Ocidental. Foi encontrada baixa relação alométricas da biomassa
seca de bambu com diâmetro e altura, resultados contrários aos encontrados por outros
autores, sugerindo haver padrões alométricos diferentes entre as populações de bambu
nesta porção da Amazônia. Em condições de floresta tropical amazônica em ambiente
de baixa variabilidade topográfica recomenda-se o uso de nuvens de pontos LiDAR com
densidade ≥ 2 m −2 para gerar métricas de estrutura da floresta e estimativa de biomassa.
As floresta abertas (+200.000 km 2 ) na Amazônia Sul-Ocidental são significativamente
diferentes de florestas em outras regiões da Amazônia. Essas diferenças podem provocar
disparidades de até 35% na biomassa florestal estimada e consequentemente nos estoques e
fluxos de carbono entre as florestas e a atmosfera. Para melhorar a acurácia das estimativas
de biomassa florestal via LiDAR deve ser levado em consideração: (1) A quantidade e
tamanho das parcelas de calibração; (2) a densidade de pontos LiDAR; e (3) o método de
computação.
Palavras-chave: Biomassa florestal. Equações alométricas. LiDAR. Acre
Evaluation of the stock and isotopic composition of carbon in the soil of Acre.
O estado do Acre está localizado no extremo oeste do Brasil, ocupando uma região que teve grande influência geológica da cordilheira dos Andes. Os solos apresentam características pedológicas bem distintas das encontradas no restante da Amazônia brasileira, predominando Cambissolos, Luvissolos e Argissolos, geralmente eutróficos, jovens e pouco intemperizados. Pouco se sabe sobre o impacto do uso da terra sobre a matéria orgânica nestas condições de solo. Os objetivos deste trabalho foram: Estimar o estoque de carbono das principais classes de solos do Estado do Acre e comparar com estudos feitos para região amazônica. Avaliar o efeito da mudança no uso e cobertura da terra sobre o estoque de carbono e composição isotópica da matéria orgânica em duas condições de solo no Acre. Para alcançar os objetivos o trabalho foi executado em duas escalas, regional e local. No primeiro caso, foram estimados os estoques de carbono até um metro de profundidade, utilizando um mapa de solos na escala 1:1.000.000 e dados analíticos de perfis de levantamentos pedológicos realizados na região. No segundo caso foram determinados a concentração de carbono, d13C e densidade do solo de amostras coletadas em pastagens de 12-15 anos, 20 anos e floresta, nas profundidades de 0-5, 5-10, 10-20, 20-30, 30-40, 50-60, 70-80 e 90-100 cm, em Argissolo (bem drenado) e Luvissolo (mal drenado). Os solos do Acre armazenam em torno de 1 Pg (1 Pg = 1015 g) de carbono no primeiro metro de profundidade, cerca de 75 % deste valor concentra-se nos primeiros 30 cm. Os solos do Acre apresentam menor concentração de carbono (média 6,5 kg m-2) quando comparados com a média dos solos da Amazônia, embora apresentem melhor fertilidade. A principal razão para este resultado é a maior taxa de decomposição da matéria orgânica nestes solos devido aos constantes ciclos de seca e umedecimento. Estes ciclos estão associados a interação entre o regime pluviométrico e as características físicas (principalmente estrutura) incipientes destes solos, que fazem com que ocorra um lençol freático suspenso que oscila no perfil do solo, podendo chegar até a superfície do mesmo. A mudança no uso da terra alterou de maneira distinta os estoques e a dinâmica da matéria orgânica em Argissolos (bem drenados) e Luvissolos (mal drenados). As pastagens sobre Luvissolos apresentaram maior estoque de carbono (média de 8,4 kg m-2 até 1 m de profundidade), entretanto, os dados isotópicos mostraram que a maior parte deste carbono era remanescente da floresta e uma pequena proporção foi introduzida pela pastagem ( 70 % na camada 0-5 cm da pastagem de 20 anos). Os resultados acima sugerem que: 1) A taxa de decomposição do carbono em Luvissolos é menor que em Argissolos, e o tempo de residência da meteria orgânica maior. Os Argissolos tendem a perder muito mais carbono com a mudança no uso e cobertura da terra. 2) A produtividade da pastagem é baixa sobre Luvissolos, indicando que alem da fertilidade do solo outras características, como estrutura, devem ser consideradas para definição das praticas de manejo que objetivam a obtenção de melhor desempenho da gramínea.The State of Acre is located in the extreme west of Brazil, occupying an area that had great geological influence from the mountain chain of Andes. The soils present pedologic characteristics very different from the ones found in the remaining of Brazilian Amazon, prevailing Inceptisols, Alfisols, and Ultisols, generally eutrophic, young and little weathered. Not much is known about the impact of the use of the earth on the organic matter in these soil conditions. This work had as objectives to estimate the stock of carbon of the main classes of soils of the State of Acre and to compare with studies carried out for the Amazon area. To evaluate the effect of the change in the use and covering of the earth on the stock of carbon and isotopic composition of the organic matter in two soil conditions in Acre. To reach the objectives the work was performed in two scales, local and regional. The first case estimated the stocks of carbon up to one meter deep, using a map of soils in the scale 1:1.000.000 and analytic data of pedologic profiles accomplished in the area. The second case determined the concentration of carbon, d13C and density of the soil of samples collected at 12-15, 20 year-old pasture lands, and forest in the depths 0-5, 5-10, 10-20, 20-30, 30-40, 50-60, 70-80 e 90-100 cm, in Ultisols (well drained) and Alfisols (poorly drained). The soils of Acre store around 1 Pg of carbon in the first meter of depth, around 75% of this value is concentrated on the first 30 cm. The soils of Acre present smaller concentration of carbon (6.5 kg m-2, average) when compared with the average of the soils of the Amazon, although they present better fertility. The main reason for this result is the large rate of incident decomposition on these soils due to the constant drought cycles and moistening. These cycles are associated with the physical characteristics (mainly structure) incipient of these soils that impede the percolation of the pluvial waters saturating very quickly and favoring superficial flow off. As the water concentrates on the surface of the soil, it tends to evaporate easily. The effect of the change in the covering and land use on stock and dynamics of the organic matter of the soils happens differently in Ultisols (well drained) and Alfisols (poorly drained). In the two conditions of soils there was a tendency to decrease the total stock of carbon and increase carbon of C4 origin, however, in Ultisols it was very stressed. Pasture lands on Alfisols presented larger stock of carbon (average of 8.4 kg m-2 to 1 m), however, the data of d13C showed that most of carbon was remaining of the forest and a small proportion was introduced by the pasture land ( 70 % to 0-5 cm in 20 yr old pasture). This result suggests two conclusions. 1) the rate of carbon decomposition in Alfisols is smaller than in Ultisols, and the time of residence of the organic matter is larger. Ultisols tend to lose carbon more readily with the change in the land use and covering of the land. 2) pasture productivity is low on Alfisols, indicating that besides soil fertility other characteristics, as structure, should be considered in order to establish the management practice to obtain the best output from the grass
Dinâmica da fragmentação florestal utilizando sensoriamento remoto no perímetro urbano de Rio Branco
In Acre state change in vegetation occurs primarily by the conversion of forest areas into pastures. It is essential to understand the process of occupation of the landscape. This study aimed to analyze the fragmentation forest dynamics through the use of remote sensing in the vicinity of the city of Rio Branco, Acre, between 1990 to 2010. In the environment of ArcGIS 10.0 software was created to mask reverse deforestation for the years 1990, 1995, 2000, 2005 and 2010, for which they were generated landscape metrics for the classes of fragment size, very small ( 100ha) using the extension Pacht Analyst 5.1. According to the results of this study we can say that the process of fragmentation, within a radius of 50km from the city of Rio Branco, has been growing over the last twenty years, being most intense between 2005 to 2010. The number of fragmentation was growing by the year 2005 and then decreased due to the extinction process of fragments, which indicate a process of extreme fragmentation. The number of fragments is related to the distance between the nearest neighbors - MNN, the smaller the number of fragments greater the MNN.Pages: 2952-295
Dynamics of forest fires in the southwestern Amazon
The synergism between climatic change and human action has provided conditions for the occurrence of forest fires in the Amazon. We used annual mapping to reconstruct the history of fire in Brazil's state of Acre to understand the forest-fire regime over a period of 33 years (1984–2016). The burn-scar index (BSI) derived from the fractions of soil and of photosynthetic and non-photosynthetic material was generated by CLASlite© software using Landsat-TM and OLI satellite images. The area of forest-fire scars totaled 525,130 ha in the period analyzed. This total includes forests that fire affected only once (388,350 ha), twice (59,800 ha) and three times (5727 ha). The years 2005 and 2010 represent 90% of the total area of forest fires in Acre, coinciding with severe droughts caused by the anomalous warming of the tropical North Atlantic Ocean. The most heavily impacted portion of Acre was in the eastern part of the state, which has the greatest forest fragmentation, consolidation of agricultural activity and presence of settlement projects. In 2005, the municipalities of Acrelândia, Plácido de Castro and Senador Guiomard accounted for more than 50% of the forest remnants impacted by fire. Of the total extent of forest fires in Acre, 43% occurred in settlement projects administered by the National Institute for Colonization and Agrarian Reform (INCRA) and 16% in conservation units administered by the Ministry of Environment (MMA). The area of forest fires was 36 times greater in the 16 years after 2000, compared to the 16 years before 2000. The frequency of fires increased dramatically from one fire episode roughly every ten years (period from 1984 to 2004), to one fire every five years (period from 2005 to 2016). With the projections of warmer climate and advancing deforestation, the forest fires in Acre will tend be more intense and frequent. © 2018 Elsevier B.V
Roads in the Southwestern Amazon, State of Acre, between 2007 and 2019
Over the past 40 years, roads have been the main driver behind the State of Acre’s occupation and development. However, the expansion of roads, has often been associated with the advance of deforestation, habitat fragmentation, and social conflicts. There are no up-to-date data available on the current extent of Acre’s road network nor its environmental and socioenvironmental impacts. In this study, we updated the State of Acre’s road network map for the period 2007 to 2019 through the visual interpretation of 153 Landsat images (5, 7, and 8) at a scale of 1:50,000. To estimate the impact of roads, we measured the distribution of roads in municipalities and in different land tenure categories and calculated the correlation between roads and annual deforestation. Up to 2019, we estimated 19,620 km of roads, of which 92% were unofficial roads, 6% federal roads, and 2% state roads. The roads increased at an average annual rate of 590 km year−1. The most significant advance in road length between 2007 and 2019 was in protected areas (240%), followed by public lands (68%) and settlement projects (66%). We recommend monitoring of the road network to understand the landscape’s evolution and support actions against illicit environmental and socioenvironmental impacts