![Sample our Environment & Sustainability journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5935/TOC-Subject-Sample-2021-Environment-Sustainability.jpg"})
Abstract
This article addresses the emergence of road networks and forest fragmentation in Central Amazônia, which has been impacted by both spontaneous and planned settlement. The first objective of the article is to broaden the discussion of fragmentation by addressing social processes that generate it through the construction of roads. Roads impact land cover change worldwide, and their role in Amazonian deforestation is known. The article also seeks to extend the literature on roads to address the social processes and individual behaviors that create the road network architecture. The second objective is to open a discussion about the biodiversity implications of different patterns of forest fragmentation. Our specific focus is the geometry of settlement associated with urban nodes, referred to here as radial fragmentation. The article pursues its objectives by implementing a conceptual framework that extends the pattern-to-process paradigm of landscape ecology by adding a (social) process-to-pattern component. This is accomplished through a mixed-method approach including (1) field-based narratives of the social processes that gave rise to radial fragmentation in the hinterland of the town of Itaituba, an important settlement in the middle Tapajós valley; (2) remote sensing of the evolution of road networks, which we then link to deforestation in a temporal analysis of emergent fragmentation patterns; and (3) computational applications to compare the biodiversity implications of radial and fishbone landscape fragmentation.
本文探讨亚马逊中部道路网络的形成与森林的破碎化, 该现象同时受到自发与规划的聚落所影响。本文的首要目标在于指出道路开发导致森林碎裂化的社会过程, 以此扩展对于碎裂化的讨论。道路在全球影响着土地覆盖的改变, 而它们在亚马逊森林破坏过程中的角色则是众所週知。本文亦寻求扩展有关道路的文献, 以此探讨创造道路网络结构的社会过程与个人行为。第二个目标在于开展有关生物多样性对于不同森林碎裂化模式的意涵之讨论。我们特别聚焦有关城市结点的聚落几何学, 在此所指为”放射状的碎裂化”。本文透过执行一个概念框架来追求上述目标, 该框架增加了形成模式的 (社会) 过程之元素, 以此延伸地景生态学中”模式形成过程”之典范。此一目标将透过混合方法取径达成之, 包含 (1) 根据田野的社会过程叙事, 该过程致使塔帕若斯河谷中段的重要聚落伊泰图巴的城镇内陆地区产生放射状的碎裂; (2) 道路网络发展的遥测, 我们接着在一个对浮现中的碎裂模式所进行的时间分析中, 将之与森林破坏相互连结; 以及 (3) 电脑化应用以比较放射状与鱼骨状地景碎裂的生物多样性意涵。
Este artículo versa sobre el surgimiento de redes viales y la fragmentación de la selva en la Amazonia Central, región que ha sido afectada por igual por asentamientos espontáneos y planeados. El primer objetivo del artículo es ampliar el debate sobre la fragmentación, abocando los procesos sociales que la generan gracias a la construcción de carreteras. Las carreteras impactan al cambiar la cobertura de la tierra en todas partes, y es bien conocido su papel en la deforestación amazónica. El artículo busca también extender la literatura sobre las carreteras para tomar en cuenta los procesos sociales y conductas individuales que crean la arquitectura de la red vial. El segundo objetivo busca iniciar una discusión acerca de las implicaciones que tienen para la biodiversidad los diferentes patrones de la fragmentación forestal. Nuestro interés se enfoca específicamente en la geometría del poblamiento asociada con los nodos urbanos, la cual es entendida aquí como fragmentación radial. El artículo persigue sus objetivos implementando un marco conceptual que expande un paradigma de patrón-proceso en la ecología del paisaje agregando un componente (social) de proceso-patrón. Esto se lleva a cabo por medio de un enfoque de método mixto que incluye (1) narrativas basadas en trabajo de campo sobre los procesos sociales que dieron lugar a la fragmentación radial en el hinterland del pueblo de Itaituba, importante asentamiento del valle medio del Tapajós; (2) datos de percepción remota sobre la evolución de las redes de carreteras, que luego nosotros ligamos a la deforestación en un análisis temporal de los patrones emergentes de fragmentación; y (3) aplicaciones computacionales para comparar las implicaciones que tiene sobre la biodiversidad la fragmentación radial o espigada del paisaje.
Acknowledgments
We acknowledge support from the National Science Foundation under two research grants (BCS 1157952 and BCS 0243102). We also thank the editor and two anonymous reviewers, whose comments greatly improved the article and William Castro for providing useful contextual information. Finally, we are indebted to Thaís Barbosa Morais for helping to conduct interviews and to all interviewees who patiently shared their knowledge with us.
Notes
1. Percolation theory typically focuses on critical probabilities, proportions of habitats, and extent beyond which transition phases between habitat disconnection or connection can be observed.
2. Brazilian counties, or municipios, are often named after the main town in the municipio.
4. PA-370, for example, originally linked Santarém to the hydroelectric dam of Curuá-Una and was extended by loggers who sought a more direct connection between the Transamazon and Santarém. Now the whole segment is incorporated into the official system.
5. This method does not capture skid trails used to transport felled trees to logging patios because the spectral signature disappears after a few years from the image (Souza and Roberts Citation2005), given the ephemeral nature of such artifacts. Because our objective is to detect permanent roads, not short-lived trails, the method described identifies the vast majority of segments (Brandão and Souza Citation2006).
6. This redundancy, common in road and railway networks (Tero et al. Citation2010), increases the overall robustness of the network against fault points in the system such as fallen bridges or flooded terrains, particularly during the rainy season. For example, during our fieldwork in June 2009, Ramal Farturão was closed because of a collapsed bridge. The comunidades Novo Horizonte and California were accessible by an alternative L-shaped route through the Transamazon and Ramal Califórnia. Likewise, Ramal Juruti and Ramal São Benedito are connected to each other near Comunidade São Jorge.
7. Distance was determined by geographic information system. This is a substantial reduction from 663 km associated with the route involving BR-163, BR-230, and boat from Santarém.
8. In an unprecedented action in January 2012, President Dilma Rousseff shrank the park's eastern boundaries. Conflict over protected areas is nothing new, nor is it unique to this particular settlement process (Almeida Citation1995; Simmons Citation2005). This is the first time a Brazilian national park has been downsized to accommodate claims from settlers, however, a precedent that raises serious moral hazard concerns.
9. The igarapés moving northeast from Itaituba to Vila Brasilia are Piracanã, Pagão, and Limão.
10. We use the Tapajós River as a geographic target to facilitate the construction of transects along our study areas. This exercise is not trying to establish any ecological necessity per se to link forest fragments to the river banks, although one might exist.
11. An analogy might help interpret the results. Suppose we grab two adjacent corners of a thin square membrane (i.e., landscape) and place droplets of water (i.e., our random points) on its upper edge. The droplets will find resistance when parts of the membrane are “deforested” and will flow down easily when it is “forested.” If we pick two such membranes with different resistance configurations, we can measure the time the droplets will take to reach the other side for each membrane. The membrane with droplets that percolate the fastest is the “best” landscape.
12. By 2008, one single deforested patch in the vicinity of EB accounted for 66 to 80 percent of the total deforested area, depending on whether patch contiguity is defined by the four or eight nearest neighbors.