This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
In 1945, the Amazon biome was still mostly intact. The scars of ancient cultural developments in Andean and lowland Amazon had healed, and the impacts of rubber and other resource exploitation were reversible. Very few roads existed, and only in its periphery. In the 1950s and especially in the 1960s, Brazil and other Andean countries launched ambitious road building and colonization projects, largely driven by Brazilian geopolitical concerns. Interest in the Amazon became much more intense in the 1970s as forest loss began to raise worldwide concern. Construction of more and better roads continued at an exponentially growing pace in each following decade, multiplying correlated deforestation and forest degradation everywhere in the Amazon. A point of no return was reached when interoceanic roads crossed the borders of Brazilian-Andean countries in the 2000s, exposing the remaining safe havens for indigenous people and nature. It is commonly estimated that today no less than 18% of the forest has been replaced with agriculture and that more than 50% of the remaining forests are significantly degraded. Most deforested land, especially in Andean countries, is wasted or scarcely used. Oil, mining, and intense urban development, as well as intensive agriculture, spread serious water and soil contamination throughout the region. Logging, fisheries, and hunting gave rise to the successive commercial extinction of valuable species.
Theories regarding the importance of biogeochemical cycles had already been in development since the 1970s, however, in the late 1980s the dominant popular view on the environmental value of the Amazon “lungs of the planet” emerged. The confirmation of the role of the Amazon as a carbon sink added some international pressure for its protection. But, in general, the many scientific discoveries regarding the Amazon have not been helpful in improving its conservation. Instead, a combination of new agricultural technologies, anthropocentric philosophies, and economic changes has strongly promoted forest clearing.
From the 1980s to the present day, Amazon conservation efforts have increasingly diversified, and now consist of five theoretically complementary strategies: (1) the creation of more, larger and better managed protected areas, including biological corridors; (2) the protection of more and larger indigenous territories; (3) the promotion of a series of “sustainable use” options such as “community based conservation,” sustainable forestry, and agroforestry; (4) the financing of conservation through debt swaps and related financial mechanisms for mitigating climate change and; (5) the use of better legislation, monitoring, and control. Five small protected areas have existed in the Amazon since the early 1960s but, in response to the road building boom of the 1970s, several larger patches of forests were set aside with the aim of conserving viable samples of biological diversity. Today, around 25 % of the Amazon is designated as protected areas, but almost half of these areas are categorized in a way that allows human presence and resource exploitation, and there is no effective management. Another 25.3% is designated to indigenous people who may or not conserve the forest. Excluding areas of overlap, both types of protected areas cover 41.2% of the Amazon. Neither strategy has fully achieved its objective, alone or together, and development pressures and threats grow as road construction and deforestation continue relentlessly with increasing funding by multilateral and national banks and pressure from transnational enterprises.
The future will be directed by unprecedented agricultural expansion and the corresponding intensification of deforestation and forest degradation. Additionally, the Amazon basin will be impacted by new, larger hydraulic works. Mining will increase and spread. Policy makers of Amazon countries still view the region as the future for expanding conventional development, and the population continues to be indifferent.
Noa Kekuewa Lincoln and Peter Vitousek
Agriculture in Hawaiʻi was developed in response to the high spatial heterogeneity of climate and landscape of the archipelago, resulting in a broad range of agricultural strategies. Over time, highly intensive irrigated and rainfed systems emerged, supplemented by extensive use of more marginal lands that supported considerable populations. Due to the late colonization of the islands, the pathways of development are fairly well reconstructed in Hawaiʻi. The earliest agricultural developments took advantage of highly fertile areas with abundant freshwater, utilizing relatively simple techniques such as gardening and shifting cultivation. Over time, investments into land-based infrastructure led to the emergence of irrigated pondfield agriculture found elsewhere in Polynesia. This agricultural form was confined by climatic and geomorphological parameters, and typically occurred in wetter, older landscapes that had developed deep river valleys and alluvial plains. Once initiated, these wetland systems saw regular, continuous development and redevelopment. As populations expanded into areas unable to support irrigated agriculture, highly diverse rainfed agricultural systems emerged that were adapted to local environmental and climatic variables. Development of simple infrastructure over vast areas created intensive rainfed agricultural systems that were unique in Polynesia. Intensification of rainfed agriculture was confined to areas of naturally occurring soil fertility that typically occurred in drier and younger landscapes in the southern end of the archipelago. Both irrigated and rainfed agricultural areas applied supplementary agricultural strategies in surrounding areas such as agroforestry, home gardens, and built soils. Differences in yield, labor, surplus, and resilience of agricultural forms helped shape differentiated political economies, hierarchies, and motivations that played a key role in the development of sociopolitical complexity in the islands.