Forecasting fire season severity in South America using sea surface temperature anomalies

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. We investigated the relationship between year-to-year changes in fire activity in South America and sea surface temperatures. We found that the Oceanic Ni?o Index was correlated with interannual fire activity in the eastern Amazon, whereas the Atlantic Multidecadal Oscillation index was more closely linked with fires in the southern and southwestern Amazon. Combining these two climate indices, we developed an empirical model to forecast regional fire season severity with lead times of 3 to 5 months. Our approach may contribute to the development of an early warning system for anticipating the vulnerability of Amazon forests to fires, thus enabling more effective management with benefits for climate and air quality.     

Neotropical mammals and the myth of amazonian biodiversity

Data were compiled on the distribution of mammal taxa (883 species, 242 genera, 45 families, and 10 orders) among South America's six major macrohabitats: lowland Amazon forest, western montane forests, Atlantic rain forest, upland semideciduous forest, southern mesophytic forest, and drylands. The drylands are the richest area in numbers of species supported and are more diverse than the other habitats, including the lowland Amazon rain forest, when endemics are considered. An analysis of number of endemic and nonendemic taxa versus size of area found a simple positive linear relationship: the drylands, almost twice as extensive as the Amazon lowlands, support more endemic taxa. Conservation plans that emphasize the wet tropics and fail to consider the drylands as special repositories of mammal diversity will be unable to preserve a significant number of novel taxa.     

Lowland forest loss in protected areas of Indonesian Borneo

The ecology of Bornean rainforests is driven by El Ni?o-induced droughts that trigger synchronous fruiting among trees and bursts of faunal reproduction that sustain vertebrate populations. However, many of these species- and carbon-rich ecosystems have been destroyed by logging and conversion, which increasingly threaten protected areas. Our satellite, Geographic Information System, and field-based analyses show that from 1985 to 2001, Kalimantan's protected lowland forests declined by more than 56% (>29,000 square kilometers). Even uninhabited frontier parks are logged to supply international markets. "Protected" forests have become increasingly isolated and deforested and their buffer zones degraded. Preserving the ecological integrity of Kalimantan's rainforests requires immediate transnational management.     

Land-use allocation protects the Peruvian Amazon

Disturbance and deforestation have profound ecological and socioeconomic effects on tropical forests, but their diffuse patterns are difficult to detect and quantify at regional scales. We expanded the Carnegie forest damage detection system to show that, between 1999 and 2005, disturbance and deforestation rates throughout the Peruvian Amazon averaged 632 square kilometers per year and 645 square kilometers per year, respectively. However, only 1 to 2% occurred within natural protected areas, indigenous territories contained only 11% of the forest disturbances and 9% of the deforestation, and recent forest concessions effectively protected against clear-cutting. Although the region shows recent increases in disturbance and deforestation rates and leakage into forests surrounding concession areas, land-use policy and remoteness are serving to protect the Peruvian Amazon.     

Amazon deforestation and climate change

A coupled numerical model of the global atmosphere and biosphere has been used to assess the effects of Amazon deforestation on the regional and global climate. When the tropical forests in the model were replaced by degraded grass (pasture), there was a significant increase in surface temperature and a decrease in evapotranspiration and precipitation over Amazonia. In the simulation, the length of the dry season also increased; such an increase could make reestablishment of the tropical forests after massive deforestation particularly difficult.     

From colonization to “environmental soy”: A case study of environmental and socio-economic valuation in the Amazon soy frontier

This paper examines the socio-economic and environmental implications of soy development in Santarém, Pará, located in the Brazilian Amazon. The settlement history of the region contributes directly to the way in which soy agriculture is currently proceeding in Santarém. Government policies and perspectives have been shaped by a history of agrarian colonization of Amazon forests, and the small farmers, or colonos, who are now being bought out by soy agribusiness are also rooted in this history. As a means of ascertaining the current state and interaction of soy actors with the burgeoning soy-based economy in the area, field research was conducted on the role of primary and secondary forests for soy production. Research also included an analysis of valuation discourses – that is, how the differing soy actors (local government, agribusiness, conservation NGOs, and small farmers) assign value to types of forests and their different interpretations of what constitutes environmental degradation. The ways in which these different actors assign such values to forests and how they structure the definition of environmental degradation is a key factor in determining who “wins” and “loses” in the realm of Amazon development. Significant environmental and socio-economic implications of soy expansion, especially for the colonos, are not taken into account because the dominant rhetoric of Amazonian development ignores their contribution to social and ecological diversity. This omission keeps colono communities living at poverty level and even exacerbates colono poverty under the soy development project. The colonos and their representatives are responding by setting forth their own, competing valuations of primary and secondary forests that contrast sharply with state soy growing schemes and NGO plans for “sustainable soy.” These have their roots in local knowledge and best practices. Corrina Steward is the Resource Rights Specialist at Grassroots International in Boston, Massachusetts. She holds a Masters degree in Environmental Science from the Yale School of Forestry and Environmental Studies in New Haven, Connecticut where she focused on social ecology, community development, and globalization. She recently co-edited the book Agroecology and the Struggle for Food Sovereignty in the Americas (2006, London, UK: International Institute for Environment and Development).     

Improved fallows: a case study of an adaptive response in Amazonian swidden farming systems

Many smallholders in the Amazon employ swidden (slash-and-burn) farming systems in which forest or forest fallows are the primary source of natural soil enrichment. With decreasing opportunities to claim natural forests for agriculture and shrinking landholdings, rotational agriculture on smaller holdings allows insufficient time for fallow to regenerate naturally into secondary forest. This case study examines how Peruvian farmers use “improved fallows” as an adaptive response to a situation of decreasing soil fertility and how the farmers describe the rationale underlying the various actions taken in these modified fallow systems. The results indicate that farmers establish improved fallows using contextual ecological knowledge and various techniques to introduce a large diversity of tree species. This practice is also used to restore degraded land to agricultural production. The tasks of maintaining productivity on agricultural land and reforesting degraded areas is becoming increasingly urgent in the Amazon, making agricultural practices that involve reforestation and tree management highly relevant. Since swidden farming systems are the basis for the livelihoods of most Amazon smallholders, good farming practices elaborated by swidden farmers are important for sustainable small-scale family farming systems in the Amazon.     

Apogeotropic roots in an Amazon rain forest

Roots of some tropical trees grow vertically upward on the stems of neighboring trees. Apogeotropic roots occur in 12 species across five families. These roots, originating as fine roots in the mineral soil, grow upward as fast as 5.6 centimeters in 72 hours. Apogeotropic root growth may be an adaptation to extremely low soil nutrient availability in Amazon forests. In these forests upward-growing roots obtain nutrients via the predictable pathway of precipitation that flows down along the stem. Apogeotropic roots form a nutrient cycling pathway in which nutrients are absorbed and transported directly from plant to plant, without entering the soil solution.     

Sparse pre-Columbian human habitation in western Amazonia

Locally extensive pre-Columbian human occupation and modification occurred in the forests of the central and eastern Amazon Basin, but whether comparable impacts extend westward and into the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across central and western Amazonia to assess the history of human occupation. Sparse occurrences of charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent, and highly localized. No human artifacts or modified soils were found at any site surveyed. Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous across this vast landscape.     

格氏栲天然林主要种群直径分布结构特征

应用 5种概率分布律对格氏栲林 8个主要树木种群的直径结构进行拟合 ,比较不同类型的拟合效果 ,探索各种群直径分布结构特征 .结果表明 ,β分布函数较好表达格氏栲林主要树木种群的直径分布结构 ,拟合效果最好 ,正态分布函数次之 ;不同群落类型的格氏栲种群直径分布均符合β分布 ,偏度大部分呈正偏 ,峰度均为负 ,表明优势种格氏栲种群直径分布范围较大、中径材占多数 .同时格氏栲种群直径 β分布参数与林分平均胸径等特征因子存在显著关系 .其研究对格氏栲林的合理经营及森林调查 ,均具有重要意义     

Herbivores promote habitat specialization by trees in Amazonian forests

In an edaphically heterogeneous area in the Peruvian Amazon, clay soils and nutrient-poor white sands each harbor distinctive plant communities. To determine whether a trade-off between growth and antiherbivore defense enforces habitat specialization on these two soil types, we conducted a reciprocal transplant study of seedlings of 20 species from six genera of phylogenetically independent pairs of edaphic specialist trees and manipulated the presence of herbivores. Clay specialist species grew significantly faster than white-sand specialists in both soil types when protected from herbivores. However, when unprotected, white-sand specialists dominated in white-sand forests and clay specialists dominated in clay forests. Therefore, habitat specialization in this system results from an interaction of herbivore pressure with soil type.     

浅析近代史上水旱灾害对农村社会的影响

中国近代史上灾害频发，水灾、旱灾、虫灾以及疫灾等，这些灾害或多或少都对人民生命财产 安全产生了危害，其中水旱灾害的发生更是对农村社会产生了巨大的影响。本文从水旱灾害发生的 原因探析中国近代史上水旱灾害对农村社会以及农村人民产生的危害，进而探讨中国近代史上乡村 在水旱灾害打击下的农业经济、社会冲突及农民生活状况的改变。     

Neutral ecological theory reveals isolation and rapid speciation in a biodiversity hot spot

South Africa's Mediterranean-climate fynbos shrubland is a hot spot of species diversity, but its diversity patterns contrast strongly with other high-diversity areas, including the Amazon rain forest. With its extremely high levels of endemism and species turnover, fynbos is made up of dissimilar local communities that are species-rich but relatively poor in rare species. Using neutral ecological theory, we show that the relative species-abundance distributions in fynbos can be explained by migration rates that are two orders of magnitude lower than they are in tropical rain forests. Speciation rates, which are indexed by the "biodiversity parameter" Theta, are estimated to be higher than they are in any previously examined plant system.     

Amazon rain-forest fires

Charcoal is common in the soils of mature rain forests within 75 kilometers of San Carlos de Rio Negro in the north central Amazon Basin. Carbon-14 dates of soil charcoal from this region indicate that numerous fires have occurred since the mid-Holocene epoch. Charcoal is most common in tierra firme forest Oxisols and Ultisols and less common in caatinga and igapo forest soils. Climatic changes or human activities, or both, have caused rain-forest fires.     

Fluvial perturbance in the Western Amazon basin: regulation by long-term sub-andean tectonics

Haffer's refuge theory proposes that during the arid climatic phases of the late Pleistocene, tropical lowland forests of Amazonia were reduced to isolated patches contributing to the high species richness of the present-day forest. The theory was developed because no obvious historic or modern geomorphic isolation barriers were recorded in Amazonia. Analyses of radar images combined with stratigraphical data show that in the basinal forelands of the tectonically active Andes the geological setting causes long-term fluvial perturbance. This leads to a temporally structured highly complex mosaic of fossil and present floodplains. These dynamics have been present with varying activity and geographic range during the Tertiary and Quaternary, providing site-turnover that has not been recognized by the biogeographic tradition of the Amazon basin.     

Participatory Extension as Basis for the Work of Rural Extension Services in the Amazon

Public extension services play a key role in the implementation of strategies for rural development based on the sustainable management of natural resources. However, the sector suffers from restricted financial and human resources. Using experiences from participatory action research, a strategy for rural extension in the Amazon was defined to increase the efficiency and the relevance of external support for local resource users. This strategy considered activities initiated and coordinated by local people. Short-term facilitation visits provided continuous external support for the purpose of establishing locally based planning and learning mechanisms. In collaboration with the municipality of Muaná in the Eastern Amazon, the strategy was tested in two traditional communities – Monte Moriat and Boa Esperança. Both communities recognized as most important the need to reduce their dependence on açaí (Euterpe oleracea Mart.), the principal source of food and income. This forest resource has been overexploited, seriously affecting açaí stands and diminishing the forest benefits fundamental for survival. Two local groups decided to raise chickens as a way to reduce nutritional problems and as an alternative source of income. Supported by monthly, short-term planning and evaluation visits, the groups managed to achieve significant progress in their endeavor. The groups identified (1) the control of decision-making and information, and (2) the absence of external obligations to be the greatest advantages of the development initiative. The study confirmed the potential of participatory strategies for public extension in the Amazon. Special attention was given to realistically define the role of forests for local development. However, drastic measures are necessary to smooth the way for real participation in governmental and non-governmental organizations acting in the Brazilian Amazon.     

Amazon river discharge and climate variability: 1903 to 1985

Reconstruction of an 83-year record (1903 to 1985) of the discharge of the Amazon River shows that there has been no statistically significant change in discharge over the period of record and that the predominant interannual variability occurs on the 2- to 3-year time scale. Oscillations of river discharge predate significant human influences in the Amazon basin and reflect both extrabasinal and local factors. Cross-spectrum analyses of Amazon flow anomalies with indicators of the El Ni?o-Southern Oscillation phenomenon suggest that the oscillations in the hydrograph are coupled to the tropical Pacific climate cycle.     

Climate and the collapse of Maya civilization

In the anoxic Cariaco Basin of the southern Caribbean, the bulk titanium content of undisturbed sediment reflects variations in riverine input and the hydrological cycle over northern tropical South America. A seasonally resolved record of titanium shows that the collapse of Maya civilization in the Terminal Classic Period occurred during an extended regional dry period, punctuated by more intense multiyear droughts centered at approximately 810, 860, and 910 A.D. These new data suggest that a century-scale decline in rainfall put a general strain on resources in the region, which was then exacerbated by abrupt drought events, contributing to the social stresses that led to the Maya demise.     

本溪地区旱涝强度指数变化与预测

利用辽宁省本溪地区1953～2008年的月平均气温和降水资料,分析本溪地区降水量、气温和蒸发量变化特征,确定利用降水量与蒸发量之差的Z指数表征旱涝强度,该指数可以较好地表征本溪地区旱涝强度状况。分析表明,本溪地区旱涝强度指数不但具有显著的年代际变化特征,且年振荡的信号也很强。Mann-Kendall方法检验结果表明,本溪地区温度发生了由冷向暖的转变,1988年气温发生突变。随着年代变化,旱涝指数发生了转变,涝的频率在减少,旱的频率在增加。运用马尔可夫链对旱涝强度指数进行预测,对指导长期预报具有重要的参考作用。     

Climate-driven increases in global terrestrial net primary production from 1982 to 1999

Recent climatic changes have enhanced plant growth in northern mid-latitudes and high latitudes. However, a comprehensive analysis of the impact of global climatic changes on vegetation productivity has not before been expressed in the context of variable limiting factors to plant growth. We present a global investigation of vegetation responses to climatic changes by analyzing 18 years (1982 to 1999) of both climatic data and satellite observations of vegetation activity. Our results indicate that global changes in climate have eased several critical climatic constraints to plant growth, such that net primary production increased 6% (3.4 petagrams of carbon over 18 years) globally. The largest increase was in tropical ecosystems. Amazon rain forests accounted for 42% of the global increase in net primary production, owing mainly to decreased cloud cover and the resulting increase in solar radiation.