Regeneration and population structure of Heliconia acuminata in Amazonian secondary forests with contrasting land-use histories

2005 ◽  
Vol 21 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Emilio M. Bruna ◽  
Maria Beatriz Nogueira Ribeiro
Keyword(s):  
Land Use ◽  
Population Structure ◽  
Tropical Forest ◽  
Human Activities ◽  
Secondary Forests ◽  
Cattle Ranching ◽  
Economic Return ◽  
Treefall Gaps ◽  
Disturbed Areas ◽  
Tropical Landscapes

An estimated 154 million ha of tropical forest are cleared each year by human activities such as cattle ranching and agriculture (Whitmore 1997). When the economic return of these sites declines, they are often abandoned and allowed to regenerate. As a result, ‘secondary’ or ‘regenerating’ forests are becoming an increasingly common feature in tropical landscapes (Guariguata & Ostertag 2001). Unlike treefall gaps and other ‘naturally’ disturbed areas, the regeneration of secondary forests on anthropogenically disturbed lands does not always follow a predictable pathway (reviewed in Guariguata & Ostertag 2001). Instead, the type and intensity of post-clearing land use has major implications for the trajectory along which succession proceeds (Guariguata & Ostertag 2001, Mesquita et al. 2001, Uhl et al. 1988).

scholarly journals Diazotrophs Show Signs of Restoration in Amazon Rain Forest Soils with Ecosystem Rehabilitation

2020 ◽  
Vol 86 (10) ◽  
Author(s):  
Babur S. Mirza ◽  
Daniel J. McGlinn ◽  
Brendan J. M. Bohannan ◽  
Klaus Nüsslein ◽  
James M. Tiedje ◽  
...  
Keyword(s):  
Land Use ◽  
Tropical Forest ◽  
Tropical Forests ◽  
High Throughput Sequencing ◽  
Secondary Forests ◽  
Β Diversity ◽  
Community Turnover ◽  
Tropical Forest Ecosystem ◽  
The Impact ◽  
Diazotrophic Community

ABSTRACT Biological nitrogen fixation can be an important source of nitrogen in tropical forests that serve as a major CO2 sink. Extensive deforestation of the Amazon is known to influence microbial communities and the biogeochemical cycles they mediate. However, it is unknown how diazotrophs (nitrogen-fixing microorganisms) respond to deforestation and subsequent ecosystem conversion to agriculture, as well as whether they can recover in secondary forests that are established after agriculture is abandoned. To address these knowledge gaps, we combined a spatially explicit sampling approach with high-throughput sequencing of nifH genes. The main objectives were to assess the functional distance decay relationship of the diazotrophic bacterial community in a tropical forest ecosystem and to quantify the roles of various factors that drive the observed changes in the diazotrophic community structure. We observed an increase in local diazotrophic diversity (α-diversity) with a decrease in community turnover (β-diversity), associated with a shift in diazotrophic community structure as a result of the forest-to-pasture conversion. Both diazotrophic community turnover and structure showed signs of recovery in secondary forests. Changes in the diazotrophic community were primarily driven by the change in land use rather than differences in geochemical characteristics or geographic distances. The diazotroph communities in secondary forests resembled those in primary forests, suggesting that at least partial recovery of diazotrophs is possible following agricultural abandonment. IMPORTANCE The Amazon region is a major tropical forest region that is being deforested at an alarming rate to create space for cattle ranching and agriculture. Diazotrophs (nitrogen-fixing microorganisms) play an important role in supplying soil N for plant growth in tropical forests. It is unknown how diazotrophs respond to deforestation and whether they can recover in secondary forests that establish after agriculture is abandoned. Using high-throughput sequencing of nifH genes, we characterized the response of diazotrophs’ β-diversity and identified major drivers of changes in diazotrophs from forest-to-pasture and pasture-to-secondary-forest conversions. Studying the impact of land use change on diazotrophs is important for a better understanding of the impact of deforestation on tropical forest ecosystem functioning, and our results on the potential recovery of diazotrophs in secondary forests imply the possible restoration of ecosystem functions in secondary forests.

Changes in soil bacterial communities, and carbon and nitrogen metrics as potential indicators of land use effects in a humid tropical forest

Pedobiologia ◽  
2021 ◽  
Vol 85-86 ◽  
pp. 150730
Author(s):  
William D. Eaton ◽  
Katie M. McGee ◽  
Morgan Larimer ◽  
Elizabeth Hoke ◽  
Olivia Karas ◽  
...  
Keyword(s):  
Land Use ◽  
Tropical Forest ◽  
Bacterial Communities ◽  
Carbon And Nitrogen ◽  
Soil Bacterial Communities ◽  
Land Use Effects ◽  
Humid Tropical Forest ◽  
Soil Bacterial

Land‐use change erodes trophic redundancy in tropical forest streams: evidence from amino acid stable isotope analysis

2021 ◽  
Author(s):  
Kenny W.J. Chua ◽  
Jia Huan Liew ◽  
Clare L. Wilkinson ◽  
Amirrudin B. Ahmad ◽  
Heok Hui Tan ◽  
...  
Keyword(s):  
Land Use ◽  
Amino Acid ◽  
Stable Isotope ◽  
Land Use Change ◽  
Tropical Forest ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Forest Streams ◽  
Acid Stable

Bewirtschaftung von tropischen Sekundärwäldern

2002 ◽  
Vol 46 (1) ◽  
Author(s):  
Dietrich Schmidt-Vogt
Keyword(s):  
Land Use ◽  
Forest Cover ◽  
Stand Structure ◽  
Secondary Forest ◽  
Secondary Forests ◽  
Tropical Asia ◽  
Land Use Systems ◽  
The Future ◽  
The Tropics ◽  
Primary Forests

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.

Landscape Pattern Analysis of Land Use in Low Mount Hilly Land of Harbin Eastern Suburb

2014 ◽  
Vol 641-642 ◽  
pp. 514-518
Author(s):  
Hai Hong Song ◽  
Yun Feng Tan
Keyword(s):  
Land Use ◽  
Landscape Pattern ◽  
Human Activities ◽  
Pattern Analysis ◽  
Landscape Index ◽  
Patch Type ◽  
Landscape Pattern Analysis ◽  
Patch Shape ◽  
Patch Connectivity ◽  
Landscape Patch

This article analyzes the general characteristics and its causes of the landscape pattern of land use, taking the Tuanjie town of DaoWai district in Harbin as an example. Using GIS and Fragstats software to calculate a series of landscape index, the data show that Tuanjie town is given priority to with agriculture landscape, and the landscape patch connectivity is stronger; the overall landscape patch shape is complex, showing the human activities interfere significantly; and each patch type concentration and fragmentation is quite different. Therefore, based on the use of their own advantages, put forward reasonable suggestions to the landscape optimization of Tuanjie town land use.

Tropical Forest for Sale! An Interdisciplinary Land-Use Simulation

1998 ◽  
Vol 60 (9) ◽  
pp. 677-680 ◽  
Author(s):  
Sara Krauskopf
Keyword(s):  
Land Use ◽  
Tropical Forest

scholarly journals Emissions of Nitrous Oxide and Nitric Oxide from Soils of Native and Exotic Ecosystems of the Amazon and Cerrado Regions of Brazil

2001 ◽  
Vol 1 ◽  
pp. 312-319 ◽  
Author(s):  
Eric A. Davidson ◽  
Mercedes M.C. Bustamante ◽  
Alexandre de Siqueira Pinto
Keyword(s):  
Nitric Oxide ◽  
Land Use ◽  
Nitrous Oxide ◽  
Photochemical Reactions ◽  
N2o Emissions ◽  
Secondary Forests ◽  
Soil Emissions ◽  
Amazonian Forests ◽  
The Impact ◽  
No Emissions

This paper reviews reports of nitrous oxide (N2O) and nitric oxide (NO) emissions from soils of the Amazon and Cerrado regions of Brazil. N2O is a stable greenhouse gas in the troposphere and participates in ozone-destroying reactions in the stratosphere, whereas NO participates in tropospheric photochemical reactions that produce ozone. Tropical forests and savannas are important sources of atmospheric N2O and NO, but rapid land use change could be affecting these soil emissions of N oxide gases. The five published estimates for annual emissions of N2O from soils of mature Amazonian forests are remarkably consistent, ranging from 1.4 to 2.4 kg N ha–1 year–1, with a mean of 2.0 kg N ha–1 year–1. Estimates of annual emissions of NO from Amazonian forests are also remarkably similar, ranging from 1.4 to 1.7 kg N ha–1 year–1, with a mean of 1.5 kg N ha–1 year–1. Although a doubling or tripling of N2O has been observed in some young (<2 years) cattle pastures relative to mature forests, most Amazonian pastures have lower emissions than the forests that they replace, indicating that forest-topasture conversion has, on balance, probably reduced regional emissions slightly (<10%). Secondary forests also have lower soil emissions than mature forests. The same patterns apply for NO emissions in Amazonia. At the only site in Cerrado where vegetation measurements have been made N2O emissions were below detection limits and NO emissions were modest (~0.4 kg N ha–1 year–1). Emissions of NO doubled after fire and increased by a factor of ten after wetting dry soil, but these pulses lasted only a few hours to days. As in Amazonian pastures, NO emissions appear to decline with pasture age. Detectable emissions of N2O have been measured in soybean and corn fields in the Cerrado region, but they are modest relative to fluxes measured in more humid tropical agricultural regions. No measurements of NO from agricultural soils in the Cerrado region have been made, but we speculate that they could be more important than N2O emissions in this relatively dry climate. While a consistent pattern is emerging from these studies in the Amazon region, far too few data exist for the Cerrado region to assess the impact of land use changes on N oxide emissions.

scholarly journals A multi-approach analysis of the genetic diversity in populations of Astyanax aff. bimaculatus Linnaeus, 1758 (Teleostei: Characidae) from Northeastern Brazil

2008 ◽  
Vol 6 (4) ◽  
pp. 621-630 ◽  
Author(s):  
Vanessa de Carvalho Cayres Pamponet ◽  
Paulo Luiz Souza Carneiro ◽  
Paulo Roberto Antunes de Mello Affonso ◽  
Viviam Souto Miranda ◽  
Juvenal Cordeiro Silva Júnior ◽  
...  
Keyword(s):  
Population Structure ◽  
Human Activities ◽  
Evolutionary History ◽  
Main Channel ◽  
Northeastern Brazil ◽  
Dam Reservoir ◽  
Effective Barrier ◽  
Significant Difference ◽  
Genetic Patterns ◽  
Structure Index

Few reports are available about the ichthyofauna of typical semi-arid rivers, although the regional diversity has been constantly threatened by human activities, mainly related to impoundment and construction of dams. The goal of the present work was to evaluate using different methods, the population genetic structure of a characin fish, Astyanax aff. bimaculatus, widespread throughout hydrographic basins of Bahia, Northeastern Brazil. Morphological (meristic and morphometric data), cytogenetic (karyotype and Ag-NOR), and molecular (RAPD and SPAR) analyses were carried out in specimens collected upstream and downstream of Pedra Dam, in the main channel of Contas River (Contas River Basin), and in the Mineiro stream, which belongs to the adjacent Recôncavo Sul basin. Few external differences were detected among populations, where the individuals collected upstream of Pedra Dam were slightly larger than the others. Cytogenetic data also showed a similar karyotypic pattern (2n=50; 6m+28sm+12st+4a; FN= 96) and NORs located on the short arms of up to two chromosome pairs, with numerical inter- and intra-populational variation. Nonetheless, RAPD and SPAR analyses differentiated reliably the three populations, revealing striking differences in the allele frequencies among the localities studied and a significant difference in population structure index (Fst=0.1868, P<0.0001). The differences between populations within a same river were as significant as those between distinct hydrographic basins, indicating that the dam/reservoir represents an effective barrier to gene flow. Additionally, environmental peculiarities from each locality are also believed to influence the genetic patterns detected herein. On the other hand, the similarity between samples from Contas River and Recôncavo Sul basins could be related to a common evolutionary history, since both basins are geographically close to each other. Finally, the present study shows that a multi-approach analysis is particularly useful in identifying the population structure of widely distributed species and to evaluate the impacts of human activities on natural fish populations.

scholarly journals Heavy metal pollution affected by human activities and different land-use in urban topsoil: A case study in Rafsanjan city, Kerman province, Iran

2016 ◽  
Vol 5 (2) ◽  
pp. 97 ◽  
Author(s):  
Milad Mirzaei Aminiyan ◽  
Farzad Mirzaei Aminiyan ◽  
Rouhollah Mousavi ◽  
Amin Heydariyan
Keyword(s):  
Heavy Metal ◽  
Land Use ◽  
Metal Pollution ◽  
Human Activities ◽  
Heavy Metal Pollution ◽  
Urban Topsoil
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