Effects of slash-and-burn fallow periods on landscape structure

2003 ◽  
Vol 30 (4) ◽  
pp. 325-333 ◽  
Author(s):  
Jean Paul Metzger
Keyword(s):  
Landscape Structure ◽  
Structural Changes ◽  
Agricultural System ◽  
Ecological Processes ◽  
Tropical Regions ◽  
Fallow Period ◽  
Slash And Burn ◽  
North East ◽  
The North ◽  
Secondary Vegetation

Slash-and-burn is a widespread agricultural system practised by more than 250 million people in tropical regions. It is sustainable when fallow periods allow for the restoration of organic matter and nutrient losses that occur during the cropping phase. However, fallow periods have been reduced in most slash-and-burn systems as population density has increased. The consequent landscape structure modification occurring throughout this process can affect several ecological processes. As a first step in understanding these modifications, the present study aimed to test the effects of fallow period reduction on landscape structure by examining a total of 34 lots of 25–250 ha each in the north-east of the Brazilian Amazon. Sixteen lots with long fallow periods (about 10 years) were compared with 18 lots where fallow periods were reduced to c. four years. The reduction in fallow period created a more homogeneous landscape, largely dominated by agricultural and young secondary vegetation. The main mechanism leading to this homogenization was a more intensive use of initial secondary vegetation for agriculture. On average, the percentage of land used more intensively for agriculture was four times higher in short fallow period areas than in long-period areas. The increase in agricultural area is related to both an increase in the number of agricultural fields and also to an increase in the area of these fields. The proportions of forest and old secondary vegetation in the landscape were reduced as a consequence of a reduction in patch size, without significant fragmentation or patch losses. These structural changes appeared to be more usual in large properties belonging to several families. Further studies are needed to understand the consequences of these modifications for landscape functioning, but it is possible to speculate, based on previous studies, that these structural changes can lead to a reduction in the speed of regeneration processes.

scholarly journals Genetic consequences of climatic oscillations in the Quaternary

2004 ◽  
Vol 359 (1442) ◽  
pp. 183-195 ◽  
Author(s):  
G. M. Hewitt
Keyword(s):  
North America ◽  
Geographical Area ◽  
The Arctic ◽  
Temperate Species ◽  
Genetic Constitution ◽  
Spatial Effects ◽  
Tropical Regions ◽  
Climatic Oscillations ◽  
North East ◽  
The North

An appreciation of the scale and frequency of climatic oscillations in the past few million years is modifying our views on how evolution proceeds. Such major events caused extinction and repeated changes in the ranges of those taxa that survived. Their spatial effects depend on latitude and topography, with extensive extinction and recolonization in higher latitudes and altitudinal shifts and complex refugia nearer the tropics. The associated population dynamics varied with life history and geography, and the present genetic constitution of the populations and species carry attenuated signals of these past dynamics. Phylogeographic studies with DNA have burgeoned recently and studies are reviewed from the arctic, temperate and tropical regions, seeking commonalities of cause in the resulting genetic patterns. Arctic species show distinct shallow genetic clades with common geographical boundaries. Thus Beringia is distinct phylogeographically, but its role as a refugial source is complex. Arctic taxa do not show the common genetic pattern of southern richness and northern purity in north-temperate species. Temperate refugial regions in Europe and North America show relatively deep DNA divergence for many taxa, indicating their presence over several Ice Ages, and suggesting a mode of speciation by repeated allopatry. DNA evidence indicates temperate species in Europe had different patterns of postglacial colonization across the same area and different ones in previous oscillations, whereas the northwest region of North America was colonized from the north, east and south. Tropical montane regions contain deeply diverged lineages, often in a relatively small geographical area, suggesting their survival there from the Pliocene. Our poor understanding of refugial biodiversity would benefit from further combined fossil and genetic studies.

The marine algae of the Solomon Islands and their place in biotic reefs

1969 ◽  
Vol 255 (800) ◽  
pp. 433-442 ◽  
Keyword(s):  
Marine Algae ◽  
Solomon Islands ◽  
North Coast ◽  
General Situation ◽  
Algal Flora ◽  
Tropical Regions ◽  
North West ◽  
North East ◽  
The North ◽  
Marine Algal

The Royal Society Expedition to the Solomon Islands aimed at examining the biogeographical relationships between these islands and other island systems of the western tropical Pacific. The marine party also studied intertidal and reef ecology. Comprehensive collections of benthic marine algae were made at the main localities visited (Florida Islands, north-west and south-east Guadalcanal, Matiu Island off the north coast and Batuona and Ulukoro Islands off the south coast of New Georgia, Banika Island in the Russell Islands, and south-east Gizo Island). Additional small collections were obtained from Kolombangara and the north coast of San Cristobal. Habitat notes accompanied each collection and preliminary determinations were made in the field where possible. General ecological observations on the reefs included profiles selected after a preliminary survey of an area. Such profiles (see below) indicate the general situation but are not based on detailed transect work; restricted time and the great variation in distribution of organisms over the reef surface (especially in the moat) rendered isolated detailed transects of limited value. The marine algal flora of the Solomon Islands has been one of the least known in tropical regions. Setchell (1935) recorded nine species from Malaita Island and also several taxa from Sikaiana Island (in the Stewart Islands, north-east of Malaita Island) and from Bellona Island, south of the Solomon Islands. Levring (i960) recorded a number of species from Rennell Island, near Bellona Island. Otherwise there are only a few scattered records in taxonomic monographs.

scholarly journals Contrasted hybridization patterns between two local populations of European wildcats in France

2018 ◽  
Author(s):  
Beugin Marie-Pauline ◽  
Salvador Olivier ◽  
Leblanc Guillaume ◽  
Queney Guillaume ◽  
Natoli Eugenia ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Local Population ◽  
Geographic Location ◽  
Domestic Cat ◽  
Ecological Processes ◽  
Fragmented Habitat ◽  
North East ◽  
The North ◽  
Northeastern France

ABSTRACTThe European wildcat (Felis silvestris silvestris) is threatened across the totality of its area of distribution by hybridization with the domestic cat F.s. catus. The underlying ecological processes promoting hybridization, remain largely unknown. In France, wildcats are mainly present in the North-East but signs of their presence in the Pyrenees have been recently provided. However, no studies have been carried out in the French Pyrenees to assess the genetic status of wildcats. We have compared a local population of wildcats living in a continuous habitat in the French Pyrenees and a local population of wildcats living in a fragmented habitat in Northeastern France to evaluate how habitat fragmentation influence the population structure of European wildcats. Close kin were not found in the same geographic location contrary to what was observed for females in the Northeastern wildcat population. Furthermore, there was no evidence of hybridization in the Pyrenean wildcats and only one domestic cat raised suspicions while hybridization was categorically detected in northeastern France. The two wildcat populations were significantly differentiated (Fst = 0.08) and the genetic diversity of the Pyrenean wildcats was lower than that of other wildcat populations in France and in Europe. Taken together, these results suggest that habitat fragmentation, and in particular the absence of agricultural fields, may play an important role in lowering the probability of hybridization by reducing the likelihood of contact with domestic cats. Moreover, our results suggest that the French Pyrenean wildcat populations is isolated and may be threatened by a lack of genetic diversity.

scholarly journals Whatever happened to the North East? Reflections on the end of regionalism in England

2018 ◽  
Vol 33 (8) ◽  
pp. 842-861 ◽  
Author(s):  
Keith Shaw ◽  
Fred Robinson
Keyword(s):  
Structural Changes ◽  
Central Government ◽  
Longitudinal Research ◽  
Regional Governance ◽  
Regional Level ◽  
Small Scale ◽  
North East ◽  
The North ◽  
External Relationships ◽  
Economic Austerity

Governance in the English regions has been undermined and weakened by recent structural changes. Although well established during the New Labour era, the regional level of governance in England did not survive the post-2010 process of institutional churn shaped by economic austerity and central government’s aversion to the regional level. This has subsequently led to rescaling to the sub-regional level and the introduction of devolution ‘deals’ involving new combined authorities with elected mayors. This article looks at the experience of North East England, where regional structures have been broken up and the region disempowered by such changes. It reviews what has happened to governance in the North East over the past 20 years and discusses why the dismantling of regional governance matters. While the region’s external relationships with central government are problematic, it is also argued that governance problems within the region are no less important and need reforming. Longitudinal research indicates that organisations providing public services in the North East have continued to be characterised by inadequate accountability, unrepresentative governance and lack of transparency. The combined effects of the devolutionary consequences of Brexit and the ineffectiveness of small-scale ‘devo-deal’ interventions mean that the ‘Regionalist case’ in England will need to be refashioned and restated. The article concludes by considering the case for reintroducing regional-level governance and points to ways of bolstering the accountability and effectiveness of this level of sub-national governance.

scholarly journals Atypical voltinism in mulberry silkworm Bombyx mori L., 1758 (Lepidoptera: Bombycidae) races Barapat and Barapolu

2021 ◽  
Vol 3 ◽  
pp. ec03001
Author(s):  
Kiran Rudramuni ◽  
Shiv Kumar ◽  
Bharath K. Neelaboina ◽  
Mir N. Ahmad ◽  
Sukhen R. Chowdhury
Keyword(s):  
Bombyx Mori ◽  
Embryonic Diapause ◽  
Tropical Regions ◽  
Diapausing Eggs ◽  
North East ◽  
The North ◽  
Bombyx Mori L ◽  
The Difference ◽  
Mulberry Silkworm ◽  
Silkworm Bombyx Mori

The mulberry silkworm, Bombyx mori L., 1758 (Lepidoptera: Bombycidae) is classified as univoltine, bivoltine, and polyvoltine based on the annual brood frequency. Voltinism in B. mori is characterized by the occurrence of embryonic diapause (facultative and obligatory diapause). Univoltine silkworms suited to cold and temperate regions lay diapausing eggs and polyvoltine silkworms suited to tropical regions lay non-diapausing eggs. In contrast, the occurrence of diapause in bivoltine silkworms is influenced by the environment. In addition to the difference in the occurrence of embryonic diapause, larval duration, and cocoon characters show distinct variations. In the present correspondence, we are presenting an interesting observation from two silkworm races Barapath and Barapolu originating from the North-East region of India that display divergence in voltinism. The unique characteristic features of univoltine, bivoltine, and polyvoltine observed in the races are discussed explaining the occurrence.

Ras al Khaimah: further archaeological discoveries

Antiquity ◽  
1976 ◽  
Vol 50 (200) ◽  
pp. 216-222
Author(s):  
Beatrice De Cardi
Keyword(s):  
United Arab Emirates ◽  
The State ◽  
Focused Attention ◽  
North East ◽  
The North ◽  
History Of ◽  
The City

Ras a1 Khaimah is the most northerly of the seven states comprising the United Arab Emirates and its Ruler, H. H. Sheikh Saqr bin Mohammad al-Qasimi, is keenly interested in the history of the state and its people. Survey carried out there jointly with Dr D. B. Doe in 1968 had focused attention on the site of JuIfar which lies just north of the present town of Ras a1 Khaimah (de Cardi, 1971, 230-2). Julfar was in existence in Abbasid times and its importance as an entrep6t during the sixteenth and seventeenth centuries-the Portuguese Period-is reflected by the quantity and variety of imported wares to be found among the ruins of the city. Most of the sites discovered during the survey dated from that period but a group of cairns near Ghalilah and some long gabled graves in the Shimal area to the north-east of the date-groves behind Ras a1 Khaimah (map, FIG. I) clearly represented a more distant past.

Lichens in the North-East regions of Cyprus

1999 ◽  
Vol 110 (5-6) ◽  
pp. 455-463 ◽  
Author(s):  
S. Güvenç ◽  
Ş Öztürk
Keyword(s):  
North East ◽  
The North

TBE in Italy

2019 ◽  
Author(s):  
Valentina Tagliapietra ◽  
Flavia Riccardo ◽  
Giovanni Rezza
Keyword(s):  
Case Series ◽  
East Part ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low incidence country for tick-borne encephalitis (TBE) in Europe. Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.

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