RECONSTRUCTION OF LATE HOLOCENE HYDROCLIMATE AND ENVIRONMENTAL CHANGE IN SOUTHERN CENTRAL AMERICA WITH AN EMPHASIS ON THE TERMINAL CLASSIC DROUGHT (TCD)

2017 ◽  
Author(s):  
Jiaying Wu ◽  
◽  
David Porinchu
The Holocene ◽  
2016 ◽  
Vol 27 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Jiaying Wu ◽  
David F Porinchu ◽  
Sally P Horn

A lake sediment profile spanning the last ~3200 years from Laguna Zoncho in the southern Pacific region of Costa Rica was analyzed for sub-fossil chironomids. Notable shifts in chironomid assemblages occurred during the late-Holocene. A distinct chironomid community, dominated by Tanypodinae such as Procladius and Labrundinia, appeared after ~550 cal. yr BP (~1400 CE). Prior to this time, the chironomid assemblage was more diverse, with taxa such as Paratanytarsus, Tanytarsus type N, and Cladotanytarsus important constituents of the chironomid community. A chironomid-based inference model for mean annual air temperature (MAAT), developed using partial least squares (PLS 2-component), was applied to sub-fossil chironomid assemblages from Laguna Zoncho to reconstruct late-Holocene thermal variability for the region. The key findings from this study are as follows: (1) chironomid-inferred MAAT at ~2740–1220 cal. yr BP (790 BCE–730 CE) was 1.2°C higher than the late-Holocene (~3200 cal. yr BP to present in this study) average of 21.3°C; (2) MAAT at ~470–90 cal. yr BP (1480–1860 CE) was 1.3°C lower than the late-Holocene average, potentially reflecting ‘Little Ice Age’ (LIA) cooling; and (3) evidence for an extended period of low lake levels between 1220 and 840 cal. yr BP (730–1110 CE) possibly indicated the influence of the Terminal Classic Drought (TCD) in southern Costa Rica. This study pioneers the use of sub-fossil chironomid remains to develop quantitative estimates of Holocene thermal variability and environmental change in Central America.


Land ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 228
Author(s):  
Richard L. Johnson

Unauthorized migration under global regimes of border and immigration enforcement has become more risky and costly than ever. Despite the increasing challenges of reaching, remaining in, and remitting from destination countries, scholarship exploring the implications of migration for agricultural and environmental change in migrant-sending regions has largely overlooked the prevalent experiences and consequences of “failed” migration. Drawing from recent fieldwork in Central America with deportees, this paper demonstrates how contemporary migration at times reverses the “channels” of agrarian change in migrant-sending regions: instead of driving remittance inflow and labor loss, migration under contemporary enforcement can result in debt and asset dispossession, increased vulnerability, and heightened labor exploitation. Diverse migration outcomes under expanded enforcement also reveal a need to move beyond the analytical binary that emphasizes differentiations between migrant and non-migrant groups while overlooking the profound socioeconomic unevenness experienced among migrants themselves. With grounding in critical agrarian studies, feminist geographies, and emerging political ecologies of migration, this paper argues that increased attention to the highly dynamic and diverse lived experiences of migration under expanded enforcement stands to enhance our understanding of the multiple ways in which contemporary out-migration shapes livelihoods and landscapes in migrant-sending regions.


The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Valentí Rull ◽  
Núria Cañellas-Boltà ◽  
Teresa Vegas-Vilarrúbia

Palynological analysis of the last ca. 4300 cal year BP using a sediment core taken from high mountain (ca. 1900 m elevation) Lake Sant Maurici sediments (southern-central Pyrenees) showed remarkable vegetation constancy during the Bronze Age and the Middle Ages. Records of the Iron Age and the Roman period were missing due to a major sedimentary gap. During the studied periods, the vegetation around the lake was largely dominated by pine ( Pinus) forests with birch ( Betula), oak ( Quercus) and hazel ( Corylus) trees, as is the case today. The composition of these forests and the abundance of their components remained quite stable, despite the occurrence of temperature and moisture shifts. The degree of human disturbance, notably that of pastoralism and cereal cultivation by scattered and temporary settlements, was very low and had little or no effect on the dominant forests. This situation contrasts with most high-elevation (subalpine and alpine) environments of the central Pyrenees that were massively anthropized during the Middle Ages. Further research should be aimed at finding sediments corresponding to the Iron Age and the Roman period to verify whether the vegetation constancy can be extended throughout the Late-Holocene. Past records of this type may allow the estimation of natural and anthropogenic thresholds for irreversible forest changes, which would be useful for conservation purposes.


2016 ◽  
Vol 8 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Mimi Stith ◽  
Alessandra Giannini ◽  
John del Corral ◽  
Susana Adamo ◽  
Alex de Sherbinin

Abstract A spatial analysis is presented that aims to synthesize the evidence for climate and social dimensions of the “regreening” of the Sahel. Using an independently constructed archival database of donor-funded interventions in Burkina Faso, Mali, Niger, and Senegal in response to the persistence of drought in the 1970s and 1980s, the spatial distribution of these interventions is examined in relation to population density and to trends in precipitation and in greenness. Three categories of environmental change are classified: 1) regions at the northern grassland/shrubland edge of the Sahel where NDVI varies interannually with precipitation, 2) densely populated cropland regions of the Sahel where significant trends in precipitation and NDVI decouple at interannual time scales, and 3) regions at the southern savanna edge of the Sahel where NDVI variation is independent of precipitation. Examination of the spatial distribution of environmental change, number of development projects, and population density brings to the fore the second category, covering the cropland areas where population density and regreening are higher than average. While few, regions in this category coincide with emerging hotspots of regreening in northern Burkina Faso and southern central Niger known from case study literature. In examining the impact of efforts to rejuvenate the Sahelian environment and livelihoods in the aftermath of the droughts of the 1970s and 1980s against the backdrop of a varying and uncertain climate, the transition from desertification to regreening discourses is framed in the context of adaptation to climate change.


Check List ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 1592
Author(s):  
Steven Aguilar ◽  
Julio E. Sánchez ◽  
Daniel Martínez

We present the first record of the Clay-colored Sparrow (Spizella pallida) in Costa Rica. An adult bird was recorded ca. 900 Km south of its common wintering range. This represents the first record of the species for the country and for southern Central America.


2018 ◽  
Vol 38 (4) ◽  
pp. 299-302
Author(s):  
Ernesto Recuero

AbstractMillipede diversity in tropical regions, and in Mexico in particular, is still mostly unknown. A modest but recurrent source of new Mexican species is the colonization of exotic species, due to human activity. The invasive speciesCylindrodesmus hirsutusPocock, 1889 has spread from its area of origin in Indonesia or Melanesia and become a virtually pantropical species. Although long known from South and Central America, reports from the Caribbean are sparse and limited to some eastern islands and southern Central America. On 9 March 2016, two adult specimens were found on Cozumel Island, Quintana Roo, in an area of medium semideciduous tropical forest. This paper comprises the first record of this species from Mexico and the northern Caribbean. Given the intense commercial activity in the region, the presence of more populations both in Cozumel Island and in the mainland coast is highly probable.


2021 ◽  
Author(s):  
Nick Pasiecznik

Abstract A shrubby species (to 5 m tall) from tropical America, where it is common in parts of southern Central America and on many West Indian Islands, in particular on Curacao and Barbados. Since its introduction in the 1920s, it has become naturalized in the Philippines and Indonesia. Its habit is similar to shrubby forms of Leucaena leucocephala (the two species are sometimes confused, but the twigs of A. glauca are more reddish and its pods shorter and more rounded).


Author(s):  
Christopher S. Beekman

This chapter addresses recent research that identifies migration as a specific form of human movement in which social groups move into new social contexts. Migration is inherently disruptive to people’s lives, and it occurs embedded within political, economic, or social processes that make it highly context-specific. I discuss the history of theory in migration research, including recent shifts away from a concern with ethnicity in favour of communities of practice. Late Mesoamerica is a data-rich environment for the study of migration within its social context. The Classic period saw regional political systems that extended their reach economically or militarily and frequently had a demographic component. The widespread disruption of the Epiclassic or Terminal Classic periods included environmental change, political collapse, and a major reorganization of the social landscape. The Postclassic witnessed the re-emergence of complex societies claiming descent from migrant populations. The contributions to this volume come from many different disciplines and assess the timing, causes, perceptions, and impacts of migrations across a variety of social contexts. Political disruption, environmental change, and migration are frequently interrelated in ways reminiscent of our world today.


Sign in / Sign up

Export Citation Format

Share Document