Four centuries of vegetation change in the mid-elevation Andean forests of Ecuador

May 29, 2019
WDG

Huisman, S.N.*, Bush, M.B. & McMichael, C.N.H. (2019) Four centuries of vegetation change in the mid-elevation Andean forests of Ecuador. Vegetation History and Archaeobotany. DOI: 10.1007/s00334-019-00715-8

* Seringe conducted the research presented in this paper during her MSc Biological Sciences at the University of Amsterdam.

Loughlin PhD Thesis 2018

July 25, 2018
nicholasloughlin

Nick recovers a sediment core for his PhD project.

Nick Loughlin

Loughlin, N.J.D. (2017) Changing human impact on the montane forests of the eastern Andean flank, Ecuador. PhD Thesis. School of Environment, Earth and Ecosystem Sciences, The Open University.

Abstract:

The montane cloud forests of South America are some of the most biodiverse habitats in the world, whilst also being especially vulnerable to climate change and human disturbance.

Today much of this landscape has been transformed into a mosaic of secondary forest and agricultural fields. This thesis uses palaeoecological proxies (pollen, non-pollen palynomorphs, charcoal, organic content) to interpret ecosystem dynamics during the late Quaternary, unravelling the vegetation history of the landscape and the relationship between people and the montane cloud forest of the eastern Andean flank of Ecuador. Two new sedimentary records are examined from the montane forest adjacent to the Río Cosanga (Vinillos) and in the Quijos Valley (Huila). These sites characterise the natural dynamics of a pre-human arrival montane forest and reveal how vegetation responded during historical changes in local human populations.

Non-pollen palynomorphs (NPPs) are employed in a novel approach to analyse a forest cover gradient across these sites. The analysis identifies a distinctive NPP assemblage connected to low forest cover and increased regional burning. Investigation into the late Pleistocene Vinillos sediments show volcanic activity to be the primary landscape-scale driver of ecosystem dynamics prior to human arrival, influencing montane forest populations but having little effect on vegetation composition.

Lake sediments at Huila from the last 700 years indicate the presence of pre-Hispanic peoples, managing and cultivating an open landscape. The subsequent colonization of the region by Europeans in the late 1500’s decimated the indigenous population, leading to the abandonment of the region in conjunction with an expansion in forest cover ca. 1588 CE. After approximately 130 years of vegetation recovery, montane cloud forest reached a stage of structural maturity comparable to that seen in the pre-human arrival forest. The following 100 years (1718-1822 CE) of low human population and minimal human impact in the region is proposed as a shifted ecological baseline for future restoration and conservation goals. This ‘cultural ecological baseline’ features a landscape that retains many of the ecosystem service provided by a pristine montane forest, while retaining the cultural history of its indigenous people within the vegetation. Continue Reading

Landscape-scale drivers of glacial ecosystem change in the montane forests of the eastern Andean flank, Ecuador

October 20, 2017
WDG

Open acess, online:

Loughlin, N.J.D., Gosling, W.D., Coe, A.L., Gulliver, P., Mothes, P. & Montoya, E. (2017) Landscape-scale drivers of glacial ecosystem change in the montane forests of the eastern Andean flank, Ecuador. Palaeogeography, Palaeoclimatology, Palaeoecology. DOI: 10.1016/j.palaeo.2017.10.011

Keen PhD Thesis 2015

September 30, 2015
WDG

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Keen, H.F. (2015) Past environmental change on the eastern Andean flank, Ecuador. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.

Abstract
The eastern Andean flank of Ecuador (EAF) contains some of the world’s most biodiverse ecosystems. Andean montane forests are threatened due to anthropogenic pressures and both current and projected climate change. This thesis examines the palaeoecological history of two stratigraphic sequences (Mera Tigre West [MTW] and Mera Tigre East [MTE]) obtained from the Ecuadorian modern lower montane forest. The sediments preserved were analysed using eight analytical techniques, allowing an insight into the ecosystem’s potential response to projected changes derived from their past responses. Palaeoecological studies on the EAF are rare, and those that do exist are debated relating to: i) the inference of robust ecological data from pollen records in floristically diverse locations, and ii) the past source area of sediments preserved in fluvially exposed sequences, potentially leading to contamination with older material.

A statistical sub-sampling tool was developed (debate i), capable of producing statistically robust count sizes for each pollen sample; MTW and MTE count sizes ranged from 196-982 showing the diversity within sequences. The depositional environment of MTE was analysed, investigating sediment provenance throughout (debate ii). Results found that large scale volcanic events were critical in the preservation of the sediments, whereas fluvial influence caused a regional sediment source area in the upper stratigraphy, impacting on the palynological interpretation of MTE. Pollen records demonstrated the presence of a diverse vegetation community with no modern analogue at MTE (abundant taxa (>15 %): Hedyosmum, Wettinia, Ilex) and upper montane forest at MTW (Alnus, Hedyosmum, Podocarpus). Fire was not the main driver for the vegetation reassortment at either site (MTW correlation coefficient: -0.37, MTE: 0.16). The two sites have demonstrated the EAF plays host to floristically dynamic ecosystems, susceptible to drivers of change (fire and landscape) and should be considered when predicting the montane forests’ future response to environmental change.

Supervisors: Dr. William D. Gosling (The Open University/University of Amsterdam), Dr. Encarni Montoya and Dr. Sarah Sherlock (both The Open University).
Examiners: Dr. Dunia Urrego (University of Exeter), and Prof. David Gowing (The Open University).
Chair: Dr. Mark Brandon (The Open University).

To borrow a copy from The Open University Library click here.

Publications (so far): Continue Reading

Cardenas PhD thesis 2011

May 20, 2014
WDG

Cárdenas, M.L. (2011) The response of western Amazonian vegetation to fire and climate change: A palaeoecological study. PhD Thesis, Department of Earth & Environmental Sciences, The Open University.

MLC Ecuador (2008)

MLC Ecuador (2008)

Abstract:

Amazonia is one of the most biodiverse regions of the world, a reputation largely earned by the floristic richness of western Amazonia, namely the Ecuadorian Andes. In particular, montane cloud forest in western Amazonia on the Andean flank has been identified as of high ecological value because of its large floristic diversity. Unfortunately, montane forests’ biodiversity have suffered a strong detrimental impact due the ongoing human activity and climate change. Consequently, understanding the dynamics of montane forest and identifying the main factors that control them is fundamental to manage and protect these ecosystems.

This thesis focuses upon paleoecological data obtained from organic sediments from Erazo (Ecuador), located today within the lower montane forest. Examination of modern vegetation and pollen rain close to Erazo revealed florist variation at the kilometer scale related to human disturbance. Modern data provided the basis for interpreting the fossil record. Radiometric dating of interbedded volcanic ash indicates the sediments were deposited c. 324,000-193,000 years ago, well before the arrival of humans in America. Fossil pollen and wood preserved within organic sediments suggest that the composition of the forest was different to modern and changed significantly during the middle Pleistocene. Taxonomic changes in the fossil pollen assemblage, coupled with the presence of Podocarpus spp. macrofossils within the sediments, indicate that temperatures reached c. 5oC cooler than modern. Given the timing and magnitude of vegetation cha

nge observed in the Erazo sediments it therefore seems likely that the variations were instigated by global temperature changes associated with Marine Isotope Stage (MIS) 9 and the MIS 7-6 transition from interglacial-glacial conditions.

The palaeoecological data from Erazo indicate that far from being a relatively stable ‘museums’ tropical forests are in fact dynamic systems undergoing long term floristic re-assortment as well as being susceptible to abrupt short term floristic reorganization.

Supervisors: Dr. William D. Gosling , Dr. Sarah Sherlock, Dr. Vincent Gauci (all The Open University), Prof. Toby Pennington (Royal Botanic Gardens Edinburgh), and Dr. Imogen Poole (University of Aberdeen).

Examined by: Dr. Juan-Carlos Berrio (University of Leicester), and Prof. Simon Kelley (The Open University).

To borrow a copy from The Open University Library click here.

Continue Reading

One short story and five scientific papers thinking about different aspects of ecological change through time.

Chekhov in 1889

Chekhov in 1889 (http://tinyurl.com/ny2msd9)

Short story:

Checkhov, A. (1889) The Pipe

SUMMARY (Will): People have long been concerned about environmental change. Observations of phenological shifts, degradation of ecosystem services and climate change are clearly presented in Checkhov’s “The Pipe” (1889).The key difference is today we have a better idea of why these things are happening!?

Scientific papers:

Garcia, R.A., Cabeza, M., Rahbek, C. & Araújo, M.B. (2014) Multiple dimensions of climate change and their implications for biodiversity. Science 344 1247579
SUMMARY (Phil): This review highlights the alternative metrics used to quantify climate change at different spatial scales, each with its own set of threats and opportunities for biodiversity. It’s a very relevant paper for palaeoecologists, with implications for how we think about climatic estimates we generate, how we interpret ecological shifts in the assemblages we study, and for demonstrating the importance thinking spatially as well as temporally. It also shows how important palaeoecological data is for setting baselines and putting projected climatic change into context.

Garzón-Orduña, I.J., Benetti-Longhini, J.E. & Brower, A.V.Z. (2014) Timing the diversification of the Amazonian biota: butterfly divergences are consistent with Pleistocene refugia. Journal of Biogeography, early online.
SUMMARY (Will): Butterfly species diverged in the Neotropics during the Pleistocene (probably).

Mitchard, E.T.A. et al. (2014) Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites. Global Ecology and Biogeography, early online.
SUMMARY (Will): It is difficult to work out how much carbon is in a tropical forest.

Stansell, N.D., Polissar, P.J., Abbott, M.B., Bezada, M., Steinmann, B.A. and Braun, C. (2014) Proglacial lake sediment records reveal Holocene climate changes in the Venezuelan Andes. Quaternary Science Reviews. 89, 44 – 55.
SUMMARY (Hayley): A study of three lake sediment records in the Venezuelan Andes to look at patterns of glacial variability, and how glaciers might have responded to changing climatic conditions during the last c. 12,000 years.

Still, C.J., Foster, P.N. & Schneider, S.H. (1999) Simulating the effects of climate change on tropical montane cloud forests. Nature, 398, 608–610.
SUMMARY (Nick): The paper attempts to model the impact of climate change on a number of cloud forests around the world by simulating atmospheric parameters at the last glacial maximum (LGM) and at twice today’s CO2 level. The models agrees with palaeoecological data of a downslope migration of the cloud forest at the LGM, while the 2xCO2 model shows reduced cloud cover and increased evapotranspiration, which results in a significant reduction in cloud forest supporting land area.

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