Detecting the presence, and impact, of peoples past impact in ecosystems and landscapes in the tropics is a challenging because the traces that they leave behind are few and disentangling them from ‘natural’ (non-human related) variability is a challenge. As an Associate Editor for Vegetation History & Archaeobotany (VHAA) I enjoy handling manuscripts that think about these issues and explore the role of humans in tropical landscapes. Two recent papers published in VHAA touched on this subject (one of which I “communicated” as an editor).
Bodin et al. (2020) studied charcoal recovered from soil at sites with a gradient of archaeological evidence for past human activity in French Guiana.
Goethals & Verschuren (2019) explored the relationship between the amount of dung fungi found in lake sediments and the herbivore populations living around the lakes.
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
I am sitting on the shore of Lago Condorcillo in Southern Ecuador, after a long day of travel, trying to control my shivering. At roughly 10,500 ft. above sea level, the lake is very cold, with wind that howls over the barren hills dotted with giant boulders. The lake is also almost always blanketed by thick fog and pelted by driving rain. When you’re surrounded by the thick fog punctuated by lightning bolts, it’s easy to believe that some lost civilization lurks just out of sight. Tonight we are experiencing lightning storms, which is adding to the feeling that some angry, ancient life form must live at Lago Condorcillo.
Tomorrow, I will be out in the cold and rain, balancing on an inflatable boat and fighting frostbite. Mark Bush, who is my Ph.D. advisor, Courtney Shadik, who is my lab partner and tent buddy, and I will be collecting cores of mud from the bottom of Condorcillo. We will create our rig for coring by tying two inflatable boats together, and placing a wooden platform between them. Mark, Courtney, and I will then collect our mud cores from this platform.
As I’m contemplating the hazards of camping in a lightning storm, Mark says, “Tell me everything that went wrong today.” Courtney pulls a sleeping bag closer to her. I begin to describe how Google Maps can’t seem to understand distance in the Andes, and so traveling to Lago Condorcillo took much longer than we anticipated. Courtney laughs beside me and adds, “We don’t have any matches to start a fire.” Despite our troubles, I am grinning from ear to ear, no doubt spoiling the grim mood Mark is attempting to cultivate and Lago Condorcillo is doing its best to enforce.
In the 4th edition of our “Amsterdam Paleoecology Club”(APC), we discussed ‘A 6900-year history of landscape modification by humans in lowland Amazonia’ by Bush et al. (2006)1. The high-resolution record presented in this paper shows impressively that what we might perceive as native rainforest today could rather be a since a long time actively modified landscape.
The chronology from Lake Sauce (Peruvian Andes) suggests a continuously forested landscape under significant anthropogenic impact over the last 6900 years. Indicators of human activity are taken to be the varying presence of crop pollen (Zea mays) throughout the record, combined with the continuous occurrence of charcoal. Two extra-large fire events are dated at c. 6700 and between 4500-4230 cal BP, probably enhanced by the relatively drier climate of the mid-Holocene. However, it is not clear yet if human actions formed a response to climate change or were part of social and cultural changes.
This is the first is a series of blog posts based on papers discussed at our “Amsterdam Palaeoecology Club” meetings. The APC meetings are organized to promote palaeoecological discussion and to help the scientific development of our MSc and BSc research students. At each meeting we discuss a paper and the progress of individual projects. Short summaries of the papers and discussions are then made by the student introducing the paper. First up is MSc researcher Rianne van Duinen with her thoughts on Kaplan et al. (2016).
Rianne on field work in Twente during the 2017 edition of the BSc Palaeoecology course at University of Amsterdam
We discussed the paper “Large scale anthropogenic reduction of forest cover in Last Glacial Maximum Europe“ by Kaplan et al. (2016) which was found by the group to be super interesting and it incited a lot of discussion. The paper was mostly concerned with the anthropogenic influences and past vegetation of Europe. The main conclusion was that humans had a very big impact on forests during the last glacial period through the use of fire. The authors suggest that human actions are the explaining factor for the low amount of forests cover suggested by pollen records during the last glacial maximum (c. 21,000 years ago). The suggestion from Kaplan et al. that human modification of forest cover through fire during the glacial links with a recent study from Sevink et al. (2018) that suggests, based on pollen and charcoal data from the Netherlands, that human use of fire altered forest cover into the Holocene. In our discussion it was also noted that animals (mega-herbivores) were not really taken into account or discussed, even though animals probably had a big impact on the vegetation (e.g. see Bakker et al., 2016). Furthermore, another discussion point was the charcoal records that were used in the Kaplan et al. study, more specifically the number of cores. Kaplan et al. only used three cores to map out the effect of charcoal. It would be interesting to see what happens when more data from more cores is used. The Global Charcoal Database has a lot of data on European cores (c. 38% of the cores are from Europe) so there is a lot of potential for this. All in all, the article by Kaplan et al. raised a lot of questions and opened up a nice discussion.
Gosling, W.D., Cornelissen, H. & McMichael, C.N.H. (2019) Reconstructing past fire temperatures from ancient charcoal material. Palaeogeography, Palaeoclimatology, Palaeoecology520, 128-137. DOI: 10.1016/j.palaeo.2019.01.029
Hooghiemstra, H., Olijhoek, T., Hoogland, M., Prins, M., van Geel, B., Donders, T., Gosling, W.D. & Hofman, C. (2018) Columbus’ environmental impact in the New World: Land use change in the Yaque River valley, Dominican Republic. The Holocene. Online DOI: 10.1177/0959683618788732
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
The final day of talks at AFQUA 2018 took a more applied approach in the first session “Applying the Quaternary: The role of the past in supporting the future”. This session focused on how we can focus Quaternary science to produce outputs that directly meet concerns and needs of society. Examples included the quantification of the fossil charcoal record to provide insights into the nature and impact of fires in the past (C. Adolf), how we can use information on past vegetation change and disturbance factors to anticipate how ecosystems on Madagascar might respond to future changes (E. Razanatsoa), and how climate histories can be extended through tree ring data (D. Colombaroli).