Bush MB. 2020. New and repeating tipping points: The interplay of fire, climate change, and deforestation in Neotropical ecosystems. Annals of the Missouri Botanical Garden 105:393-404. DOI: 10.3417/2020565
USING PALAEOECOLOGICAL PROXIES TO DETERMINE ANTHROPOGENIC IMPACT ON VEGETATION DURING PRE-COLONIAL, COLONIAL AND POST-COLONIAL PERIOD IN KENYA’S HIGHLANDS-CASE STUDY ABERDARE RANGES
In spite of the challenges and uncertainties that the larger scientific community is currently facing, I am delighted and humbled to accept one of the British Ecological Society’s Ecologist in Africa research grant for 2020. The grant will support my historical ecology project whose main goal is to apply palaeoecological and archaeological proxies to investigate the extent of anthropogenic impacts on vegetation structure and composition of one of the Kenyan Central highlands before, during, and after the colonial period.
The Aberdare range forest provide an ideal setting for this study because they have been farmed by local populations since long before colonialism, and they were heavily impacted during colonial times because of their fertile soils. This pilot project aims to reveal the land-use and land-cover dynamics of the Aberdare range forest, and it is hoped that eventually similar studies will be undertaken in other parts of the Kenyan highland forests.
An African Pollen Database data steward training event was held at the Institute for Biodiversity & Ecosystem Dyanmics (University of Amsterdam, 27-29 January 2020) where training in the use of the Neotoma database was provided by Eric Grimm. The participants are now enabled curate and archive data within Neotoma. If you have a palaeoecological data set that you would like to contribute to Neotoma, or if you would like training as well, these people can now help you. Contact details below:
The African Pollen Database (APD; Vincens et al., 2007) has recently received a new life thanks to the work of Anne-Marie Lezine, Eric Grimm, Sarah Ivory and Jack Williams who have obtained funding to develop the digital infrastructure and link to the Neotoma Palaeoecology Database (Williams et al., 2018) and the Institut Pierre-Simon Laplace (IPSL) Paleoclimate database. The kick off meeting was held at the IRD centre in Bondy (October 2019), and the next step (training the data stewards) will be held in my department within the Institute for Biodiversity & Ecosystems Dynamics (University of Amsterdam) next week (January 2020).
We are delighted to be able to host sixteen researchers of many nationalities conducting research in many different countries. The aim of the training event is to provide researchers with the skills to manage Neotoma and strengthen the African pollen research community. I am excited to be involved, I am confidence that much new research will be brought together, and I hope that we can get good plans in place for further steps and growth of this network.
Vincens, A., Lézine, A.-., Buchet, G., Lewden, D. & Le Thomas, A. (2007) African pollen database inventory of tree and shrub pollen types. Review of Palaeobotany and Palynology 145, 135-141. DOI: 10.1016/j.revpalbo.2006.09.004
Williams, J.W., Grimm, E.C., Blois, J.L., Charles, D.F., Davis, E.B., Goring, S.J., Graham, R.W., Smith, A.J., Anderson, M., Arroyo-Cabrales, J., Ashworth, A.C., Betancourt, J.L., Bills, B.W., Booth, R.K., Buckland, P.I., Curry, B.B., Giesecke, T., Jackson, S.T., Latorre, C., Nichols, J., Purdum, T., Roth, R.E., Stryker, M. & Takahara, H. (2018) The Neotoma Paleoecology Database, a multiproxy, international, community-curated data resource. Quaternary Research 89, 156-177. DOI: 10.1017/qua.2017.105
Fast forward to 2019, the Aguarico is now lined by small homesteads interspersed with larger settlements, some laid out by the oil companies, and a couple of oil ports. I asked our guide how far the park was ahead of us, and he looked surprised and said “We are in it”. When we arrived at the Zancudo River there was a cell tower and a village of probably 30-50 houses on the junction with the Aguarico. Ten minutes downstream was a tourist lodge. What a difference! The frontier had expanded ~140 km down the Aguarico. One family with a shotgun eliminates all game larger than a marmoset within 5 km, and these homesteads were packed so tight it was unsurprising that we saw almost no wildlife.
The next day we ventured onto Zancudococha. The Zancudo stream was still pretty, overhung by trees, and had no barriers to navigation. Three boats full of tourists passed us coming out of the lake, clearly having spent the night there. There were no logs to clear, and the path through the Montricardia marsh was two boats wide. There are only two patches of high, dry land on the edge of the lake. One was regularly used as a campsite and the other had a lodge built on it that was operated intermittently by the Zancudo community.
We saw no monkeys, let alone tapirs, this was an empty forest. But we weren’t there to be ecotourists, we were there to raise a sediment core. This time our questions were about the Pre-Columbian use of the lake. Was the lake occupied prior to European arrival? How much did people alter the forest? Was there a surge of forest regrowth following Conquest? Given these questions, the 1 m of sediment that we recovered with a Universal piston corer was all that we needed. One meter of mud from this system spans about 1500 years and that would provide us with the trajectory of use (or non-use) into the colonial period and its aftermath. Our mood in camp was happy, we had been successful in our intent. So, my message is you can’t go back to find what was there before, but that doesn’t mean that it will be a bad experience. Shifting baselines apply to nature in every setting, but they also apply to science as our questions and interests undergo inter-generational changes.
Mark Bush is a Professor of Biological Science at the Florida Institute of Technology, Melbourne, FL, USA.
The next two days were spent in motorized dugouts sitting on our gear bags, with tarps pulled over us. Every now and then the driving rain would relent and we would see macaws and toucans flying across the Aguarico River. We stayed one night in a village that had been abandoned due to recent floods, another with Siona hunters who were preparing their blow darts (for monkeys). There were very few houses along the river and we hardly saw another boat in three days. Then we arrived, well almost. We had turned off the main channel onto the tiny Zancudo river. Little used, this stream was a jumble of fallen trees that the Siona chopped their way through. A large tree just beneath the surface posed a problem that was solved by stripping the bark from Cecropiatrees and laying it inside surface facing up, backing up, revving the engine, and aiming straight for the bark. The slick insides of the Cecropiaallowed the canoes to shoot the trunk and on we went. Then we reached the marsh. When I say ‘marsh’ it was a forest of Montricardia arborescens. This is an aquatic Aroid that grows about 3 m high. The trunks are about 3-5 cm in diameter and is THE favored hangout for caiman and anaconda (I have since learned). No Siona in their right mind gets out of a boat in such a marsh and so we were stuck……so close but yet so far. Our only chance of getting through the marsh was to hop out of the boats and pull them through.
We had two boats and so the most dispensable members of the team, Paulo de Oliveira and I, were given the job of hauling the boats. A couple of happy hours later we were through the marsh and onto the lake.
Our first jobs were to find somewhere dry enough to camp, unload, set up camp, and survey the lake. Paul Colinvaux the team leader always launched an inflatable and surveyed the lake on first arrival. Meanwhile the rest of us set up camp. About 20 minutes into all this activity there was the unmistakable crack of a shotgun. In a few more minutes the Chief’s sons emerged from the forest with the news that they had shot a large tapir. The tapir fed the group for the next few days, but I ate tuna and a sausage that had turned blue and slimy, unable to reconcile my role in, what to me, was an unfortunate outcome of our petitioning the Siona to bring us to their sacred lake. The coring was more successful than at Cuyabeno in that we recovered 5m of sediment, but it was clearly a young system and wouldn’t answer our research question. This expedition was a disappointment scientifically, but an incredible snapshot along the gradient of Amazonian development.
To be continued…
We are often told that you “cannot go back”, meaning that a place that provided wonderful memories will disappoint when revisited. Putting this into current conservation-speak we don’t like to be reminded that our baselines are shifting. Recently I had a chance to revisit a part of Ecuadorean Amazonia I had not been to for 30 years. I was a bit hesitant to go. Would I be disappointed or could the experience live up to my recollection?
In 1988, I went on a lengthy field season in Ecuador. We were searching for a glacial-age record that could test the refugial hypothesis of Amazonian speciation. Some lakes that lay in Ecuadorian Amazonia showed promise as they appeared to be a long way from major river channels, and only connected by their outlets into the Cuyabeno River. Would these lakes hold glacial-aged records? Would they show a history of rainforest or savanna during the last ice age?
We started from the frontier town of Lago Agrio, which was rough in every way, dirty, and somewhere we couldn’t wait to leave. Driving to the end of the road and then picking up motorized canoes we were, by nightfall, able to get to the first tourist/research lodge to be established in what is now the Cuyabeno Faunistic Reserve. The trip there was basically uneventful, but a quick tour of the lake in our motorized dugout revealed a substantial inflowing river that had been hidden by cloud on the aerial imagery. We had been hoping for a headwater system, not an essentially riverine lake. Nevertheless, we cored the middle of the lake. The coring was tough as the river was washing clays into the system and these settled to form stiff, sticky, gray sediments. After one or two meters of coring, hammering was essential to get any penetration, but getting the core back out was the real challenge. The inflatable boats were sinking as we strained upward on the coring rig, but still we couldn’t break the device free from the clay. We tried everything: we clamped the boats to the coring rig when they were fully flooded, then bailed the boats out, hoping the added buoyancy would break the corer free. It didn’t. So we refilled the boats, re-clamped, bailed, and then all jumped out. Still nothing. In the end we resorted to the nuclear option, which is to hammer upward on the drill rig. The modified Livingstone coring rig we were using was designed to be hammered downward, but hammering upward can seriously damage the drill string. Nevertheless, it worked. Darkness was closing over us by the time we managed to free the rig, but already we knew that the core wasn’t the glacial-age record we had been hoping for. Faces in camp that evening were pretty glum. As the old axiom goes, we defined insanity by repeating the procedure in the next lake in the chain and, unsurprisingly, got the same outcome – another young core.
We resolved to move on and try another target system, Laguna Zancudococha. Our hosts and guides were members of the Siona nation, and their Hako (Chief) was a vibrant 82-year old called Victoriano. There was a long discussion deciding whether we could go to Zancudococha as it was their ‘origin’ lake and therefore sacred. Eventually, it was decided that we could go. The journey would take at least two days and although Victoriano knew the way, none of the others had been there before.
To be continued…
Zhang, Y., van Geel, B., Gosling, W.D., Sun, G., Qin, L. & Wu, X. (2019) Typha as a wetland food resource: evidence from the Tianluoshan site, Lower Yangtze Region, China. Vegetation History and Archaeobotany. DOI: 10.1007/s00334-019-00735-4