Category: Labwork

In order for us to determine the impact of past human activity on local vegetation communities, we rely on a range of proxy (or substitute) indicators. The most common of these, fossil pollen and phytoliths (silica bodies found within certain plant cells), can be used to identify changes in vegetation composition over time. However, these records are not without their limitations. For example, the size and shape of pollen grains can affect how far they travel, while a plant’s method of pollination (e.g., wind versus animal dispersal) influences the number of grains it produces.

These distorting factors make it necessary to understand the relationship between different vegetation communities and the pollen assemblages they produce. One of our postdocs, Joe Hirst, is currently investigating this in the forest communities of the Bladen reserve. During last year’s fieldwork, pollen traps were set up across several of our botanical plots to measure the associated pollen rain. Those traps have now returned to the University of Exeter, giving us a first glimpse of the pollen grains they collected. You can see some of them on this page.

In addition to investigating the relationships between humans and the vegetation communities of the Bladen valley, our team members are constantly engaging and collaborating with the wider Mayanist archaeological community. Joe Hirst is currently working with Sam Krause (Texas State University), Tim Beach, and Sheryl Luzadder-Beach (University of Texas at Austin) to reconstruct human-induced changes in vegetation and fire activity at Laguna Verde, a lake within the Blue Creek area of northern Belize. Blue Creek has an extensive history of human habitation and cultivation, with prior pollen work at Laguna Verde indicating that the local area was a site of wetland cultivation during the Archaic and Preclassic periods^1,2. Joe is working on a different sediment core collected from the lake to produce a new record of human-induced environmental change in this incredible setting.

1. Beach et al. 2009 “A review of human and natural changes in Maya Lowland wetlands over the Holocene” Quaternary Science Reviews ↩︎
2. Morse 2009 “Pollen from Laguna Verde, Blue Creek, Belize: Implications for paleoecology, paleoethnobotany, agriculture, and human settlement” PhD Thesis, Texas A&M ↩︎

The first project phytolith identification is in! Dr. Harper Dine identified a spheroid echinate phytolith from Arecaceae (the palm family) after processing the first batch of Bladen Legacy sediments. A palm (Asytrocaryum mexicanum) was one of the most abundant trees in the 2024 botanical plots, including the botanical plot that this phytolith came from, so this identification goes hand-in-hand with ecological observations on the ground.

Phytoliths are produced by plants within and between their cells. Made up of biogenic silica, these structures can often survive in soils long after the plant that produced them has decayed.

Contributed by Dr. Harper Dine

Phytolith processing of soils collected during the 2024 field season has begun at the University of Exeter Chem Lab! To maximize phytolith visibility under the microscope, the soils must undergo an extensive sequence of steps including deflocculation (breaking up clumps), sieving, clay removal, and digestion of carbonates and organics. Here you can see the dramatic before-and-after from clay removal.

Phytolith datasets from these samples will contribute to our understanding of long-term ecology, plant management, and agriculture in the region. Keep an eye out for exciting updates!

Sediments retrieved during the 2024 field season will be analysed for pollen, charcoal, and phytolith content, along with their geochemical composition. These components reveal the environments through time present in the Bladen project area.

This week, the lab at the University of Exeter is up and running for macrocharcoal analysis. This dataset will reveal fire incidence through time. More soon!