Author: beawedeux

Making sense of canopies

Béatrice Wedeux and David Coomes published a paper in Biogeosciences analysing how environmental factors and selective logging interact to shape the canopies of tropical forests. Using airborne laser scanning technology across a 750 km2peat swamp forest landscape in Borneo, the study reveals strong shifts in canopy height and gap patterns along environmental gradients linked to changing peat depth. In areas where logging roads were detected on historical satellite imagery, the canopy is lowered and has larger gaps, especially so on deep peat where tree growth is thought to be limited by low nutrient availability and waterlogging. The study identifies a close link between the height and the gap structure of tropical peat swamp forests at the landscape scale and reinforces the vulnerability of this ecosystem to human disturbance. The degradation of tropical peat swamps has been at the heart of climate negotiations in Paris, as emissions from fires in Indonesian peatlands over the last couple of months – exacerbated by a dry El Niño spell – approach the total annual emissions of Brazil (1.62 billion metric tons;www.wri.org).

image

Airborne laser scanning allows the detection of openings at different height cross-sections of the canopies of old-growth and selectively logged forests.

Read online: Wedeux, BMM and Coomes DA (2015) Landscape-scale changes in forest canopy structure across a partially logged tropical peat swamp, BIOGEOSCIENCES 12(22):6707–6719, DOI: 10.5194/bg-12-6707-2015.

Advertisements

Out of the wild

My year started off with a field trip to the peat swamp forests of Borneo. The aim was to wrap up data collection for my PhD project looking at drivers, both environmental and human-made, of structural patterns in these little-studied forests. Supported by a fantastic team of three local research assistants, I established a series of plots and collected leaf samples of most abundant species for trait analyses.

Tropical peat swamp forests grow, as the name suggests, on peat layers that can extend to more than 10 m depth forming so-called ‘peat domes’. During their formation over thousands of years peat domes become purely ombrotrophic (rain-fed) and develop convex water tables that remain close or above the surface. Gradients in fertility and possibly waterlogging along peat domes are thought to lead to the observed succession of different forest communities. Tropical peatlands are major global carbon stores and are bound to play a key role in climate change mitigation.

Extreme conditions for the trees are matched by extreme conditions and many challenges for researchers: deep water, soft grounds full of hollows, mosquitoes without an end. But it all brightens up when an orange forest fellow makes an appearance.