Florian Hofhansl

Tropical Ecosystem Research


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TLS comparing vegetation structure along topographic gradients

Recently we have been investigating species composition and vegetation structure in 20 one-hectare plots established along edaphic and topographic gradients across the OSA peninsula, Costa Rica comparing plot-based field measurements with data derived from terrestrial laser scanning (TLS). Check out some scans right here:

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LACOSA project update

In the currently running LACOSA project we will be investigating species composition and vegetation structure of >10.000 tree individuals that have been mapped and identified in 20 one-hectare plots established in SW Costa Rica. By using TLS to map aboveground C stocks across topoedaphic and successional gradients on the OSA peninsula we aim to create a more mechanistic understanding of how the controlling state factors (e.g. climate, geology, time and biota) determine the distribution of aboveground C stocks at the landscape-scale. Check out some of the scans right here:


ATBC 2016 conference meeting, Montpellier, France

The impacts of elevated atmospheric CO2 (eCO2) and alterations in nutrient availability on the carbon storage capacity and resilience of the Amazon forest remain highly uncertain. Carbon dynamics are controlled by multiple eco-physiological processes responding to environmental change, but we lack solid experimental evidence, hampering theory development and thus representation in ecosystem models.

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Here, we present two ecosystem-scale manipulation experiments, to be carried out in the Amazon, that examine tropical ecosystem responses to eCO2 and alterations in nutrient availability and thus will elucidate the representation of crucial ecological processes by ecosystem models.

We highlight current gaps in our understanding of tropical ecosystem responses to projected global changes in light of the eco-physiological assumptions considered by current ecosystem models.

We conclude that a more detailed process- based representation of the spatial (e.g., soil type; plant functional type) and temporal (seasonal and inter-annual) variability of tropical forests is needed to enhance model predictions of ecosystem responses to projected global environmental change.

Link to contribution “Amazon forest responses to elevated atmospheric CO2”: http://journal.frontiersin.org/article/10.3389/feart.2016.00019/full


AGU 2015 fall meeting, San Francisco, USA

The proportion of carbon (C) allocated to tree stems is an important determinant of the C sink-strength of global forest ecosystems. Understanding the mechanisms controlling stem growth is essential for parameterization of global vegetation models and to accurately predict future responses of global forest ecosystems in terms of C sequestration. However, due to their underrepresentation in global synthesis we still lack a thorough understanding of intra-annual variations in stem growth of tropical forest ecosystems, which could be especially prone to projected climatic changes.

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We here present high-resolution data (≤ 6 µm; ≥ 1 min) from a novel monitoring network of wireless devices for automated measurement of expansion and contraction in tree diameter using a membrane potentiometer, point dendrometers on phloem and xylem and sap flow modules to analyze diurnal changes in stem growth. Our results indicate that diurnal changes in stem diameter were associated with sap flow and related to seasonal variations in daytime temperature and water availability, such that daily maximum stem growth was positively related to temperature during the wet season but showed the opposite trend during the onset of the dry season. We show that high-resolution monitoring of wood hydraulics and carbon storage of tropical trees is crucial to determine the response of tropical C storage to intra-annual climate variation and therefore will be key to accurately predict future responses of tropical aboveground carbon storage, and should be of special interest for tropical ecosystem research and earth system science.

Link to the contribution “A high resolution monitoring network investigating tropical stem growth”: http://abstractsearch.agu.org/