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In models of plant volatile isoprenoid emissions, the instantaneous compound emission rate typically scales with the plant's emission potential under specified environmental conditions, also called as the emission factor, ES. In the most widely employed plant isoprenoid emission models, the algorithms developed by Guenther and colleagues (1991, 1993), instantaneous variation of the steady-state em

Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for the Alaskan Arctic from four recent model intercomparison projects - NACP (North American Carbon Program) site and regional syntheses, TRENDY (Trends in net land atmosphe

Natural disturbance dynamics, such as fire, have a fundamental control on forest composition and structure. Knowledge of fire history and the dominant drivers of fire are becoming increasingly important for conservation and management practice. Temporal and spatial variability in biomass burning is examined here using 170 charcoal and 15 fire scar records collated throughout Fennoscandia and Denma

Continued warming of the Arctic will likely accelerate terrestrial carbon (C) cycling by increasing both uptake and release of C. Yet, there are still large uncertainties in modelling Arctic terrestrial ecosystems as a source or sink of C. Most modelling studies assessing or projecting the future fate of C exchange with the atmosphere are based on either stand-alone process-based models or coupled

In this study we examined ecosystem respiration (R-ECO) data from 104 sites belonging to FLUXNET, the global network of eddy covariance flux measurements. The goal was to identify the main factors involved in the variability of R-ECO: temporally and between sites as affected by climate, vegetation structure and plant functional type (PFT) (evergreen needleleaf, grasslands, etc.). We demonstrated t

The aim of this study was to establish the main drivers of the spatial variability in growing season CH4 flux within an arctic wetland ecosystem. During 3 years (2011-2013) we measured CH4 flux and potential drivers, e.g., CO2 fluxes (net ecosystem exchange (NEE), gross primary productivity (GPP) and ecosystem respiration), temperature, water table depth, pore-water concentration of organic acids

QuestionHow do pollen-based functional and phylogenetic diversity help to explain post-glacial vegetation change in relation to climate and human influence? LocationEstonia and Latvia, NE Europe. MethodsWe used a data set of 1062 pollen samples from 20 sites covering the last 14500yrs to estimate plant richness, evenness, functional and phylogenetic diversity (community-weighted mean and mean pair

Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use LPJ-GUESS, a dynamic vegetation model

There is compelling new evidence that semi-arid ecosystems are playing a pivotal role in the inter-annual variability and greening trend of the global carbon cycle (Ahlström et al., 2015). The situation is exemplified by the vast inland region of Australia, the driest inhabited continent. Using a global model, Poulter et al. (2014) inferred that Australian ecosystems contributed 57% of a record gl

We use a nested-grid version of the GEOS-Chem chemistry transport model, constrained by isoprene emissions from the Model of Emissions of Gases and Aerosols from Nature (MEGAN), and the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) bottom-up inventories, to evaluate the impact that surface isoprene emissions have on formaldehyde (HCHO) air-mass factors (AMFs) and vertical column densit

The major objectives of this paper are: (1) to review the pros and cons of the scenarios of past anthropogenic land cover change (ALCC) developed during the last ten years, (2) to discuss issues related to pollen-based reconstruction of the past land-cover and introduce a new method, REVEALS (Regional Estimates of VEgetation Abundance from Large Sites), to infer long-term records of past land-cove

In this study, a reconstruction of the long-term development and lateral expansion of a south Swedish peat bog was performed using a multi-proxy approach, including dendrochronology, peat stratigraphy and macrofossil and pollen analyses. By combining mapping of cross-dated subfossil trees with radiocarbon-dated peat sequences, an improved approach to reconstruction of lateral peat expansion was ap

In this study, we assessed the performance of discharge simulations by coupling the runoff from seven Dynamic Global Vegetation Models (DGVMs; LPJ, ORCHIDEE, Sheffield-DGVM, TRIFFID, LPJ-GUESS, CLM4CN, and OCN) to one river routing model for 16 large river basins. The results show that the seasonal cycle of river discharge is generally modeled well in the low and middle latitudes but not in the hi

Although much attention in recent years has been devoted to methane (CH4) emissions from northern wetlands, measurement based data sets providing full annual budgets are still limited in number. This study was designed to help fill the gap of year-round measurements of CH4 emissions from subarctic mires. We report continuous eddy correlation CH4 flux measurements made during 2006 and 2007 over the

Soil temperature (Ts) change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the active-layer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organ

Using a spectral vegetation index (VI) is an efficient approach for monitoring plant phenology from remotely-sensed data. However, the quantitative biophysical meaning of most VIs is still unclear, and, particularly at high northern latitudes characterized by low green biomass renewal rate and snow-affected VI signals, it is difficult to use them for tracking seasonal vegetation growth and retriev