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Revisiting the role of transpiration in the variation of ecosystem water use efficiency in China

Efforts to develop effective climate strategies necessitate a better understanding of the relationship between terrestrial water and carbon cycles. Water use efficiency (WUE) has been often used to characterize this relationship, while the role of transpiration (T) in the variation of ecosystem WUE has been less investigated. Here, we partitioned WUEET (the ratio of gross primary productivity (GPP

Wood structure explained by complex spatial source-sink interactions

Wood is a remarkable material with great cultural, economic, and biogeochemical importance. However, our understanding of its formation is poor. Key properties that have not been explained include the anatomy of growth rings (with consistent transitions from low-density earlywood to high density latewood), strong temperature-dependence of latewood density (used for historical temperature reconstru

Comparing soil microbial responses to drying-rewetting and freezing-thawing events

Climate change is expected to alter the frequency and intensity of soil drying-rewetting (D/RW) and freezing-thawing (F/TW) events, with consequences for the activities of microorganisms. Although both D/RW and F/TW events cause respiration pulses from soil to the atmosphere, it remains unknown whether the underlying microbial control is similar. Recent work has revealed that soil microbial respon

Widespread Unquantified Conversion of Old Boreal Forests to Plantations

Across the boreal biome, clear-cutting of old, previously non clear-cut forests with high naturalness followed by tree planting or seeding is a major land use change. However, how much previously uncut forest has been converted to plantations remains unquantified. We combine Swedish national databases on clear-cuts and forest inventories to show that at least 19% of all clear-cuts since 2003 have

A new parameterization of cloud droplet activation applicable to general circulation models

A new parameterization is proposed to link the droplet number concentration to the size distribution and chemical composition of aerosol and updraft velocity. Except for an empirical assumption of droplet growth, the parameterization is formulated almost entirely on first principles to allow for satisfactory performance under a variety of conditions. For a series of updraft velocity ranging from 0

Separation of net ecosystem exchange into assimilation and respiration using a light response curve approach: critical issues and global evaluation

The measured net ecosystem exchange (NEE) of CO2 between the ecosystem and the atmosphere reflects the balance between gross CO2 assimilation [gross primary production (GPP)] and ecosystem respiration (R-eco). For understanding the mechanistic responses of ecosystem processes to environmental change it is important to separate these two flux components. Two approaches are conventionally used: (1)

alpha-Amylase-catalysed synthesis of alkyl glycosides

Alkyl glycosides were synthesised from starch and alcohols using Aspergillus oryzae a-amylase as catalyst. In the degradation of starch by a-amylase, the alcohols competed with water as glycosyl acceptors. In the reaction with methanol, methyl maltoside and methyl maltotrioside were the main alcoholysis products. Conversion of 45 g/1 starch in 30% methanol resulted in a product mixture containing

Exploring potential drivers of European biomass burning over the Holocene: a data-model analysis

AimTo reconstruct spatial and temporal patterns of European fire activity during the Holocene and to explore their potential drivers, by relating biomass burning to simulated biotic and abiotic parameters. LocationEurope. MethodsHolocene fire activity was investigated based on 156 sedimentary charcoal records from lakes and peat bogs across Europe. Charcoal data covering the last 9000 years were s

Evaluation of terrestrial carbon cycle models for their response to climate variability and to CO2 trends

The purpose of this study was to evaluate 10 process-based terrestrial biosphere models that were used for the IPCC fifth Assessment Report. The simulated gross primary productivity (GPP) is compared with flux-tower-based estimates by Jung etal. [Journal of Geophysical Research 116 (2011) G00J07] (JU11). The net primary productivity (NPP) apparent sensitivity to climate variability and atmospheric

Isoprene emission from Sphagnum species occupying different growth positions above the water table

Isoprene emission from Sphagnum species naturally growing at different positions above the water table were measured in a subarctic peatland and at monoliths from a temperate bog. Our objectives were to investigate (1) whether emission rates were species and/or moisture dependent, and (2) whether short-term temperature history had an influence on emission capacity. We expected greater emission cap

Large herbivore grazing affects the vegetation structure and greenhouse gas balance in a high arctic mire

Herbivory is an important part of most ecosystems and affects the ecosystems' carbon balance both directly and indirectly. Little is known about herbivory and its impact on the carbon balance in high arctic mire ecosystems. We hypothesized that trampling and grazing by large herbivores influences the vegetation density and composition and thereby also the carbon balance. In 2010, we established fe

An Optical Sensor Network for Vegetation Phenology Monitoring and Satellite Data Calibration

We present a network of sites across Fennoscandia for optical sampling of vegetation properties relevant for phenology monitoring and satellite data calibration. The network currently consists of five sites, distributed along an N-S gradient through Sweden and Finland. Two sites are located in coniferous forests, one in a deciduous forest, and two on peatland. The instrumentation consists of dual-

Antiproliferative activity of extracts of some Bolivian medicinal plants

Twenty-six plant species from the native flora used in Bolivian folk medicine were selected for studies of bioactivity. They belonged to the following families namely: Asteraceae (11), Brassicaceae (1), Cactaceae (1), Caesalpinaceae (2), Chenopodiaceae (1), Frankeniaceae (1), Geraniaceae (1), Laureaceae (1), Oxalidaceae (1), Piperaceae (1), Plantaginaceae (1), Rosaceae (1), Solanaceae (1) and Verb

Importance of vegetation dynamics for future terrestrial carbon cycling

Terrestrial ecosystems currently sequester about one third of anthropogenic CO 2 emissions each year, an important ecosystem service that dampens climate change. The future fate of this net uptake of CO 2 by land based ecosystems is highly uncertain. Most ecosystem models used to predict the future terrestrial carbon cycle share a common architecture, whereby carbon that enters the system as net p

A SVD-based classification of bird singing in different time-frequency domains using multitapers

In this paper, a novel method for analysing a bird’s song is presented. The song of male great reed warblers is used for developing and testing the methods. A robust method for detecting syllables is proposed and a classification of those syllables as compared to reference syllables is done. The extraction of classification features are based on the use of singular vectors in different time-freque

Does canopy mean nitrogen concentration explain variation in canopy light use efficiency across 14 contrasting forest sites?

The maximum light use efficiency (LUE = gross primary production (GPP)/absorbed photosynthetic photon flux density (aPPFD)) of plant canopies has been reported to vary spatially and some of this variation has previously been attributed to plant species differences. The canopy nitrogen concentration [N] can potentially explain some of this spatial variation. However, the current paradigm of the N-e