Reply to Leifeld et al.: Enhanced top soil carbon stocks under organic farming is not equated with climate change mitigation

In their letter, Leifeld et al. (1) argue that our metaanalysis to identify differences in soil organic carbon (SOC) between organic (OF) and nonorganic farming [conventional farming (CF)] (2) selected CF systems that were nonrepresentative. This was not the case. We included data from all available pairwise field comparisons between OF and CF identified in the literature. The observed difference in external carbon (C) inputs between OF and CF did not result from a bias in the selection of studies/treatments but was attributable to the fact that the field comparisons we analyzed (2) were not from fertilization experiments but from pairwise farming system comparisons where the design and the underlying treatments reflected the current farming practices in the region in which the studies were conducted at the time the experiments were initiated

Determinants of legacy effects in pine trees - implications from an irrigation-stop experiment

Tree responses to altered water availability range from immediate (e.g. stomatal regulation) to delayed (e.g. crown size adjustment). The interplay of the different response times and processes, and their effects on long-term whole-tree performance, however, is hardly understood. Here we investigated legacy effects on structures and functions of mature Scots pine in a dry inner-Alpine Swiss valley after stopping an 11-yr lasting irrigation treatment. Measured ecophysiological time series were analysed and interpreted with a system-analytic tree model. We found that the irrigation stop led to a cascade of downregulations of physiological and morphological processes with different response times. Biophysical processes responded within days, whereas needle and shoot lengths, crown transparency, and radial stem growth reached control levels after up to 4 yr only. Modelling suggested that organ and carbon reserve turnover rates play a key role for a tree's responsiveness to environmental changes. Needle turnover rate was found to be most important to accurately model stem growth dynamics. We conclude that leaf area and its adjustment time to new conditions is the main determinant for radial stem growth of pine trees as the transpiring area needs to be supported by a proportional amount of sapwood, despite the growth-inhibiting environmental conditions.Peer reviewe

Night and day - Circadian regulation of night-time dark respiration and light-enhanced dark respiration in plant leaves and canopies

The potential of the vegetation to sequester C is determined by the balance between assimilation and respiration. Respiration is under environmental and substrate-driven control, but the circadian clock might also contribute. To assess circadian control on night-time dark respiration (RD) and on light enhanced dark respiration (LEDR) - the latter providing information on the metabolic reorganization in the leaf during light-dark transitions - we performed experiments in macrocosms hosting canopies of bean and cotton. Under constant darkness (plus constant air temperature and air humidity), we tested whether circadian regulation of RD scaled from leaf to canopy respiration. Under constant light (plus constant air temperature and air humidity), we assessed the potential for leaf-level circadian regulation of LEDR. There was a clear circadian oscillation of leaf-level RD in both species and circadian patterns scaled to the canopy. LEDR was under circadian control in cotton, but not in bean indicating species-specific controls. The circadian rhythm of LEDR in cotton might indicate variable suppression of the normal cyclic function of the tricarboxylic-acid-cycle in the light. Since circadian regulation is assumed to act as an adaptive memory to adjust plant metabolism based on environmental conditions from previous days, circadian control of RD may help to explain temporal variability of ecosystem respiration.This study benefited from the CNRS human and technical resources allocated to the ECOTRONS Research Infrastructures as well as from the state allocation ‘Investissement d'Avenir’ AnaEE-France ANR-11-INBS-0001, ExpeER Transnational Access program, Ramón y Cajal fellowships (RYC-2012-10970 to VRD and RYC-2008-02050 to JPF), the Erasmus Mundus Master Course MEDfOR, internal grants from UWS-HIE to VRD and ZALF to AG and Juan de la Cierva-fellowships (IJCI-2014-21393 to JGA). We remain indebted to E. Gerardeau, D. Dessauw, J. Jean, P. Prudent (Aïda CIRAD), J.-J. Drevon, C. Pernot (Eco&Sol INRA), B. Buatois, A. Rocheteau (CEFE CNRS), A. Pra, A. Mokhtar and the full Ecotron team, in particular C. Escape, for outstanding technical assistance

Assessment of the implementation of the Convention: financing and technology transfer

This document contains the synthesis and preliminary analysis of information submitted by country Parties and other reporting entities on operational objective 5 of the 10-year strategic plan and framework to enhance the implementation of the Convention (2008–2018): Financing and technology transfer. It provides updates on the five relevant performance indicators from the global, regional and subregional perspectives and identifies possible trends towards reaching the targets set for these indicators. The document also offers some recommendations for consideration by the Committee for the Review of the Implementation of the Convention on the need to adjust, streamline and strengthen measures aimed at achieving this objective. Considerations regarding the reporting process, including possible refinement in the set of performance indicators and associated methodologies, are summarized in the recommendations to be included in the iterative process

Bud break of ash trees in a forest near Birmensdorf/ZH, Switzerland (2012-2015)

<p>Comparison of bud break of ash trees in a forest near Birmensdorf/ZH, Switzerland in the last four years (2012-2015). Chalara dieback of ash [Chalara fraxinea] (in German: Eschentriebsterben) destroys roughly 30% of the buds and this leads to a reduced leaf development in ashes. This figure is available in German, French or Italian.</p

TreeNet homepage design

<p>Screenshot of the TreeNet homepage on October 9, 2015 (http://www.treenet.info/).</p

Tree heights and diameters of Switzerland's Sanasilva forests

Measurements of tree heights and crown sizes are essential in long-term monitoring of spatially distributed forests to assess the health of forests over time. In Switzerland, in 1994 and 1997, more than 4'500 trees have been recorded in a 8x8 km plot within the Sanasilva Inventory, which comprises the Swiss Level I sites of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests' (ICP Forests). Tree heights and crown sizes were measured for the dominant and co-dominant trees (n = 1,723), resulting in a data set from 171 plots in Switzerland, spreading over a broad range of climatic gradient and forest characteristics (species recorded = 20). Average tree height was 22.1 m, average DBH 34.6 cm and crown diameter 6.5 m. The data set presented here is open to use and shall foster research in allometric equation modelling

Meteorological data, stem radius measurements (SR) and derivates of SR of the three Swiss forest sites Visp, Davos and Lägeren

- Separating continuously measured stem radius (SR) fluctuations into growth-induced irreversible stem expansion (GRO) and tree water deficit-induced reversible stem shrinkage (TWD) requires a concept to decide on potential growth processes during periods of shrinking and expanding SR below a precedent maximum. Here we investigated two physiological concepts: the linear growth (LG) concept assuming linear growth vs. the zero growth (ZG) concept assuming no growth during periods of shrunken stems. - We evaluated the physiological mechanisms underlying these two concepts and assessed the respective plausibility with SR data obtained from 15 deciduous and evergreen trees. - The LG concept showed steady growth rates, whereas the ZG concept showed strongly varying growth rates over time, more in accordance with mechanistic expectations. Further, growth increased for maximally 120 min after periods of shrunken stems, indicating limited growth activity during that period. However, the fraction of this extra growth was found to be small. Furthermore, TWD of the ZG concept was better explained by a hydraulic plant model than TWD of the LG concept. - We conclude that periods of shrunken stems allow for very little growth in the four tree species investigated. However, further studies should focus on obtaining independent growth data to ultimately validate these findings