How much water is used by a black locust (Robinia pseudoacacia L.) short-rotation plantation on degraded soil?

Black locust is a tree species autochthonous from North America, were its distribution range from humid to sub-humid climate. As an early successional and nitrogen-fixing species, black locust grows rapidly as a pioneer tree species under a wide range of site condition. Black locust short-rotation plantations for bioenergy production is raising interest, particularly for those areas were conventional crops systems are economically not profitable. In southern Brandenburg black locust have been successfully used for land reclamation and biomass production in recultivated open-cast lignite mining areas, where nutrient and water resources are limited. An open key question is the water use of the trees under drought conditions which are quite common in these areas. For the determination of transpiration at whole plant level we used a modified wick lysimeter system, which allows us to study plant growth under controlled water regime. Water amount is controlled by the actual evapotranspiration and water demand of the plants and supplied by an automatic drip irrigation system. Transpiration is calculated from the experimental water balance in daily intervals. Photosynthesis is the essential process for biomass productivity including CO2 uptake and water loss controlled by the stomata on the leaf level. Therefore, the ecophysiological response of the plants to drought stress is investigated by using a portable gas exchange system, which allows the measurements of transpiration under various temperature and air humidity regimes. Water use at whole plant level has been linked to their ecophysiological performance

Succession of N cycling processes in biological soil crusts on a Central European inland dune

Biological soil crusts (BSCs) are microbial assemblages that occur worldwide and facilitate ecosystem development by nitrogen (N) and carbon accumulation. N turnover within BSC ecosystems has been intensively studied in the past; however, shifts in the N cycle during BSC development have not been previously investigated. Our aim was to characterise N cycle development first by the abundance of the corresponding functional genes (in brackets) and second by potential enzyme activities; we focussed on the four processes: N fixation (nifH), mineralisation as proteolysis and chitinolysis (chiA), nitrification (amoA) and denitrification (nosZ). We sampled from four phases of BSC development and from a reference located in the rooting zone of Corynephorus canescens, on an inland dune in Germany. BSC development was associated with increasing amounts of chlorophyll, organic carbon and N. Potential activities increased and were highest in developed BSCs. Similarly, the abundance of functional genes increased. We propose and discuss three stages of N process succession. First, the heterotrophic stage (mobile sand without BSCs) is dominated by mineralisation activity. Second, during the transition stage (initial BSCs), N accumulates, and potential nitrification and denitrification activity increases. Third, the developed stage (established BSCs and reference) is characterised by the dominance of nitrificatio

Improving nutrient and water use efficiency of IGNISCUM® – a new bioenergy crop

The new cultivars IGNISCUM Candy® and IGNISCUM Basic® of the Sakhalin Knotweed (Fallopia sachalinensis, Fam. Polygonaceae) are new bioenergy crops, which are characterized by a high annual biomass. The objectives of our study are to investigate (i) the water consumption; (ii) the interrelations between nutrient supply, biomass production, and transpiration; and (iii) the optimization of the biomass production

Monitoring der initialen Bodenentwicklung im künstlichen Wassereinzugsgebiet „Hühnerwasser“

Das Monitoringprogramm im künstlichen Wassereinzugsgebiet „Hühnerwasser“ umfasst u.a. relevante Parameter zur Erfassung der initialen Bodenentwicklung. Aufbau und erste Ergebnisse der initialen Zustandserfassung werden gezeig

Effects of Drought Frequency on Growth Performance and Transpiration of Young Black Locust ( Robinia pseudoacacia

Black locust (Robinia pseudoacacia L.) is a drought-tolerant fast growing tree, which could be an alternative to the more common tree species used in short-rotation coppice on marginal land. The plasticity of black locust in the form of ecophysiological and morphological adaptations to drought is an important precondition for its successful growth in such areas. However, adaptation to drought stress is detrimental to primary production. Furthermore, the soil water availability condition of the initial stage of development may have an impact on the tree resilience. We aimed to investigate the effect of drought stress applied during the resprouting on the drought tolerance of the plant, by examining the black locust growth patterns. We exposed young trees in lysimeters to different cycles of drought. The drought memory affected the plant growth performance and its drought tolerance: the plants resprouting under drought conditions were more drought tolerant than the well-watered ones. Black locust tolerates drastic soil water availability variations without altering its water use efficiency (2.57 g L−1), evaluated under drought stress. Due to its constant water use efficiency and the high phenotypic plasticity, black locust could become an important species to be cultivated on marginal land

Editorial: Ecological Development and Functioning of Biological Soil Crusts After Natural and Human Disturbances

[no abstract available

Effect of nitrogen fertilizer and compost on photosynthesis and growth of Virginia fanpetals (Sida hermaphrodita Rusby)

Als mehrjährige Bioenergiepflanze kann Sida hermaphrodita eine wichtige Rolle für den Anbau auf marginalen Standorten in der nahen Zukunft spielen. In einem kon­trollierten Topfexperiment wurde der Einfluss von verschiedenen Kompostgehalten (10, 20, 30, 50%) und mineralischem Stickstoffdünger (100 kg N ha–1) auf Biomasse, Wuchshöhe und Kohlenstoffallokation während der Etablierungsphase untersucht. Weiterhin wurden ökophysiologische Parameter (Gaswechsel, Chlorophyllfluoreszenz, Chlorophyllgehalte) mit nicht-destruktiven Methoden bestimmt. Die Ergebnisse des Experimentes zeigen, dass sowohl die Stickstoffdüngung als auch die Kompostgabe positive Effekte für das Wachstumsverhalten hat. Während der Etablierungsphase erreichten die gedüngten Pflanzen eine mittlere Pflanzenhöhe von bis zu 127 cm (maximale Wuchshöhe 168 cm). Die Photosynthese wurde nicht durch die unterschiedlichen Behandlungen beeinflusst. Die mittlere CO2-Austauschrate variiert zwischen 5,8 und 9,9 μmol m–2 s–1 und die Elektronentransportrate zwischen 34,5 und 53,9 μmol m–2 s–1. Die Verwendung von Kompost und Stickstoff ist für eine bessere Biomasseproduktion von Sida in marginalen Böden möglich, auch wenn das Wachstum im ersten Jahr limitiert ist und es negative Rückwirkungen auf die Bestandesetablierung gibt.As a perennial bioenergy crop Sida hermaphrodita can play an important role on marginal lands in the near future. In a controlled pot experiments the influence of various proportions of compost (10, 20, 30, 50%) and nitrogen fertilizer (100 kg N ha–1) on biomass, plant height, and carbon allocation were investigated during the establishment phase. Furthermore, ecophysiological parameters (gas exchange, chlorophyll fluorescence, chlorophyll content,) were determined with non-destructive methods. The results of this experiment demonstrated that nitrogen fertilization and compost application has an overall positive effect on the overall growth performance. During the establishment phase, the fertilized plants reached a mean high of up to 127 cm (maximal plant height up to 168 cm). Photosynthesis was not influenced by the treatments and the mean net CO2-exchange rates varied between 5,8 and 9,9 μmol m–2 s–1 and the electron transport rate between 34,5 and 53,9 μmol m–2 s–1. The application of compost and nitrogen for a better biomass production of Sida on marginal soils is possible, however the growth is limited in the first year with negative effects on the establishment of larger crops

Effects of nitrogen and phosphate fertilization on leaf nutrient content, photosynthesis, and growth of the novel bioenergy crop <i>Fallopia sachalinensis</i> cv. ‘Igniscum Candy‘

The aim of the study was to determine the effects of nitrogen and phosphate fertilization on the growth performance of the novel bioenergy crop Fallopia sachalliensis cv. ‘Igniscum Candy’ (Polygonaceae). In a controlled pot experiment various nitrogen (0, 50, 150, 300 kg N ha-1) and phosphate (20, 40, 80 kg P ha-1) fertilizer amounts were applied to measure the effect on the biomass, height, leaf area and nitrogen and phosphate use efficiency. Furthermore, ecophysiological processes (chlorophyll content, chlorophyll fluorescence, gas exchange) were measured with non-destructive methods. The application of nitrogen correlated positively with biomass production, while phosphate fertilization did not show a significant effect on plant growth or ecophysiological parameters. The leaf nitrogen contents were significantly correlated with the nitrogen applications, while the leaf phosphate contents did not show a correlation with the P fertilizations, but increased with the leaf nitrogen contents. A significant linear correlation between the measured SPAD values and chlorophyll contents as well as with the leaf nitrogen contents could be determined. Under the influence of the nitrogen fertilization, net photosynthesis increased from 3.7 to 6.6 μmol m-2 s-1. The results of this experiment demonstrated that nitrogen fertilization has an overall positive correlation with leaf nutrient content, photosynthesis, and overall growth of the bioenergy crop Fallopia sachalinensis var. Igniscum Candy

Development of biological soil crusts in initial ecosystems in Lusatia, Germany

During initial ecosystem development vegetation cover is sparse, but the space between shrubs is not bare and is often covered by a topsoil biological crust composed by cyanobacteria, green algae, mosses and lichens. These cryptogames are the first colonizer of initial ecosystems. The development of soil surface crusts plays a major role for the further vegetation pattern and ecosystem development through changes to the physico-chemical conditions and influencing various ecosystem processes. We studied the development of biological soil crusts on quaternary substrate of the initial artificial water catchment ´Neuer Lugteich´ located in the former open-cast lignite mining area near Welzow (Brandenburg, Germany). Chlorophyll, Corg, pH were determined to classified various soil crusts types. Some of these Kryptogames excrete exopolysaccharides that bind the inorganic fine-grained particles that form the matrix of the topsoil crust. Due to lack of organic matter in the geological substrate, photoautotrophic organisms like green algae and cyanobacteria are important for soil organic matter accumulation in first millimetre of topsoil of initial ecosystems. The biological soil crusts decrease infiltration rates and influence the hydrological conditions

Exploring environmental and physiological drivers of the annual carbon budget of biocrusts from various climatic zones with a mechanistic data-driven model

Biocrusts are a worldwide phenomenon, contributing substantially to ecosystem functioning. Their growth and survival depend on multiple environmental factors, including climatic ones, and the relations of these factors to physiological processes. Responses of biocrusts to individual environmental factors have been examined in a large number of field and laboratory experiments. These observational data, however, have rarely been assembled into a comprehensive, consistent framework that allows quantitative exploration of the roles of multiple environmental factors and physiological properties for the performance of biocrusts, in particular across climatic regions. Here we used a data-driven mechanistic modelling framework to simulate the carbon balance of biocrusts, a key measure of their growth and survival. We thereby assessed the relative importance of physiological and environmental factors for the carbon balance at six study sites that differ in climatic conditions. Moreover, we examined the role of seasonal acclimation of physiological properties using our framework, since the effects of this process on the carbon balance of biocrusts are poorly constrained so far. We found substantial effects of air temperature, CO2 concentration, and physiological parameters that are related to respiration on biocrust carbon balance, which differ, however, in their patterns across regions. The ambient CO2 concentration is the most important factor for biocrusts from drylands, while air temperature has the strongest impact at alpine and temperate sites. Metabolic respiration cost plays a more important role than optimum temperature for gross photosynthesis at the alpine site; this is not the case, however, in drylands and temperate regions. Moreover, we estimated a small annual carbon gain of 1.5 g m−2 yr−1 by lichen-dominated biocrust and 1.9 g m−2 yr−1 by moss-dominated biocrust at a dryland site, while the biocrusts lost a large amount of carbon at some of the temperate sites (e.g. −92.1 for lichen-dominated and −74.7 g m−2 yr−1 for moss-dominated biocrust). These strongly negative values contradict the observed survival of the organisms at the sites and may be caused by the uncertainty in environmental conditions and physiological parameters, which we assessed in a sensitivity analysis. Another potential explanation for this result may be the lack of acclimation in the modelling approach, since the carbon balance can increase substantially when testing for seasonally varying parameters in the sensitivity analysis. We conclude that the uncertainties in air temperature, CO2 concentration, respiration-related physiological parameters, and the absence of seasonal acclimation in the model for humid temperate and alpine regions may be a relevant source of error and should be taken into account in future approaches that aim at estimating the long-term biocrust carbon balance based on ecophysiological data.</p