Environmental control of daily stem growth patterns in five temperate broad-leaved tree species     

Köcher P  Horna V  Leuschner C 《Tree physiology》2012,32(8):1021-1032

Tree ring analysis investigates growth processes at time horizons of several weeks to millennia, but lacks the detail of short-term fluctuation in cambial activity. This study used electronic high-precision dendrometry for analyzing the environmental factors controlling stem diameter variation and radial growth in daily resolution in five co-existing temperate broad-leaved tree species (genera Fraxinus, Acer, Carpinus, Tilia and Fagus) with different growth and survival strategies. Daily stem radius change (SRC(d)) was primarily influenced by the atmospheric demand for water vapor (expressed either as vapor pressure deficit (D) or relative air humidity (RH)) while rainfall, soil matrix potential, temperature and radiation were only secondary factors. SRC(d) increased linearly with increasing RH and decreasing D in all species. The positive effect of a low atmospheric water vapor demand on SRC(d) was largest in June during the period of maximal radial growth rate and persisted when observation windows of 7 or 21 days instead of 1 day were used. We found a high synchronicity in the day-to-day growth rate fluctuation among the species with increment peaks corresponding to air humidity maxima, even though the mean daily radial growth rate differed fivefold among the species. The five -species also differed in the positive slope of the growth/RH relationship with the steepest increase found in Fraxinus and the?lowest in Fagus. We explain the strong positive effect of high RH and low D on radial stem increment by lowered transpiration which reduces negative pressure in the conducting system and increases turgor in the stem cambium cells, thereby favoring cell division and expansion. The results suggest that mechanistic models of tree growth need to consider the atmospheric water status in addition to the known controlling environmental factors: temperature, soil moisture and precipitation. The results further have implications for sensitivity analyses of tree growth to climatic changes.  相似文献   

Impact of nitrogen and phosphorus additions on soil gross nitrogen transformations in a temperate desert steppe     

Ping Yue  Jinbo Zhang  Gaodi Zhu  Xiaoyue Yin  Xiaoxue Zhang  Shaokun Wang  Christoph Müller  Tom Misselbrook  Xiaoan Zuo 《European Journal of Soil Science》2023,74(5):e13416

Nutrient addition has a significant impact on plant growth and nutrient cycling. Yet, the understanding of how the addition of nitrogen (N) or phosphorus (P) significantly affects soil gross N transformations and N availability in temperate desert steppes is still limited. Therefore, a ¹⁵N tracing experiment was conducted to study these processes and their underlying mechanism in a desert steppe soil that had been supplemented with N and P for 4 years in northwestern China. Soil N mineralization was increased significantly by P addition, and N and P additions significantly promoted soil autotrophic nitrification, rather than NH₄⁺-N immobilization. The addition of N promoted dissimilatory NO₃⁻ reduction to NH₄⁺, while that of P inhibited it. Soil NO₃⁻-N production was greatly increased by N added alone and by that of N and P combined, while net NH₄⁺-N production was decreased by these treatments. Soil N mineralization was primarily mediated by pH, P content or organic carbon, while soil NH₄⁺-N content regulated autotrophic nitrification mainly, and this process was mainly controlled by ammonia-oxidizing bacteria rather than archaea and comammox. NH₄⁺-N immobilization was mainly affected by functional microorganisms, the abundance of narG gene and comammox Ntsp-amoA. In conclusion, gross N transformations in the temperate desert steppe largely depended on soil inorganic N, P contents and related functional microorganisms. Soil acidification plays a more key role in N mineralization than other environmental factors or functional microorganisms.  相似文献   

Greenhouse gas emissions from Silphium perfoliatum and silage maize cropping on Stagnosols     

Björn Kemmann  Thorsten Ruf  Reinhard Well  Christoph Emmerling  Roland Fuß 《植物养料与土壤学杂志》2023,186(1):79-94

Background

The sustainability of bioenergy is strongly affected by direct field-derived greenhouse gas (GHG) emissions and indirect emissions form land-use change. Marginal land in low mountain ranges is suitable for feedstock production due to small impact on indirect land-use change. However, these sites are vulnerable to high N₂O emissions because of their fine soil texture and hydrology.

Aims

The perennial cup plant (Silphium perfoliatum L.) might outperform silage maize (Zea mays L.) on cold, wet low mountain ranges sites regarding yield and ecosystem services. The aim of this study was to assess whether the cultivation of cup plant also provides GHG mitigation potential compared to the cultivation of maize.

Methods

A t-year field experiment was conducted in a low mountain range region in western Germany to compare area and yield-scaled GHG emissions from cup plant and maize fields. GHG emissions were quantified using the closed chamber method.

Results

Cup plant fields emitted an average of 3.6 ± 4.3 kg N₂O-N ha^–1 year^–1 (–85%) less than maize fields. This corresponded to 74.0 ± 94.1 g CO_2-eq kWh^–1 (–78%) less emissions per produced electrical power. However, cup plant had a significantly lower productivity per hectare (–34%) and per unit of applied nitrogen (–32%) than maize.

Conclusion

Cup plant as a feedstock reduces direct field-derived GHG emissions compared to maize but, due to lower yields cup plant, likely increases emissions associated with land-use changes. Therefore, the increased sustainability of bioenergy from biogas by replacing maize with cup plant is heavily dependent on the performance of maize at these sites and on the ecosystem services of cup plant in addition to GHG savings.  相似文献   

Evaluation of calibrated passive sampling for quantifying ammonia emissions in multi-plot field trials with slurry application     

Martin ten Huf  Thorsten Reinsch  Christof Kluß  Christoph Essich  Reiner Ruser  Caroline Buchen-Tschiskale  Andreas Pacholski  Heinz Flessa  Hans-Werner Olfs 《植物养料与土壤学杂志》2023,186(4):451-463

Background

There is a great need for simple and inexpensive methods to quantify ammonia emissions in multi-plot field trials. However, methods that meet these criteria have to be thoroughly validated. In the calibrated passive sampling approach, acid traps placed in the center of quadratic plots absorb ammonia, enabling relative comparisons between plots. To quantify ammonia emissions, these acid trap samplings are scaled by means of a transfer coefficient (TC) obtained from simultaneous measurements with the dynamic tube method (DTM). However, dynamic tube measurements are also comparatively costly and time-consuming.

Aims

Our objective was to assess the best practice for using calibrated passive sampling in multi-plot field trials. One particular challenge in such experiments is to evaluate the influence of ammonia drift between plots.

Methods

In a series of eight multi-plot field trials, acid traps and DTM were used simultaneously on all plots to measure ammonia emissions caused by different slurry application techniques. Data obtained by both methods were correlated, and the influence of the ubiquitous ammonia background on both methods was evaluated by comparing net values, including the subtraction of the background with gross values (no background subtraction). Finally, we provide recommendations for calculating a TC for calibrating relative differences between plots, based on simultaneous acid trap and dynamic tube measurements on selected plots.

Results

Treatment mean values obtained by both methods correlated well. For most field trials, R² values between 0.6 and 0.8 were obtained. Ammonia background concentrations affected both methods. Drift between plots contributed to the background for the acid traps, whereas the contamination of the chamber system might have caused the background for the DTM. Treatments with low emissions were comparatively more affected by that background.

Conclusion

For a robust application of calibrated passive sampling, we recommend calculating the TC based on a treatment with high ammonia emissions, reducing the relative influence of the ubiquitous ammonia background.  相似文献   

Low light acclimation in five temperate broad-leaved tree species of different successional status: the significance of a shade canopy     

Nicole Legner  Stefan Fleck  Christoph Leuschner 《Annals of Forest Science》2013,70(6):557-570

?Context

Tree species differ largely in their capability to produce characteristic shade leaves with effective morphological and physiological acclimation to low light.

?Aims

By examining the sun/shade leaf differentiation in leaf morphology, foliar nitrogen and photosynthetic capacity in five temperate tree species of different successional status, we aimed at identifying those leaf traits that determine the development of a typical shade crown with low light-acclimated leaves.

?Methods

Leaf morphology, foliar N content, photosynthetic capacity (V _cmax, J _max and A _max) and leaf dark respiration (R _d) were measured in the canopies of 26 adult trees of Fraxinus, Acer, Carpinus, Tilia and Fagus species.

?Results

Six traits (the sun/shade leaf differentiation in specific leaf area, leaf size, A _max per leaf area or per mass, photosynthetic N use efficiency and R _d) were found to characterise best the degree of low light acclimation in shade leaves. All five species exhibited certain modifications in leaf morphology and/or physiology in response to low light; Fagus sylvatica showed the highest and Fraxinus excelsior the lowest shade leaf acclimation.

?Conclusions

Our results indicate that the five early/mid- to late-successional species have developed species-specific low light acclimation strategies in their shade crowns which differ in terms of the relative importance of leaf morphological and physiological acclimation.  相似文献   

Mandibular corrective osteotomy using novel locking compression plate 3.5/4.5/5.0 mm metaphyseal plates     

Christoph S. Klaus DVM  Carsten Vogt DVM  CeqD  Prof. Christoph J. Lischer DVM  Diplomate ECVS 《Veterinary surgery : VS》2013,42(8):984-988

  相似文献   

Sward patterns created by patch grazing are stable over more than a decade     

Bettina Tonn  Christoph Raab  Johannes Isselstein 《Grass and Forage Science》2019,74(1):104-114

Under extensive grazing, a mosaic pattern of frequently defoliated short patches and rarely defoliated tall patches is often formed. The agronomic and ecological consequences of this patch‐grazing pattern strongly depend on its stability between successive years. We assessed patch structure and temporal stability under three intensities of cattle stocking (moderate, lenient and very lenient) in a cattle grazing experiment established in 2002. Aerial images of the whole area taken in 2005, 2010, 2013 and 2015 were classified into short and tall patches using random forest classification. These were complemented by annual sward height measurements (2007‐2017) at 10 permanent plots per paddock, which were classified into sward height classes. The mean proportion (0.72, 0.32, 0.19) and size of short patches decreased with stocking intensity, while size of tall patches increased. Inter‐annual stability depended on patch type and stocking intensity and was particularly high for the respective dominant patch type. Of the short patch area in 2015, 0.62, 0.29 and 0.30 were classified as short in all four aerial images under moderate, lenient and very lenient grazing, respectively; the corresponding proportions for tall patches were 0.10, 0.53 and 0.65. Our results imply that short and tall patches experience persistent differences in local grazing intensity over extended periods. The long‐term effects of this heterogeneity on soil properties and vegetation composition need to be monitored to assess agronomic sustainability and ecological potential of patch‐grazed pastures.  相似文献   

Nitrogen retention and plant uptake on a highly weathered central Amazonian Ferralsol amended with compost and charcoal     

Christoph Steiner  Bruno Glaser  Wenceslau Geraldes Teixeira  Johannes Lehmann  Winfried E.H. Blum  Wolfgang Zech 《植物养料与土壤学杂志》2008,171(6):893-899

Leaching losses of N are a major limitation of crop production on permeable soils and under heavy rainfalls as in the humid tropics. We established a field trial in the central Amazon (near Manaus, Brazil) in order to study the influence of charcoal and compost on the retention of N. Fifteen months after organic‐matter admixing (0–0.1 m soil depth), we added ¹⁵N‐labeled (NH₄)₂SO₄ (27.5 kg N ha^–1 at 10 atom% excess). The tracer was measured in top soil (0–0.1 m) and plant samples taken at two successive sorghum (Sorghum bicolor L. Moench) harvests. The N recovery in biomass was significantly higher when the soil contained compost (14.7% of applied N) in comparison to only mineral‐fertilized plots (5.7%) due to significantly higher crop production during the first growth period. After the second harvest, the retention in soil was significantly higher in the charcoal‐amended plots (15.6%) in comparison to only mineral‐fertilized plots (9.7%) due to higher retention in soil. The total N recovery in soil, crop residues, and grains was significantly (p < 0.05) higher on compost (16.5%), charcoal (18.1%), and charcoal‐plus‐compost treatments (17.4%) in comparison to only mineral‐fertilized plots (10.9%). Organic amendments increased the retention of applied fertilizer N. One process in this retention was found to be the recycling of N taken up by the crop. The relevance of immobilization, reduced N leaching, and gaseous losses as well as other potential processes for increasing N retention should be unraveled in future studies.  相似文献   

Charcoal and smoke extract stimulate the soil microbial community in a highly weathered xanthic Ferralsol   总被引：2，自引：0，他引：2  

Christoph Steiner  Keshav C. Das  Marcos Garcia  Bernhard Frster  Wolfgang Zech 《Pedobiologia》2008,51(5-6):359-366

The influence of charcoal and smoke condensates (pyroligneous acid, PA) on microbial activity in a highly weathered Amazonian upland soil was assessed via measurements of basal respiration (BR), substrate-induced respiration (SIR), and exponential population increase after substrate addition. PA extracts are commonly used for fertilizer or as pest control in Brazil, where phosphorus (P) availability and nitrogen (N) leaching are among the most severe limitations for agriculture. Microbes play an important role in nutrient cycling and solubilizing of phosphate. BR, microbial biomass, population growth and the microbe's efficiency (expressed by the metabolic quotient) increased linearly and significantly with increasing charcoal concentrations (50, 100 and 150 g kg⁻¹ soil). Application of PA caused a sharp increase in all parameters. We suppose that the condensates from smoke contain easily degradable substances and only small amounts of inhibitory agents, which could be utilized by the microbes for their metabolism.  相似文献   

Groundwater level controls CO2, N2O and CH4 fluxes of three different hydromorphic soil types of a temperate forest ecosystem     

Hermann F. Jungkunst  Heiner Flessa  Christoph Scherber  Sabine Fiedler 《Soil biology & biochemistry》2008,40(8):2047-2054

Hydromorphic soils should exhibit higher climate change feedback potentials than well aerated soils since soil organic matter (SOM) losses in them are predicted to be much larger than those of well aerated soils. To evaluate a combined feedback relationship between groundwater level (GWL) and total greenhouse gas (GHG) emission, a greenhouse microcosm experiment was performed by exposing three hydromorphic forest soil types that differed in carbon content to three water levels (?40, ?20 and ?5 cm) while plants were excluded. Net GHG fluxes were measured continuously. GHG concentrations plus oxygen were measured in soil air and soil water at different depths. In this study, soil type hardly affected GHG emissions but GWL did. CO₂ emissions peaked at GWL of ?40 cm and declined on average to 65 and 33% during GWL at ?20 and ?5 cm, respectively. CH₄ emissions showed the opposite pattern having the highest emission rates at GWL of ?5 cm and compared to that on average only ?3 and ?8% during GWL at ?20 and ?40 cm, respectively. The highest mean N₂O emissions were detected at the intermediate GWL of ?20 cm, whereas it is reduced on average to 18% for GWL at ?40 cm and at ?5 cm. The highest greenhouse gas emissions (in CO₂ equivalents) were calculated for GWL at ?20 cm. During GWL at ?40 cm, CO₂ equivalent fluxes were only insignificantly lower. CO₂ equivalent fluxes reduced explicitly in mean to 35% with GWL at ?5 cm. The outcome emphasizes that anaerobic SOM decomposition apparently produces a lower warming potential than aerobic SOM decomposition. Undoubtedly, hydromorphic soils have to be considered for climate–carbon feedback scenarios.  相似文献