TY - GEN A1 - Rieser, Jakob A1 - Veste, Maik A1 - Thiel, Michael A1 - Schönbrodt-Stitt, Sarah T1 - Coverage and Rainfall Response of Biological Soil Crusts Using Multi-Temporal Sentinel-2 Data in a Central European Temperate Dry Acid Grassland T2 - Remote Sensing N2 - Biological soil crusts (BSCs) are thin microbiological vegetation layers that naturally develop in unfavorable higher plant conditions (i.e., low precipitation rates and high temperatures) in global drylands. They consist of poikilohydric organisms capable of adjusting their metabolic activities depending on the water availability. However, they, and with them, their ecosystem functions, are endangered by climate change and land-use intensification. Remote sensing (RS)-based studies estimated the BSC cover in global drylands through various multispectral indices, and few of them correlated the BSCs’ activity response to rainfall. However, the allocation of BSCs is not limited to drylands only as there are areas beyond where smaller patches have developed under intense human impact and frequent disturbance. Yet, those areas were not addressed in RS-based studies, raising the question of whether the methods developed in extensive drylands can be transferred easily. Our temperate climate study area, the ‘Lieberoser Heide’ in northeastern Germany, is home to the country’s largest BSC-covered area. We applied a Random Forest (RF) classification model incorporating multispectral Sentinel-2 (S2) data, indices derived from them, and topographic information to spatiotemporally map the BSC cover for the first time in Central Europe. We further monitored the BSC response to rainfall events over a period of around five years (June 2015 to end of December 2020). Therefore, we combined datasets of gridded NDVI as a measure of photosynthetic activity with daily precipitation data and conducted a change detection analysis. With an overall accuracy of 98.9%, our classification proved satisfactory. Detected changes in BSC activity between dry and wet conditions were found to be significant. Our study emphasizes a high transferability of established methods from extensive drylands to BSC-covered areas in the temperate climate. Therefore, we consider our study to provide essential impulses so that RS-based biocrust mapping in the future will be applied beyond the global drylands KW - Biological soil crusts Y1 - 2021 SN - 2072-4292 VL - 13 IS - 16 ER - TY - GEN A1 - Sheppard, Jonathan P. A1 - Bohn Reckziegel, Rafael A1 - Borrass, Lars A1 - Chirwa, Paxie W. A1 - Cuaranhua, Claudio J. A1 - Hassler, Sibylle K A1 - Hoffmeister, Svenja A1 - Kestel, Florian A1 - Maier, Rebekka A1 - Mälicke, Mirko A1 - Morhart, Christopher A1 - Ndlovu, Nicholas P. A1 - Veste, Maik A1 - Funk, Roger A1 - Lang, Friedericke A1 - Seifert, Thomas A1 - du Toit, Ben A1 - Kahle, Hans-Peter T1 - Agroforestry: An Appropriate and Sustainable Response to a Changing Climate in Southern Africa? T2 - Sustainability N2 - Agroforestry is often discussed as a strategy that can be used both for the adaptation to and the mitigation of climate change effects. The climate of southern Africa is predicted to be severely affected by such changes. With agriculture noted as the continent’s largest economic sector, issues such as food security and land degradation are in the forefront. In the light of such concerns we review the current literature to investigate if agroforestry systems (AFS) are a suitable response to the challenges besetting traditional agricultural caused by a changing climate. The benefits bestowed by AFS are multiple, offering ecosystem services, influence over crop production and positive impacts on rural livelihoods through provisioning and income generation. Nevertheless, knowledge gaps remain. We identify outstanding questions requiring further investigation such as the interplay between trees and crops and their combination, with a discussion of potential benefits. Furthermore, we identify deficiencies in the institutional and policy frameworks that underlie the adoption and stimulus of AFS in the southern African region. We uphold the concept that AFS remains an appropriate and sustainable response for an increased resilience against a changing climate in southern Africa for the benefit of livelihoods and multiple environmental values KW - agroforestry KW - Southern Africa Y1 - 2020 UR - https://www.mdpi.com/2071-1050/12/17/6796 U6 - https://doi.org/10.3390/su12176796 VL - 12 IS - 17 ER - TY - GEN A1 - Veste, Maik A1 - Herppich, Werner B. T1 - Comparative ecophysiology of the leaf-succulents Augea capensis (C3) and Malephora purpureo-crocea (CAM) in the Knersvlakte, Succulent Karoo, South Africa T2 - Flora N2 - The generally accepted assumption that CAM is an important adaptation to the drought conditions in arid deserts is mainly based on studies in controlled environments comparing the respective photosynthetic pathways in plants of different morphology. Comparative long-term field studies on the ecophysiology of C3- and CAM succulents co-occurring in the same desert habitat are too rare to satisfactorily answer the old question whether the metabolic pathway or the succulence is more important to guarantee survival in such a harsh habitat. Thus, relevant ecophysiological parameters were repeatedly monitored on plants of the leaf succulents Augea capensis (C3) and Malephora purpureo-crocea (CAM), which commonly dominate a habitat in the Knersvlakte, Namaqualand, South Africa. Under identical conditions in the same habitat, carbon gain of the C3 species was higher than that of the CAM plant, but their WUE lower and maximum photosynthetic activity nearly the same. In M. purpureo-crocea, irrigation induced rapid whole day stomatal opening at drastically increased daytime but decreased night-time CO2-uptake, while respective responses of the C3 species were delayed. These different response dynamics were due to different rooting depth, root morphology and water acquisition strategy of the flat rooting CAM and the deep-rooting C3 species. This, however, may not explain the highly similar growth success. Anyway, the results verify that CAM provides no advantage over C3 for long-term survival in the same desert environment in morphologically similar succulents. KW - Mode of photosynthesis Y1 - 2021 U6 - https://doi.org/10.1016/j.flora.2021.151807 SN - 1618-0585 SN - 0367-2530 VL - 278 ER - TY - GEN A1 - Griebenow, Stian A1 - Makunga, Nokwanda P. A1 - Privett, Sean A1 - Strauss, Paula A1 - Veste, Maik A1 - Kleinert, Aleysia A1 - Valentine, Alexander J. T1 - Soil pH influences the organic acid metabolism and exudation in cluster roots of protea species from the Mediterranean-type fynbos ecosystem, Western Cape, South Africa T2 - Rhizosphere N2 - In nutrient-poor ecosystems, certain plant families have evolved specific adaptations for phosphate acquisition, namely cluster roots or proteoid roots. Cluster rooted species have a unique suite of adaptations that enable them to survive in nutrient poor ecosystems, such as the Fynbos biome of South Africa. The Fynbos biome has heterogeneous soils which caused radiation of varying soil pH within small localised areas. Previous studies on cluster rooted species ignored the possibility that cluster root functioning may differ at varying soil pH levels and soil types. Therefore, two native Fynbos protea species, Protea cynaroides (L.) L. and Protea obtusifolia H.Buek ex Meisn. were compared to assess the impact of different soil pH levels on organic acid metabolism and exudation in cluster rooted species. Our results show that cluster roots of the acidic-soil grown P. cynaroides is more effective and more efficient than that of the alkaline-soil grown P. obtusifolia. Our findings indicate that the mechanisms for P acquisition vary greatly, depending on substrate and plant organ type. This suggests that the metabolism of each species is adapted to specific soil pH and that these species have evolutionary adapted their P acquisition mechanisms for these extreme soils. The limited nutrient availability and variation in soil pH South African soils has led to various localised adaptations for cluster rooted species. KW - Phosphorus KW - Nutrient poor ecosystems KW - Root research Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S2452219822000167 U6 - https://doi.org/10.1016/j.rhisph.2022.100486 VL - Vol. 21 ER - TY - GEN A1 - Veste, Maik A1 - Littmann, Thomas A1 - Kunneke, Anton A1 - Du Toit, Ben A1 - Seifert, Thomas T1 - Windbreaks as part of climate-smart landscapes reduce evapotranspiration in vineyards, Western Cape Province, South Africa T2 - Plant, Soil and Environment N2 - Under the conditions of climate change in South Africa, ecological and technical measures are needed to reduce the water consumption of irrigated crops. Windbreak hedges are long-rated systems in agriculture that significantly reduce wind speed. Their possibilities to reduce evapotranspiration and water demand are being investigated at a vineyard in the Western Cape Province, South Africa. Detailed measurements of meteorological parameters relevant for the computation of reference and crop-specific evapotranspiration following the FAO 56 approaches within a vineyard in the Western Cape Province of South Africa have shown the beneficial effect of an existing hedgerow consisting of 6 m high poplars (Populus simonii (Carrière) Wesm.). With reference to a control station in the open field, the mean wind speed in a position about 18 m from the hedgerow at canopy level (2 m) was reduced by 27.6% over the entire year and by 39.2% over the summer growing season. This effect leads to a parallel reduction of reference evapotranspiration of 15.5% during the whole year and of 18.4% over the growing season. When applying empirical crop-specific Kc values for well-irrigated grapes, the reduction of evapotranspiration is 18.8% over the summer growth period. The introduced tree shelterbelts are a suitable eco-engineering approach to reduce water consumption and to enhance water saving in vineyards. KW - dry areas KW - viticulture KW - climate change KW - agroforestry Y1 - 2020 UR - https://www.agriculturejournals.cz/web/pse.htm?type=article&id=616_2019-PSE U6 - https://doi.org/10.17221/616/2019-PSE SN - 1214-1178 SN - 1805-9368 VL - 66 IS - 3 SP - 119 EP - 127 ER - TY - GEN A1 - Geldenhuys, Heinrich A1 - Lötze, Elmi A1 - Veste, Maik T1 - Fruit Quality and Yield of Mandarin (Citrus reticulata) in Orchards with Different Windbreaks in the Western Cape, South Africa T2 - Erwerbs-Obstbau N2 - Windbreaks, trees, structures, and shade nets are used in South Africa to protect citrus orchards from wind scar damage to avoid major losses in export quality. Severe southeasterly winds in the Western Cape during spring and summer are the main causes of significant external peel damage. In this study, wind scar damage of ‘Tango’ mandarin (Citrus reticulata) fruit was quantified at different distances from established Casuarina cunninghamiana (Beefwood) and Populus simonii (Chinese Poplar) windbreaks around Stellenbosch, Western Cape, South Africa. The yield efficiency was not significantly affected by distance from the windbreak in either of the trials. Fruit at 2 H and 3 H had significantly lower ratios of total soluble solids to titratable acidity, but export standards for mandarins were still met. The wind speed was consistently higher at 16 H, compared with 3 H during summer. The highest packout (class 1 fruit) was observed near the windbreak (3 H) and decreased as the distance increased towards 10 H and 16 H. There were no significant differences for severe wind scar damage incidence between the distance treatments. Our results confirmed the impact of wind on external fruit quality and the limitation of tree-based windbreaks with an increase in distance, which partly supports the current movement towards full enclosure of orchards with shade nets. KW - Agroforestry KW - Citrus orchards KW - yield KW - South Africa Y1 - 2022 U6 - https://doi.org/10.1007/s10341-022-00725-3 SN - 1439-0302 VL - 65 (2023) IS - 4 SP - 959 EP - 969 ER - TY - GEN A1 - Kidron, Giora J. A1 - Veste, Maik A1 - Lichner, Lubomir T1 - Biological factors impacting hydrological processes: Pecularities of plants and biological soil crusts T2 - Journal of Hydrology and Hydromechanics N2 - The effects of biological factors on the water cycle and subsequently on hydrological processes have wide and profound consequences on ecosystem structure, function and management. A profound understanding of their effects is of prime importance especially in light of climate change projection KW - Biological soil crusts Y1 - 2021 U6 - https://doi.org/10.2478/johh-2021-0031 SN - 1338-4333 VL - 69 IS - 4 SP - 357 EP - 359 ER - TY - GEN A1 - Wachendorf, Magnus A1 - Schloz, Mona A1 - Küppers, Manfred A1 - Güney, Aylin A1 - Veste, Maik T1 - Wintertime photosynthesis and spring recovery of Ilex Aquifolium L. T2 - iForest Biogeosciences and Forestry N2 - Former studies using the chlorophyll fluorescence technique on evergreen Ilex aquifolium L. showed that its photosynthetic potential for electron transport in winter recovers quickly when exposed to more favorable conditions. Since little is known, however, about its photosynthetic carbon gain in winter, we investigated its leaf gas exchange over an entire winter and spring period. Measurements were made rotationally in the field and in the laboratory to also investigate if I. aquifolium profits from warmer phases during winter in terms of net carbon gain. From the end of autumn until the end of spring, three different climate-driven phases of photosynthetic responses could be distinguished: first, an acclimation phase which lasted until February and was characterized by a gradually decreasing light-saturated gross photosynthesis (Amax(gross)), decreasing apparent quantum yield of CO₂-assimilation (ɸi) and a decreasing ability of these parameters to recover overnight inside the laboratory. At the same time, maximal quantum yield of PSII (Fv/Fm) could fully regenerate. In this phase, single warmer days had a positive effect on carbon assimilation. Second, a phase of relatively constant but low photosynthesis which was virtually unaffected by temperature, lasting for almost two months occurred. Here, Amax(gross) and ɸi had lost their ability to recover from winter conditions in the field, while Fv/Fm was much less affected. I. aquifolium was still able to conduct positive light-saturated net photosynthesis at a leaf temperature of -0.5°C, but during this time it could not profit from milder temperatures in terms of carbon gain. Third, a phase of increasing photosynthesis (spring recovery) occurred, starting in March when the 5-day average temperature was above 5°C and radiation in the field increased, and where all parameters slowly recovered from winter depressions. Our findings show that I. aquifolium is photosynthetically active over the whole winter, even at temperatures around 0°C. In terms of carbon gain, however, I. aquifolium does not profit from warmer phases during winter, despite the fast recovery seen in chlorophyll fluorescence measurements. Y1 - 2019 U6 - https://doi.org/10.3832/ifor2983-012 SN - 1971-7458 VL - 12 IS - 4 SP - 389 EP - 396 ER - TY - GEN A1 - Thell, Arne A1 - Hansson, Mats A1 - Persson, Per-Erik A1 - Seaward, Mark R.D. A1 - Veste, Maik A1 - Hedrén, Mikael T1 - ETS and plastid sequence data indicate a spontaneous origin of Scandinavian betony, Betonica officinalis L. T2 - Biologia Futura N2 - Background and aims: Betony (Betonica officinalis L.) is one of the rarest and most spectacular plants in the Scandinavian flora. A long-term question has been whether it is spontaneous or introduced, or whether it comprises both spontaneous and introduced populations. This study aimed to answer this question by analyzing sequence data from the nuclear external transcribed spacer (ETS) region and three regions of the plastid genome, the trnT–trnL intergenic spacer (IGS) region, tRNA-Leu (trnL) intron, and the trnS–trnG IGS. Materials and methods: Altogether 41 samples from 11 European countries were analyzed. A unique duplication in the trnT–trnL IGS was detected in material from Skåne (southern Sweden), the “Skåne-duplication.” Populations with this duplication are united on a moderately supported branch in the phylogeny based on plastid sequences. A distinct heath genotype from Yorkshire was discovered in the phylogeny based on plastid sequences and in a comparative cultivation. Results: Phylogeny based on ETS sequences does not support any Scandinavian group, whereas a principal coordinates analysis ordination based on variable ETS positions indicated a spontaneous origin for all Scandinavian populations, which comprise a genetically well-defined subgroup of the species, most closely related to other spontaneous populations from adjacent parts of continental parts of Northern Europe. Discussion: Seven possible naturally occurring localities remain in Scandinavia, five in central Skåne, southernmost Sweden, and two on the southwestern part of the Danish island of Lolland. Y1 - 2019 U6 - https://doi.org/10.1556/019.70.2019.27 SN - 2676-8607 VL - 70 IS - 3 SP - 218 EP - 239 ER - TY - GEN A1 - Seserman, Diana-Maria A1 - Freese, Dirk A1 - Swieter, Anita A1 - Langhof, Maren A1 - Veste, Maik T1 - Trade-Off between Energy Wood and Grain Production in Temperate Alley-Cropping Systems: An Empirical and Simulation-Based Derivation of Land Equivalent Ratio T2 - Agriculture N2 - The alley-cropping systems (ACSs), which integrate parallel tree strips at varying distances on an agricultural field can result, complementarity of resource use, in an increased land-use efficiency. Practitioners’ concerns have been directed towards the productivity of such systems given a reduced area covered by agricultural crops. The land equivalent ratio (LER) serves as a valuable productivity indicator of yield performance and land-use efficiency in ACSs, as it compares the yields achieved in monocultures to those from ACSs. Consequently, the objective of this combined experimental and simulation study was to assess the tree- and crop-yields and to derive the LER and gross energy yield for two temperate ACSs in Germany under different design scenarios, i.e., tree arrangements (lee- or wind-ward) and ratios of tree area to crop area. Both LER and gross energy yields resulted in a convex curve where the maximum values were achieved when either the tree or crop component was dominant (>75% of the land area) and minimum when these components shared similar proportions of land area. The implications of several design scenarios have been discussed in order to improve the decision-making, optimization, and adaptation of the design of ACSs with respect to site-specific characteristics Y1 - 2019 U6 - https://doi.org/10.3390/agriculture9070147 SN - 2077-0472 VL - 9 IS - 7 ER - TY - GEN A1 - Kleefeld, Andreas A1 - Gypser, Stella A1 - Herppich, Werner B. A1 - Bader, Georg A1 - Veste, Maik T1 - Identification of spatial pattern of photosynthesis hotspots in moss- and lichen-dominated biological soil crusts by combining chlorophyll fluorescence imaging and multispectral BNDVI images T2 - Pedobiologia N2 - Although biological soil crusts can be found in open landscapes worldwide, their species composition depends on soil properties such as texture and pH, on microclimate, and their respective developmental stage. In addition, local variations in water holding capacity and/or chemical properties of soils influence the formation of spatial patterns and different types of biocrusts on the landscape level. For the evaluation of biocrusts functions and their impact on soil carbon pools, the analysis of the interrelationship between photosynthetic activity and the variations of spatial distribution pattern and types of biocrust is indispensable. For this purpose, an image processing approach was applied that combined chlorophyll fluorescence analyses and multispectral BNDVI to comprehensively characterize the spatial patterns of photosynthetic hotspots in biological soil crusts. For image analysis, five biological soil crust samples with different ratios of substrate, mosses and lichens were collected on an inland dune system in Lieberose, dominated by the moss Polytrichum piliferum, and the lichens Cladonia fimbriata and C. coccifera. RGB-images of the biocrusts were taken with a standard consumer camera Nikon 5200, BNDVI images with a modified Canon S110 NIR camera and chlorophyll fluorescence images with a modular open FluorCAM FC 800-O/1010, respectively. BNDVI and Fv/Fm were nearly in the same range for all biocrust samples related to the total surface area. Although mosses showed higher BNDVI than lichens within the separate biocrust samples. F0 and Fm increased with species coverage and with advancing biocrust development. Overlapping of BNDVI with F0 and Fm images showed that not all crustal organisms contribute to BNDVI and chlorophyll fluorescence. The overlapping areas of BNDVI and F0 ranged between 13% and 29%, that of BNDVI and Fm between 17% and 47%. Matching of RGB, BNDVI and CFI allows visualizing spatial pattern with high or low photosynthesis in biocrusts. Y1 - 2018 U6 - https://doi.org/10.1016/j.pedobi.2018.04.001 SN - 1873-1511 VL - 68 SP - 1 EP - 11 ER - TY - GEN A1 - Carl, Christin A1 - Biber, Peter A1 - Veste, Maik A1 - Landgraf, Dirk A1 - Pretzsch, Hans T1 - Key drivers of competition and growth partitioning among Robinia pseudoacacia L. trees T2 - Forest Ecology and Management N2 - Competition for above- and below-ground resources depends on their availability and results in varied growth partitioning. This becomes clear as the supply and limitation of the main resources influence the slope of the size-growth relationship in stands. Nevertheless, growth partitioning among trees, especially among black locust (R. pseudoacacia) trees is not understood in sufficient detail. To scrutinize and estimate the mode of competition of R. pseudoacacia, this research analyzed 1333 trees in Germany in 10 study sites, consisting in total 27 sample plots, with similar climate but varying soil conditions. The stand age ranged from 2 to 32 years, with a diameter at breast height ranging from 0.6 to 29.1 cm. The main focus of the study was to evaluate the impact of nitrogen, phosphorus, and water supply on the competition mode of R. pseudoacacia by varying growth partitioning. We applied the size–growth relationship in a mixed-effects model with a random intercept and slope. Fixed effects were the basal area, phosphorus, water, the sunlight competition index, and the interactions between below- and above-ground resources. Site specific effects of the analyzed stands were quantified with the aid of the random effects. Depending on the supply and limitation of phosphorus and water, this study determined how the competition mode as well as the growth partitioning among R. pseudoacacia trees were influenced. Hence, if phosphorus and water availability increased, then the competition for above-ground resources (primarily sunlight) and the slope of the size–growth relationship increased. Large trees grew disproportionately more than smaller trees. If the available phosphorus and water decreased, then the competition for the below-ground resources increased and the slope of the size–growth relationship decreased – to be more flattened. Moreover, it was found that available nitrogen as a below-ground resource had no influence on the mode of competition. In summary, phosphorus was the most important nutrient and, together with water, was the main driver of growth partitioning among R. pseudoacacia trees. Y1 - 2018 U6 - https://doi.org/10.1016/j.foreco.2018.08.002 SN - 0378-1127 VL - 430 SP - 86 EP - 93 ER - TY - GEN A1 - Fischer, Thomas A1 - Veste, Maik T1 - Carbon cycling of biological soil crusts mirrors ecological maturity along a Central European inland dune catena T2 - Catena N2 - Photosynthesis and respiration of biological soil crusts (BSCs) sampled along a mobile inland dune catena were determined to evaluate the applicability of Odum’s P/R ratio, determined under controlled conditions, for estimation of ecosystem maturity. The theory is that in the early stages of ecological succession, the total photosynthesis (P) exceeds the rate of community respiration (R), so that the P/R ratio is greater than 1, and that P/R approaches 1 as succession occurs. In the special case of organic pollution, the P/R ratio is typically less than 1. Samples were collected in the deflation zone of the dune near the crest (BSC1, thickness 2-3 mm), at the lee side of grass tussocks at the slope (BSC2, thickness 2-4 mm) and near the base (BSC3, thickness 4-6 mm). Non crusted sand was used as control (BSC0). Photosynthesis, respiration, crust biomass, as well as fossil and allochthonous pedogenic carbon entering the system with mineral substrate were determined. The respiration of the BSC1 was dominated by the degradation of allochthonous organic matter, leading to a diminished P/R ratio. The better developed BSC2 and BSC3 were less influenced by allochthonous organic matter, where BSC maturity increased downslope with biomass increase. No significant relation between the P/R ratio and soil water tension was found. Crust carbon pools increased and flows intensified, but mineralization constants decreased with system maturation. It was concluded that Odum’s P/R ratio and accumulation of recalcitrant to biodegradation organic matter are indicative for biocrust maturity. Y1 - 2018 U6 - https://doi.org/10.1016/j.catena.2017.09.004 SN - 0341-8162 VL - 160 SP - 68 EP - 75 ER - TY - GEN A1 - Seserman, Diana-Maria A1 - Pohle, Ina A1 - Veste, Maik A1 - Freese, Dirk T1 - Simulating Climate Change Impacts on Hybrid-Poplar and Black Locust Short Rotation Coppices T2 - Forestry N2 - In Brandenburg, north-eastern Germany, climate change is associated with increasing annual temperatures and decreasing summer precipitation. Appraising short rotation coppices (SRCs), given their long-time planning horizon demands for systematic assessments of woody biomass production under a considerable spectrum of climate change prospects. This paper investigates the prospective growth sensitivity of poplar and black locust SRCs, established in Brandenburg to a variety of weather conditions and long-term climate change, from 2015 to 2054, by a combined experimental and simulation study. The analysis employed (i) a biophysical, process-based model to simulate the daily tree growth and (ii) 100 realisations of the statistical regional climate model STAR 2K. In the last growing period, the simulations showed that the assumed climate change could lead to a decrease in the woody biomass of about 5 Mg ha -1 (18%) for poplar and a decrease of about 1.7 Mg ha -1 (11%) for black locust trees with respect to the median observed in the reference period. The findings corroborate the potential tree growth vulnerability to prospective climatic changes, particularly to changes in water availability and underline the importance of coping management strategies in SRCs for forthcoming risk assessments and adaptation scenarios. Y1 - 2018 U6 - https://doi.org/10.3390/f9070419 SN - 1464-3626 VL - 9 IS - 7 ER - TY - GEN A1 - Matos, Eduardo da Silva A1 - Freese, Dirk A1 - Slazak, Anna A1 - Bachmann, Ute A1 - Veste, Maik A1 - Hüttl, Reinhard F. T1 - Organic-carbon and nitrogen stocks and organic-carbon fractions in soils under mixed pine and oak forest stands of different ages in NE Germany T2 - Journal of plant nutrition and soil science Y1 - 2010 SN - 1522-2624 VL - 173 IS - 5 SP - 654 EP - 661 ER - TY - GEN A1 - Fischer, Thomas A1 - Veste, Maik A1 - Eisele, Andreas A1 - Bens, Oliver A1 - Spyra, Wolfgang A1 - Hüttl, Reinhard F. T1 - Small Scale Spatial Heterogeneity of Normalized Difference Vegetation Indices (NDVI) and Hot Spots of Photosynthesis in Biological Soil Crusts T2 - Flora N2 - Normalized Difference Vegetation Indices (NDVIs) are typically determined using satellite or airborne remote sensing, or field portable spectrometers, which give an averaged signal on centimetre to metre scale plots. Biological soil crust (BSC) patches may have smaller sizes, and ecophysiological, hydrological as well as pedological processes may be heterogeneously distributed within this level of resolution. A ground-based NDVI imaging procedure using low-cost equipment (Olympus Camedia 5000z digital camera equipped with a Hoya R72 infrared filter) was developed in this study to fill this gap at the level of field research, where carrying costly and bulky equipment to remote locations is often the limiting factor for data collection. Method principle and field data are presented, and the field experiment was deepened comparing NDVI measurements and CO2 turnover of soil crust samples in the laboratory, backing the reliability of the approach. A commercially available colour rendition chart with known red (600–700 nm) and NIR (800–900 nm) reflectances was placed into each scene and used for calibration purposes on a per-image basis. Generation of NDVI images involved (i) determination of red and NIR reflectances from the pixel values of the red and NIR channels, respectively, and (ii) calculation and imaging of the NDVI, where NDVI values of −1 to +1 were mapped to grey values of 0 to 255. The correlation between NDVI values retrieved from these images and NDVI values determined using field spectrometry was close (r2 = 0.91), the 95% confidence interval amounted to 0.10 NDVI units. The pixel resolution was 0.8 mm in the field and 0.2 mm in the laboratory, but can still be improved significantly with closer distance to the crust or with higher camera resolution. NDVI values obtained using the new method were related to the net CO2 uptake of BSCs, where both slope and correlation coefficient of the respective regression function conformed with literature data. Geostatistical analysis revealed that both spatial variability of net CO2 uptake as well as size of individual hot spots of this parameter increased with crust development. The latter never exceeded 4 mm in the investigated crusts, which points to the necessity of high resolution imaging for linking remote sensing with ecophysiology. Perspectively, the new method could be used for field monitoring of both biological soil crusts and vascular vegetation. Y1 - 2012 U6 - https://doi.org/10.1016/j.flora.2012.01.001 VL - 207 IS - 3 SP - 159 EP - 167 ER - TY - GEN A1 - Fischer, Thomas A1 - Veste, Maik A1 - Schaaf, Wolfgang A1 - Dümig, Alexander A1 - Kögel-Knabner, Ingrid A1 - Wiehe, Wolfgang A1 - Bens, Oliver A1 - Hüttl, Reinhard F. T1 - Initial pedogenesis in a topsoil crust 3 years after construction of an artificial water catchment in Brandenburg, NE Germany T2 - Biogeochemistry N2 - Cyanobacteria and green algae present in biological soil crusts are able to colonize mineral substrates even under extreme environmental conditions. As pioneer organisms, they play a key role during the first phases of habitat colonization. A characteristic crust was sampled 3 years after installation of the artificial water catchment “Chicken creek”, thus representing an early successional stage of ecosystem development. Mean annual rainfall and temperature were 559 mm and 9.3°C, respectively. We combined scanning electron microscopy (SEM/EDX) and infrared (FTIR) microscopy to study the contact zone of algal and cyanobacterial mucilage with soil minerals in an undisturbed biological soil crust and in the subjacent sandy substrate. The crust was characterized by an approximately 50 μm thick surface layer, where microorganisms resided and where mineral deposition was trapped, and by an approximately 2.5 mm thick lower crust where mineral particles were stabilized by organo-mineral structures. SEM/EDX microscopy was used to determine the spatial distribution of elements, organic compounds and minerals were identified using FTIR microscopy and X-ray diffraction (XRD). The concentration of organic carbon in the crust was about twice as much as in the parent material. Depletion of Fe, Al and Mn in the lower crust and in the subjacent 5 mm compared to the geological substrate was observed. This could be interpreted as the initial phase of podzolization. Existence of bridging structures between mineral particles of the lower crust, containing phyllosilicates, Fe compounds and organic matter (OM), may indicate the formation of organo-mineral associations. pH decreased from 8.1 in the original substrate to 5.1 on the crust surface 3 years after construction, pointing to rapid weathering of carbonates. Weathering of silicates could not be detected. Y1 - 2010 U6 - https://doi.org/10.1007/s10533-010-9464-z SN - 1573-515X VL - 101 IS - 1-3 SP - 165 EP - 176 ER - TY - GEN A1 - Veste, Maik A1 - Halke, Christian A1 - Garbe, Daniel A1 - Freese, Dirk T1 - Einfluss von Stickstoffdüngung und Kompost auf Photosynthese und Wachstum der Virginiamalve (Sida hermaphrodita Rusby) T2 - Journal für Kulturpflanzen N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1399/JFK.2016.12.13 SN - 1867-0911 SN - 1867-0938 VL - 68 IS - 12 SP - 423 EP - 428 ER - TY - GEN A1 - Veste, Maik A1 - Kriebitzsch, Wolf-Ulrich T1 - Photosyntheseverhalten der Stechpalme (Ilex aquifolium L.) in milden Winter in Mitteleuropa: Ein ökophysiologischer Vorteil durch den Klimawandel? T2 - Allgemeine Forst- und Jagd-Zeitung N2 - Die Wintertemperaturen und insbesondere Frost sind wichtige Umweltfaktoren, die das Verbreitungsgebiet der Stechpalme (Ilex aquifolium L.) Mitteleuropa beschränken. Bereits heute profitiert diese Art von dem Klimawandel durch eine erweiterte Verbreitung in Mitteleuropa und an seiner nördlichen Verbreitungsgrenze in Skandinavien. In dieser Arbeit wird die Bedeutung der milder werdenden Wintertemperaturen für den Stoffwechsel von I. aquifolium untersucht, insbesondere die Akklimatisation der Photosynthese während des Winters. Dafür wurde die Photosynthese mit der Chlorophyllfluoreszenz-Methode gemessen. Während milder Wintertage bei Temperaturen wenig unter 0°C erholte sich die Photosynthese innerhalb von zwei Stunden, sobald die Pflanzen Raumtemperatur ausgesetzt wurden. Dagegen war die Photosynthese nach langanhaltenden Frostperioden und die gemessenen Elektronentransportraten der im Freiland wachsenden Ilex-Bäume um bis zu 50% niedriger als bei den Vergleichspflanzen im Gewächshaus. Somit wird die Photosynthese im Winter von der minimalen Temperatur und der Frostdauer beeinflusst. In der Regel war die immergrüne Stechpalme in der Lage ihre Photosynthese im Winter aufrecht zu erhalten und flexibel auf frostfreie Tage zu reagieren. Damit profitiert die Stechpalme während milder Tage im Winter und Frühjahr von dem im Vergleich zu den Sommermonaten hohem Lichtgenuss im Unterwuchs, wenn die sommergrünen Bäume in der Baumschicht unbelaubt sind. Y1 - 2019 SN - 0002-5852 VL - 189 IS - 7/8 SP - 143 EP - 153 ER - TY - GEN A1 - Veste, Maik T1 - Bioenergie aus Wüstenpflanzen T2 - Naturwissenschaftliche Rundschau Y1 - 2014 SN - 0028-1050 VL - 67 IS - 2 SP - 80 EP - 81 ER -