Climate Change In Central Europe Research Articles

Future forests and biodiversity: Effects of Douglas fir introduction into temperate beech forests on plant diversity

Introduction of drought-tolerant exotic tree species is seen as an important adaptation measure of forest management to climate change in Central Europe. Douglas fir (Pseudotsuga menziesii) is particularly favored in this context, because it is adapted to summer droughts due to the climate in its natural distribution range in temperate western North America and it is also fast-growing and the wood is readily marketable. In Germany, there are plans to grow Douglas fir on a large scale in mixed forests with other tree species on acidic soils. Potential ecological consequences have not yet been sufficiently scrutinized. Here, we analyze effects of Douglas fir introduction into forests of European beech (Fagus sylvatica), which would naturally predominate Central Europe’s forests. We analyzed vascular plant diversity and species composition of the ground vegetation in a gradient with increasing Douglas fir canopy fraction that ranged from pure beech (0% Douglas fir) via mixed stands (25%, 50%, 75% Douglas fir) to pure (100%) Douglas fir forest. Species richness, Shannon diversity, and Simpson diversity increased with increasing Douglas fir canopy fraction. However, this increase was primarily driven by an increase of nitrogen-tolerant disturbance indicators, whereas the share of forest species that were predominant in pure beech forests decreased. Beech forest species declined gradually with increasing Douglas fir canopy fraction, but these declining species were fewer than the number of species increasing due to Douglas fir introduction. Cover of ∼30% of species remained constant when Douglas fir was introduced. Strong changes in the ground vegetation were observed at Douglas fir canopy fractions > 40 – 50% and the original character of the ground vegetation was completely lost beyond a threshold of 75%. Therefore, we discourage from high Douglas fir proportions beyond these thresholds in production forests and from any introduction of Douglas fir where nature conservation is a priority.

Experimental evaluation of waterlogging and drought tolerance of essential Prunus species in central Europe

Fruit-bearing and flowering minority tree species, such as many species from the Prunus genus, are essential for multiple ecosystem services in the landscape. Although common, but never dominating, these minority species are often overlooked compared to commercial timber trees in relation to climate change. Induced stress on trees through climate change in central Europe will not only be caused by drought but also by extreme precipitation and pluvial flooding. This study experimentally address this by testing both waterlogging and drought tolerance in three key species of Prunus for central Europe that naturally span a wide variation of habitat conditions. The selected species Prunus mahaleb, Prunus avium and Prunus padus were subjected to both drought and waterlogging in a greenhouse experiment. Plant functionality in the form of midday leaf water potential, stomatal conductance and turgor loss point together with different aspects of biomass allocation and growth was tested. All included species lost their stomatal conductance and leaf water potential within a few days in the waterlogging treatment. Only P. padus had the capacity to recover with new leaves after the waterlogging ended, suggesting that avoidance strategies though leaf shedding can be a complementary mechanism to withstand waterlogging. P. padus kept its stomatal conductance and water potential for the longest time in the drought treatment followed by P. mahaleb and P.avium. This longevity in the drought treatment for P. padus could be explained by both tolerance strategies through lower turgor loss point, but also avoidance strategies with fast changes in growth and higher allocation of biomass to the roots. There is a clear risk that ecosystem service from Prunus species in the landscape can be negatively affected not only by drought but also by increased events of waterlogging. This highlights the need for including minority species and also other climate stressors in addition to drought in the planning and management of multifunctional landscapes.

Evaluating the impact of a 2.5–3°C increase in temperature on drought-stressed German wheat cultivars under natural stress conditions

Climate change in Central Europe is expected to influence crop growth through frequent drought and heat extremes. Wheat contributing about 20% of the total dietary calories and proteins worldwide, is sensitive to heat and drought, especially during its reproductive stages. To develop strategies to improve climate resilience in wheat, a comprehensive field evaluation was carried out under drier and warmer field conditions in Moldova from 2016 to 2019 for forty winter wheat varieties from Germany and Eastern Europe. The grain yield of German cultivars grown in Moldova ranged from 4.46–6.58 t/ha from 2016 to 2019 and was 40% lower compared to the same cultivars grown in Southern Germany. This is significantly more than the reduction predicted by current process-based crop yield models considering only seasonal temperature effects and not combined drought effects. Among all the wheat varieties tested in Moldova, Eastern European varieties and German hybrids achieved the best yield performance across the years. The lower grain yield of German wheat varieties was mainly due to the reduction in grain filling duration, which led to a decrease in the grain filling rate and thousand-grain weight. A higher grain filling rate contributed to a higher grain yield in the Eastern European varieties. These results suggest that well-adapted varieties with a faster rate of development and an earlier start of grain filling have a notable advantage under drought and heat conditions, providing a useful genetic source to increase heat and drought tolerance in future plant breeding programs. The space-for-time approach used in this study allows for the investigation of combined heat and drought, reflecting anticipated or future climate conditions without taking into account CO2 effects.

Validity and reliability of drought reporters in estimating soil water content and drought impacts in central Europe

Increasing drought is considered one of the major threats associated with climate change in central Europe. To provide an objective, quantitative tool that represents current drought conditions, the Czech Drought Monitor System (CzechDM) was established in 2012. Like other drought monitoring systems worldwide, the CzechDM uses several approaches to provide drought data. However, the CzechDM is unique internationally due to its utilization of a network of voluntary reporters (farmers) who complete a weekly online questionnaire to provide information about soil water content and the impacts of drought on crop yield. In this study, the results from the questionnaires from individual farms were aggregated by district. Reporters’ data were compared and validated with the outputs of the SoilClim model (a core tool of the CzechDM) and with other drought monitoring tools, such as the water balance model, the soil water index and the evaporative stress index. The soil water content estimated by the reporters was significantly correlated (on average r = 0.8) with the outputs of the SoilClim model. Conversely, the correlation between the drought impacts on yield estimated by the reporters and the SoilClim outputs was lower (on average r = 0.4), suggesting that in situ observations by farmers provide additional insights into the occurrence of drought impacts. Importantly, it was found that farmers reported significant drought impacts on yield earlier in the season than any other methods (models or remote sensing). The main findings of this study are that the drought monitoring provided by reporters is a useful and reliable component of the CzechDM. We conclude that weekly reports by farmers represent a significant enhancement to drought monitoring and have potential for use in developing automated approaches that combine in situ, modeling and remote sensing data within a data fusion or machine learning framework.

Geographic variation in the population trends of common breeding birds across central Europe

Recent declines of many European bird species have been linked with various environmental changes, especially land-use change and climate change. Since the intensity of these environmental changes varies among different countries, we can expect geographic variation in bird population trends. Here, we compared the population trends of bird species among neighbouring countries within central Europe (Czech Republic, Denmark, Germany, Switzerland) between 1990 and 2016 and examined trait-associations with population trends at both national and international scales. We found that Denmark had the highest proportion of declining species while Switzerland had the lowest. Species associated with farmland had negative trends, but the effect size tended to differ among countries. A preference for higher temperature was positively associated with population trends and its effect size was similar among countries. Species that were increasing across all four countries were associated with forest; while species that were decreasing across all countries were long-distance migrants or farmland birds. Our results suggest that land-use change tends to be a more regionally variable driver of common bird population trends than climate change in central Europe. For species declining across all countries, international action plans could provide a framework for more efficient conservation. However, farmland birds likely need both, coordinated international action (e.g. through a green agricultural policy) to tackle their widespread declines as well as regionally different approaches to address varying national effect trajectories.

The Relationships of Texture and Hydrophysical Properties in Soil Profiles Under Selected Exotic Trees in the Context of Climate Change in Central Europe

The Relationships of Texture and Hydrophysical Properties in Soil Profiles Under Selected Exotic Trees in the Context of Climate Change in Central Europe

Dependence of milk production of dairy sheep on climate conditions

Article Details: Received: 2020-10-14 | Accepted: 2020-11-27 | Available online: 2021-01-31 https://doi.org/10.15414/afz.2021.24.mi-prap.85-88 The aim of the study was to determine the influence of selected climatic characteristics on the milk production of ewes during lactation. Data of ewes from sheep farm Liptovska Teplicka located in moderate climate zone (latitude 48°57'50.3N, longitude 20°04'31.0E) were analysed. In period from 2017 to 2019, the following milk traits: total morning milk production (TMPM), total evening milk production (TMPE), total morning+evening production (TMPM+E) and average daily milk production per ewe (ADMP) were measured on a daily basis. Traditional (Carpatian) production system was applied: ewes were on pasture and machine milked twice a day. Climate characteristics were monitored in 10-minute intervals by standard weather station (supplier: firm PHYSICUS), located near sheep farm. The influence of air temperature - T (°C), of relative humidity - RH (%), of wind speed (m.s -1 ) and of total precipitation (mm)recorded daily between 5 a.m. and 4 p.m. in period from April to September on milk traits was analysed. Temperature-humidity index (THI) was calculated according to National Research formula. The influence of year, of month and of interaction year x month was also analysed. Covariance analysis and Pearson correlation coefficients using statistical programme SASv9.2 (procedures GLM and CORR) were employed. The influence of month and of interaction year x month, respectively, on milk traits was found (P 40.0 and THI <= 68.0). Preliminary results suggest that milk production traits of dairy sheep may be significantly influenced by climate also in moderate climatic zone. Keywords: sheep, thermal stress, milk yield, temperate zone References Al Dawood, A. 2017. Towards heat stress management in small ruminants – a review. Ann. Anim. Sci., 17(1), 59-88. DOI: 10.1515/aoas-2016-0068 Finocchiaro, R., Van Kaam, J.B.C.H.M., Portolano, B., Misztal, I. 2005. Effect of heat stress on production of Mediterranean dairy sheep. J. Dairy Sci. , 88, 1855-1864. Gauly, M., Ammer, S. 2020. Review: Challenges for dairy cow production systems arising from climate changes. Animal,. 14:S1, s196-s203. doi:10.1017/S1751731119003239 Gauly, M., Bollwein, H., Breves, G., Brugemann, K., Danicke, S., Das, G., Demeler, J., Hansen, H., Isselstein, J., Konig, S., Loholter, M., Martinshon, M., Meyer, U., Potthoff, M., Sanker, C., Schroder, B., Wrange, N., Meibaum, B., von Samson-Himmelstjerna, G., Stinshof, Wrenzycki, C., 2013. Future consequences and challenges for dairy cow production systems arising from climate change in Central Europe – a review. Animal, 7, 843-859. doi:10.1017/S1751731112002352 Ramon, M., Diaz, C., Perez-Guzman, M.D., Carabano, M.J. 2016. Effect of exposure to adverse climatic conditions on production in Manchega dairy sheep. J. Dairy Sci., 99 , 5764-5779. http://dx.doi.org/10.3168/jds.2016-10909 Hamzaoui, S., Salama, A.A.K., Albanell, E., Such, X., Caja, G. 2013. Physiological responses and lactational performances of late-lactation dairy goats under heat stress conditions. J. Dairy Sci., 96, 6355-6365 . http://dx.doi.org/ 10.3168/jds.2013-6665 National Research Council (NRC). 1971. A guide to envronmental research on animals. Washington, DC: National Academy of Science. Sanches-Molano, E., Kapsona, V.V., Ilska, J.J., Desire, S., Conington, J., Mucha, S., Banos., G. 2019. Genetic analysis of novel phenotypes for farm animal resilience to weather variability. BMC Genetics., 20-84. https://doi.org/10.1186/s12863-019-0787-z Silanikove, N., N. Koluman (Darcan). 2015. Impact of climate change on the dairy industry in temperate zones: predications on the overall negative impact and on the positive role of dairy goats in adaptation to earth warming. Small Rumin Res ., 123, 27-34. http://dx.doi.org/10.1016/j.smallrumres.2014.11.005

Height growth-related competitiveness of oak (Quercus petraea (Matt.) Liebl. and Quercus robur L.) under climate change in Central Europe. Is silvicultural assistance still required in mixed-species stands?

Sessile oak (Quercus petraea (Matt.) Liebl.) and pedunculate oak (Quercus robur L.) play an important role in increasing the resistance of central European forests to severe droughts. But outside their real niche the competitiveness of both oak species can be low in mixed-species stands. This paper examines the height growth of oaks depending on environmental conditions and inter-specific competition. Height growth of trees was analysed using data from forest inventories covering monospecific and mixed-species stands within the German federal state of Bavaria. By means of regression analyses of 23,607 height measurements, we found that site conditions and stand structure have strong effects on the height growth of oak. Summer temperature, water balance in the vegetation period and base saturation were the main explanatory site variables. The first positive effect of summer temperature had no influence at warmer sites with mean summer temperatures above 16.4 °C, while the effect of water balance was positively linear. In addition, stand density modified the height growth of oak in a mainly positive manner. Vertical structure also had a positive effect, which was found for most species compositions, except monospecific stands and oak-hornbeam mixture. In most mixtures, oaks height growth seemed to be less climate-sensitive compared to monocultures. A currently warmer and drier climate seemed to favour the height growth superiority of European beech, whereas it decreased the superiority of Scots pine. The results indicated that even if the climate changes as predicted, the growth of oak will depend upon silvicultural promotion. Our findings can be used to improve regional guidelines for oak silviculture with special regard to climate-sensitive height growth. For example, a regionally delayed introduction of admixed species can reduce silvicultural treatments by ensuring oak vitality in mixed forests at the same time.

Isotopic and time series investigations of recent stalagmites (1945–2018), Schlossberg tunnels, Graz, Austria: implications for climate change in Central Europe

Abstract For the first time, we present a decadal-scale stable isotope record (δ 18 O, δ 13 C) of 67 speleothem calcite samples coming from an artificial tunnel network located in Graz, Austria. Stable isotope data are interpreted with the help of time series (TS) analysis of mean air temperatures (MAT) and mean annual precipitations (MAP) that have been monitored and recorded in a neighbouring meteorological station. Speleothem records have proved to be very useful in reconstructing changes of environmental conditions. For studied stalagmites, which grew between 1945 and 2018, the δ 18 O values average −18.64‰ and range from −23‰ to −17‰ (VPDB, Vienna Pee Dee Belemnite), suggesting variable climatic conditions. The δ 18 O values of calcite increase along the growth axis and are correlated with high temporal resolution MAT, MAP and weighted mean annual δ 18 O of precipitations. For the same time interval, while the temperature TS show an increasing trend, with a steeper gradient since the 1980s, the precipitation TS presents a weak decreasing tendency. Increase in the δ 13 C values of speleothems from −33‰ to −24‰ (VPDB) is correlated with increasing temperature and drought, associated CO 2 degassing and soil erosion over the tunnel system.

Spatiotemporal variability of air temperature during a heat wave in real and modified landcover conditions: Prague and Brno (Czech Republic)

More frequent and severe heat waves rank among the most serious impacts of climate change in Central Europe. At the same time, increasing awareness of the importance of municipalities acting in climate change adaptation leads to a higher demand for urban climate modelling. In this study we use MUKLIMO_3 model for a simulation of spatiotemporal pattern of air temperature in Prague and Brno. Our aim is to simulate theoretical land cover modifications and their potential impacts on air temperature during a heat wave event. The model suggests that an albedo increased by 0.25 leads to a difference of −0.2 °C in daily average temperature in both Prague and Brno while an albedo increased by 0.5 leads to a daily average temperature difference of −0.5 °C in Prague and − 0.4 °C in Brno. Increasing the number of trees by 30% generally leads to higher temperatures during daytime and lower temperatures during night-time. In most neighbourhoods the cooling effect of additional trees was 0.0 °C to −0.2 °C on the daily average. In some cases of compact midrise development, additional trees might even cause an increase in temperature. This fact underlines the importance of careful individual assessment of adaptation measures before their implementation at particular locations.

Microclimate edge effect in small fragments of temperate forests in the context of climate change

A long-distance edge effect influences structure of species-rich plant communities in temperate forest fragments surrounded by an agricultural landscape in Central Europe. Though the edge effect may be an aggregate of many environmental conditions, the thermal gradient from the forest edge to the forest interior deserves particular attention due to increasing ambient air temperature over the past decades. With regard to ongoing climate change, any reliable information about magnitude and distance of thermal gradients in these forest fragments has become of great importance. Therefore, we carried out seasonal measurements of forest air and soil temperature at a total 40 sites in 14 forest fragments in central Bohemia with areas ranging between 0.3 and 255 ha. In addition, we assessed spatial and vertical air temperature variability at two sites, on both south and north facing slopes. We found that differences in daily mean air temperature in these forest fragments is significantly modified by slope aspect (and/or slope inclination) and distance to the forest edge. A negative monotonic edge-related thermal gradient was apparent up to 100 m towards the forest interior with differences in daily mean air temperatures of about 0.3 °C. The magnitude of this edge thermal gradient is comparable to the effect of slope aspect. In addition to mean air temperature, maximum and minimum daily temperatures as well as mean soil temperature inside forest fragments also showed impacts caused by the edge effect and other environmental conditions (e.g. forest structure, elevation). The edge-related area closer than 100 m from the forest edge represents the majority (78%) of forested land in the study area as well as a considerable part of temperate forests in Central Europe (40%), including less fragmented mountain forests. Hence, the edge alteration of forest microclimate should be taken into serious consideration when planning adaptation measures against the consequences of climate change in Central Europe. The edge influence could be partially mitigated by preventing further forest fragmentation and the adoption of timber harvesting methods that avoid creation of clearings, such as single-tree selection. Even if such forest management measures are implemented in the study area, spatial patterns and gradients of environmental heterogeneity may be gradually reduced in the forest fragments as a result of further exposure to the combined effects of climate change and edge influence.

Effect of native habitat on the cooling ability of six nursery-grown tree species and cultivars for future roadside plantings

Vegetation in urban areas provides benefits to people, which are increasingly assessed and valued as ecosystem services (ESS). The regulation of the urban microclimate is one of these services, since trees have the potential to reduce urban heat loads by evapotranspiration and shading. Simultaneously, it has been suggested that trees from dry habitats should be used to cope with the increasing risks of drought under climate change in Central Europe. The underlying properties that enable those trees to reduce dependence on the environment, however, are assumed to come at the expense of biomass production and water loss. In the potentially conflicted area between drought tolerance and ESS we compared water consumption, water-use efficiency (WUE), crown structure and growth of six roadside species/cultivars, which are assumed to vary in drought tolerance, due to differing resource supplies in their native habitats. Acer platanoides, Carpinus betulus ‘Fastigiata’, and Tilia cordata ‘Greenspire’ were compared with Acer campestre, Ostrya carpinifolia, and Tilia tomentosa ‘Brabant’, the latter presumably being less water-demanding. Measurements took place in the municipal nursery of Munich during summer 2016.Surprisingly, the less water-demanding species/cultivars exhibited on average 1.24 times higher values of maximum daily sap flux density and up to seven times higher growth rates, both contributing to higher WUE. Scaled to leaf level, however, their mean daily transpiration rates were on average lower (0.21 and 0.31 kg H2O m−2 d−1, respectively). They also showed higher flexibility in response to changing weather with increased growth and transpiration under favorable conditions in early summer, but a more conservative water use in dry late summer. The results suggest that these species/cultivars tend to regulate their water use stronger under increasing dryness, whereas canopy size and leaf amount are still the main important determinants of species and cultivar differences in water use.

Drought- and frost-induced accumulation of soluble carbohydrates during accelerated senescence in Quercus pubescens

Different environmental conditions affect tree senescence by different patterns of carbohydrate concentrations and have specific impact on the dissection of the photosynthetic apparatus. A proactive cultivation of Mediterranean broadleaf species, including oaks, has been suggested to fill possible temporal and spatial gaps in forestry created by Climate Change in Central Europe in the future. Climate can affect trees in several different ways, e.g., by modulating the course of leaf senescence. Senescence-associated processes, like regulation of carbohydrates and changes in chlorophyll fluorescence under drought stress conditions were studied with leaf tissue of drought-tolerant downy oak (Quercus pubescens). Two months of consistent drought stress in a frost-free greenhouse led to significantly earlier senescence and significant increased amounts of soluble sugars in the leaves of the drought-stressed group in comparison to a well-watered control group. Similar sugar accumulation was observed in trees outdoors, after exposure to frost. In contrast to monocarpic plants the accumulation of free sugars is neither triggering leaf senescence, nor is it a side effect of age-depending changes in Q. pubescens. Instead, sugar accumulation is induced by abiotical factors, like drought and frost. Furthermore, we suggest that the senescence process in the absence of drought stress or frost depends on the source status of the leaf, which, in term, is a function of light (through photosynthesis) and night temperature (through respiration). Contents of the storage metabolite starch decreased during late summer in all three groups. Drought-stressed plants showed a decline of the connectivity of photosystem II antenna, reflected as the L-band in the chlorophyll fluorescence induction curves, and stronger correlations between the declines in the capacity of photosynthetic dark reactions and electron transport-associated chlorophyll fluorescence parameters. We conclude that the disassembly of single parts of the photosynthetic apparatus during leaf senescence is a uniform process, but the onset of this process depends on abiotical environmental factors.

Exposure to climate change in Central Europe: What can be gained from regional climate projections for management decisions of protected areas?

Climate change is expected to become an important driver influencing biodiversity. To protect biological diversity in the long term, nature conservationists must include potential climate change impacts in their management decisions. In order to incorporate effective climate change adaption strategies in the management of protected areas, potential threats of climate change need to be identified. In this study, climate model projections have been evaluated to derive information about the future exposure of nature parks to climate change. Indicators reflecting climate boundary conditions were selected in a cooperative process, considering both scientifically reliable climate scenario analysis and the requirements of park managers. The evaluation exhibits large uncertainties depending on the indicator. While for temperature, a warming trend is projected for all the regions, future projections for precipitation show the largest inter-model uncertainties. The Climatic Water Balance reflects the potential water availability and aids clarification to stakeholders, as it incorporates the temperature trend. The analysis robustly indicates a prolongation for the climatic growing season. The main challenges related to climate model information for decision-making are the uncertainties, different scales of climate and ecosystem processes and the finding of a common communication level for knowledge transfer. The results are useful for climate-influenced decision-making and provide one part of evidence for making adaptation decisions.

Growth reaction patterns of tree height, diameter, and volume of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) under acute drought stress in Southern Germany

Climate change in Central Europe may come along with acute drought stress, which can severely reduce growth and vitality of forest trees and whole stands. For a tree species such as Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) which is cultivated far beyond its natural range in Europe, knowledge of its behaviour under stress is crucial for the cultivation of Douglas-fir in view of a changing climate. Because of its easy accessibility, growth response to stress was mainly studied based on diameter growth at breast height. In long-term experiments on one dry and one moist site in Southern Germany, stem analyses of 133 mature and even-aged Douglas-firs were performed. The short-term growth reaction pattern under acute drought stress of 2003 had not only consequences on diameter but more pronounced effects can be observed when studying tree height: Respecting the different age trends by previous detrending, height increment only reacted more sensitive on the dry site. We also showed that extrapolating a particular decline in basal area increment to the whole stem can result in misunderstandings. However, results were less biased, when original data were smoothed or short-term assessment of volume growth was based on basal area measurements. By means of a linear mixed model approach, the influence of site, tree, and stand characteristics on Lloret’s indices of resistance and resilience (Lloret et al. in Oikos 120:1909–1920. doi:10.1111/j.1600-0706.2011.19372.x, 2011) were analysed. For Douglas-fir, site played a crucial role and became more important considering the age trend. On the contrary, the positive influence of site quality on drought tolerance decreased with data processing. However, more growing space by thinning can advance tree resistance and resilience regarding height, diameter, and volume growth. Large individual crown volume improved the growth pattern under drought, and large stand density impaired it. Douglas-fir is obviously equipped with a morphological variability, which fosters lateral rather than vertical growth allocation under severe stress. Silviculture can mitigate stress through the choice of the site and through lower stand densities by thinning. Our refined stress response analysis confirmed a favourable growth and resilience of Douglas-fir even under extreme drought events.

Forschung zu Wald und Klimawandel in Mitteleuropa: eine Werkschau

Research on forests and climate change in Central Europe: state of the art How are trees in Central European forests affected by climate change, yesterday, today and tomorrow? To answer this question, 250 researchers met for the international conference “ClimTree 2013” that took place in Zurich in September 2013. The answers are manifold and confirm that knowledge on this subject is not fully consolidated yet. Nevertheless, there is agreement on the two most important factors causing marked changes: aggravated water shortage during the growing season leading to growth and regeneration changes and inducing mortality, and rising temperatures that accelerate both biotic and abiotic processes, in particular pest outbreaks and forest fires. The question which tree species will dominate under future climatic conditions is lively debated due to novel results from experiments and dendroecological studies that have only partially been considered in forest succession models to date. Thus, the discussion on a next generation of such models has started. The present conference report summarizes the state of the art as well as new research questions in this field.

Climatic turning point for beech and oak under climate change in Central Europe

The growth behavior of coexisting tree species under climate change is important from an ecological, silvicultural and economic perspective. While many previous studies are concerned with climatic limits for species occurrence, we focus on climate related shifts in interspecific competition. A landmark for these changes in competition is the ‘climatic turning point' (CTP): those climate conditions under which a rank reversal between key tree species occurs. Here, we used a common type of temperate mixed forest in Central Europe with European beech (Fagus sylvaticaL.) and sessile oak (Quercus petraea(Matt.) Liebl.) to explore the CTP under a future climate projection of increasing temperature and aridity. We selected a dry region where the prerequisite of differential climate sensitivity in mixed beech‐oak forests was fulfilled: In‐situ dendrochronological analyses demonstrated that the currently more competitive beech was more drought sensitive than sessile oak. We then used two complementary forest growth models, namely SILVA and LandClim, to investigate the climate induced rank‐reversal in species dominance and to quantify it as the CTP from beech to oak by simulating future forest development from the WETTREG 2010 A1B climate projection. Utilizing two models allowed us to draw conclusions robust against the assumptions of a particular model. Both models projected a CTP at a mean annual temperature of 11–12°C (July temperature &gt;18°C) and a precipitation sum of 500–530 mm. However, the change in tree species composition can exhibit a time‐lag of several decades depending on past stand development and current stand structure. We conclude that the climatic turning point is a simple yet effective reference measure to study climate related changes in interspecific competition, and confirm the importance of competition sensitivity in climate change modeling.

Prolonged summer droughts retard soil N processing and stabilization in organo-mineral fractions

Prolonged summer droughts are projected to occur as a consequence of climate change in Central Europe. The resulting reduced soil water availability may lead to alterations in rates of soil processes such as nitrogen partitioning among soil organic matter fractions and stabilization within soil. To study the effect of climate change-induced drought on (1) the distribution of nitrogen among soil organic matter fractions and (2) nitrogen stabilization, we performed a space-for-time climate change experiment. We transferred intact plant–soil–microbe mesocosms of a Rendzic Leptosol with a young beech tree from a slope with northwestern exposure in southern Germany characterized by a cool-moist microclimate across a narrow valley to a slope with southwestern exposure with a warm-dry microclimate, which reflects projected future climatic conditions. A control transfer was also done on the northwest-facing slope within the same area of origin. We combined a homogenous 15N labeling approach using ammonium nitrate with a physical fractionation procedure and chemical soil extraction protocols. Our aim was to follow the partitioning of 15N in different soil organic matter fractions, i.e. light fractions, organo-mineral fractions, and extractable soil fractions including microbial biomass, ammonium, nitrate, and dissolved organic nitrogen. Within less than one growing season, we observed a modified partitioning of recently applied inorganic 15N between different soil fractions in relation to drier summer conditions, with attenuated nitrogen turnover under drought and consequently significantly higher 15N concentrations in the relatively labile light fractions. We ascribed this effect to a decelerated mineralization immobilization turnover. We conclude that prolonged summer droughts may alter the stabilization dynamics because the induced inactivity of microorganisms may reduce the transfer of nitrogen to stabilization pathways. A retarded stabilization in organo-mineral associations enhances the risk of nitrogen losses during extreme rainfall events, which are projected to increase in the 21st century predicted by future climate change scenarios for Central Europe.

Future consequences and challenges for dairy cow production systems arising from climate change in Central Europe – a review

It is well documented that global warming is unequivocal. Dairy production systems are considered as important sources of greenhouse gas emissions; however, little is known about the sensitivity and vulnerability of these production systems themselves to climate warming. This review brings different aspects of dairy cow production in Central Europe into focus, with a holistic approach to emphasize potential future consequences and challenges arising from climate change. With the current understanding of the effects of climate change, it is expected that yield of forage per hectare will be influenced positively, whereas quality will mainly depend on water availability and soil characteristics. Thus, the botanical composition of future grassland should include species that are able to withstand the changing conditions (e.g. lucerne and bird's foot trefoil). Changes in nutrient concentration of forage plants, elevated heat loads and altered feeding patterns of animals may influence rumen physiology. Several promising nutritional strategies are available to lower potential negative impacts of climate change on dairy cow nutrition and performance. Adjustment of feeding and drinking regimes, diet composition and additive supplementation can contribute to the maintenance of adequate dairy cow nutrition and performance. Provision of adequate shade and cooling will reduce the direct effects of heat stress. As estimated genetic parameters are promising, heat stress tolerance as a functional trait may be included into breeding programmes. Indirect effects of global warming on the health and welfare of animals seem to be more complicated and thus are less predictable. As the epidemiology of certain gastrointestinal nematodes and liver fluke is favourably influenced by increased temperature and humidity, relations between climate change and disease dynamics should be followed closely. Under current conditions, climate change associated economic impacts are estimated to be neutral if some form of adaptation is integrated. Therefore, it is essential to establish and adopt mitigation strategies covering available tools from management, nutrition, health and plant and animal breeding to cope with the future consequences of climate change on dairy farming.

Nitrogen dynamics in oak model ecosystems subjected to air warming and drought on two different soils

Being tolerant to heat and drought, oaks are promising candidates for future forestry in view of climate change in Central Europe. Air warming is expected to increase, and drought decrease soil N availability and thus N supply to trees. Here, we conducted a model ecosystem experiment, in which mixed stands of young oaks (Quercus robur, Q.petraea and Q.pubescens) were grown on two different soils and subjected to four climate treatments during three growing seasons: air warming by 1-2°C, drought periods (average precipitation reduction of 43-60%), a combination of these two treatments, and a control. In contrast to our hypotheses, neither air warming nor drought significantly affected N availability, whereas total amounts, vertical distribution and availability of soil N showed substantial differences between the two soils. While air warming had no effect on tree growth and N accumulation, the drought treatment reduced tree growth and increased, or tended to increase, N accumulation in the reduced biomass, indicating that growth was not limited by N. Furthermore, (15) N-labelling revealed that this accumulation was associated with an increased uptake of nitrate. On the basis of our results, climate change effects on N dynamics are expected to be less important in oak stands than reduced soil water availability.