MASTREE+: Time-series of plant reproductive effort from six continents.

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≥20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics

Parameterizing tree growth with standard meteorological data

In dieser Arbeit sollen zwei neue Methoden zur Parametrisierung von phänologischen Baumparametern über meteorlogische Standardmessungen diskutiert werden. Konkret untersucht werden dabei der Start des Baumumfangswachstums und der Leaf-Area-Index (LAI). Die zu diesem Zwecke verwendeten Daten, werden vom Bundesforschungszentrum für Wald (BFW) und der Zentralanstalt für Meteorologie und Geodynamik (ZAMG) zur Verfügung gestellt. Die zu untersuchenden Daten wurden über sieben Jahre (2011-2017) von drei verschiedenen Messstationen in der näheren Umgebung von Klausen Leopoldsdorf, Niederösterreich aufgezeichnet. Dabei befindet sich eine der Stationen direkt im Bestand (Bestandsstation), die zweite im Bereich des Waldrands (Klimastation) und bei der dritten Station handelt es sich um eine Freilandstation außerhalb Des Waldgebietes (Referenzstation). An allen drei Stationen werden meteorologische Messungen durchgeführt, wobei für diese Arbeit lediglich die Strahlungsmessung an der Klimastation (in einer zeitlichen Auflösung von 15 Minuten) und die Temperaturmessungen an der Bestandsstation (in einer zeitlichen Auflösung von 15Minuten) sowie der Referenzstation (täglich Werte des Maximum-,Minimum- und Mittelwerts) verwendet werden. Zusätzlich werden Messungen der Baumumfangsänderung (in stündlicher Auflösung) an sieben verschiedenen Bäumen und jährlichen LAI Messungen (ermittelt über hemisphärische Fotografien an 16 verschiedenen Messpunkten) verwendet, beide Messungen erfolgen an der Bestandsstation. Für die erste beschriebene Methode werden die jährlichen akkumulierten Strahlungssummen aus der Klimastation verwendet, um den Start des Baumumfangswachstums zu parametrisieren. Dabei zeigt sich, dass der Start des Baumumfangswachstums dann auftritt, wenn eine Strahlungsssumme von etwa 800000MJ/m2 erreicht wird, wobei der mittlere absolute Fehler bei rund zehn Tagen liegt. Bei der zweiten Methode wird die Differenz zwischen der täglichen Maximumtemperatur der Bestandsund Referenzstation (DMAX) verwendet um den LAI zu parametrisieren. Nach der grafischen Darstellung des mittleren Jahresgangs von DMAX werden zwei charakteristische Belaubungsphasen identifiziert: Die Phase maximaler Belaubung im Sommer, sowie die Phase ohne Belaubung, die ab dem Spätherbst beginnt und bis in den Vorfrühling reicht. Der Vergleich zwischen dem über DMAX parametrisierten und dem gemessenen LAI zeigte eine hohe Korrelation von 0,9. Ein weiterer Vergleich des parametrisierten LAI mit dem Baumumfangswachstum zeigt, dass die Korrelation beider Parameter ihr Maximum von 0,48 erreicht, wenn die Zeitreihe des parametrisierten LAIs um 48 Tage nach Hinten verschoben wird. Die Ergebnisse unterstützen die Annahme, dass meteorologische Größen für die Parametrisierung von charakteristischen Baumparametern geeignet sind.This study presents two novel methods to parametrize phenological tree parameters, namely stem growth start and leaf-area-index (LAI), using standard meteorological data. For the purpose of this study phenological as well as meteorological data was provided by the Austrian Research Centre for Forests (BFW) and the Austrian Central Institute for Meteorology and Geodynamics (ZAMG). Used data stems from three different measurement sites in the vicinity of Klausen Leopoldsdorf in Lower Austria across seven years (2011-2017). The first site is located directly in the forest (forest site), the second site is at the edge of the forest (climate site) and the third site is an open ground site outside the forest area (reference site). Meteorological measurements are carried out at all three measurement sites. Where, for this study only the solar radiation measurement at the climate site (with a temporal resolution of 15 minutes) and the temperature measurements at the forest site (with a temporal resolution of 15 minutes) and the reference site (which provided measurements of daily minimum, maximum and mean) are used. In addition, measurements of growth in tree girth at seven different trees (with a temporal resolution of one hour) and annual LAImeasurements (using hemispherical photographs at 16 points) are conducted at the forest site. The first method described in this study uses the annual accumulated solar radiation sum at the climate site to parametrize stem growth start. Results indicate that stem growth start is observed when an accumulated solar radiation sum of roundabout 800000MJ/m2 is reached with the obtained mean absolute error being approximately 10 days. For the second method the difference in daily maximum temperature at the forest site and the reference site (referred to as DMAX) is used to parametrize the LAI. For DMAX the average course of the year is plotted and the graph is sectioned into two different foliage phases: A maximum foliage phase during summertime and a no foliage phase ranging from late autumn to early spring. Comparison of the LAI parametrization derived from DMAX and the average LAI obtained via measurements showed a high correlation of 0,90. Further comparison of the parametrized LAI to measurements of growth in girth showed that the correlation of both parameters is maximised to 0,48 when a shift of 48 days was applied to the parametrized LAI time series. The findings of this study provide support for the hypothesis that stem growth start and LAI can be parametrized using standard meteorological data

Dynamics of standing deadwood in Austrian forests under varying forest management and climatic conditions

Standing deadwood is an important structural component of forest ecosystems. Its occurrence and dynamics influence both carbon fluxes and the availability of habitats for many species. However, deadwood is greatly reduced in managed, and even in many currently unmanaged temperate forests in Europe. To date, few studies have examined how environmental factors, forest management and changing climate affect the availability of standing deadwood and its dynamics. Data from five periods of the Austrian National Forest Inventory (1981-2009) were used to (I) analyse standing deadwood volume in relation to living volume stock, elevation, eco-region, forest type, ownership and management intensity, (II) investigate the influence of forest ownership and management intensity on snag persistence and (III) define drivers of standing deadwood volume loss for seven tree genera (Abies, Alnus, Fagus, Larix, Picea, Pinus and Quercus) using tree-related, site-related and climate-related variables, and predict volume loss under two climate change scenarios. Standing deadwood volume was mainly determined by living volume stock and elevation, resulting in different distributions between eco-regions. While forest type and management intensity influenced standing deadwood volume only slightly, the latter exhibited a significant effect on persistence. Snag persistence was shorter in intensively managed forests than in extensively managed forests and shorter in private than in public forests. Standing deadwood volume loss was driven by a combination of diameter at breast height, elevation, as well as temperature, precipitation and relative humidity. Volume loss under climate change predictions revealed constant rates for moderate climate change (RCP2.6) by the end of the 21st century. Under severe climate change conditions (RCP8.5), volume loss increased for most tree genera, with Quercus, Alnus and Picea showing different predictions depending on the model used as the baseline scenario. We observed trends towards faster volume loss at higher temperatures and lower elevations and slower volume loss at high precipitation levels. The tree genera most susceptible to climate change were Pinus and Fagus, while Abies was least susceptible. Synthesis and applications. We recommend to protect standing dead trees from regular harvesting to ensure the full decomposition process. The consequences for decomposition-dependent species must be taken into account to evaluate the influences of management and climate change on standing deadwood dynamics.ISSN:0021-8901ISSN:1365-266

Comparing environmental impacts of alien plants, insects and pathogens in protected riparian forests

The prioritization of alien species according to the magnitude of their environmental impacts has become increasingly important for the management of invasive alien species. In this study, we applied the Environmental Impact Classification of Alien Taxa (EICAT) to classify alien taxa from three different taxonomic groups to facilitate the prioritisation of management actions for the threatened riparian forests of the Mura-Drava-Danube Biosphere Reserve, South East Europe. With local experts we collated a list of 198 alien species (115 plants, 45 insects, and 38 fungi) with populations reported in southeast European forest ecosystems and included them in the EICAT. We found impact reports for 114 species. Eleven of these species caused local extinctions of a native species, 35 led to a population decrease, 51 to a reduction in performance in at least one native species and for 17 alien species no effects on individual fitness of native species were detected. Fungi had significantly highest impact and were more likely to have information on their impacts reported. Competition and parasitism were the most important impact mechanisms of alien species. This study is, to our knowledge, the first application of EICAT to all known alien species of several taxonomic groups in a protected area. The impact rankings enabled to identify taxa that generally cause high impacts and to prioritize species for the management in protected areas according to their impact magnitudes. By following a standardized impact protocol, we identified several alien species causing high impacts that do not appear on any expert-based risk list, which are relevant for policymakers. Thus, we recommend that alien species be systematically screened to identify knowledge gaps and prioritize their management with respect to spatio-temporal trends in impact magnitudes

Effects of Climate and Atmospheric Nitrogen Deposition on Early to Mid-Term Stage Litter Decomposition Across Biomes

Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1-3.5% and of the more stable substrates by 3.8-10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4-2.2% and that of low-quality litter by 0.9-1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.This work was performed within the TeaComposition initiative, carried out by 190 institutions worldwide. We thank for funding support for the workshop and data analysis from the ILTER. We acknowledge support by the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation (FZT 118), Scientific Grant Agency VEGA (Grant No. 2/0101/18), as well as by the European Research Council under the European Union’s Horizon 2020 Research and Innovation Program (Grant Agreement No. 677232). Thanks are due to FCT/MCTES for the financial support to CESAM (UIDB/50017/2020 + UIDP/50017/2020) and to the project PORBIOTA (POCI-01-0145-FEDER-022127). AI Sousa was funded by national funds through the FCT-Foundation for Science and Technology, I.P., under the project CEECIND/00962/2017. HS and CB acknowledge FCT support to cE3c through UID/BIA/00329/2013, UID/BIA/00329/2019, and UIDB/00329/2020, and the project PORBIOTA - POCI-01-0145-FEDER-022127. We are also thankful to UNILEVER for sponsoring the Lipton tea

Effects of climate and atmospheric nitrogen deposition on early to mid-term stage litter decomposition across biomes

International audienceLitter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1– 3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate