Search results for "climatology"

High-elevation inter-site differences in Mount Smolikas tree-ring width data

2017

Abstract We present the longest high-elevation tree-ring width dataset in the Mediterranean reaching back to the 6th century CE. The network includes 101 living and 92 relict Pinus heldreichii Christ trees from four differently exposed sites in the 2100–2200 m a.s.l. elevation range of Mt. Smolikas in the Pindus Mountains in Greece. Though the sites were all sampled within a distance of 1550–2014  = 0.65–0.87), indicating site exposure might affect tree-ring formation. We here explore the consequence of exposure differences on the climate signals in an eastern Mediterranean treeline ecotone. Temporally stable growth/climate relationships reveal similar seasonal patterns among the four sites…

2021

Maximum latewood density (MXD) measurements from long-lived Black pines (Pinus nigra spp. laricio) growing at the upper treeline in Corsica are one of the few archives to reconstruct southern European summer temperatures at annual resolution back into medieval times. Here, we present a compilation of five MXD chronologies from Corsican pines that contain high-to-low frequency variability between 1168 and 2016 CE and correlate significantly (p < 0.01) with the instrumental April–July and September–October mean temperatures from 1901 to 1980 CE (r = 0.52−0.64). The growth–climate correlations, however, dropped to −0.13 to 0.02 afterward, and scaling the MXD data resulted in a divergence of…

Summer drought reconstruction in northeastern Spain inferred from a tree ring latewood network since 1734

2017

Drought recurrence in the Mediterranean is regarded as a fundamental factor for socio-economic development and the resilience of natural systems in context of global change. However, knowledge of past droughts has been hampered by the absence of high-resolution proxies. We present a drought reconstruction for the northeast of the Iberian Peninsula based on a new dendrochronology network considering the Standardized Evapotranspiration Precipitation Index (SPEI). A total of 774 latewood width series from 387 trees of P. sylvestris and P. uncinata were combined in an inter-regional chronology. The new chronology, calibrated against gridded climate data, reveals a robust relationship with the S…

Predictions of avian Plasmodium expansion under climate change.

2013

International audience; Vector-borne diseases are particularly responsive to changing environmental conditions. Diurnal temperature variation has been identified as a particularly important factor for the development of malaria parasites within vectors. Here, we conducted a survey across France, screening populations of the house sparrow (Passer domesticus) for malaria (Plasmodium relictum). We investigated whether variation in remotely-sensed environmental variables accounted for the spatial variation observed in prevalence and parasitemia. While prevalence was highly correlated to diurnal temperature range and other measures of temperature variation, environmental conditions could not pre…

Ecological and conceptual consequences of Arctic pollution

2020

Although the effect of pollution on forest health and decline received much attention in the 1980s, it has not been considered to explain the ‘Divergence Problem’ in dendroclimatology; a decoupling of tree growth from rising air temperatures since the 1970s. Here we use physical and biogeochemical measurements of hundreds of living and dead conifers to reconstruct the impact of heavy industrialisation around Norilsk in northern Siberia. Moreover, we develop a forward model with surface irradiance forcing to quantify long‐distance effects of anthropogenic emissions on the functioning and productivity of Siberia’s taiga. Downwind from the world’s most polluted Arctic region, tree mortality ra…

Interannual memory effects for spring NDVI in semi-arid South Africa

2008

[1] Almost 20 years of Normalized Difference Vegetative Index (NDVI) and precipitation (PPT) data are analysed to better understand the interannual memory effects on vegetation dynamics observed at regional scales in Southern Africa (SA). The study focuses on a semi-arid region (25°S–31°S; 21°E–26°E) during the austral early summer (September–December). The memory effects are examined using simple statistical approaches (linear correlations and regressions) which require the definition of an early summer vegetation predictand (December NDVI minus September NDVI) and a consistent set of potential predictors (rainfall amount, number of rainy days, rainfall intensity, NDVI and Rain-Use-Efficie…

Climate vs grapevine pests and diseases worldwide: The first results of a global survey

2016

<p class="Abstract"><strong>Aim:</strong> This paper aimed to address the relationship between grapevine disease, pest occurrences and climate. The extremely large extension of viticulture worldwide offers the possibility to evaluate the impacts of climate variability on many aspects of the grape growing system. For this, we initiated a global survey to retrieve the most important diseases and pests in many grape growing regions worldwide and to identify the risk of exposure to pests and diseases of viticulture as a function of climate.</p><p class="Abstract"><strong>Methods and results:</strong> Based on the answer of respondent about the main repo…

Testing macroecological abundance patterns:the relationship between local abundance and range size, range position and climatic suitability among Eur…

2020

Aim A fundamental question in macroecology centres around understanding the relationship between species' local abundance and their distribution in geographical and climatic space (i.e. the multi-dimensional climatic space or climatic niche). Here, we tested three macroecological hypotheses that link local abundance to the following range properties: (a) the abundance-range size relationship, (b) the abundance-range centre relationship and (c) the abundance-suitability relationship. Location Europe. Taxon Vascular plants. Methods Distribution range maps were extracted from the Chorological Database Halle to derive information on the range and niche sizes of 517 European vascular plant speci…

The Spatial Dimension in Population Fluctuations

1997

Theoretical research into the dynamics of coupled populations has suggested a rich ensemble of spatial structures that are created and maintained either by external disturbances or self-reinforcing interactions among the populations. Long-term data of the Canadian lynx from eight Canadian provinces display large-scale spatial synchrony in population fluctuations. The synchronous dynamics are not time-invariant, however, as pairs of populations that are initially in step may drift out of phase and back into phase. These observations are in agreement with predictions of a spatially-linked population model and support contemporary population ecology theory.

Long-Term Climate Trends and Extreme Events in Northern Fennoscandia (1914–2013)

2017

We studied climate trends and the occurrence of rare and extreme temperature and precipitation events in northern Fennoscandia in 1914–2013. Weather data were derived from nine observation stations located in Finland, Norway, Sweden and Russia. The results showed that spring and autumn temperatures and to a lesser extent summer temperatures increased significantly in the study region, the observed changes being the greatest for daily minimum temperatures. The number of frost days declined both in spring and autumn. Rarely cold winter, spring, summer and autumn seasons had a low occurrence and rarely warm spring and autumn seasons a high occurrence during the last 20-year interval (1994–2013…