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Improved knowledge of the time scales at which drought stress mostly influences tree growth is crucial for the early detection of forest dieback. This study aimed to evaluate the impact of climate (temperature and precipitation) on vegetation activity (normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI)) of Pinus halepensis Mill. and Pinus pinea L. mixed forest located in western Albania and to assess the drought impact (standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI)) calculated at different time scales (1-12 months) on radial growth (earlywood width, latewood width, and tree-ring width) and vegetation activity of these species. Both vegetation indices showed a negative response to August temperatures, and the EVI responded positively to September precipitation. NDVI and EVI were significantly affected by the SPI in spring and late summer. All tree-ring features in P. halepensis were positively related with EVI in August, whereas P. pinea latewood width showed a significant and positive relationship with NDVI in September. Radial growth of P. halepensis responded significantly to both drought indices in late summer and early autumn, particularly the latewood width. Contrastingly, in P. pinea, only earlywood width showed vulnerability, mostly to the summer SPEI drought indices. These results are relevant to understand the impacts of increased drought intensity and frequency on tree radial growth and vegetation activity in a region that is vulnerable to climate variability. Key words: climate, drought, tree ring, Pinus halepensis, Pinus pinea, vegetation indices. Il est essentiel de savoir a quelle echelle de temps le stress du a la secheresse influence le plus la croissance des arbres pour la detection precoce du deperissement des forets. Cette etude a cherche a determiner l'impact du climat (temperature et precipitation) sur l'activite de la vegetation (indice de vegetation par difference normalisee (NDVI), indice de vegetation ameliore (EVI)) dans les forets mixtes de Pinus halepensis Mill. et de P. pinea L. situees dans l'ouest de l'Albanie. Elle avait aussi pour but d'evaluer l'impact de la secheresse (indice de precipitation normalise (SPI), indice de precipitation et d'evapotranspiration normalise (SPEI)) calcule a differentes echelles de temps (1 a 12 mois) sur la croissance radiale (bois initial (BI), bois final (BF) et largeur du cerne annuel (LCA)) et sur l'activite vegetale de ces especes. Les deux indices de vegetation avaient une reaction negative aux temperatures du mois d'aout tandis que l'indice EVI reagissait positivement a la precipitation du mois de septembre. L'indice SPI avait un impact significatif sur les indices NDVI et EVI au printemps et a la fin de l'ete. Toutes les caracteristiques des cernes annuels de P. halepensis etaient positivement reliees a l'indice EVI au mois d'aout tandis que le BF de P. pinea etait significativement et positivement relie a l'indice NDVI en septembre. La croissance radiale de P. halepensis reagissait significativement aux deux indices de secheresse a la fin de l'ete et au debut de l'automne, particulierement la largeur du BF. A l'oppose, chez P. pinea seul le BI s'est montre vulnerable surtout aux indices de secheresse SPEI durant l'ete. Ces resultats sont pertinents pour comprendre les impacts d'une augmentation de la frequence et de l'intensite de la secheresse sur la croissance radiale des arbres et sur l'activite de la vegetation dans une region vulnerables aux variations climatiques. [Traduit par la Redaction] Mots-cles : climat, secheresse, cerne annuel, Pinus halepensis, Pinus pinea, indices de vegetation., Introduction Climatic predictions indicate that the Mediterranean area will be affected by an increase in mean air temperature and a higher frequency of extreme climatic events (i.e., severe drought, extreme [...]

This paper deals with the response of silver fir (Abies alba Mill.) growth to climate, mainly drought, presenting data from southern Kosovo, for which only little information is available. Two cores from 55 dominant trees were extracted at two sites representing the limits of the natural distribution of silver fir. We built 80- and 112-year-long chronologies for each site. Comparison of both ring width chronologies showed that they were diverse. Pointer year analysis indicated that high spring temperatures and ample rainfall (1082 mm) influenced positively silver fir growth (wide ring), while low spring temperatures and scarce precipitation had an inverse effect. Bootstrapped response functions confirmed that April and May temperatures of the current growth year influenced positively silver fir growth at the low-elevation site, while the July precipitation of the previous growth year had a negative influence. At the high-elevation site, warm previous December temperatures had a positive influence on silver fir growth. Drought indices indicated two periods (1953-1961 and 1994-2001) with moderate drought. Correlation analysis between silver fir radial growth and drought indices revealed that the impact of drought on radial growth was significant at the time scale of 1.5 months during the summer months. Resume: Cet article porte sur la reaction de la croissance du sapin pectine (Abies alba Mill.) au climat, surtout a la seche-resse, selon des donnees provenant du sud du Kosovo, une region pour laquelle il y a peu d'information disponible. Deux carottes ont ete prelevees sur 55 arbres dominants dans deux stations situees a la limite de l'aire naturelle de repartition du sapin pectine. Nous avons construit des series dendrochronologiques d'une duree de 80 et 112 ans pour chacune des sta-tions. La comparaison des deux series dendrochronologiques a montre qu'elles etaient differentes. L'etude des annees carac-teristiques a indique que les temperatures printanieres elevees et amplement de precipitations (1 082 mm) ont influence positivement la croissance du sapin pectine (larges cernes), tandis que des temperatures printanieres basses et des precipitations peu abondantes ont eu un effet inverse. Des fonctions de reponse basees sur la methode de reechantillonnage ont confirme que les temperatures des mois d'avril et mai de l'annee en cours ont influence positivement la croissance du sapin pectine dans la station situee a faible altitude tandis que la precipitation du mois de juillet de l'annee precedente a eu une influence negative. Dans la station situee a haute altitude, les temperatures chaudes du mois de decembre precedant ont eu une influence positive sur la croissance du sapin pectine. Deux periodes (1953-1961 et 1994-2001) ont connu une seche-resse moderee selon les indices de secheresse. L'analyse de correlation entre la croissance radiale du sapin pectine et les indices de secheresse a revele que l'impact de la secheresse sur la croissance radiale etait significatif a une echelle de temps de 1,5 mois pendant les mois d'ete. [Traduit par la Redaction], Introduction Climate changes and their impacts already observed globally are expected to become more pronounced in the future. Climate observations show that the global average temperature has increased by 0.8 [...]

In the context of changing climate conditions, it is crucial to understand how trees maintain resistance and resilience to and recover from drought stress and management-related disturbances, and how management (intensive/extensive) modulates tree growth responses to climate. Dendrochronological methods were used to examine radial growth rates, to reconstruct disturbance history and to evaluate growth resistance and resilience to and recovery from disturbance events identified by pointer year analysis in two coexisting Quercus species (Q. macrolepis Kotschy and Q. trojana Webb). Moreover, a dendro-ecological approach was used to quantify climate–growth relationships, including a drought index, the Standardised Precipitation Index (SPI). Q. trojana/Q. macrolepis showed major/moderate growth releases and moderate growth suppression. Q. trojana demonstrated statistically lower growth recovery than Q. macrolepis. The climatic drivers of radial growth in Q. macrolepis were May, June, September precipitation, July temperatures and the SPI accumulated since the previous year (up to 18 months); whereas Q. trojana responded significantly to May and June precipitation, July temperatures and the SPI at mid-time scales (< 8 months). Under intensive management, both species were more responsive to precipitation, temperature and short to mid-time scale SPI than during the extensive management period where they showed loss of sensitivity to spring–summer precipitation, temperature and SPI. These results are relevant to understand species vulnerability to climate and management/ human-related disturbances, and the effects of intensive/extensive management in modulating climate (drought)–growth relationships in Q. macrolepis and Q. trojana trees. [ABSTRACT FROM AUTHOR]

This study presents the evaluation of two approaches (field and remote sensing - GIS) applied for inventorying pasture condition in Albania. The field inventory was carried out by trained experts in the context of the latest Albanian National Forest Inventory (ANFI), based on 162 sample plots chosen randomly over the pasture areas. At each sample plotit was collected detailed data about pasture condition which were made available for this study. The second approachwe applied, consisted of a combination of Remote Sensing and GIS algorithms to derive several variable maps(classified into a number of classes): cover components of pastures, slope, aspect, elevation, erosion, distance from the hydrologic network, road network and the location of villages. The results indicated significant differences between both methodologies, especially for the cover components of pastures, where a difference of 14% was found regarding the evaluation of herbaceous species. Environmental and pasture use variables appeared to be evaluated differently too, especially the erosion level and distances of pastures from thevillages, networks of roads and water sources. We conclude that the main reason for such discrepancy should bethe low coverage of pasture area in terms of number of sample plots as well as their distribution. Based on the findings of this study, it is recommended that in the future, inventory of pasture condition should be done as much as possible using Remote Sensing and GIS technology because it guarantees full coverage of the study area, reduces the field work which is expensive and time consuming, and provides more reliable evaluation of pasture condition. [ABSTRACT FROM AUTHOR]

Assessing the risk, the severity and the likely evolution of droughts are key tasks for improving preparedness of regions prone to drought conditions, and mitigation of drought consequences. The access to real-time and high-quality climatic information is essential for this purpose. Different climatic databases are being developed and made available on real time by climatic research institutions, but their capability for quantifying droughts characteristics including severity, or spatio-temporal variability, is uncertain given their low spatial resolution. In this study, we assessed the capability of three databases with contrasted spatial resolution for measuring spatial and temporal variability of drought occurrence. The standardized precipitation index, calculated for each database, showed that the low resolution datasets allow an acceptable measurement of the magnitude, intensity and duration of droughts, while failing mostly in detecting the spatial patterns of the specific drought episodes. Moreover, the capability of the datasets for assessing the impacts of droughts on surface hydrology and tree growth was examined. Results confirmed the usefulness of the drought index for assessing drought impacts on water resources and forest ecosystems even when low resolution databases are used. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

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