Drought investigation and trend assessment in Macta watershed (Algeria) by SPI and ITA methodology

Land degradation is recognized as an important environmental and social problem in arid and semi-arid regions, particularly within a climate change context. In the last three decades the entire Mediterranean basin has been affected by more frequent droughts, covering large sectors and often lasting more than one year. The Iberian Peninsula has been equally affected by intense drought events since the 1980s. According to the latest IPCC report the Mediterranean region will suffer further hydrological stress in the coming decades, as a consequence of diminishing of precipitation and increasing of average and extreme temperatures. This climatic outlook coupled with the land abandonment and/or intensification of some areas requires a continuous monitoring and early detection of degradation. The present work intends to contribute to such objectives.Land degradation could be stated as a longstanding deterioration in ecosystems productivity. Here we assess the ability of NDVI to be used as an indicator of land degradation over Iberia, from 1982 to 2012. The negative trends of the residuals obtained after removing the precipitation influence on NDVI were assumed to indicate land degradation. A widespread land improvement was observed over Iberia with few hot spots of land degradation located mainly in central and southern sectors and in east Mediterranean and Atlantic coasts. The comparison of spatial patterns of residual trends with dryness for the aridity regions over Iberia highlighted the relatively small fraction of land degradation that experiences an increased dryness, although almost totality belonging to semi-arid region. On the other hand, land improvement is only associated with a tendency of wetness in the northeastern humid sector. Moreover, less than 20% of the area presenting land degradation corresponds to regions associated with land cover changes, being the new land cover types associated with transitional woodland-shrub, permanent and annual crops and permanently irrigated land areas.

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Summertime stratospheric processes at northern mid-latitudes: comparisons between MANTRA balloon measurements and the Canadian Middle Atmosphere Model

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-11621-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 11621-11646 ◽

Cited By ~ 1

Author(s):

S. M. L. Melo ◽

R. Blatherwick ◽

J. Davies ◽

P. Fogal ◽

J. de Grandpré ◽

...

Keyword(s):

Middle Atmosphere ◽

Polar Vortex ◽

Late Summer ◽

Atmospheric Nitrogen ◽

Vertical Diffusion ◽

Trend Assessment ◽

Atmosphere Model ◽

Vertical Diffusion Coefficient ◽

Self Consistency ◽

Balloon Measurements

Abstract. In this paper we report on a study conducted using the Middle Atmospheric Nitrogen TRend Assessment (MANTRA) balloon measurements of stratospheric constituents and temperature and the Canadian Middle Atmosphere Model (CMAM) in order to evaluate the ability of the model to reproduce the measured fields and to thereby test our ability to describe mid-latitude summertime stratospheric processes. The MANTRA measurements used here are vertical profiles of ozone, temperature, N2O, CH4, HNO3, and HCl obtained during four campaigns, involving the launch of both ozonesondes and large balloons from Vanscoy, Saskatchewan, Canada (52° N, 107° W). The campaigns were conducted in August and September 1998, 2000, 2002 and 2004. During late summer at mid-latitudes, the stratosphere is close to photochemical control, providing an ideal scenario for the study reported here. From this analysis we found that: (1) reducing the value for the vertical diffusion coefficient in CMAM to a more physically reasonable value results in the model better reproducing the measured profiles of long-lived species; (2) the existence of compact correlations among the constituents, as expected from independent measurements in the literature and from models, confirms the self-consistency of the MANTRA measurements; and (3) the 1998 ozone measurements show a narrow layer of low ozone centered near 25 km that is consistent with fossil debris from the polar vortex, suggesting that localized springtime ozone anomalies can persist through summer, affecting ozone levels at mid-latitudes.

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Bud blight (Gemmamyces piceae) in the eastern part of the Krušné hory Mountains

Journal of Forest Science ◽

10.17221/11/2020-jfs ◽

2020 ◽

Vol 66 (No. 8) ◽

pp. 309-317

Author(s):

Jiri Sefl ◽

Veronika Mottlová ◽

Iva Schořálková

Keyword(s):

Life Cycle ◽

Blue Spruce ◽

Picea Pungens ◽

Host Trees ◽

Sprouting Ability ◽

Trend Assessment ◽

Krušné Hory Mountains

A survey was carried out in 2013–2019 on the life cycle of the bud blight Gemmamyces piceae (Borthw.) Casagrande and the trend assessment in the infestation of the Colorado blue spruce Picea pungens Engelm. stands. Four ecologically different plots were chosen in the Fláje region in the Eastern part of the Krušné hory Mountains. The pycnidia were formed at the beginning of June on buds infested the previous year. Later, in the second half of June, they formed on the spring attack buds. Conidia occurred in the first week of July on the buds of the old infestation, or later in the case of the spring attack buds, in the middle of July. The production of conidia lasted till the end of September. Ascospores occurred in the middle of July and were produced until the end of September. The ability of host trees to sprout became continually weaker, along with the defoliation progress. A distinct decline in the sprouting ability was noticed on stands with a dense crown canopy and on stands with competition of broad-leaved trees – with an admixture of birch.

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