Meteorological Data
Year 2001
A very good year for the first half of it. Then all changed. Noticeable :
- the Winter 2000-2001 was the mildest one since the creation of the Arboretum with a lowest temperature of only -4.4°C (in February). Of course all seedlings made it through the Winter season, even the less hardy like Widdringtonia cupressoides, Pinus michoacana and Pinus maximartinezii;
- late Spring frost was recorded (1st of May), but no visible damage, as if the the temperature below 0°C did not happen everywhere;
- for the second year in a row a serious drought occurred form August until beginning of November; even if September (as displayed by the diagram) was not a dry month, the rainfalls were not in such quantities at one time to water more than the first few soil millimeters. Some seedlings could not make it, even a few which were planted some years ago. In these cases the failures can be explained mostly by planting at the wrong place (too shallow soil, wrong exposure, mainly). Oldest seedlings lost (around 1 meter high or higher) : Picea abies, Thuja plicata, Sequoiadendron giganteum (1 specimen); youngest seedlings lost : Pinus resinosa, Pinus attenuata, Pinus strobus; fortunately not all trees of one species were lost, and all those species are still present in the Arboretum or will be replaced quite soon;
- the first frost in Fall came late (second week of November) and was not low, bringing rain and snow at the same time over a dry soil. The end of the year was exceptionnally cold, not by the minimal temperatures, but by the temperatures remaining below 0°C even at daytime (except for the sunny places) for two weeks. Fortunately the soil was protected by the 6cm of snow layer. It went already colder in the Arboretum in the previous years, but the unusual length of the frost will give interesting informations about the hardiness of the trees. No important damage was visible at this time of the year, but Spring must be waited to draw any conclusions. Araucaria angustifolia is still looking all right, to the contrary of Pinus morissonicola;
- With a minimal rainfall this year, it appears that drought could be more of a problem in the long run than cold weather. It is adviseable to plant the right tree at the right place using the different exposures to minimize the risks. The depth of the soil is also one important factor (for which it is not possible to draw a map a priori).
Total of the precipitations : 735.6 mm, is lowest rainfall since the creation of the Arboretum.
Lowest temperature : -6.9° C (December).
Highest temperature : +34.0° C (August).
Mean yearly temperature : +11.5° C.
Number of days with highest temperature > +30° C : 19.
Number of days with highest temperature > +25° C : 56.
Number of days with highest temperature < 0° C
: 2.
Number of days with lowest temperature <
0° C : 40.
Number of days with lowest temperature < -5° C :
8.
Number of days with lowest temperature < -10° C :
0.
Year 2000
A rather good year for the growing of the seedlings in the Arboretum. Noticeable :
- the Winter 1999-2000 was mild even if the first frost came already in October (absolute minimal temperature: of this Winter -7.9° C). It was no hardiness test1 for the species installed in the Arboretum;
- although some Spring frosts occurred, no damage was seen;
- the only potential threath was a serious drought in August and September (as displayed by the diagram). Only a few young seedlings (mostly Pinus resinosa) suffered from it. All seedlings planted in July (more than one hundred) did well, especially the Cupressus species;
- the first frost in Fall came late (in November) and was not low. The end of the year was exceptionnally mild (with even the absolute maximum temperature rising in December !) to give the lowest temperature only on the last day of the Millenium (-3.5° C).
Total of the precipitations : 1054.3 mm, is quite close to the average.
Lowest temperature : -7.4° C (January).
Highest temperature : +32.0° C (August).
Mean yearly temperature : +11.5° C.
Number of days with highest temperature > +30° C : 3.
Number of days with highest temperature > +25° C : 40.
Number of days with highest temperature < 0° C
: 0.
Number of days with lowest temperature <
0° C : 50.
Number of days with lowest temperature < -5° C :
3.
Number of days with lowest temperature < -10° C :
0.
Year 1999
A good year for the growing of the seedlings in the Arboretum :
- the Winter 1998-99 rather long and colder [absolute minimal temperature: -10.4° C in November 1998] than the previous one. It killed the Pinus canariensis, Pinus michoacana, Callitris tasmanica and an unknown species wrongly labelled Fitzroya cupressoides;
- no late frost (as a result of the long Winter, all trees were still dormant at Easter);
- no real drought (July was at the limit, but no trouble even for the Metasequoia); the Summer was less warm than the previous year;
- again the first frost in Fall came early, but was not unusually low.
Two catastrophic events struck France during the last two months of 1999 :
- in November heavy rainfalls on a short period (up to 500 mm) in the Aude valley resulted in a massive flooding of the valley near the sea;
- in December two storms crossed France, destroying many trees and forests; although the wind blew strongly one night, no tree was harm in the region of Villardebelle.
Total of the precipitations : 1023.2 mm, is quite close to the average.
Lowest temperature : -7.9° C (December).
Highest temperature : +31.3° C (August).
Mean yearly temperature : +11.2° C.
Number of days with highest temperature > +30° C : 6.
Number of days with highest temperature > +25° C : 54.
Number of days with highest temperature < 0° C
: 8.
Number of days with lowest temperature <
0° C : 53.
Number of days with lowest temperature < -5° C :
6.
Number of days with lowest temperature < -10° C :
0.
Year 1998
Not a good year for the growing of the seedlings in the Arboretum :
- the Winter 1997-98 was quite mild (absolute minimal temperature : -7.9° C);
- a late frost at Easter (-3° C on the 14 April) resulted in some damage to Abies
numidica, Cedrus deodara, Cedrus libani and Metasequoia;
- an important drought in June and July, calling for some watering of the most sensitive
plants; the needles of most pines where shorter than usual;
- the first frost in Fall came early and was unusually low (-10.4° C).
The overall yearly precipitation (735.9 mm) is even lower as the total of the previous year
(808.7 mm - average 1972-1997 : 1'074.4 mm).
Lowest temperature : -10.4° C (November).
Highest temperature : +34.5° C (August).
Mean yearly temperature : +11.2° C.
Number of days with highest temperature > +30° C : 13.
Number of days with highest temperature > +25° C : 48.
Number of days with highest temperature < 0° C
: 0.
Number of days with lowest temperature <
0° C : 63.
Number of days with lowest temperature < -5° C :
5.
Number of days with lowest temperature < -10° C :
1.
Year 1997
A short drought at the end of Winter was the only negative factor for the young trees.
The overall yearly precipitation (808.7 mm) is notably inferior to the normal one
(average 1972-1997 : 1'074.4 mm).
Lowest temperature : -7.8° C (January).
Highest temperature : +32.9° C (August).
Mean yearly temperature : +12.1° C.
Number of days with highest temperature > +30° C : 7.
Number of days with highest temperature > +25° C : 60.
Number of days with highest temperature < 0° C
: 2.
Number of days with lowest temperature <
0° C : 49.
Number of days with lowest temperature < -5° C :
4.
Number of days with lowest temperature < -10° C :
0.
