'Storm damages in 'Pinar de Valsain' forest - Ctba

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'Storm damages in 'Pinar de Valsain' forest - Ctba

Storm Damages in "Pinar de Valsaín" forest: historic data and

problems coming from January 1996 storm.

ABSTRACT CONCERNING : Common practice

TYPE OF DOCUMENT : Technical publication

THEME : Harvesting operations 7; Economic aspects

TITLE ABSTRACT : Storm Damages in "Pinar de Valsaín" forest: historic data and problems comimg from

january 1996 storm.

ORIGINAL TITLE : Daños por temporales en el monte "Pinar de Valsaín". Datos históricos y problemas

generados por el temporal de enero de 1996

AUTHORS : Javier DONÉS y Montserrat GARRIDO

PUBLICATION DATE: 2001

ORGANISATION : Public Forest Organism "Centro de Montes de Valsaín" and Public Forest Enterprise

"TRAGSA"

COUNTRY: Spain

REFERENCE ABSTRACT: Proceedings of the 3rd National Forest Congress "Sierra Nevada 2001" (Granada,

Spain). Vol. V, pag. 315-320. Ed. Junta de Andalucía-Tragsa-Sociedad Española de Ciencias Forestales.

ABSTRACT CONTENT:

This communication comments the series of repeated storm damages in this emblematic Spanish public Scots

pine natural forest, located in a mountain region of Central Spain. Main interest is devoted to the recent 1996

storm, from wich data on affected surfaces, volume obtained and harvesting costs are presented.

Regarding historic series of storm damages, many references from XVIIth century to 1940 are registered, but the

complete data set about number of stem and volume affected are presented from 1940 to present. The most

important damages came from 1959/60, 1974/75, 1980/81 and 1995/96 storm (Figure 1 and Tables 1 and 2).


Figure I: Number of trees (less dark columns) and volume (darker columns) series of wind damages at Valsaín

forest.

TABLE Nº 1. VOLUME AND NUMBER OF EXTRACTED TREES (FROM THE 1966 STORM) EACH

YEAR

AÑO NUMBER OF VOLUME M

TREES (Ø >

30 CM)

3 UB NUMBER OF

SMALL TREES (10

TO 30 CM)

1996 39.849 29.619 54.433

1997 9.666 5.753 33.027

1998 7.976 2.939 49.257

1999 4.538 1.567 17.887

2000 44.235 6.216 5.193

TOTAL 106.264 46.094 159.797

TABLE Nº 2. PINES WITH DIAMETER LESS THAN 30 CM FROM DAMAGES CAUSED BY JANUARY

1996 STORM. RESULTS OF AUCTION SELLINGS

1996

YEAR

1997 1998 1999 2000 TOTAL

Tones


4.584,1 3.066,4 3.464,8 2.723,0 3.023,3 16.861,5 t

75.832,60 49.869,70 56.349,50 44.285,50 42.288,30 268.625,70 €

The last 1996 storm was those from which more volume was extracted, totalling (up to 2000) more than 46000

cubic metres from more than 260000 stems with diameter greater than 10 cm (106000 of them with diameter

greater than 20 cm, see Table 1).

Damages were spread over 6600 ha, more than 80 per cent of forest total surface. Main difficulties were found in

young even stands very strongly damaged (950 ha with average costs between 1800 and 2520 €/ha)

Total harvesting cost have been some 3 million € from 1996 to 2000.

Harvesting methods were manual (chainsaw) and skidding was performed by mules and horses combined with

winch skidders and forwarders. Besides, a big construction crane was employed to winch-skid timber in steep

areas.


The obtained timber was sawn in the public sawmill that exists besides the "Pinar de Valsaín" forest, except

almost 17000 tonnes of trees smaller than 30 cm that were sold at public auctions. An amount of some more than

265000 € was obtained in the cited 5-year period by this way (see Table 2).

Sanitary problems were not so great than expected. Piles were sprayed with synthetic pyretrines at landing

Young regeneration areas have been affected by Tomicus scolytus, but damages have not been very severe.

Damages caused by Ips scolytus and Diprion pini butterfly were detected but they were not so severe than

expected. Ips was treated using dead stems as tramps, which were treated afterwards.

Management derived implications are also commented: thinned stands are less affected than unthinned. Very

strong extractions are not recommended while leaving trees with well-shaped crowns and good h/d ratio is

necessary to avoid severe damages. Besides, the manager must planify the cuttings beginning from the opposite

side to the prevailing winds.

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