The Sanasilva Sub-Programme 'Determination of Forest Condition through lnfrared Aerial Photo-graphs'
Between 1984 and 1987, as part of the Sanasilva Sub-Programme 'Aerial Photographs', about one third of the forested area in Switzerland was surveyed through colour infrared aerial photography at a scale of 1 :9000.
By 1987 some 150 000 ha of forest had been evaluated.
Thls was ajoint project between the Swiss federal (WSL) and cantonal governments and the Principality of Liechtenstein. The experiences gained are summarized below.
Method
This method forthe large-scale, stand-by-stand determi-nation of forest damage has proved valuable in practice.
Evaluation of the infrared aerial photographs at a scale of 1 :9000 has shown that trees may be sorted into the following damage classes:
- no damage visible on the photograph - discolouration/yellowing of the crown - slight leaf or needle lass
- heavy leaf or needle loss - dead.
Interpretation of the aerial photographs should only be done by highly trained staff using high quality interpret-ation instruments.
In practical application, two types of map have become established tools . One is the classic damage map showing the percentage area covered by damaged or healthy trees per stand; this type of map is preferred by the majority of cantons and gives the better picture of areas with only slight damage. The other, the damage intensity map, is given preference by the authorities of cantons with severe damage, who are mainly interested in damage intensity.
While this method has proved a valuable aid in practice, it does not provide information on the causes of forest damage.
30
Organization and Services
The idea that the aerial surveys and the training of the interpreters be centrally organized and conducted by the federal authorities while the actual interpretation of the aerial photographs be carried out by each canton indi-vidually was welcomed by all cantonal authorities. This arrangement contributed greatly to the facts that, on one hand, high quality photographs conforming to uniform conditions were available for uniform damage assess-ment, and on the other, that it was possible to communi-cate the findings to practical foresters rapidly.
lt was possible to deliver most of the photographs in high quality on time.This was largely thanks to the expertise and efficiency of the flight service of the Fed-eral Directorate of Cadastral Surveys and the firm Wild-Leitz, Heerbrugg.
The photographs were centrally archived at the WSL, which also supervised their lending; this arrange-ment has proved convenient, and it is recommended that it be continued in its present form .
Staff Training and Refresher Courses
The interpretation of aerial photographs sets high de-mands on the staff. One is perfect eyesight; all would-be interpreters must pass sight and stereovision tests be-fore being accepted for training .
The basic training course lasts at least 4 to 5 weeks, and the staff must attend regular refresher cour-ses and discussions, so as to ensure the quality and comparability of the interpretations.
lt is only worthwhile to meet these demands if the individual staff members are willing to commit themselves for a considerable period. To recruit such personnel, attractive conditions of employment and guaranteed assistance from the cantonal forest services must be offered.
Practical Application of the Findings
Experience has shown that when damage maps pure and simple, without explanations, are delivered to non-specialists, misinterpretations are likelyto occur. Conse-quently, thefollowing procedurewas elaborated and has proved its worth: a member of the cantonal forest service
studies the basics of damage determination, data analy-sis, and mapping, and is responsible for interpreting the findings in practical terms and communicating these to the foresters and forest owners. His main function is to determine the regional distribution of forest damage, pinpoint areas with damage, and relate the distribution pattern to site conditions and silvicultural treatment. He is also responsible for presenting the findings accurately but in layman's terms to the media and the general public.
Aerial Photographs as Records
Aerial photographs serve as important records in tracing the consequences of natural events. For instance, aerial photographs taken before and after the event helped in the detailed analysis of the effects of a forest fire at Balzers, a landslide at Giswil, and a flood at Poschiavo.
Further, aerial photographs provide a permanent record available at any time for research projects dealing with new problems.
Aerial photographs are also being increasingly used in other fields, e.g.:
- stand mapping in view of revised management planning;
- silvicultural planning;
- re-afforestation and installation of defence - tracing forest limits on cadastral maps;
- assessing damage in orchards and arable land.
Recommendation
Aerial photographs and their interpretation through the method described above are recommended as:
- aids in the large-scale, stand-by-stand determination of forest damage or forest condition, in particular in problems areas for which revised silvicultural, management, and re-afforestation plans are needed;
- particularly accurate records of forest condition . Translation: Margaret J. Sieber
Literatur
EGGENBERGER U., 1986: Auswertung von Infrarot-Luftbil-dern. Bündner Wald 39, 6: 14-17.
FLüHLER, H., KIENAST, F., ScHERRER, H.U., 0ESTER, B., POLOMSKI, J., KELLER, T ., SCHWAGER, H., SCHWEIN-GRUBER, F.H., MAHRER, F., BLASER, P., 1981 : Wald-schäden im Walliser Rhonetal (Schweiz) . Eidg.
Anst. forstl. Versuchswes., Mitt. 57, 4: 361-499 HÄGELI, M., CARTIER, F, HAUENSTEIN, P., JESCHKI, W., LEUPPI,
E., SCHERRER, H.U., SCHWARZENBACH, F.H., STOLL, E., 1987: Waldschäden im unteren Aaretal. Eidg. Anst.
forstl. Versuchswes., Ber. 296: 63 S.
MAsuMv, S.A., ScHLÄPFER, E., 1987: Beurteilung des Vi-talitätszustandes von Obstbäumen durch Infrarot-luftbilder. Erwerbs-Obstbau 29, 7: 211-218.
[OESTER, B.], 1985: Waldschadenerfassung anhand von Infrarot-Luftbildern. In: Ergebnisse der Sanasilva-Waldschadeninventur 1985. Birmensdorf, Eidg.
AnstaltfürdasforstlicheVersuchswesen, S. 39-43.
[OESTER, B.], 1986: Drei lokale Beispiele für die Entwick-lung der Waldschäden - eine BeurteiEntwick-lung anhand von Infrarot-Luftbildern. In: Sanasilva-Waldscha-denbericht 1986. Birmensdorf, Eidg. Anstalt für das forstliche Versuchswesen, S . 16-17.
0ESTER, B, 1987: Waldschadenkartierung anhand von Infrarot-Luftbildern 1 : 9000. Schweiz. Z. Forstwes.
138, 9: 787-798.
0ESTER, B, ScHERRER, H.U., 1985: Development of forest damaQe assessment with infrared aerial photogra-phy in Switzerland. European Association of Re-mote Sensing Laboratories, Workshop Vienna, S.
49-53.
RAGETH. M., 1986: Was ist ein Infrarot-Luftbild? Bündner Wald 39, 6: 8-9.
RAGETH, M., 1988: Kartierung der Waldverlichtung mit-tels Infrarot-Luftbildern - ein Versuch, dargestellt am Beispiel des Versamertobels. Bündner Wald 41, 1: 37-41.
ScHERRER. H.U., 1987: Areal Determination of Forest Damage through lnfrared Aerial Photography 1 : 9000. Proc. Eleventh Bienn. Workshop Color Aer. Photogr. Plant Sei., Weslaco, Tex., Am. Soc.
Photogramm. Remote Sens., S. 53-60.
32
ScHERRER, H.U., OESTER, B., 1985: Flächenhafte Wald-schadenerfassung mit Infrarot-Luftbildern im Maß-stab 1 : 9000. In: lnventorying and Monitoring Endangered Forests. IUFRO Conference Zurich 1985. Birmensdorf, Eidg. Anstalt für das forstliche Versuchswesen, S. 177-178.
ScHERRER, H .U ., REBMANN, E., 1987: Waldschaden-kartierung mit Infrarot-Luftbildern. Phoenix lnt. 5, 2: 11-17.
SCHERRER, H.U„ GAUTSCH!, H., HAUENSTEIN, P., 1990:
Flächendeckende Waldzustandserfassung mit In-frarot-Luftbildern. Eidg. Anst.forstl. Versuchswes., Ber. 318: 1 02 S .
SCHLAEPFER, R., MANDALLAZ, D., COMMARMOT, B., GüNTER, R., SCHMID, B., 1985: Der Gesundheitszustand des Waldes im Raum Schaffhausen. Schweiz. Z. Forst-wesen. 176, 1: 1-18.
SCHWARZENBACH, F.H., 0ESTER, B., SCHERRER, H.U., GAUTSCH!, H., EICHRODT, R., HÜBSCHER, R., HÄGELI, M., 1986: Flächenhafte Waldschadenerfassung mit In-frarot-Luftbildern 1 : 9000. Eidg. Anst. forstl. Ver-suchswes., Ber. 285: 76 S.
SCHWARZENBACH, F.H., GREMINGER, P., OESTER, B., 1986:
Sanasilva-Teilprogramm 3: Waldschadeninventur mit Infrarot-Luftbildern. Bündner Wald 39, 6: 4-5.
ZoJA, M., 1988: Potentielle Waldlawinen -Abklärungen an Hand von Infrarot-Luftbildern und Waldscha-denkarten. Bündner Wald 41, 1: 32-36.
ZuBER, R., 1986a: Anwendungsbereiche von Infrarot-luftbildern und Waldschadenkarten in Graubün-den. Bündner Wald 39, 6: 18-19.
ZuBER, R., 1986b: Infrarot-Luftbildauswertung im Kanton Graubünden. Bündner Wald 39, 6: 6- 7.
ZUBER, R., 1986c: Infrarot-Waldschadenkartierung-zwei Beispiele. Bündner Wald 39, 6: 33-41 .
Schlußberichte
Programm Sanasilva 1984-1987
Sanasilva ist ein auf die Praxis gerichtetes wissenschaftliches Pro-gramm. Es will die schweizerische Forstwirtschaft bei der Lösung von Problemen unterstützen, die durch die Waldschäden neu oder verstärkt erwachsen sind. Ursachen und Mechanismen der Waldschäden sind Gegenstand von weiteren Projekten, die insbesondere im Nationalen Forschungsprogramm 14+ bearbeitet werden. Die erste Phase des Programmes (1984 bis 1987) besteht aus elf Projekten. deren Er-gebnisse und Erfahrungen in den folgenden Schlußberichten für die Praxis zusammengefaßt und 1989/90 veröffentlicht werden:
1. Synthesebericht der Programmkoordination 2. Terrestrische Waldschadeninventur
3. Waldzustandserfassung mit Infrarot-Luftbildern 4. Optimierung der Methoden der Waldschadenerfassung 5. Phytosanitärer Beobachtungs- und Meldedienst 6. Veränderung von Waldstandorten
7. Holzbringung mit Mobilseilkran
8. Fallstudien zur Erhaltung gefährdeter Gebirgsschutzwälder 9. Aus- und Weiterbildung der Praxis in waldbaulicher und
betrieblicher Hinsicht 10. Holzqualität
11. Direkte betriebswirtschaftliche Verluste als Folge von Zwangs-nutzungen
Rapports finaux
Programme Sanasilva 1984-1987
Sanasilva est un programme scientifique dont le but est d'aider le service forestier a resoudre des problemes nouveaux ou aggraves par le deperissement des forets. Les projets ont debute en 1984 et traitent de l'observation des degäts. des mesures a prendre en foret et de consequences possibles pour certaines prestations de la foret.
Les causes et mecanismes du deperissement sont l'objet d' autres
Rapporti finali
Programme Sanasilva 1984-1987
Sanasilva e un programma scientifico orientato verso la pratica. Lo scopo e quello di aiutare il servizio forestale nella soluzione dei problemi ehe, a causa del deperimento delle foreste. si presentano in forma nuova o aggravata. 1 progetti di questo programma iniziato nel 1984 trattano dell'osservazione dei danni. delle controm isure da attuare e delle possibili conseguenze sulle prestazioni della foresta. Le ricerche sulle cause e sui meccanismi del deperimento sono invece affidate al programma nazionale di ricerca 14+. 1 presenti «Rapporti finali Sanasilva In riassumono per gli operatori della pratica i risultati e le esperienze raccolte negli 11 progetti della prima fase del programma (1984-1987). Nel corso del 1989/90 verranno pubblicati i seguenti rapporti finali :
1. Rapporto di sintesi della coordinazione del programma 2. lnventario terrestre dei danni ai boschi
3. Rilievo dello stato del bosco per mezzo di fotografie aeree agli infrarossi
4. Ottimalizzazione dei metodi d'inventario dei danni alle foreste 5. Servizio fitosanitario d'osservazione e di informazione 6. Mutamenti nelle stazioAi forestali
7. Esbosco con gru a cavo a stazione motrice mobile 8. Studio di casi per il mantenimento dei boschi protettivi di
montagna in pericolo
9. Formazione e perfezionamento degli operatori della pratica in selvicoltura e in conduzione aziendale
10. Oualita del legno
11. Perdite dirette sopportate dai proprietari di bosco in seguito alle realizzazioni forzate
Final Reports
Programme Sanasilva 1984-1987
Sanasilva is a scientific programme aimed at ass1st1ng practical foresters in Switzerland in solving problems arising from or aggravated by forest damage. Research on causes and mechanisms is being conducted in other projects. in particular those of the National Research Programme 14+. The first phase of the Sanasilva programme (1984- 1987) comprised eleven projects, the experiences and findings