Cypress mortality (mal del cipres) in the Patagonian Andes: comparisons with similar forest diseases and declines in North America

Abstract

Widespread mortality of Cordilleran cypress (Austrocedrus chilensis) occurs in developed and pristine forests in south-western Argentina and possibly south-eastern Chile. Affected trees may die rapidly but mortality is commonly preceded by several decades of severely restricted radial stem growth. Roots are often affected by one or more types of decay. Cypress mortality, locally termed 'mal del cipres', is similar to a major forest disease in North America: Port-Orford-cedar (Chamaecyparis lawsoniana) root disease in Oregon and California and a major tree decline: Alaska yellow-cedar (Chamaecyparis nootkatensis) decline in south-east Alaska. This paper discusses several hypotheses concerning mal del cipres and compares current forest decline research in Patagonia with North America.

The decline of Austrocedrus chilensis forests in Patagonia, Argentina: soil features as predisposing factors

“…The cause of the decline is unknown. Filip and Rosso (1999) summarized the characteristics of the disease and discussed several hypotheses on its origin. Biotic causes have been suggested and screening of soil phytopathogenic fungi such as Phytophthora and Pythium has been carried (Rajchenberg et al, 1998), as well as screening for wood-rotting basidiomycetes responsible for brown root-rots in decaying trees (Barroetaveña and Rajchenberg, 1996).…”

“…The decline and mortality of Chamaecyparis nootkatensis (D. Don) Spach in Alaska, which has important similarities with ''mal del ciprés'' (Filip and Rosso, 1999), has been associated with boggy and semi-boggy sites (Hennon et al, 1990). In Poland, oak decline develops on soils with lower water uptake compared to healthy sites (Maciaszek, 1996).…”

The presence of the marsupial Dromiciops gliroides in Parque Nacional Los Alerces, Chubut, Southern Argentina, after the synchronous maturation and flowering of native bamboo and subsequent rodent irruption

“…(an organism that causes root rot) spread by human activity, causing mortality to cypress trees (Filip and Rosso 1999). It is possible the high volume of predators and threats from domestic animals and tourism contributed to the low capture rate of D. gliroides during the study.…”

Can a natural experiment be used as a tool to design partial cutting regimes? The decline of Austrocedrus chilensis forests, an example

“…In this area, we sampled eight post-fire stands dominated by A. chilensis from a population of stands exhibiting symptoms of 'mal del cipre´s'. The most common visible symptoms include trees with chlorotic foliage or partial defoliation, as well as standing and fallen dead trees (Havrylenko et al 1989;Rajchenberg and Cwielong 1993;Filip and Rosso 1999). Since the purpose of the study was solely to investigate the recruitment as consequence of the overstory mortality, we carefully selected stands with no signs of grazing or past logging.…”

“…Reported about 60 years ago (Hranilovic 1988), this spatially erratic process of overstory mortality is presently found across the range of distribution of A. chilensis in Argentina. Thus, the mortality occurring in cypress forests develops slowly in individual trees (Calí 1996) and cannot be explained by only a single factor but rather a complex interaction of biotic (Greslebin et al 2007) and abiotic factors (Baccalá et al 1998;La Manna and Rajchenberg 2004;La Manna et al 2008a) has lead to the idea that 'mal del cipre´s' is a type of forest decline (Baccalá et al 1998;Filip and Rosso 1999;La Manna and Rajchenberg 2004).…”