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Journal of Vegetation Science 20: 1176–1190, 2009& 2009 International Association for Vegetation Science Replacement patterns and species coexistence in an Andean Fajardo, Alex1,2Ã & Gonza´lez, Mauro E.3 1Centro de Investigacio´n en Ecosistemas de la Patagonia, Bilbao 449, Coyhaique, Chile; 2College of Forestry and Conservation, The University of Montana, Missoula, MT 59812 USA; 3Laboratorio de Ecologı´a de Bosques, Instituto de Silvicultura, Universidad Austral de Chile, Casilla 567, Valdivia, Chile; E-mail maurogonzalez@uach.cl; ÃCorresponding author; E-mails alex.fajardo@ciep.cl, fajardo.alex@gmail.com in those open areas after seed masting and will coexist withA. araucana.
Questions: Fire appears to affect both replacement pat-terns and coexistence of Araucaria araucana-Nothofagus Keywords: Araucaria araucana; Chile; Life-history strategies; pumilio forests in the Andean Araucarian region of south- Nothofagus pumilio; Pair-correlation function; Semivario- central Chile. A quantitative assessment of coexistence in grams; Space as a surrogate; Villarrica National Park.
the absence of recent fires, however, is lacking. In thisstudy, we considered the life-history attributes, time ofrecruitment and spatial pattern of individuals of both tree Nomenclature: Marticorena & Rodrı´guez (2003).
species to address the following questions. How regularhas recruitment of both species been in time? Is there anytemporal niche differentiation? Are the two species posi-tively or negatively associated in space and, if so, at what scale and for what age and size classes? Is there any spatialniche differentiation? structure in ecosystems, disturbances influence com- Location: Andean Araucarian region of Chile, VillarricaNational Park (39 petition and environment, substrate and resource availability (Peterson & Pickett 1995; White & Methods: We stem-mapped and cored a total of 1073 trees Jentsch 2001), creating opportunities for tree species in a 1-ha plot in a late-successional post-fire stand to establishment (Veblen 1992). Fire is the dominant examine spatiotemporal patterns of establishment. We form of disturbance in many forest ecosystems used semivariogram modelling and the pair-correlation worldwide, including the Araucaria-Nothofagus for- function to distinguish between regeneration modes and ests in the Andean Araucarian region of south- central Chile (Burns 1993; Veblen et al. 1995, 2005;Gonza´lez et al. 2005). Post-fire development of tree Results: The two species differ in their regeneration mode: populations has been widely documented in the whereas A. araucana appeared to recruit more continu- northern hemisphere in boreal (e.g. De Grandpre´ et ously in time and space, episodic pulses of establishmentwere dominant for N. pumilio. At small scales, younger al. 2000; Johnstone & Chapin 2006) and temperate age-class stems of A. araucana were randomly distributed, subalpine forests (e.g. Sherriff & Veblen 2006; Sibold while older age-class stems were aggregated. This was in et al. 2007), but there has been little study of fire in contrast to common patterns for temperate tree species, temperate forests of South America (but see Veblen including N. pumilio, following processes of self-thinning.
& Lorenz 1987; Burns 1993; Gonza´lez et al. 2005), Younger age classes of A. araucana were distributed particularly after the occurrence of fire. A. araucana independently of older trees of both species, but younger (Molina) K. Koch (Araucariaceae) forests constitute age classes of N. pumilio had a negative association with a relict from the Tertiary; they have generally been older conspecifics at scales similar to crown diameter.
displaced by other broadleaf species and are currentlyfound only at sites of low productivity at high alti- Conclusions: In the absence of recent fires, it is likely thatA. araucana would dominate the stand alone, given its tudes (Schmithu¨sen 1960; Veblen 1982). During the greater shade tolerance, greater longevity and continuous twentieth century, the species’ distribution has been recruitment. However, while canopy closure is still incom- dramatically reduced following logging (Lara et al.
plete, the shade-intolerant N. pumilio will be able to recruit 1999), which has caused considerable concern over

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