Effects of bamboo flowering and overstorey neighborhood on tree seedling establishment in a mixed Patagonian forest

CACCIA, F.D.; KITZBERGER, T.; CHANETON, E.J.

Bariloche

Congreso; VI Southern Connection Congress; 2010

Southern Connection

We conducted a 2-year field experiment to examine how overstorey neighborhoods identity and episodic bamboo flowering affect seedling recruitment in a mixed temperate forest at Lago Currhué Grande, Lanín National Park (Neuquén, Argentina). Treatments consisted of a factorial combination of overstorey identity (Nothofagus alpina or N. dombeyi), bamboo patch conditon (flowered/dead or non-flowered/alive) and access to rodents (with or without exclosure). We planted 8 pairs of newly emerged N. alpina and N. dombeyi seedlings in each overstorey by bamboo combination (n = 5 stands); half of the seedlings in each stand were protected from rodents with a wire exclosure. Rodent exclosures increased seedling survival of both species irrespective of bamboo condition and overstorey identity. N. alpina seedlings survived nearly twice as much under heteroespecific (N. dombeyi) as beneath conspecific canopy (40 vs 18%) and within flowered bamboo relative to non-flowered patches (41 vs 16%). These patterns resulted mostly from differences in invertebrate predation. In contrast, overstorey identity and bamboo condition had no net effects on N. dombeyi survival. Bamboo flowering decreased invertebrate predation on N. dombeyi seedlings (30 vs 57%), but this effect was cancelled out by higher mortality through abiotic stress. Invertebrate herbivores and abiotic factors both played an important role shaping spatial patterns of seedling establishment of canopy species in this temperate forest.