- BEILSCHMIEDIA MIERSII: EFFECTS OF LEAF LITTER AND PRECIPITATION - 253 Applied Vegetation Science 7: 253-257, 2004 © IAVS; Opulus Press Uppsala. Abstract Question: What effects do leaf litter and rainfall regime have on seed germination (time and probability) and seedling sur- vival of the endangered tree species Beilschmiedia miersii (Lauraceae)? Location: The species is a native tree from the mediterranean climate region of Chile. Seeds were collected from La Campana National Park (Chile). The study was carried out under con- trolled conditions at the Laboratory of Ecology, University of Chile, Santiago, Chile. Methods: During April 2001, 200 seeds were assigned to four experimental treatments: high precipitation, with and without litter and low precipitation, with and without litter. Each treatment had 50 individual seeds, each seed in an individual pot. For statistical purposes, we considered each seed as one replicate. High and low values of artificial rainfall corre- sponded to mean dry and wet years, respectively, for the period 1958 - 1993 in the central zone of Chile. Results: Seeds germinated earlier, and in higher proportion, in the presence of leaf litter, but only under low rainfall. Seedling survival was insensitive to both litter and precipitation. Conclusions: We conclude that the presence of litter in native populations facilitates seed germination and recruitment of B. miersii, particularly during dry years. We suggest that the reduction of leaf litter due to extraction for gardens and horticultural activities might preclude regeneration of this endangered species. Keywords: Chile; Facilitation; Mediterranean ecosystem; Plant recruitment; Plant regeneration; Threatened species. Effects of leaf litter and precipitation on germination and seedling survival of the endangered tree Beilschmiedia miersii Becerra, Pablo I. 1,2 ; Celis-Diez, Juan L. 1,3 & Bustamante, Ramiro O. 1* 1 Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile; 2 E-mail pbecer@yahoo.com.ar; 3 E-mail jlcelis@uchile.cl; * Corresponding autor; Fax +5622727363; E-mail rbustama@uchile.cl Introduction Accumulation of leaf litter modifies light, moisture and microhabitat environment; hence it may affect seed germination and seedling survival (Harper 1977; Rathcke & Lacey 1985; Facelli 1994). Leaf litter nega- tively affects seed germination and seedling growth, e.g., acting as a mechanical barrier for radicular growth (Bosy & Reader 1995) and shoot emergence (Green 1999). Leaf litter may also modify the quantity and quality of light received by a seed in the ground, transmitting longer wavelengths that may be strongly inhibitory for the germination of seeds (Facelli & Pickett 1991a; Yirdaw & Leinonen 2002). Leaf litter may also modify the chemical environment of seeds, inhibiting germination (Bosy & Reader 1995; Hilhorst & Karssen 2000). On the other hand, leaf litter may positively affect seed germination due to its role as refuge against predators (Myster & Pickett 1993; Cintra 1997), or its moderating effect on soil temperature and moisture (Facelli & Pickett 1991a; Bosy & Reader 1995). The sign and magnitude of litter effects are variable and seem to depend on the regeneration requirements of plant species and on ecosystems properties such as climate, soil and vegetation (Rice 1979; Carson & Peterson 1990; Facelli & Pickett 1991b; Bosy & Reader 1995; Foster & Gross 1997). Leaf litter effects on soil moisture may be crucial for water demanding species. However, the favourable ef- fect on these species may depend on the amount of rain that falls in a given season or at a particular place (Callaway & Pugnaire 1999). Leaf litter effects on soil moisture are important when rainfall becomes scarce. By reducing evaporation from the soil, leaf litter main- tains soil moisture necessary for seed germination dur- ing dry periods or at dry sites (Callaway & Pugnaire 1999). This potentially important interaction between leaf litter and rainfall has not yet been experimentally assessed.