Despite many studies have documented that fragmentation facilitates biological invasions, studies performed in different taxonomic groups have observed contrasting patterns. Unfortunately, the use of different ecosystems and fragmentation metrics among studies does not allow assessing the generality of the effect of fragmentation on invasion among different taxa. Studies evaluating the simultaneous responses of exotic species from different taxonomic groups to the same fragmentation patterns may help to assess generality of this relationship. Temperate forests in coastal central Chile are largely a suite of fragments of different sizes surrounded mainly (but not exclusively) by Pinus radiata plantations. Here, we evaluated exotic species richness of vascular plants, insects, mammals and birds in the coastal Maulino forest in a continuous native forest, fragments of native forest and Pinus radiata plantations. Species richness of exotic species of all taxa varied similarly across landscape units. Plantations presented the highest number of exotic species, followed by fragments and finally the continuous forest. In addition, regarding all exotic species, landscape units showed a nested pattern in which most exotic species present in the continuous forest were also present in fragments; and most species present in fragments were present in the pine plantation as well. Our results suggest that fragmentation may affect invasion of different taxa in a similar way, and that continuous forests may efficiently resist invasion. Our results also suggest that given that most of the native forest of south-central Chile is distributed in small fragments, it seems urgent to start an exotic species control to maintain their conservation value.

Irrigation has frequently been considered a necessary step in reforesting open areas of semiarid ecosystems. However, the success of irrigation has mainly been assessed using young and small plants, typically younger than two years old. Few studies have explored whether irrigation is also important with older and larger plants, and if the use of larger plants may enhance reforestation success. We tested the effect of irrigation and plant size on survival and height growth of six tree species from the Mediterranean region of Chile, for planting on a reclaimed fly ash landfill lacking woody vegetation. Between 2008 and 2010 we planted and monitored 160 plants of each species in a factorial design including 1- and 4-year-old trees (smaller and larger, respectively), with and without irrigation. Irrigation improved survival in more water-demanding species regardless of plant size, and primarily among smaller plants for species classified in the middle of a water requirement gradient. With more drought-resistant species, irrigation was not important for survival. The use of larger plants enhanced survival but not growth, and mainly in more water-demanding species. In general, height growth for some species was higher with irrigation and mainly among smaller plants.

Native forest replacement by exotic forestry plantations and fragmentation may have different consequences for biodiversity. In the transition zone between the Mediterranean and Temperate Regions of Chile, native forests have been replaced and fragmented, and currently are surrounded by Pinus radiata plantations. However, the effects of these changes on biodiversity are still poorly understood. In this study, we evaluated how the replacement and fragmentation of these native forests have affected plant communities of a coastal area of the Maule Region in central Chile. We compared plant communities between three types of landscape units: pine plantations, small forest fragments and a continuous native forest. On each landscape unit, we evaluated richness and composition of native and exotic species on 100 m² plots located in two positions: edge and interior. Native species richness decreased and exotic invasion increased in plantations compared to fragments and continuous forests. Fragmentation increased invasion of exotic species, nonetheless did not affect native species richness. Small fragments were significantly similar to the continuous forest in native species composition (~52 % similarity). Exotic species composition of the plantation was significantly similar to edges of fragments (> 53 % similarity). Our results suggest that, although several native species may inhabit pine plantations, these are not able to support as many native plants as do native forests. Furthermore, plantations facilitate exotic invasion. Despite that fragments have been invaded, the fact that many native species are growing there suggests that small fragments of native forest may be considered as high-value areas for conservation.

Latitudinal and altitudinal patterns of plant species richness have frequently been related to different climate variables such as precipitation, temperature and evapotranspiration. However, studies assessing this relationship have mostly compared different regions and used regional scales of richness (in quadrants of several km2). It is less known the relationship between climate and geographical patterns of species richness in local scales (richness in < 1 ha plots). For central Chile some studies have described geographical patterns of plant species richness, but only using regional scales to quantify richness. It is not known how local richness of plant species varies geographically and if climate variables are related to this variation. In this paper I evaluated latitudinal and altitudinal trends of local richness of woody species within forest ecosystems of the Mediterranean-type climate region in central Chile, and explored if these patterns are related to climatic variables. We used data collected in the field as well as published data of composition of woody species in plots of 100 m2 collected in different localities within this region. Climatic variables were obtained for each locality from isoclimate curves published for the whole region. Local woody species richness was positively related to latitude and negatively related to elevation. Also, it was positively related to annual precipitation and atmospheric relative moisture, and negatively to mean minimal temperature of winter. In addition, precipitation increased with latitude, and minimal temperature of winter decreased with elevation. These results suggest that climate may be an important driver of altitudinal and latitudinal patterns of local species richness of woody species in central Chile.