Alien plant species are a growing concern in protected areas, yet little information is available on the role of roads as corridors for alien species and the effects of elevation, land use, and landscape context in these invasions. These concerns are of particular interest in temperate zones of South America, where protected areas have high concentrations of endemic species. We studied roadside alien plant communities and forest-road edges in Villarrica and Huerquehue national parks in the Andean portion of south-central Chile. We sampled alien species and their abundance along 21 km of roads inside parks and 22 km outside parks, using 500-m roadside transects. We also sampled plant species and recorded their abundance in 15 transects located perpendicular to forest-road edges in four forest types. Of the 66 alien species encountered along roadsides, 61 were present outside parks and 39 inside parks. Elevation and alien species richness along roadsides were significantly and negatively correlated (R 2 = −0.56, p < 0.001). Elevation, land use, and their interaction explained 74% of the variation in alien species richness along roadsides (p < 0.001). Transects located in pasture or disturbed secondary forests had significantly more alien species. We found no significant edge effect on native and alien species richness in any forest type. Few alien species have percolated into forest interiors. Native and alien diversity in edge plots were not related. Almost half the alien species belonged to three families and 85% were native to Eurasia. Our results suggest that alien species are moving into parks along road corridors and that elevation and land use of the matrix influence these invasion processes. Our findings corroborate the importance of early detection and control of invasive species in protected areas and highlight the importance of considering surrounding matrix land use in developing conservation strategies for reserves. Resumen:Las invasiones de especies de plantas exóticas son una preocupación creciente enáreas protegidas, sin embargo se dispone de escasa información sobre el papel de los caminos como corredores para especies exóticas y los efectos de la altitud, uso de suelo y contexto del paisaje en estas invasiones. Estas preocupaciones son de interés especial en las zonas templadas de Sudamérica, donde lasáreas protegidas presentan altas concentraciones de especies endémicas. Estudiamos las comunidades de plantas exóticas en bordes de caminos y en bordes de caminos dentro de bosques en los parques nacionales de Villarrica y Huerquehue en la porción andina del centro-sur de Chile. Muestreamos especies exóticas y su abundancia a lo largo de 21 km de caminos dentro de los parques y 22 km fuera de los parques, utilizando transectos de 500 m. También muestreamos especies de plantas y registramos su abundancia a lo largo de 15 transectos localizados perpendicularmente a los bordes de los caminos dentro de bosques en cuatro tipos de bosque. De las 66 especies de plantas Alien Plant Invasions along Roadsides ...

Understory vegetation undergoes successional stages during the 1st 300 yr after logging or fire disturbance in the coastal Picea—Tsuga forests of southeast Alaska. Residual shrubs and tree seedlings increase their growth within 5 yr after overstory removal. Understory biomass peaks at 5 Mg°ha—1°yr—1°15—25 yr after logging. Shrubs and herbs are virtually eliminated (<0.1 Mg/ha) from the understory after forest canopies close at stand ages of 25—35 yr. Bryophytes and ferns dominate understory biomass during the following century. An understory of deciduous shrubs and herbs is reestablished after 140—160 yr. Thereafter, biomass of the shrubs, herbs, and ferns continues to increase, while bryophyte biomass and tree productivity decline. Departures from this developmental sequence are related to unusual types of stand establishment, soil, microclimate, or disturbance. The development and duration of the depauperate understory that succeeds canopy closure in southeast Alaska is closely related to the canopy structure of shade—tolerant Tsuga forests with their high foliar biomass. In young—growth forests (<100 yr), the decline in understory development immediately after canopy closure is significantly associated with tree basal area and percentage of tree canopy cover. In old—growth forests, in contrast, understory biomass is correlated with mean tree diameter, age, and volume. It is hypothesized that understory development over the chronosequence responds primarily to changes induced in the light environment by developments in the forest canopy. Maintenance of the most productive forests in the aggradation stages of development (0—100 yr) through forest management will minimize the development of a productive vascular understory and thus deprive herbivores of forage during 70—80% of the forest rotation.

We synthesized an expert review of climate change implications for hydroecological and terrestrial ecological systems in the northern coastal temperate rainforest of North America. Our synthesis is based on an analysis of projected temperature, precipitation, and snowfall stratified by eight biogeoclimatic provinces and three vegetation zones. Five IPCC CMIP5 global climate models (GCMs) and two representative concentration pathways (RCPs) are the basis for projections of mean annual temperature increasing from a current average (1961-Climatic Change (2015 1990) of 3.2°C to 4.9-6.9°C (5 GCM range; RCP4.5 scenario) or 6.4-8.7°C (RCP8.5), mean annual precipitation increasing from 3130 mm to 3210-3400 mm (3-9 % increase) or 3320-3690 mm (6-18 % increase), and total precipitation as snow decreasing from 1200 mm to 940-720 mm (22-40 % decrease) or 720-500 mm (40-58 % decrease) by the 2080s (2071-2100; 30-year normal period). These projected changes are anticipated to result in a cascade of ecosystem-level effects including: increased frequency of flooding and rain-on-snow events; an elevated snowline and reduced snowpack; changes in the timing and magnitude of stream flow, freshwater thermal regimes, and riverine nutrient exports; shrinking alpine habitats; altitudinal and latitudinal expansion of lowland and subalpine forest types; shifts in suitable habitat boundaries for vegetation and wildlife communities; adverse effects on species with rare ecological niches or limited dispersibility; and shifts in anadromous salmon distribution and productivity. Our collaborative synthesis of potential impacts highlights the coupling of social and ecological systems that characterize the region as well as a number of major information gaps to help guide assessments of future conditions and adaptive capacity.

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