Catherine Kleier

The Importance of Nurse Associations for Three Tropical Alpine Life Forms

Abstract We investigated biotic and abiotic associations for four growth forms in Chiles Parque Nacional Lauca, a tropical alpine puna ecosystem. We determined the biotic associations between Parastrephia lucida (Meyen) Cabr. [Asteraceae] and Festuca orthophylla Pilger. [Poaceae]. To determine if F. orthophylla was acting as a nurse plant for P. lucida, we used chi-square analysis to test for nurse plant effects. Our results indicated that F. orthophylla roots more often on bare ground and that P. lucida grows more often in association with F. orthophylla than would be expected. In testing for abiotic associations, we observed that both a tree, Polylepis tarapacana [Rosaceae], and a cactus, Tephrocactus ignescens [Cactaceae], showed positive abiotic associations with large boulders. These studies indicate that in an extreme environment, such as the South American puna, abiotic and biotic associations are important for plant survival.

Photosynthesis and biomass allocation of radish cv. Cherry Belle in response to root temperature and ozone

To determine if ozone (O3) and root zone temperature (RZT) affect plant biomass allocation and photosynthesis, radish (Raphanus sativus) plants were grown in controlled environment laboratory chambers in one of four treatments: episodic O3 (average delivery 0.063 mumol mol-1) with RZT at 13 degrees C, episodic O3 (same delivery) with RZT at 18 degrees C, charcoal-filtered air with RZT at 13 degrees C and charcoal-filtered air with RZT at 18 degrees C. O3 reduced total biomass and shoot biomass of radish at 13 degrees C RZT but had no effect at 18 degrees C RZT. Low (13 degrees C) RZT decreased total biomass in both O3 and charcoal-filtered air. RZT had no overall effect on biomass allocation, but O3 lowered root-to-shoot ratios for plants grown at 18 degrees C RZT. Photosynthesis was reduced for plants grown at 18 degrees C RZT and O3, but stomatal conductance was not affected by O3 nor RZT. These results indicate that O3 and low RZT decrease biomass, but that plant photosynthesis is decreased by O3 and warm RZT.

Ecological and ecophysiological patterns in a pre-altiplano shrubland of the Andean Cordillera in northern Chile

We report on community structural, ecophysiological, phenological, and morphological measurements made on woody plant species in the high elevation pre-altiplano zone on the western slopes of the Andean Cordillera of northern Chile. Notwithstanding extreme conditions of low rainfall, high atmospheric vapour demand and diurnal temperature fluctuation, a diversity of habitats (associated with drainage and slope aspect), appreciable local plant species richness (28 woody perennial plant species in a small area), and an array of adaptive morphological ecophysiological and phenological traits are present among woody species in these shrublands. Family diversity was low with four families accounted for 82% of the species. A range of gas exchange and watering use efficiency strategies was present ranging from highly efficient CAM species with a carbon isotope discrimination (Δ) of 3.7–7.5‰ through C3 species with varying stomatal and gas exchange characteristics with a Δ of 14.4 to 19.8‰. Drought-deciduous small-leaved amphistomatic species from arid slopes generally had high stomatal conductance and high carbon assimilation rates during the rainy season. These drought deciduous species were largely leafless and, with one exception had low water potentials, during the dry season. Wash and less xeric site species commonly had broader evergreen to semi-evergreen leaves, higher dry season water potentials, and relatively consistent and moderate rates of gas exchange throughout the year. For all species, intrinsic water use efficiency (as estimated from the inverse of ci:ca ratio) correlated positively with mean leaf width (broader leaves had a lower higher intrinsic WUE) and dry season water potential. The charismatic high altitude tree, Polylepis rugulosa (Roaceae), had a population structure that suggests highly episodic establishment of seedlings, likely in sequences of wet years. Little of the area of these significant shrublands is currently protected. It would be desirable to add areas of pre-altiplano shrublands to adjacent national parks to ensure the persistence of these important communities.

Plant community variation across a puna landscape in the Chilean Andes

Describimos los patrones de abundancia de las especies vegetales y las formas de vida en la vegetacion de puna en el Parque Nacional Lauca, Chile. A una altitud que excede los 4.300 m de altitud, el habitat extremo de nuestro sitio de estudio presenta relativamente pocas especies. Dichas especies, sin embargo, representan un arreglo diverso de formas de vida organizadas con respecto a distintos gradientes ambientales. Tanto la riqueza de especies como el habito de crecimiento aumentaron en los suelos mas rocosos y en las pendientes expuestas al norte y al este, cuya vegetacion es mas xerofila. Dichos sitios presentaron la mayor abundancia en formas de cojines. Los sitios menos rocosos con un suelo mas desarrollado presentaron una mayor abundancia de pastos y arbustos. Distintos microhabitats fueron ocupados por especies congenericas que con frecuencia divergieron en su habito de crecimiento. Los patrones observados sugieren que el agua y el estres termico son fuerzas criticas que moldean la forma funcional de las especies vegetales asi como la organizacion de las comunidades de plantas en la puna altoandina

Size class structure, growth rates, and orientation of the central Andean cushion Azorella compacta

Azorella compacta (llareta; Apiaceae) forms dense, woody, cushions and characterizes the high elevation rocky slopes of the central Andean Altiplano. Field studies of an elevational gradient of A. compacta within Lauca National Park in northern Chile found a reverse J-shape distribution of size classes of individuals with abundant small plants at all elevations. A new elevational limit for A. compacta was established at 5,250 m. A series of cushions marked 14 years earlier showed either slight shrinkage or small degrees of growth up to 2.2 cm yr−1. Despite their irregularity in growth, cushions of A. compacta show a strong orientation, centered on a north-facing aspect and angle of about 20° from horizontal. This exposure to maximize solar irradiance closely matches previous observations of a population favoring north-facing slopes at a similar angle. Populations of A. compacta appear to be stable, or even expanding, with young plants abundant.

Impacts of recreation management practices in a subalpine wetland system dominated by the willow plant, Salix planifolia

Wetland habitat in the subalpine Rocky Mountains is an area of high biodiversity and includes many species of willow. These willow-dominated communities are often used for both summer and winter recreation. The maintenance of winter recreation trails has the potential to disturb wetland vegetation and compromise the long-term persistence of the wetland. In Breckenridge, Colorado, willow plants are clipped in October to a uniform height to prevent stems from protruding through the snow onto the ski trails, and large grooming tractors compact the snow on the trails. Our objective was to investigate the impact of winter recreation trail maintenance on growth and reproductive output of Salix planifolia (common names: planeleaf or diamondleaf willow) and to determine impacts on community diversity in a willow-dominated wetland system. Catkin production, plant height, and branch elongation were evaluated in meter-squared quadrats within paired belt transects both inside and outside a ski trail during the growing seasons of 2008 and 2009. In addition, percent cover of total vegetation was estimated for each species to calculate species richness and diversity. We found that maintenance of winter trails reduced catkin production and limited willow growth. Additionally, winter trail maintenance may have promoted the introduction of invasive species within the willow community. The activities associated with winter trail maintenance could interfere with the long-term persistence of the willow community adjacent to ski trails and should be considered when planning new trails in or along a wetland ecosystem.

Using CREATE in the Undergraduate Ecology Classroom

• Students remark that CREATE helps them improve their ability to read scientific articles, especially figure and table interpretation. • These skills are transferrable across the curriculum. • Students successfully apply the scientific process they are analyzing through CREATE to novel field investigations they design in their grant proposals. • CREATE is a pedagogy designed for students to analyze primary scientific literature in a structured way. • CREATE, pioneered by Hoskins et al. (2007) and Hoskins (2008) in genetics and neurobiology classes, favors depth rather than breadth in curricular coverage. • CREATE asks students to: Consider, Read, Elucidate the hypotheses, Analyze and interpret the data, and Think of the next experiment using a scaffolded approach (See Application section for more details). • CREATE has been shown to help students read critically, analyze data, and improve understanding of science and research as processes rather than a disconnected body of facts (Hoskins et al. 2007) .

An exploratory study of facilitation in three species of Raoulia

ABSTRACT In order to determine the roles that size, temperature, moisture and pH play in ecological facilitation, we investigated facilitation in two cushion plant species (Raoulia eximia and R. bryoides) and one semi-compact creeping cushion (R. australis) on South Island, New Zealand. We measured canopy moisture, pH and temperature as a function of size to determine if these species might have different microenvironments within their canopies and whether these abiotic factors might correlate to increased facilitation. We found that R. eximia showed increasing canopy moisture and decreasing pH with increasing size, indicating microenvironment changes with canopy of the cushion. Temperature at 2 cm canopy depth did not differ with size in any species, nor did it differ from 2 cm depth in open soil. Only R. eximia exhibited plant facilitation by showing more species within the canopy than in nearby soil. This work supports the importance of cushion microclimate in facilitation.

Variation in reproductive investment and floret gender ratios in two gynodioecious mat daisies (Raoulia, Asteraceae)

ABSTRACT Widespread species could be expected to demonstrate greater among-population variation in reproductive traits than species with limited distributions. We investigated variability in floret gender and capitula number in populations of two gynomonoecious mat daisies, the widespread Raoulia australis and the alpine specialist Raoulia hectori in Central Otago, lower South Island. Gynomonoecy (female and hermaphrodite florets in a capitulum) is common in the daisy family Asteraceae. Varying gender ratios within capitula could allow for plasticity in reproductive investment in relation to environment and life-history stage. We found that the ratio of female to hermaphrodite florets within capitula did not vary significantly among populations or with plant size for either Raoulia species. Instead, the number of capitula produced varied among populations within species, independent of plant size, and showed different patterns in relationship to plant size between the two species. Smaller plants of the alpine specialist R. hectori consistently showed a proportionally greater allocation to reproduction than larger plants, whereas the relationship between plant size and reproductive allocation varied markedly among populations of R. australis. These results suggest that allocation to capitula may be a key component of reproduction in Raoulia species, and is potentially responsive to environment and life-history stage. However, as our study included few populations and did not follow through to seed production, this hypothesis requires further testing. Moreover, our values for floret gender ratios differed from standard species descriptions, so broader geographic variation in floret gender ratios may still exist.