Environmental effects of ozone depletion and its interactions with climate change: progress report, 2011.

The parties to the Montreal Protocol are informed by three panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with two focal issues. The first focus is the effects of increased UV radiation on human health, animals, plants, biogeochemistry, air quality, and materials.

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2009.

The parties to the Montreal Protocol are informed by three panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with UV radiation and its effects on human health, animals, plants, biogeochemistry, air quality and materials. Since 2000, the analyses and interpretation of these effects have included interactions between UV radiation and global climate change.

Serious complications in experiments in which UV doses are effected by using different lamp heights.

Many experiments examining plant responses to enhanced ultraviolet-B radiation (280-315nm) simply compare an enhanced UV-B treatment with ambient UV-B (or no UV-B radiation in most greenhouse and controlled-environment studies). Some more detailed experiments utilize multiple levels of UV-B radiation. A number of different techniques have been used to adjust the UV dose.

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2008.

After the enthusiastic celebration of the 20th Anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer in 2007, the work for the protection of the ozone layer continues. The Environmental Effects Assessment Panel is one of the three expert panels within the Montreal Protocol. This EEAP deals with the increase of the UV irradiance on the Earth's surface and its effects on human health, animals, plants, biogeochemistry, air quality and materials.

Root turnover and relocation in the soil profile in response to seasonal soil water variation in a natural stand of Utah juniper (Juniperus osteosperma).

Juniper species are noted for long-lived foliage, low and persistent gas exchange activity and drought tolerance. Because leaves and roots of the same species are thought to be similar in structure and life history, we hypothesized that Juniperus osteosperma (Torr.) Little (Utah juniper) fine roots would reflect the persistent aboveground foliage characteristic of this species.

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2004.

The complexity of the linkages between ozone depletion, UV-B radiation and climate change has become more apparent.

Fine root distribution and persistence under field conditions of three co-occurring Great Basin species of different life form.

Fine roots of an annual grass, a perennial grass and a perennial shrub were examined. Based on life histories and tissue composition, we expected the greatest root persistence for the shrub and shortest for the annual grass. Roots were observed with minirhizotrons over 2 yr for number, length and diameter changes.

Plant responses to current solar ultraviolet-B radiation and to supplemented solar ultraviolet-B radiation simulating ozone depletion: an experimental comparison.

Field experiments assessing UV-B effects on plants have been conducted using two contrasting techniques: supplementation of solar UV-B with radiation from fluorescent UV lamps and the exclusion of solar UV-B with filters. We compared these two approaches by growing lettuce and oat simultaneously under three conditions: UV-B exclusion, near-ambient UV-B (control) and UV-B supplementation (simulating a 30% ozone depletion). This permitted computation of "solar UV-B" and "supplemental UV-B" effects.

Field testing of biological spectral weighting functions for induction of UV-absorbing compounds in higher plants.

Action spectra are typically used as biological spectral weighting functions (BSWF) in biological research on the stratospheric ozone depletion issue. Despite their critical role in determining the amount of UV supplied in experiments, there has been only limited testing of different functions under realistic field conditions. Here, we calculate effective radiation according to five published BSWF and evaluate the appropriateness of these BSWF in representing the induction of UV-absorbing compounds.

Reduction of solar UV-B mediates changes in the Sphagnum capitulum microenvironment and the peatland microfungal community.

The influence of near-ambient and reduced solar UV-B radiation on a peatland microfungal community was assessed by exposing experimental plots to UV-selective filtration. Replicate plots were covered with special plastic films to effect treatments of near-ambient and attenuated solar UV-B. The microfungal community from the top 1 cm of Sphagnum capitulum in a Tierra del Fuego peatland was censused throughout three growing seasons, between 1999 and 2002.

Six years of solar UV-B manipulations affect growth of Sphagnum and vascular plants in a Tierra del Fuego peatland.

•  Tierra del Fuego is subject to increases in solar UV-B radiation in the austral spring and summer due to ozone depletion. •  Plastic films were used to filter solar UV-B radiation over peatland plots through six field seasons, resulting in near-ambient (c. 90%) and reduced (c.

Terrestrial ecosystems, increased solar ultraviolet radiation and interactions with other climatic change factors.

Based on research to date, we can state some expectations about terrestrial ecosystem response as several elements of global climate change develop in coming decades. Higher plant species will vary considerably in their response to elevated UV-B radiation, but the most common general effects are reductions in height of plants, decreased shoot mass if ozone reduction is severe, increased quantities of some phenolics in plant tissues and, perhaps, reductions in foliage area. In some cases, the common growth responses may be lessened by increasing CO2 concentrations.

Root responses and nitrogen acquisition by Artemisia tridentata and Agropyron desertorum following small summer rainfall events.

Resources in the Great Basin of western North America often occur in pulses, and plant species must rapidly respond to temporary increases in water and nutrients during the growing season. A field study was conducted to evaluate below ground responses of Artemisia tridentata and Agropyron desertorum, common Great Basin shrub and grass species, respectively, to simulated 5-mm (typical summer rain) and 15-mm (large summer rain) summer rainfall events. The simulated rainfall was labeled with K(15)NO(3) so that timing of plant nitrogen uptake could be monitored.

Carbon acquisition and water use in a Northern Utah Juniperus osteosperma (Utah juniper) population.

Water use and carbon acquisition were examined in a northern Utah population of Juniperus osteosperma (Torr.) Little. Leaf-level carbon assimilation, which was greatest in the spring and autumn, was limited by soil water availability.

A meta-analysis of plant field studies simulating stratospheric ozone depletion.

The potential effects of increased ultraviolet-B radiation (UV-B, 280-320 nm) simulating stratospheric ozone depletion in field studies with vascular plants have previously been summarized only in narrative literature reviews. In this quantitative synthesis, we have assessed the significance of solar UV-B enhancement for ten commonly measured variables involving leaf pigmentation, plant growth and morphology, and photosynthesis using meta-analytic statistical methods. Of 103 papers published between 1976 and mid-1999 from field studies, more than 450 reports from 62 papers were included in the database.

Solar ultraviolet-B radiation affects plant-insect interactions in a natural ecosystem of Tierra del Fuego (southern Argentina).

We examined the effects of solar ultraviolet-B radiation (UVB) on plant-herbivore interactions in native ecosystems of the Tierra del Fuego National Park (southern Argentina), an area of the globe that is frequently under the Antarctic "ozone hole" in early spring. We found that filtering out solar UVB from the sunlight received by naturally-occurring plants of Gunnera magellanica, a creeping perennial herb, significantly increased the number of leaf lesions caused by chewing insects. Field surveys suggested that early-season herbivory was principally due to the activity of moth larvae (Lepidoptera: Noctuidae).

Hydraulic lift: consequences of water efflux from the roots of plants.

Hydraulic lift is the passive movement of water from roots into soil layers with lower water potential, while other parts of the root system in moister soil layers, usually at depth, are absorbing water. Here, we review the brief history of laboratory and field evidence supporting this phenomenon and discuss some of the consequences of this below-ground behavior for the ecology of plants. Hydraulic lift has been shown in a relatively small number of species (27 species of herbs, grasses, shrubs, and trees), but there is no fundamental reason why it should not be more common as long as active root systems are spanning a gradient in soil water potential (Ψ) and that the resistance to water loss from roots is low.

Species interactions at the level of fine roots in the field: influence of soil nutrient heterogeneity and plant size.

Interference at the level of fine roots in the field was studied by detailed examination of fine root distribution in small soil patches. To capture roots as they occur in natural three-dimensional soil space, we used a freezing and slicing technique for microscale root mapping. The location of individual roots intersecting a sliced soil core surface was digitized and the identity of shrub and grass roots was established by a chemical technique.

The effects of shading and N status on root proliferation in nutrient patches by the perennial grass Agropyron desertorum in the field.

Competition for light can affect exploitation of spatially heterogeneous soil resources. To evaluate the influence of shoot status on root growth responses in nutrient-rich soil patches, we studied the effects of shading and whole-plant nitrogen status on root growth in N-enriched and nonenriched patches by mature Agropyron desertorum plants growing in the field with below-ground competition. Roots in enriched patches had greater length to weight ratios (specific root length, SRL), indicating increased absorptive surface areas, compared with roots in control patches.

Effects of soil temperature and nitrogen status on kinetics of NO uptake by roots of field-grown Agropyron desertorum (Fisch. ex Link) Schult.

Plant NO - acquisition is largely determined by root uptake capacity. Although root uptake capacity has been shown to be sensitive to both root temperature and previous nitrogen (N) supply in hydroponic systems, the uptake capacity response to similar environmental factors under field conditions has not been investigated. Using NO , root uptake capacities were determined in excised roots of Agropyron desertorum (Fisch.

Leaf epidermal transmittance of ultraviolet radiation and its implications for plant sensitivity to ulraviolet-radiation induced injury.

Leaf epidermal transmittance of ultraviolet radiation (280-400 nm) was examined in several plant species to determine the capability of the epidermis to attenuate solar ultraviolet radiation. Epidermal samples were mechanically isolated and examined with a spectroradiometer/integrating sphere for transmittance. A survey of 25 species exposed to natural insolation was conducted.

Competitive interaction in plant populations exposed to supplementary ultraviolet-B radiation.

Changes in plant growth and competitive balance between pairs of competing species were documented as a result of supplementary ultraviolet-B radiation (principally in the 290-315 nm waveband) under field conditions. This component of the terrestrial solar spectrum would be intensified if the atmospheric ozone layer were reduced. A method for calculating and statistically analyzing relative crowding coefficients was developed and used to evaluate the competitive status of the species pairs sown in a modified replacement series.

Carbon balance, productivity, and water use of cold-winter desert shrub communities dominated by C and C species.

Common generalizations concerning the ecologic significance of C photosynthesis were tested in a study of plant gas exchange, productivity, carbon balance, and water use in monospecific communities of C and C salt desert shrubs. Contrary to expectations, few of the hypotheses concerning the performance of C species were supported. Like the C species, Ceratoides lanata, the C shrub, Atriplex confertifolia, initiated growth and photosynthetic activity in the cool spring months and also exhibited maximum photosynthetic rates at this time of year.

Gas exchange of four arctic and alpine tundra plant species in relation to atmospheric and soil moisture stress.

Gas exchange measurements of two arctic tundra plants, Dupontia fischeri and Carex aquatilis, and two alpine tundra species, Deschampsia caespitosa and Geum rossii, were conducted under a range of atmospheric and soil moisture stress conditions to determine if photosynthetic adaptations to water stress may play a role in the local distributions of these species. Under low soil moisture stress, the species which are normally restricted to wet sites, Dupontia and Deschampsia, exhibited higher net photosynthetic rates than Carex and Geum which are more widely distributed. However, photosynthetic of the wider ranging species was not so abruptly curtailed as that of the wet site species when the plants were exposed to increasing atmospheric or soil moisure stress.