Plant species richness, functional type and soil properties of grasslands and allied vegetation in English Environmentally Sensitive Areas

To facilitate the maintenance and restoration of semi-natural grasslands, it is important to understand their relationships with soil properties. Semi-natural grasslands typically have a high incidence of stress-tolerant species (measured here by high stress radius values), but not all have high species richness. Species richness and stress radius values were related to soil pH. Olsen extractable phosphorus (P), extractable potassium (K) and magnesium (Mg), total nitrogen (N) and organic matter (OM) at 571 sites representing a wide range of temperate grasslands. Highest species richness (>30 m-2) occurred at pH > 6 and 4-15 mg l-1 P, but species richness was also highly variable at 4-15 mg l-1 P. At pH < 5, species richness was low (<20 m-2). Stress radius values were highest (mainly calcareous and heath grasslands and mires) at pH c. 8.0 and < 5.0, and at the lowest soil P levels (<5 mg l-1). A wide range of stress radius values occurred at low soil P levels because appropriate management is also needed to maintain semi-natural grasslands. Reducing soil P is difficult in practice, so grassland restoration in the presence of elevated soil-extractable P levels merits re-assessment

Impact of changes in natural ultraviolet radiation on pigment composition, physiological and morphological characteristics of the Antarctic moss, Grimmia antarctici

The impact of ambient ultraviolet (UV)-B radiation on the endemic bryophyte, Grimmia antarctici, was studied over 14 months in East Antarctica. Over recent decades, Antarctic plants have been exposed to the largest relative increase in UV-B exposure as a result of ozone depletion. We investigated the effect of reduced UV and visible radiation on the pigment concentrations, surface reflectance and physiological and morphological parameters of this moss. Plexiglass screens were used to provide both reduced UV levels (77%) and a 50% decrease in total radiation. The screen combinations were used to separate UV photoprotective from visible photoprotective strategies, because these bryophytes are growing in relatively high light environments compared with many mosses. G. antarctici was affected negatively by ambient levels of UV radiation. Chlorophyll content was significantly lower in plants grown under near-ambient UV, while the relative proportions of photoprotective carotenoids, especially beta-carotene and zeaxanthin, increased. However, no evidence for the accumulation of UV-B-absorbing pigments in response to UV radiation was observed. Although photosynthetic rates were not affected, there was evidence of UV effects on morphology. Plants that were shaded showed fewer treatment responses and these were similar to the natural variation observed between moss growing on exposed microtopographical ridges and in more sheltered valleys within the turf. Given that other Antarctic bryophytes possess UV-B-absorbing pigments which should offer better protection under ambient UV-B radiation, these findings suggest that G. antarctici may be disadvantaged in some settings under a climate with continuing high levels of springtime UV-B radiation

Use of Deschampsia antarctica for nest building by the kelp gull in the Argentine Islands area (maritime Antarctica) and its possible role in plant dispersal

During the last 50 years, the western coast of the Antarctic Peninsula and adjacent archipelagos, also known as the maritime Antarctic, has experienced notable climate warming. As a result, expansion of the local distributions of the two native species of vascular plants, Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth.) Bartl., over previously unoccupied ground has been noted. Birds have been suggested to be partially responsible for this spread. The focus of the present study was to document the use of vascular plants in nest building by the kelp gull (Larus dominicanus) in the Argentine Islands region. During the 2009/2010 season, samples from kelp gull nests were collected and analyzed. Besides nests, material lost by birds during transfer was also studied. We demonstrate that, in the Argentine Islands region, Deschampsia antarctica and some bryophytes contribute the majority of nest building material for the kelp gull. Other materials, including lichens, gull feathers, and limpet shells, are used less frequently. The plants can reestablish upon transfer via vegetative or generative means. It thus seems that the kelp gull may potentially serve as a dispersal agent for Deschampsia antarctica