The design, launch and assessment of a new volunteer-based plant monitoring scheme for the United Kingdom

Volunteer-based plant monitoring in the UK has focused mainly on distribution mapping; there has been less emphasis on the collection of data on plant communities and habitats. Abundance data provide different insights into ecological pattern and allow for more powerful inference when considering environmental change. Abundance monitoring for other groups of organisms is well-established in the UK, e.g. for birds and butterflies, and conservation agencies have long desired comparable schemes for plants. We describe a new citizen science scheme for the UK (the ‘National Plant Monitoring Scheme’; NPMS), with the primary aim of monitoring the abundance of plants at small scales. Scheme development emphasised volunteer flexibility through scheme co-creation and feedback, whilst retaining a rigorous approach to design. Sampling frameworks, target habitats and species, field methods and power are all described. We also evaluate several outcomes of the scheme design process, including: (i) landscape-context bias in the first two years of the scheme; (ii) the ability of different sets of indicator species to capture the main ecological gradients of UK vegetation; and, (iii) species richness bias in returns relative to a professional survey. Survey rates have been promising (over 60% of squares released have been surveyed), although upland squares are under-represented. Ecological gradients present in an ordination of an independent, unbiased, national survey were well-represented by NPMS indicator species, although further filtering to an entry-level set of easily identifiable species degraded signal in an ordination axis representing succession and disturbance. Comparison with another professional survey indicated that different biases might be present at different levels of participation within the scheme. Understanding the strengths and limitations of the NPMS will guide development, increase trust in outputs, and direct efforts for maintaining volunteer interest, as well as providing a set of ideas for other countries to experiment with.

Single channel analysis of a novel NMDA channel from Xenopus oocytes expressing recombinant NR1a, NR2A and NR2D subunits

Two types of subunit (an NR1 subunit and one of the NR2 subunits) are sufficient to form efficient NMDA receptors. In order to investigate whether functional receptors may contain more than one sort of NR2 subunit, NR1, NR2A and NR2D subunits were co-expressed in Xenopus oocytes. Single channel recordings from the oocytes showed, as expected, channel openings that are characteristic of NR1/NR2A receptors (ca 50 and 40 pS conductances), and channels characteristic of NR1/NR2D receptors (ca 40 and 20 pS conductances). However, they also contained a novel channel that contained conductances of ca 30, 40 and 50 pS, with direct transitions between all three levels. It is postulated that the novel channel contains NR1, NR2A and NR2D subunits. The implications of this for receptor stoichiometry are discussed. The novel channel was intermediate between the NR1/NR2A and NR1/NR2D 'duplet' receptors in the length of the channel activations, and in the probability of being open during activation. Its glycine sensitivity was much higher than that of NR1/NR2A, and was comparable with that of the other 'duplet' receptors.

Malate transport and vacuolar ion channels in CAM plants

Malate is a ubiquitous vacuolar anion in terrestrial plants that plays an important role in carbon metabolism and ionic homeostasis. In plants showing crassulacean acid metabolism (CAM), malate is accumulated as a central intermediary in the process of photosynthetic carbon assimilation, and it is also one of the major charge-balancing anions present in the vacuole. During the CAM cycle, malic acid produced as a result of dark CO(2) fixation accumulates in the vacuole at night (2 H(+) per malate), and is remobilized from the vacuole in the following light period. CAM plants thus provide a good model for studying both the mechanism and control of malate transport across the tonoplast. Thermodynamic considerations suggest that malate(2-) (the anionic species transported out of the cytosol) is passively distributed across the tonoplast. Malic acid accumulation could thus be explained by malate(2-) transport into the vacuole occurring electrophoretically in response to the transmembrane electrical potential difference established by the tonoplast H(+)-ATPase and/or H(+)-PPase. Recent studies using the patch-clamp technique have provided evidence for the existence of a vacuolar malate-selective anion channel (VMAL) in both CAM species and C(3) species. The VMAL current has a number of distinctive properties that include strong rectification (opening only at cytosolicside negative membrane potentials that would favour malate uptake into the vacuole), lack of Ca(2+) dependence, and slow activation kinetics. The kinetics of VMAL activation can be resolved into three components, consisting of an instantaneous current and two slower components with voltage-independent time constants of 0.76 s and 5.3 s in Kalanchoë daigremontiana. These characteristics suggest that the VMAL channel represents the major pathway for malate transport into the vacuole, although the strong rectification of the channel means there may be a separate, still-to-be-identified, transport mechanism for malate efflux.