Water relations, phenology and drought adaptation of understorey trees in tropical lowland rain forest.

1. The ecology of common understorey species associated with ridges was compared with species found on lower-slopes and those species occurring ubiquitously in two 4-ha plots in lowland rain forest at Danum, Sabah, East Malaysia (4" 58’ N, 117’ 46’ E) over 3 years. 2. During the study period one dry period occurred (psychrometer-measured ridge soil water potential, 20 cm depth -0.67 MPa), but other, more severe, dry periods have occurred since records began in 1985 (estimated ridge water potential -1.21 MPa, March 1992). Lower soil water potentials occurred on ridges which had up to 0.22 MPa lower water potentials than lower-slopes (estimated difference March 1992, 0.40 MPa). 3. At dry times, Dimorphocatyx muricatus (ridge species) had higher pre-dawn (-0.21 v. -0.57 MPa; all quoted differences are significant at p<0.05) and mid-day (-0.59 v. -1.77 MPa) leaf w'ater potentials than Mallotus wrayi (ubiquitous). Leaf osmotic potentials of D. muricatus were higher (-1.11 v. - 1.58 MPa), and both species osmotically adjusted between wet and dry times. D. muricatus trees were more deeply rooted (mean root depth, 97.4 cm) than M. wrayi trees (69.8 cm). M. wrayi seedlings on ridges had lower assimilation rates than on lower-slopes (1.9 v. 3.4 pmol CO2 m " s '). 4. Leaf production of Arciisia co/orata (ubiquitous), Cleistanthus glaber (ridge), D. muricatus and A/. wrayi trees varied from year to year. C. glaber, D. muricatus, and A/, wrayi all had peaks in leaf and flower production associated with sunnier drier spells, A. colorata did not. A. colorata leaves were longer lived (5.7 years, estimated from leaf turn-over) than D. muricatus (2.7 years) and M. wrayi (2.2 years). There were no size or site differences for leaf life-span or leaf production. More large trees flowered than small trees. More trees flowered on ridges than lower-slopes but more trees set fruit on lower-slopes. 5. D. muricatus seedlings grew equally well on ridges and lower-slopes under different water regimes. A/, wrayi and D. muricatus cutting mortality was higher than D. muricatus seedling mortality for all treatments. M. wrayi cutting mortality was highest in lower-slope drought plots. Cutting mortality was higher in logged forest than primary forest. 6. A/, wrayi seed germination rates (1 %) were much lower than Baccaurea stipulata (lower-slope) (65 %) and D. muricatus (53 %). Germination rates were higher on ridge than lower-slope sites. D. muricatus nursery germination rates (32 %) were lower than in the field. B. stipulata seed took longer to germinate (35 days) than D. muricatus (21 days). 7. Under nursery conditions A/, wrayi wildings grown under 2.7 % daylight grew taller and increased leaf area, specific leaf area (SLA) and fine and coarse root weight than under 1.2 % daylight. Addition of phosphate had no effect on growth 8. Un-watered D. muricatus seedlings took significantly longer to wilt (36 v. 16 days) and die (46 v. 29 days) than B. stipulata seedlings. 9. The results suggest that droughts may have an important effect on understorey ridge community species composition at Danum

7.2% efficient polycrystalline silicon photoelectrode

After etching, n-type cast polycrystalline silicon photoanodes immersed in a solution of methanol and a substituted ferrocene reagent exhibit photoelectrode efficiencies of 7.2%±0.7% under simulated AM2 illumination. Scanning laser spot data indicate that the grain boundaries are active; however, the semiconductor/liquid contact does not display the severe shunting effects which are observed at a polycrystalline Si/Pt Schottky barrier. Evidence for an interfacial oxide on the operating polycrystalline Si photoanode is presented. Some losses in short circuit current can be ascribed to bulk semiconductor properties; however, despite these losses, photoanodes fabricated from polycrystalline substrates exhibit efficiencies comparable to those of single crystal material. Two major conclusions of our studies are that improved photoelectrode behavior in the polycrystalline silicon/methanol system will primarily result from changes in bulk electrode properties and from grain boundary passivation, and that Fermi level pinning by surface states does not prevent the design of efficient silicon-based liquid junctions

A 14% efficient nonaqueous semiconductor/liquid junction solar cell

We describe the most efficient semiconductor/liquid junction solar cell reported to date. Under W‐halogen (ELH) illumination, the device is a 14% efficient two‐electrode solar cell fabricated from an n‐type silicon photoanode in contact with a nonaqueous electrolyte solution. The cell′s central feature is an ultrathin electrolyte layer which simultaneously reduces losses which result from electrode polarization, electrolyte light absorption, and electrolyte resistance. The thin electrolyte layer also eliminates the need for forced convection of the redox couple and allows for precise control over the amount of water (and other electrolyte impurities) exposed to the semiconductor. After one month of continuous operation under ELH light at 100 mW/cm^2, which corresponds to the passage of over 70 000 C/cm^2, thin‐layer cells retained over 90% of their efficiency. In addition, when made with Wacker Silso cast polycrystalline Si, cells yield an efficiency of 9.8% under simulated AMl illumination. The thin‐layer cells employ no external compensation yet surpass their corresponding experimental (three‐electrode) predecessors in efficiency

More About Choosing a Hog System

The extent to which contract hog farming and specialized multiple farrowing hog systems are adopted in the state may depend very much on how they fit into the operations and plans of individual Iowa farm operators

Care farming and green care in Salford

This report presents a University of Salford (UoS) investigation into the potential for care farming in Salford as part of the University’s teaching, research and enterprise activities. The work has critically engaged with the notion of care farming with a view to better understand how this approach can contribute to helping communities with diverse needs in terms of physical and mental health as well as wider determinants of health such as social inclusion and employability. Through the establishment of, and engagement with a network of key local stakeholders, the work developed a model that has explored the potential of a care farm. What has emerged is a first step towards the design and establishment of an urban care farm that that could serve as a centre for learning and research as well as integrate existing activities as part of a green and blue network identified through the stakeholder engagement work. This report provides a direction for future work on care farming in Salford in general, and in terms of the University’s teaching and learning activities in particular

The effectiveness of Payments for Ecosystem Services at delivering improvements in water quality: lessons for experiments at the landscape scale

Background Randomised Control Trials (RCTs) are used in impact evaluation in a range of fields. However, despite calls for their greater use in environmental management, their use to evaluate landscape scale interventions remains rare. Payments for Ecosystem Services (PES) incentivise land users to manage land to provide environmental benefits. We present the first RCT evaluation of a PES program aiming to improve water quality. Watershared is a program which incentivises landowners to avoid deforestation and exclude cattle from riparian forests. Using this unusual landscape-scale experiment we explore the efficacy of Watershared at improving water quality, and draw lessons for future RCT evaluations of landscape-scale environmental management interventions. Methods One hundred and twenty-nine communities in the Bolivian Andes were randomly allocated to treatment (offered Watershared agreements) or control (not offered agreements) following baseline data collection (including Escherichia coli contamination in most communities) in 2010. We collected end-line data in 2015. Using our end-line data, we explored the extent to which variables associated with the intervention (e.g. cattle exclusion, absence of faeces) predict water quality locally. We then investigated the efficacy of the intervention at improving water quality at the landscape scale using the RCT. This analysis was done in two ways; for the subset of communities for which we have both baseline and end-line data from identical locations we used difference-in-differences (matching on baseline water quality), for all sites we compared control and treatment at end-line controlling for selected predictors of water quality. Results The presence of cattle faeces in water adversely affected water quality suggesting excluding cattle has a positive impact on water quality locally. However, both the matched difference-in-differences analysis and the comparison between treatment and control communities at end-line suggested Watershared was not effective at reducing E. coli contamination at the landscape scale. Uptake of Watershared agreements was very low and the most important land from a water quality perspective (land around water intakes) was seldom enrolled. Discussion Although excluding cattle may have a positive local impact on water quality, higher uptake and better targeting would be required to achieve a significant impact on the quality of water consumed in the communities. Although RCTs potentially have an important role to play in building the evidence base for approaches such as PES, they are far from straightforward to implement. In this case, the randomised trial was not central to concluding that Watershared had not produced a landscape scale impact. We suggest that this RCT provides valuable lessons for future use of randomised experiments to evaluate landscape-scale environmental management interventions

Born-Regulated Gravity in Four Dimensions

Previous work involving Born-regulated gravity theories in two dimensions is extended to four dimensions. The action we consider has two dimensionful parameters. Black hole solutions are studied for typical values of these parameters. For masses above a critical value determined in terms of these parameters, the event horizon persists. For masses below this critical value, the event horizon disappears, leaving a ``bare mass'', though of course no singularity.Comment: LaTeX, 15 pages, 2 figure