Effects of long-term removal of sheep grazing on the seedbanks of high-level grasslands and blanket bogs

Many areas of vegetation in the British uplands have reduced species diversity as a result of sheep overgrazing. It has been suggested that abandonment or re-wilding strategies might be used to reverse this. A likely first step would be the removal or reduction of grazing livestock from upland areas, with a presumption that this would lead to a recovery in species richness. However, we do not know if this would work, or the timescales involved. One of the important areas where more knowledge is needed is information on the size and composition of soil seedbanks as regeneration from zseed is a likely pathway of recovery. Here, we compared seedbanks in both grazed and ungrazed plots in five experiments at Moor House NNR in the northern Pennines; these sheep grazing exclusion experiments were started 52 and 63/64 years ago. Soil samples (n=10) were collected from both grazed and ungrazed plots in each experiment, and seed emergence counted in glasshouse trials. We detected only seeds of common species and very few dicotyledonous species. This suggests that the soil seedbank is unlikely to be a reliable source of the less common species for ecological restoration in these upland communities, suggesting an extinction debt. Therefore, seed addition and the creation of suitable safe-sites for germination may be needed in conjunction with grazing controls to allow the establishment of plants that will increase the species richness of the vegetation. However, this interventionist restoration approach remains to be tested

A simplified (modified) Duke Activity Status Index (M-DASI) to characterise functional capacity: A secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) study

Background Accurate assessment of functional capacity, a predictor of postoperative morbidity and mortality, is essential to improving surgical planning and outcomes. We assessed if all 12 items of the Duke Activity Status Index (DASI) were equally important in reflecting exercise capacity. Methods In this secondary cross-sectional analysis of the international, multicentre Measurement of Exercise Tolerance before Surgery (METS) study, we assessed cardiopulmonary exercise testing and DASI data from 1455 participants. Multivariable regression analyses were used to revise the DASI model in predicting an anaerobic threshold (AT) >11 ml kg −1 min −1 and peak oxygen consumption (VO 2 peak) >16 ml kg −1 min −1, cut-points that represent a reduced risk of postoperative complications. Results Five questions were identified to have dominance in predicting AT>11 ml kg −1 min −1 and VO 2 peak>16 ml.kg −1min −1. These items were included in the M-DASI-5Q and retained utility in predicting AT>11 ml.kg −1.min −1 (area under the receiver-operating-characteristic [AUROC]-AT: M-DASI-5Q=0.67 vs original 12-question DASI=0.66) and VO 2 peak (AUROC-VO2 peak: M-DASI-5Q 0.73 vs original 12-question DASI 0.71). Conversely, in a sensitivity analysis we removed one potentially sensitive question related to the ability to have sexual relations, and the ability of the remaining four questions (M-DASI-4Q) to predict an adequate functional threshold remained no worse than the original 12-question DASI model. Adding a dynamic component to the M-DASI-4Q by assessing the chronotropic response to exercise improved its ability to discriminate between those with VO 2 peak>16 ml.kg −1.min −1 and VO 2 peak<16 ml.kg −1.min −1. Conclusions The M-DASI provides a simple screening tool for further preoperative evaluation, including with cardiopulmonary exercise testing, to guide perioperative management

How long do bracken (Pteridium aquilinum (L.) Kuhn) control treatments maintain effectiveness?

Pteridium aquilinum is a problematic, perennial, invasive species worldwide that poses serious problems in the British uplands. However, there is a lack of knowledge on long-term success in terms of weed control and land improvement. We assessed the effects of six P. aquilinum-control treatments at two acid-grassland sites in the Scottish Borders (Sourhope 1 & 2). There were six treatments: (i) untreated, (ii) cutting once-yearly, (iii) cutting twice-yearly, (iv) asulam sprayed in year 1, (v) cutting once in year 1/asulam in year 2, and (vi) asulam in year 1/cut in year 2. The annual cutting treatments were stopped after 9/10 years. We measured the response of three variables over 25/26-years assessing P. aquilinum-performance, agricultural-improvement and species richness. We estimated the treatment “effect window”, defined as the period over which the P. aquilinum-control treatments had a significant effect relative to untreated experimental-controls. Results were completely different for all variables in the two experiments. At Sourhope 1 the cutting treatments had much longer “effect windows” than the herbicide-based treatments in reducing P. aquilinum performance, especially the cut twice-yearly treatment with a 25-year window. At Sourhope 2, the treatment differences were much reduced with the best treatment (cut twice yearly) producing a 13-year window. At both experiments, asulam-based treatments produce a minimum “effect window” of 10 years. Increases in both the agricultural-improvement index and species richness were also obtained at both sites. “Effect windows” for both agricultural-improvement index (TVI) and species richness also showed some improvement; “effect windows” were obtained of 12–20 and 9–20 years for TVI, and 7–17 and 2–10 years for species richness at Sourhope 1 and Sourhope 2 respectively. Species richness declined though time in both experiments. Cutting, and preferably twice per year, was the most effective treatment but also the costliest, with the most cost-effective approach being a single asulam spray. However, the length of the “effect windows” suggest that repeat-spraying every 10-years is needed. Unfortunately, where the aim is to recover biodiversity interventionist techniques such as seeding will also be needed. The use of “effect windows” for estimating long-term impact of perennial weed control is novel and may be of use in other situations.We thank DEFRA (Project BD1226) and the Basque-Country Government (J.G.A BFI-2010-235) for financially supporting the original experimental work and early analyses; the Heather Trust and the Leverhulme Trust (EM-2018-073/2) funded the field data collection in 2013 and 2019 respectively. J.G.A. was supported by Ramon y Cajal fellowship (RYC-2016-20528) and I.A. was supported by a scholarship from the Ministry of National Education of the Turkish Republic. The James Hutton Institute and R.W. and S.D. Flintoff allowed the experiments to be sited and maintained on the Sourhope Estate