Summary 1. Many plant species germinate from herbivore dung. However, there has been little assessment of how widespread this dispersal mechanism is. 2. A survey of the germinable seed in rabbit and sheep dung from 10 sites in the UK was used to identify the characteristics of species dispersed internally by animals. 3. A wide range of species germinated; the commonest species being ‘weeds’ of grazed communities. 4. Species that did germinate were characterized by small seed size and the capability of forming a persistent seedbank. 5. A substantial quantity and range of seeds are dispersed by herbivores in grazed ecosystems, and this could have a significant effect on the dynamics and species richness of these systems.
As there is no agreed national list of species of socio-economic and/or cultural value for
Scotland, we developed a set of criteria for selecting species. These include:
• Species prioritised for conservation value
• Species identified as being culturally important
• Species providing important ecosystem services
• Game species
• Species collected for food or medicine
Using these criteria, we selected 26 species for initial assessment. For each species, we
produced a Genetic Scorecard, outlining:
• Relevant genetic conservation issues for the species in question
• The importance of its genetic diversity on an international scale
• An evaluation of the genetic risks facing in situ populations
• A statement of confidence in the assessment
• The degree to which representation in ex situ collections mitigate against genetic
diversity loss.
• An overall ‘traffic light’ score of genetic risks and whether current conservation actions
are effective
Using 2010 as a baseline reference point, the approach assesses contemporary genetic
issues, and likely future issues during a 25-year window from the point of assessment.
For quantification of levels of risk, we adopted the following framework:
• Negligible: No obviously detectable genetic problems occurring or expected over the
next 25 years.
• Moderate: Moderate genetic problems occurring or expected over the next 25 years;
e.g.:
- Moderate loss of populations that are likely to contain unique diversity (e.g.,
resulting in losses of up to 25% of important genetic types / distinct populations);
- Clearly observable fitness problems in up to 25% of populations due to low
genetic variation and subsequent inbreeding depression;
- Marked and clearly observable loss of genetic integrity by hybridisation at up to
25% of populations;
- Severe restrictions on regeneration/recruitment/reproduction in many or most
populations of long-lived species limiting evolutionary change in the immediate
future.
• Serious: Serious genetic problems occurring or expected over the next 25 years; e.g.:
- Severe loss of populations that are likely to contain unique diversity (e.g.,
resulting in losses of > 25% of important genetic types / distinct populations);
- Loss of any highly divergent endemic lineages that are globally unique;
- Strong, clearly observable fitness problems in >25% of populations due to low
genetic variation and subsequent inbreeding depression;
- Marked and clearly observable loss of genetic integrity by hybridisation at >25%
of populations.
The assessment is based on expert opinion, using direct genetic data, where available,
combined with information on species biology, abundance and distribution. Where no direct genetic data are available, the genetic risk assessment is based on species biology,
abundance and distribution.
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.
Abstract Question: Does the degree and timing of disturbance contribute significantly to the pattern and process of regeneration in plant communities as a consequence of the availability and number of species of propagules present? Location: Acid grassland at 230 m a.s.l., eastern Scotland, UK. Methods: Plots were surface disturbed or had their soil profile inverted at monthly intervals at 12 dates during a year. Seed bank and seed rain were assessed at each treatment time. The effect of disturbance intensity and timing on the regenerating vegetation was assessed. Results: Removing the seed bank significantly slowed regeneration, as it contributed 43 % of developing cover after one year where it was present. At an individual seed level, seed in the seed rain had a much higher likelihood of contributing to the regenerating vegetation than a seed in the seed bank. Some species showed a reliance on the seed bank for regeneration, and hence there was a significant difference in the vegetation that developed b...
Capsule Changing agricultural activity and soil chemistry appear to be associated with some changes in breeding wader assemblages on the machair of the Outer Hebrides, Scotland, between the 1980s and 2000s.
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