To address biodiversity declines within semi‐natural habitats, land management must cater for diverse taxonomic groups. Through one of the largest multi-taxa experiments yet attempted in a European grassland, Hawkes and colleagues show that interventions inspired by history and autecological knowledge enhance priority biodiversity.
Conservationists have traditionally focused on the idea that ‘mimicking’ elements of history will support large numbers of species that benefit from human activity e.g. conservation grazing – where land managers reintroduce livestock to semi-natural habitats with the primary aim of reducing vegetation.
Crucially, the idea of so-called ‘traditional’ management tends to be overly simplified, favoring a limited number of charismatic and popular species (e.g. birds). Instead, knowledge of land use history inspires radical ‘complex’ interventions that encourage physical disturbance, grazing, nutrient removal, and that these things should vary in space and time to create open and structurally complex habitats. Many ‘off-radar’ species, such as those below, thrive off these conditions.
More recently, interventionist approaches have been challenged by the idea of ‘rewilding’, with some supporters advocating that restoring natural processes will deliver better conservation outcomes.
Although the intervention versus rewilding debate can be regarded complementary philosophies to the same problem, this still leaves conservationists with an unanswered dilemma – what is the right approach for rare, scarce and threatened species within my system?
The biodiversity audit approach
The biodiversity audit approach— where biodiversity records are collated and priority species with shared ecological requirements are grouped into ‘management guilds’ —provides an objective way of informing and optimising management interventions within specific regions for all biodiversity, not just a handful of flagships (read more here).
Given this approach uses existing biological data and expert knowledge alone, biodiversity audits are considerably cheaper and quicker than detailed land management experiments. Nevertheless, experimental confirmation, involving multiple taxonomic groups, is needed to validate this approach before it can be advocated more widely.
Validating the audit approach through a landscape scale experiment
In our study, we implemented one of the largest land management experiments in Europe. We focused on internationally important grasslands of Breckland in Eastern England, where biodiversity auditing encourages radical management incorporating ground disturbance that varies in space and time, and developed forty 4-ha management complexes over three successive winters.
Our complex treatments used widely available farm machinery to create physical ground disturbance through ploughing and rotivating and implemented these across 3,850 ha of closed grassland and heathland. To create the variability in space and time, each complex took three years to build up and comprised four 1-ha sub-treatments that varied in fallow age and disturbance frequency.
To test biodiversity outcomes, we sampled 132,251 invertebrates from 877 species and 28,846 plant observations from 167 species. Sampling occurred on the treatment complexes and twenty-one 4-ha untreated controls that were exposed to the current grassland management, which was extensive grazing by sheep.
It took 18 months and seven taxonomic experts to identify these specimens or records to species level, emphasizing the considerable time and financial requirements of these types of experiments.
- Complex treatments doubled the species richness of rare, scarce and threatened (priority) plants and invertebrates compared to the lightly grazed controls, irrespective of the whether the plots were created through ploughing or rotivating
- Although one sub-treatment within the plot complexes was particularly effective for priority species, different sub-treatments supported different assemblages – this suggests that the full complement of sub-treatments is needed to support the widest suite of species.
- The effectiveness of the treatment was consistent across different gradients of semi-natural grassland that vary in plant composition, challenging a long-held belief that subtle variations in vegetation classifications should predicate management decisions.
- Perhaps most important, the species the biodiversity auditing predicted to benefit most from the management (i.e. species with a requirement for heavy physical disturbance) responded particularly well to the treatments.
Synthesis and applications
Our experiment confirmed the considerable biodiversity value of interventions informed by biodiversity auditing.
Such audits have already occurred in contrasting landscapes in Eastern England and are having a dramatic effect on regional conservation – from the interventions we advocate in semi-natural habitats, to the underpinning of England’s largest farmer-led wildlife network (The Breckland Framers Wildlife Network)
However, to inform a radical rethink of biodiversity conservation in cultural landscapes on a grand scale there is a pressing need to extend the audit approach. Until this happens, I encourage the readers of this blog to consider the ecological requirements of the key conservation priorities within their systems, including the ‘off-radar’ species. This information can be used to inspire management solutions (potentially radical!) that cater for their needs.
Your thinking need not be constrained to semi-natural habitats alone – as the Breckland Farms Wildlife Network has shown – such solutions can be applied across systems.
Read the Open Access article Experimental evidence that novel land management interventions inspired by history enhance biodiversity in Journal of Applied Ecology.