Ecological time lags and the journey towards conservation success.

Global conservation targets to reverse biodiversity declines and halt species extinctions are not being met despite decades of conservation action. However, a lack of measurable change in biodiversity indicators towards these targets is not necessarily a sign that conservation has failed; instead, temporal lags in species' responses to conservation action could be masking our ability to observe progress towards conservation success. Here we present our perspective on the influence of ecological time lags on the assessment of conservation success and review the principles of time lags and their ecological drivers. We illustrate how a number of conceptual species may respond to change in a theoretical landscape and evaluate how these responses might influence our interpretation of conservation success. We then investigate a time lag in a real biodiversity indicator using empirical data and explore alternative approaches to understand the mechanisms that drive time lags. Our proposal for setting and evaluating conservation targets is to use milestones, or interim targets linked to specific ecological mechanisms at key points in time, to assess whether conservation actions are likely to be working. Accounting for ecological time lags in biodiversity targets and indicators will greatly improve the way that we evaluate conservation successes.

Measuring the success of climate change adaptation and mitigation in terrestrial ecosystems.

Natural and seminatural ecosystems must be at the forefront of efforts to mitigate and adapt to climate change. In the urgency of current circumstances, ecosystem restoration represents a range of available, efficient, and effective solutions to cut net greenhouse gas emissions and adapt to climate change. Although mitigation success can be measured by monitoring changing fluxes of greenhouse gases, adaptation is more complicated to measure, and reductions in a wide range of risks for biodiversity and people must be evaluated. Progress has been made in the monitoring and evaluation of adaptation and mitigation measures, but more emphasis on testing the effectiveness of proposed strategies is necessary. It is essential to take an integrated view of mitigation, adaptation, biodiversity, and the needs of people, to realize potential synergies and avoid conflict between different objectives.

Large extents of intensive land use limit community reorganization during climate warming.

Climate change is increasingly altering the composition of ecological communities, in combination with other environmental pressures such as high-intensity land use. Pressures are expected to interact in their effects, but the extent to which intensive human land use constrains community responses to climate change is currently unclear. A generic indicator of climate change impact, the community temperature index (CTI), has previously been used to suggest that both bird and butterflies are successfully 'tracking' climate change. Here, we assessed community changes at over 600 English bird or butterfly monitoring sites over three decades and tested how the surrounding land has influenced these changes. We partitioned community changes into warm- and cold-associated assemblages and found that English bird communities have not reorganized successfully in response to climate change. CTI increases for birds are primarily attributable to the loss of cold-associated species, whilst for butterflies, warm-associated species have tended to increase. Importantly, the area of intensively managed land use around monitoring sites appears to influence these community changes, with large extents of intensively managed land limiting 'adaptive' community reorganization in response to climate change. Specifically, high-intensity land use appears to exacerbate declines in cold-adapted bird and butterfly species, and prevent increases in warm-associated birds. This has broad implications for managing landscapes to promote climate change adaptation.

Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years.

Cereal fields are central to balancing food production and environmental health in the face of climate change. Within them, invertebrates provide key ecosystem services. Using 42 years of monitoring data collected in southern England, we investigated the sensitivity and resilience of invertebrates in cereal fields to extreme weather events and examined the effect of long-term changes in temperature, rainfall and pesticide use on invertebrate abundance. Of the 26 invertebrate groups examined, eleven proved sensitive to extreme weather events. Average abundance increased in hot/dry years and decreased in cold/wet years for Araneae, Cicadellidae, adult Heteroptera, Thysanoptera, Braconidae, Enicmus and Lathridiidae. The average abundance of Delphacidae, Cryptophagidae and Mycetophilidae increased in both hot/dry and cold/wet years relative to other years. The abundance of all 10 groups usually returned to their long-term trend within a year after the extreme event. For five of them, sensitivity to cold/wet events was lowest (translating into higher abundances) at locations with a westerly aspect. Some long-term trends in invertebrate abundance correlated with temperature and rainfall, indicating that climate change may affect them. However, pesticide use was more important in explaining the trends, suggesting that reduced pesticide use would mitigate the effects of climate change.