Understanding spatial variation in carbon storage in natural habitats is critical for climate change mitigation efforts such as REDD. Terrestrial forests are being mapped with increasing accuracy, but the distribution of "blue carbon" in marine ecosystems remains poorly understood. We reviewed the literature to obtain field data on carbon storage and fluxes in mangroves world-wide. Using this material we developed a climate-based model for potential mangrove above-ground biomass (AGB) with almost four times the explanatory power of the only previous published model. From this model, we present the first ever global map of potential mangrove AGB and estimate a total global mangrove AGB of 2.83 Pg, with an average of 184.8 t ha −1 . Data on other carbon stocks and fluxes confirm the importance of mangroves in carbon accounting. The map highlights the high variability in mangrove AGB and indicates areas that should be prioritised for mangrove conservation and restoration.

A key assumption underlying any management practice implemented to aid wildlife conservation is that it will have similar effects on target species across the range it is applied. However, this basic assumption is rarely tested. We show that predictors [nearly all associated with agri-environment scheme (AES) options known to affect European birds] had similar effects for 11 bird species on sites with differing farming practice (pastoral vs. mixed farming) or which differed in the density at which the species was found. However, predictors from sites in one geographical region tended to have different effects in other areas suggesting that AES options targeted at a regional scale are more likely to yield beneficial results for farmland birds than options applied uniformly in national schemes. Our study has broad implications for designing conservation strategies at an appropriate scale, which we discuss.

Summary 1.Yellowhammer Emberiza citrinella populations have declined rapidly in the UK over recent decades, and a clear understanding of their habitat requirements is important to help inform conservation schemes. We aimed to disentangle and rank the effects of winter versus breeding season habitat characteristics. 2. We used information theoretic methods to analyse the factors determining yellowhammer distribution across 26 sites in England and Wales. We did this at two spatial levels: individual field boundaries and individual territories, the latter consisting of spatial clusters of boundaries. 3. We considered the role of nine predictor variables, all of which have been suggested in the literature as potentially important. These comprised boundary height and width, and the presence of hedges, trees, ditches, boundary strips, tillage crops, winter set-aside and winter stubbles. 4. The results of the statistical modelling showed that winter habitats play an important role in determining where birds locate territories in summer. In particular, the presence of rotational set-aside fields in winter showed the strongest association with summer territories. 5. There were minor differences between the territory-and boundary-based models. Most notably, the territory data demonstrated a strong preference for territories containing trees, but this was not observed in the boundary data set. We suggest that the differences between the models may reflect different scales of habitat selection. Boundary occupancy reflects broad distributions of habitat suitability; territory occupancy patterns better reveal detailed habitat requirements. 6. Regional densities were more closely correlated with the predictions of the boundarybased model than those of the territory-based model, and we discuss the implications of this for interpreting habitat association models. 7. Synthesis and applications. Provision of winter set-aside fields for summer territory selection by yellowhammers is an important consideration for farm management where conservation is a priority. We show that models based on occupancy of individual boundary units (e.g. hedgerows) correlate with the density of territories at the farm scale; thus farm management practices link directly to population sizes through effects on the quality of breeding habitat.

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