The Importance of Conserving Biodiversity Outside of Protected Areas in Mediterranean Ecosystems

Mediterranean-type ecosystems constitute one of the rarest terrestrial biomes and yet they are extraordinarily biodiverse. Home to over 250 million people, the five regions where these ecosystems are found have climate and coastal conditions that make them highly desirable human habitats. The current conservation landscape does not reflect the mediterranean biome's rarity and its importance for plant endemism. Habitat conversion will clearly outpace expansion of formal protected-area networks, and conservationists must augment this traditional strategy with new approaches to sustain the mediterranean biota. Using regional scale datasets, we determine the area of land in each of the five regions that is protected, converted (e.g., to urban or industrial), impacted (e.g., intensive, cultivated agriculture), or lands that we consider to have conservation potential. The latter are natural and semi-natural lands that are unprotected (e.g., private range lands) but sustain numerous native species and associated habitats. Chile has the greatest proportion of its land (75%) in this category and California-Mexico the least (48%). To illustrate the potential for achieving mediterranean biodiversity conservation on these lands, we use species-area curves generated from ecoregion scale data on native plant species richness and vertebrate species richness. For example, if biodiversity could be sustained on even 25% of existing unprotected, natural and semi-natural lands, we estimate that the habitat of more than 6,000 species could be represented. This analysis suggests that if unprotected natural and semi-natural lands are managed in a manner that allows for persistence of native species, we can realize significant additional biodiversity gains. Lasting biodiversity protection at the scale needed requires unprecedented collaboration among stakeholders to promote conservation both inside and outside of traditional protected areas, including on lands where people live and work

The Effect of Carbon Credits on Savanna Land Management and Priorities for Biodiversity Conservation

Carbon finance offers the potential to change land management and conservation planning priorities. We develop a novel approach to planning for improved land management to conserve biodiversity while utilizing potential revenue from carbon biosequestration. We apply our approach in northern Australia's tropical savanna, a region of global significance for biodiversity and carbon storage, both of which are threatened by current fire and grazing regimes. Our approach aims to identify priority locations for protecting species and vegetation communities by retaining existing vegetation and managing fire and grazing regimes at a minimum cost. We explore the impact of accounting for potential carbon revenue (using a carbon price of US$14 per tonne of carbon dioxide equivalent) on priority areas for conservation and the impact of explicitly protecting carbon stocks in addition to biodiversity. Our results show that improved management can potentially raise approximately US$5 per hectare per year in carbon revenue and prevent the release of 1–2 billion tonnes of carbon dioxide equivalent over approximately 90 years. This revenue could be used to reduce the costs of improved land management by three quarters or double the number of biodiversity targets achieved and meet carbon storage targets for the same cost. These results are based on generalised cost and carbon data; more comprehensive applications will rely on fine scale, site-specific data and a supportive policy environment. Our research illustrates that the duel objective of conserving biodiversity and reducing the release of greenhouse gases offers important opportunities for cost-effective land management investments

Fire frequency regulates tussock grass composition, structure and resilience in endangered temperate woodlands

The importance of disturbance for regulating the structure and diversity of grassy ecosystems is widely recognized, but disturbance-mediated interactions between grassland composition and grassland resilience, and consequent implications for conservation management, are less well documented. We established replicated burning, mowing and (non-livestock) grazing regimes in two contrasting grassy woodland remnants in south-eastern Australia, and monitored the dynamics and resilience of the matrix-forming tussock grasses, Poa sieberiana (Poa) and Themeda australis (Themeda), over 12 years. Introduction of frequent burning to a Poa-dominated understorey in a rarely burnt woodland enhanced dominance by Themeda, and conversely, reduced fire frequency in a frequently burnt Themeda grassland substantially increased Poa abundance. Burning was potentially detrimental in the Poa-dominated woodland, but sward resilience (recovery after the 2002 burn) increased as Themeda increased with repeated burning. By contrast, the Themeda grassland was resilient to 4- and 8-yearly burning, but biennial burning led to poor resilience and high tussock mortality under drought conditions. Contrary to other mesic grasslands, cessation of burning had not caused sward collapse by 14 years post-fire despite high litter accumulation, potentially due to compensatory growth of Poa, lower site productivity and drought. Biennial mowing without slash removal was similar to 4-yearly burning in effects, while exclusion from kangaroo and rabbit grazing significantly increased sward biomass and contributed to increased Poa cover and inflorescence production. We conclude that functional complementarity associated with mixed dominants enhances resilience to variable disturbance regimes, and that below certain thresholds of abundance of each dominant, this resilience declines. Conservation management of Themeda-Poa ecosystems should thus aim to maintain an effective balance of these dominants