Cost-effectiveness of silvicultural measures to increase substrate availability for red-listed wood-living organisms in Norway spruce forests

It is important that measures to maintain biodiversity are taken in a way that is cost-effective for the landowner. We analyzed the cost-effectiveness of silvicultural measures that aim at increasing the substrate availability for red-listed (species that are threatened, near threatened or where species probably are threatened but data is deficient) saproxylic (wood-inhabiting) organisms. We modelled stands of Norway spruce (Picea abies) in three regions of Sweden by using computer simulations and a database with substrate requirements of saproxylic beetles and cryptogams on the Swedish Red-List. Conclusions concerning cost-effectiveness of silvicultural measures depend on the extinction thresholds of the species they are intended to conserve; measures that generate only small amounts of coarse woody debris (CWD) may provide too little substrate to be useful for species with high extinction thresholds. In northern Sweden, forestland is relatively inexpensive, so a cost-effective strategy to increase the amount of spruce CWD was to set aside more forests as reserves. In central and southern Sweden, more emphasis should instead be given to increasing the amount of CWD in the managed forest. The regulations by the Forest Stewardship Council (FSC) could be made more cost-effective by prescribing creation of more high stumps and retention of larger amounts of naturally dying trees. Large-sized CWD, CWD from slow-growing trees, and CWD in late decay stages are substrate types that were particularly rare in managed forest in relation to unmanaged forests. Manual soil scarification and retention of living trees are measures that can increase the proportion of these underrepresented CWD types.     

Using farmland prices to evaluate cost-efficiency of national versus regional reserve selection in Denmark

The current study focuses on the influence of geopolitical coordination of conservation strategies on cost and efficiency in terms of species representation when selecting network of protected areas. Conservation policies in the EU are implemented at many different administrative levels: from the European Union and national levels, to regional or/county levels within member countries. This arise the question what size of efficiency gains could be achieved if planning of conservation priorities could be coordinated between geopolitical units. Using data for the nationwide distribution of 763 species, representing all Danish species within eight taxa, we compared illustrative costs for the addition of new areas to the existing conservation network in order to ensure full coverage of all species. We found that the cost of independent regional planning is 20-fold higher than an inter-regional and nationally co-ordinated strategy. We also found that substituting land prices for a simple land-area measure in our analyses increased the expected conservation costs differential significantly, without increasing coverage of species representations. We suggest that in economic and biodiversity terms it can largely be a win-win situation to set a common goal, to develop priority-strategies, and to coordinate actions at higher rather than lower levels of administration.     

Development and application of a model for robust, cost-effective investment in natural capital and ecosystem services

Identifying good investments in environmental management is complex as several prioritization strategies may be used and significant uncertainty often surrounds cost, benefits, and agency budgets. In this paper I developed a model for robust portfolio selection based on preference programming to support cost-effective environmental investment decisions under uncertainty and applied it to the South Australian Murray-Darling Basin. Benefits and costs of 46 investment alternatives (called targets) for managing natural capital and ecosystem services were quantified and the associated uncertainty estimated. Thirty-six investment portfolios were selected using mathematical programming under four investment prioritization strategies (cost-effectiveness (E-max), cost-effectiveness including a suite of pre-committed (or core) costs (E-max^∗), cost-only (C-rank), and benefit-only (B-rank)), three decision rules (pessimistic, most likely, and optimistic), and three budget scenarios (minimum, most likely, maximum). Compared to the optimally performing investment strategy E-max, the E-max^∗ and C-rank strategies only slightly reduced portfolio performance and altered portfolio composition. However, the B-rank strategy reduced performance by half and radically changed composition. Uncertainty in costs, benefits, and available budgets also strongly influenced portfolio performance and composition. I conclude that in this case study the consideration of uncertainty was at least as important as investment strategy in effective environmental decision-making. Targets whose selection was less sensitive to uncertainty were identified as more robust investments. The results have informed the allocation of AU$69 million in the study area and the techniques are readily adaptable to similar conservation and environmental investment decisions in other areas at a variety of scales.     

Integration of species persistence, costs and conflicts: An evaluation of tree conservation strategies in Cambodia

Cambodia forms part of the Indo-Burma hotspot. Its extent of biodiversity, however, is subject to considerable uncertainty, as there has been little systematic collection of flora and fauna. During the Khmer Rouge regime institutions were banned, academics were prosecuted and written documentation systematically destroyed. Compared with neighbouring countries Cambodia has a low population density and relatively large natural areas that are still intact. However, deforestation is expanding rapidly and a significant but un-estimated area of forest has been degraded by development of agro-industries, encroachment, illegal logging, over-harvesting and forest fire as well as the use of chemicals during war. The purpose of the paper is to: (i) apply reserve selection methods to design more robust conservation networks when knowledge of species occurrence is incomplete and habitat is threatened, and (ii) evaluate the usefulness of systematic conservation planning in a developing country where data are limited and institutions for implementation are weak. This study investigates the performance of four non-probabilistic strategies: (i) a so-called ‘rule of thumb’, (ii) hotspot, (iii) minimum cost representation, and (iv) maximum coverage; and one probabilistic design strategy, i.e. maximum expected coverage. The maximum expected coverage approach is between 15% and 24% more efficient than the non-probabilistic strategies. Finally, the relevance of such tools to real-world conservation planning in Cambodia is investigated. By incorporating experts in the generation of data, running the models and setting up premises, they acknowledge that it is possible to contribute to more systematic conservation planning in developing countries.     

Evaluating cost-effectiveness of conservation management actions in an agricultural landscape on a regional scale

Agricultural landscapes are the dominating landscape types in many parts of the world. Land-use intensification and spatial homogeneity are major threats to biodiversity in these landscapes. Thus cost-effective strategies for species conservation in large-scale agricultural landscapes are required. Spatial optimisation methods can be applied to identify the most effective allocation of a given budget for conservation. However, the optimisation of spatial land-use patterns in real landscapes on a large spatial scale is often limited by computational power. In this paper, we present a simplifying methodology for analysing cost-effectiveness of management actions on a regional scale. A spatially explicit optimisation approach is employed to identify optimum agricultural land-use patterns with respect to an ecological-economic goal function. Based on the optimisation results for small scale landscape samples we derive a target- and site-specific cost-benefit function that can be applied to predict ecological improvement as a function of costs and local conditions on a large spatial scale. Thus, it is possible to identify areas where management actions for ecological improvement are most efficient with respect to a certain conservation goal. The fitted function is validated independently. In a case study, we analyse cost-effectiveness of management actions to enhance habitat suitability for three different target species. The approach is flexible and could be applied to a variety of other landscape planning problems dealing with the effective allocation of management measures.     

Habitat suitability models of saproxylic red-listed boreal forest species in long-term matrix management: Cost-effective measures for multi-species conservation

Understanding of how a large landscape or network of conservation areas and habitats of red-listed species change in time is an important topic when addressing the temporal interplay between protected areas and matrix. We developed models of habitat suitability indices (HSI) for saproxylic red-listed invertebrate and fungal species, accounting for roughly 70% of all red-listed boreal forest species of the study area in eastern Finland. By using a forestry planning program that incorporates various optimisation methods we analysed trade-offs between timber production and amount of habitats of saproxylic red-listed species within a 60-year period. We also produced production possibility frontiers that show how to increase quality of the matrix with least costs. Moreover, we analysed how habitat suitability criteria used in optimisations affect the area of different habitat quality classes.

Our analysis shows that by adopting HSI models in long-term matrix management, it is possible to increase habitats for several red-listed species without substantial losses in timber production. The increase in habitat area is achieved mainly by decreasing the area that is thinned compared to intensive timber production plan. In the long term, this seems to be a novel cost-effective method to increase the quality of the matrix for red-listed saproxylic species. However, the selected optimisation method and the criteria or specification of the management objective for red-listed forest species have a strong effect on results when HSI models are used in conservation planning. Therefore any practical application must be performed with great care.     

Using occupancy models of forest breeding birds to prioritize conservation planning

As urban development continues to encroach on the natural and rural landscape, land-use planners struggle to identify high priority conservation areas for protection. Although knowing where urban-sensitive species may be occurring on the landscape would facilitate conservation planning, research efforts are often not sufficiently designed to make quality predictions at unknown locations. Recent advances in occupancy modeling allow for more precise estimates of occupancy by accounting for differences in detectability. We applied these techniques to produce robust estimates of habitat occupancy for a subset of forest breeding birds, a group that has been shown to be sensitive to urbanization, in a rapidly urbanizing yet biological diverse region of New York State. We found that detection probability ranged widely across species, from 0.05 to 0.8. Our models suggest that detection probability declined with increasing forest fragmentation. We also found that the probability of occupancy of forest breeding birds is negatively influenced by increasing perimeter-area ratio of forest fragments and urbanization in the surrounding habitat matrix. We capitalized on our random sampling design to produce spatially explicit models that predict high priority conservation areas across the entire region, where interior-species were most likely to occur. Finally, we use our predictive maps to demonstrate how a strict sampling design coupled with occupancy modeling can be a valuable tool for prioritizing biodiversity conservation in land-use planning.     

The value of forest strips for understorey birds in an Amazonian plantation landscape

Remnant forest strips are frequently proposed as valuable conservation tools in fragmented tropical landscapes, yet we currently lack evidence to evaluate their potential conservation value for native biota. We examined the potential value for understorey forest birds of 30-year-old riparian and terra firme (unflooded) primary forest strips within a large silvicultural landscape in the north-east Brazilian Amazon, where the matrix is dominated by Eucalyptus plantations. We conducted mist-netting in eight forest strips connected to continuous forest (four of each forest type), with a total of 24 replicate sampling sites located near to (<1 km), far from (2.5-9 km), and within undisturbed forest controls (i.e. 16 samples within the strips, and 8 in controls). Bird communities in both strip types changed with increasing distance along forest remnants into the plantation matrix. Matrix-embedded samples were characterised by a higher representation of birds typical of secondary growth forest but not those typical of the Eucalyptus-dominated matrix. While the long-term viability of the bird populations in these remnants remains unclear, our data demonstrate that forest strips can provide important habitat for many bird species that are otherwise rarely found outside primary forest. Forest strips therefore provide an important tool to enhance biodiversity conservation in plantation landscapes. The relative practical ease with which these areas can be selected and maintained means that the protection of forest strips as part of a wider conservation strategy is likely to have particular appeal to policy makers and landscape managers working in the human-dominated tropics.     

Conservation planning with dynamic threats: The role of spatial design and priority setting for species’ persistence

Conservation actions frequently need to be scheduled because both funding and implementation capacity are limited. Two approaches to scheduling are possible. Maximizing gain (MaxGain) which attempts to maximize representation with protected areas, or minimizing loss (MinLoss) which attempts to minimize total loss both inside and outside protected areas. Conservation planners also choose between setting priorities based solely on biodiversity pattern and considering surrogates for biodiversity processes such as connectivity. We address both biodiversity processes and habitat loss in a scheduling framework by comparing four different prioritization strategies defined by MaxGain and MinLoss applied to biodiversity patterns and processes to solve the dynamic area selection problem with variable area cost. We compared each strategy by estimating predicted species’ occurrences within a landscape after 20 years of incremental reservation and loss of habitat. By incorporating species-specific responses to fragmentation, we found that you could improve the performance of conservation strategies. MinLoss was the best approach for conserving both biodiversity pattern and process. However, due to the spatial autocorrelation of habitat loss, reserves selected with this approach tended to become more isolated through time; losing up to 40% of occurrences of edge-sensitive species. Additionally, because of the positive correlation between threats and land cost, reserve networks designed with this approach contained smaller and fewer reserves compared with networks designed with a MaxGain approach. We suggest a possible way to account for the negative effect of fragmentation by considering both local and neighbourhood vulnerability to habitat loss.     

Beyond parks as monoliths: Spatially differentiating park-people relationships in the Tadoba Andhari Tiger Reserve in India

Parks represent spatially and socially heterogeneous conservation units, yet are often assessed and managed using spatially homogeneous approaches. This paper represents an effort to focus on the larger social-ecological landscapes within which protected areas are embedded, to understand why conservation succeeds and fails in different parts of the landscape. In a wildlife sanctuary in the central plains of India (Tadoba Andhari Tiger Reserve), we address: (i) how people living within and immediately outside a park differentially impact its resources and (ii) how the park differentially impacts communities living within. Using forest plots, satellite imagery and interviews, we evaluate park conservation by assessing plant diversity, land cover change, forest fragmentation, and attitudes of local communities towards conservation. We find that interior villages have a negative impact on regeneration, but there is a decline in tree species diversity, and increased forest cover change and fragmentation at the park periphery. Interior villages suffer greatly from crop and livestock depredations by wildlife and consider park rules to be unfairly devised. Yet, they affirm the importance of the park for conservation, and are willing to work with park authorities for stricter protection. Park authorities largely focus on resettlement of interior villages, when they should also pay attention to protecting the peripheral areas of the park from severe degradation by surrounding villages. In summary, we find that different parts of the park landscape face different conservation challenges. Taking into account spatial variations in the factors influencing conservation can greatly benefit the management of protected areas.     

Gaps in the protected area network for threatened Afrotropical birds

Protected areas established for wildlife conservation (IUCN category I-VI protected areas) or for forest and watershed conservation (forest reserves) across mainland sub-Saharan Africa have high biodiversity values. However, they fail to cover over half of the 106 threatened bird species, and thus leave these vulnerable to extinction. An analysis of Red List bird species that are not represented in existing reserves indicates gaps in the current network of protected areas, namely: Mt. Cameroon-Bamenda highlands (Cameroon), the Angolan scarp (Angola), the Drakensberg Highlands (South Africa), the Highveld (South Africa), the Eastern Arc Mountains (Tanzania), the eastern African coastal forest mosaic (Kenya and Tanzania), the Albertine Rift (Uganda, Rwanda, Burundi, eastern Democratic Republic of Congo and western Tanzania), and the Ethiopian Highlands. The addition of Forest Reserves to the existing protected areas closes some of the reservation gaps for threatened birds in Africa. We suggest that these Forest Reserves should be included within official lists of protected areas, and that National forestry authorities be encouraged to manage these areas. Publication of scientific articles showing the conservation value of Forest Reserves is needed to raise local and international support and funding.     

Gap analysis of terrestrial vertebrates in Italy: Priorities for conservation planning in a human dominated landscape

In the last 40 years, Italy has seen important changes: human pressure is increasing in flat and coastal areas while internal mountainous areas are being abandoned and naturally reforested. These changes have substantial impacts on the biodiversity of the region but no conservation strategy has ever explicitly considered them, and no systematic assessment of the existing protected areas has been carried out. We used a combination of distribution models and extents of occurrence to perform a gap analysis and an irreplaceability analysis. We evaluated the effectiveness of the protected areas for the conservation of terrestrial vertebrates, and we identified regions, species, and strategies that appear to be priorities for expanding and consolidating the existing network. The existing protected areas cannot be considered fully representative, and this is especially true for Sardinia where many of the gap species are located. The Alps and the Apennines represent the strongholds of species diversity, but most of the species of conservation interest are concentrated in the Mediterranean part of the peninsula, as well as in small areas of the plains, where human pressure is higher. Biodiversity and human presence are functionally linked through traditional agriculture and pasture and the only option for conservation is that of considering human presence and activities as an integral part of the system. In a human dominated landscape, protected areas must be planned and managed in conjunction with the matrix in which they are embedded and in the context of the environmental history of the region.     

Effectiveness of protected areas in north-eastern New South Wales: recent trends in six measures

We applied six measures of effectiveness to recent decisions about additional conservation areas in north-eastern New South Wales. Three have been widely used previously: (1) number of conservation areas; (2) total extent of conservation areas; and (3) representativeness (the proportion of natural features such as forest types or animal species represented in conservation areas to some targeted level). The other measures were: (4) efficiency or representation bias (the extent to which some features are protected above target levels at the expense of others that remain poorly protected); (5) relative protection of vulnerable areas within public land (percentage protection of flat, fertile areas relative to that of steep and/or infertile areas); and (6) relative protection of vulnerable areas across all tenures (the correlation between the amount of protection given to features and their vulnerabilities to clearing). We applied the measures in two chronological comparisons: the reserve system in 1994, 1996 and 1997; and before and after the Interim Assessment Process of 1996 which involved negotiations over new reserves and extensive unreserved areas that were temporarily deferred from logging. Over the study period, despite expansion of formal conservation and progress towards quantitative conservation targets, gazetted reserves remained strongly biased to the steep and/or infertile parts of public lands. Both gazetted reserves and areas deferred from logging increased the bias in protection away from forest types most vulnerable to clearing and for which regional conservation targets had already been most compromised. Two major challenges for future conservation decisions in the region are common to conservation planning generally: (1) to focus protection within public tenure on habitats and species most vulnerable to threatening processes such as logging; and (2) to provide more effective conservation management on private lands where loss of native vegetation continues.     

Three-dimensional partitioning of diversity informs state-wide strategies for the conservation of saproxylic beetles

Global conventions on biological diversity force governments to develop region-wide conservation strategies. Such strategies are difficult to design for all taxa because little is known about the important spatial scales. Here we applied additive partitioning of the diversity of saproxylic beetles in Bavarian forests in Southern Germany using a nested hierarchical design of five increasingly broader spatial levels: trap, strata, forest stand, forest site, and ecoregion. We consistently found a significantly higher percentage than expected by chance of between ecoregion diversity and significantly lower α diversity within traps. A significant proportion of β diversity was also found between stands. Analysis of species represented by <0.005% of all specimens in our samples and of species classified as threatened revealed similar results. Critical spatial scales for threatened species encompassed the critical levels of common species. Within habitat substratum guilds, the proportion of β diversity increased from species associated with fresh wood to those associated with rotten wood to those associated with fungi. Our results suggest that the most effective way to ensure saproxylic beetle diversity in a state-wide strategy is to add new conservation sites within different ecoregions and to establish new conservation areas in additional forest stands, rather than to enlarge reserves. Our findings further suggest that monitoring of saproxylic beetle diversity on a broader scale in European temperate forests can be restricted to “monitoring species”, i.e. a subgroup of families easy to identify, and that canopy sampling can be neglected without a substantial loss of information.     

Pre-emptive conservation versus “fire-fighting”: A decision theoretic approach

How can conservation planners optimally and effectively allocate limited resources between imminently threatened and presently secure areas? Such choices must be made at multiple spatial scales involving a variety of conservation targets. Allocation strategies range from a “fire-fighting” approach, which gives priority to heavily developed areas at high risk of further habitat loss, to a “pre-emptive” approach giving priority to intact habitat tracts before they become threatened. We determined optimal dynamic reserve selection strategies when selections are made in imminently threatened and presently secure areas that will become threatened at uncertain times in the future. The objective was to maximize the expected number of endemic species conserved, predicted with species-area curves. The model was solved for three forms of species-area curve proposed in theoretical studies of habitat loss. Alternative scenarios were considered on the relationship between land prices and development risk. For the most commonly proposed form of the species-area relationship, the fire-fighting approach is optimal even if land prices rise substantially when presently secure areas become threatened. This reflects the assumption that species decline accelerates only after a large proportion of original habitat has been lost. The possibility of large species losses at lower levels of habitat loss justifies at least some pre-emptive conservation, even if land prices are not correlated with threat. If species decline is proportional with habitat loss, the optimal conservation strategy depends strongly on land price dynamics.     

Do community-conserved areas effectively conserve biological diversity? Global insights and the Indian context

The view that biodiversity-rich areas partially or largely managed by local residents, sometimes referred to as community-conserved areas (CCAs), can be effective in biological conservation has gained considerable ground over the past decade. In this paper, we review available scientific information on the conservation effectiveness of such areas globally. We compiled studies undertaken during the last 5 years (2004-2009) that use quantifiable ecological attributes to: (1) compare CCAs with strictly protected areas (SPAs); (2) compare CCAs with open-access ecosystems and (3) study trends in biological attributes of CCAs over time. We found that there were few consistent differences in diversity/species richness of flora or fauna protected under the two types of management or in deforestation rates. However, CCAs tend to harbour a species complement distinct from that of SPAs and show lowered abundances of monitored taxa that are of conservation importance. CCAs conserve biological values more effectively than open-access areas. Also, biological values tend to decline in CCAs over time. We conclude that CCAs could represent a significant improvement over open-access areas in terms of conservation effectiveness, yet fall short of the needs of comprehensive biological conservation. While extremely few studies have been undertaken in India, the trends seen largely concur with global ones. This review, based on a limited sample size, is only a beginning, and is expected to serve as an invitation for further research to address both the question of biological effectiveness of diverse forest governance regimes as well as the socio-economic, demographic and institutional reasons underlying these differences.     

The influence of fruit abundance on the use of forest and cultivated field habitats by the endemic Madeira laurel pigeon Columba trocaz: Implications for conservation

This study was conducted over a two year period in the north west of Madeira Island (Macaronesian Atlantic Islands, Portugal). It investigates the relationship between fruiting patterns in the indigenous forest and the use by the Madeira laurel pigeon of forest habitats and cultivated areas. Habitat use observations were carried out using line-transects in forest sites where the availability of fruit (the most important element of the diet) was assessed. The use of agricultural fields was measured indirectly by the assessment of the damage caused to crops. The findings provided strong evidence that bird movements and shifts in abundance are related to fruit usage and availability. The use of fruits is mostly opportunistic but when many species are available, selection was observed. From an ecological perspective, our findings indirectly confirm a high concordance between pigeon diet, studied by microhistological techniques, and habitat use. The use of crops also seems to be mostly opportunistic and is governed by the birds’ movements within the adjacent forest. It is hypothesised that fruit phenology will influence the use of agricultural areas only to the extent that it governs such movements; there is no strong evidence that crops are attacked only when the availability of natural foods is low. Our results suggest that the current management strategy for the forest is adequate for the conservation of this pigeon but that the conservation value of forest edges should be redefined. It is also proposed that crop damage may be reduced by identifying the proximate factors, which lead to the use of specific fields.     

Adapting global conservation strategies to climate change at the European scale: The otter as a flagship species

Climate change has created the need for new strategies in conservation planning that account for the dynamics of factors threatening endangered species.Here we assessed climate change threat to the European otter, a flagship species for freshwater ecosystems, considering how current conservation areas will perform in preserving the species in a climatically changed future. We used an ensemble forecasting approach considering six modelling techniques applied to eleven subsets of otter occurrences across Europe. We performed a pseudo-independent and an internal evaluation of predictions. Future projections of species distribution were made considering the A2 and B2 scenarios for 2080 across three climate models: CCCMA-CGCM2, CSIRO-MK2 and HCCPR HADCM3. The current and the predicted otter distributions were used to identify priority areas for the conservation of the species, and overlapped to existing network of protected areas.Our projections show that climate change may profoundly reshuffle the otter’s potential distribution in Europe, with important differences between the two scenarios we considered. Overall, the priority areas for conservation of the otter in Europe appear to be unevenly covered by the existing network of protected areas, with the current conservation efforts being insufficient in most cases. For a better conservation, the existing protected areas should be integrated within a more general conservation and management strategy incorporating climate change projections. Due to the important role that the otter plays for freshwater habitats, our study further highlights the potential sensitivity of freshwater habitats in Europe to climate change.     

Woody species diversity in temperate Andean forests: The need for new conservation strategies

Chile has more than half of the temperate forests in the southern hemisphere. These have been included among the most threatened eco-regions in the world, because of the high degree of endemism and presence of monotypic genera. In this study, we develop empirical models to investigate present and future spatial patterns of woody species richness in temperate forests in south-central Chile. Our aims are both to increase understanding of species richness patterns in such forests and to develop recommendations for forest conservation strategies. Our data were obtained at multiple spatial scales, including field sampling, climate, elevation and topography data, and land-cover and spectrally derived variables from satellite sensor imagery. Climatic and land-cover variables most effectively accounted for tree species richness variability, while only weak relationships were found between explanatory variables and shrub species richness. The best models were used to obtain prediction maps of tree species richness for 2050, using data from the Hadley Centre’s HadCM3 model. Current protected areas are located far from the areas of highest tree conservation value and our models suggest this trend will continue. We therefore suggest that current conservation strategies are insufficient, a trend likely to be repeated across many other areas. We propose the current network of protected areas should be increased, prioritizing sites of both current and future importance to increase the effectiveness of the national protected areas system. In this way, target sites for conservation can also be chosen to bring other benefits, such as improved water supply to populated areas.     

Replacement cost: A practical measure of site value for cost-effective reserve planning

Conservation needs are often in direct competition with other forms of land-use, and therefore protection of biodiversity must be cost-efficient. While common reserve selection algorithms address this problem, quantitative planning tools often suggest an optimal set of sites that is not necessarily convenient for practical conservation. Besides cost-effective solutions we require flexibility if land-use conflicts are to be effectively resolved. We introduce a novel concept for site value in quantitative reserve planning. Replacement cost refers to the loss in solution value given that the optimal cost-efficient solution cannot be protected and alternative solutions, with particular sites forcibly included or excluded, are needed. This cost can be defined either in terms of loss of biological value or in terms of extra economic cost, and it has clear mathematical definitions in the context of benefit-function-based reserve planning. A main difference with the much-used concept of irreplaceability is that the latter tells about the likelihood of needing a site for achieving a particular conservation target. Instead, replacement cost tells us at what cost (biological or economic) can we exclude (or include) a site from the reserve network. Here, we illustrate the concept with hypothetical examples and show that replacement-cost analysis should prove useful in an interactive planning process, improving our understanding of the importance of a site for cost-efficient conservation.