Invest in Opportunity, Not Inventory of Hotspots

Regions with large numbers of endemic species that are extensively threatened by human activities have been termed hotspots (Myers et al. 2000), and these have been prioritized for conservation interventions by many organizations. Most hotspots are found in low-latitude nations that lack a history of, and capacity for, comprehensive species inventory. Conservation scientists have responded to this situation by pleading for developed nations to invest in long-term, comprehensive species inventories to more effectively identify priorities for conservation action (Raven & Wilson 1992; Prance & Campbell 1998; Balmford & Gaston 1999; Brooks et al. 2004). Others are skeptical of the value for conservation of comprehensive species inventory in hotspots (e.g., Janzen 1997; Whitten et al. 2001; New 2006). Inventory is time consuming and expensive (Ramos et al. 2001; Gardner et al. 2008), unlikely to be achieved comprehensively for all but the most conspicuous species groups (Tobler et al. 2007; Cáceres et al. 2008), and may not even be necessary for effective prioritization (Grantham et al. 2008). Moreover, time to conserve areas is dwindling as rates of habitat destruction in hotpots continue to escalate (Bradshaw et al. 2009; Underwood et al. 2009), further imperiling the persistence of hundreds of thousands of range-restricted species (Pimm & Raven 2000), most of which have yet to be collected and described (Prance & Campbell 1998). In the face of rapid habitat loss, it may be prudent to devote limited resources to conservation action rather than invest in more comprehensive species inventory and subsequent ongoing spatial prioritization, as has been demonstrated in several recent studies (Meir et al. 2004; Grantham et al. 2008, 2009). Here we present a case from South Africa's Cape Floristic Region (CFR) hotspot that illustrates the futility of species inventory as a means of generating data for identifying conservation priorities. Our case study is Grootbos, a 1750-ha property located along the Atlantic Ocean coast of South Africa about 150 km southeast of Cape Town (34° 32′ 50″ S, 19° 24′ 50″ E). It forms the western margin of the Agulhas Plain, an area with an extraordinarily high diversity of endemic plants and several unique terrestrial and aquatic habitats, all of which are threatened by habitat loss through alien plant invasions, clearing for agriculture, and coastal resort development (Heydenrych et al. 1999). Three systematic conservation plans have been completed for the region: two for the Agulhas Plain designed to achieve targets for habitats and occurrences of endemic plant species (Lombard et al. 1997; Cole et al. 2000) and one for the entire CFR (Cowling et al. 2003) designed to achieve targets for a variety of features, including a charismatic plant taxon (Proteaceae), regarded as the most comprehensive species databases for any taxon in any hotspot (Grantham et al. 2008). All three plans identified Grootbos as an area of low conservation value (or irreplaceability) because it lacked endemic species and unique habitats and had an impoverished and unremarkable Proteaceae flora and because targets for ecological and evolutionary processes could be better achieved in areas that harbored unique or underrepresented pattern features. Grootbos was purchased in 1991 by a creative and entrepreneurial family who had the vision, and the social and financial capital, to turn it into one of South Africa's leading private nature reserves and ecotourism facilities (http://www.grootbos.com). Substantial investment in ecologically and socially sustainable management of the property has been made (Privett et al. 2002, http://www.grootbosfoundation.org). Shortly after establishment of the Grootbos Private Nature Reserve, management invested in research facilities and capacity building. The first task—undertaken by one of us (S.D.J.P.)—was to systematically survey the plant communities (Mergili & Privett 2008) and generate a comprehensive list of plant species for the reserve (S.D.J.P. & H. Lutzeyer, unpublished). The initial list was compiled over a 3-month period in the austral winter of 1997 and was derived from a survey of 48, 5 × 10 m plots sampled for vegetation description (Mergili & Privett 2008). Surveys were supplemented with targeted searches for species not recorded in the plots. This plot-based survey, which was comprehensive by any scientific standard (Tchouto et al. 2006; Cáceres et al. 2008), yielded 250 species—31 of which are listed in the South African Red Data Book (i.e., are vulnerable to extinction, albeit to varying degrees) (Fig. 1). We used a standard technique (Colwell & Coddington 1994) to estimate the total species tally for Grootbos via simulation of the plot data. The four estimators (Chao1, Chao2, jackknife 1, and jackknife 2) yielded tallies of 332, 349, 330, and 377 species, respectively. Plant species accumulation curves for Grootbos Private Nature Reserve. The upper curve represents an inventory undertaken between 1997 and January 2009 and includes a plant community survey in which 48, 5 × 10 m plots were sampled (indicated by the steep accumulation at that time). The lower curves are four predictions of the total species tally derived from simulations of the plot data in Estimate S (Colwell & Coddington 1994). Heiner Lutzeyer, a member of the founding family and a keen amateur botanist, continued collecting plants on Grootbos every year since the initial systematic survey in 1997. By January 2009 the tally of positively identified, herbarium-catalogued species had risen to 753 species, representing between 2.0 and 2.3 times the number of species estimated from the simulated plot data (Fig. 1). Moreover, 67 of these additional species are listed in the South African Red Data Book and five are new to science (S.D.J.P. & H. Lutzeyer, unpublished). There is nothing about the biophysical conditions at Grootbos that would have made us anticipate these astonishing results. In addition, the increasingly comprehensive plant inventory of habitat fragments on the CFR's west coastal lowlands has greatly increased the tally of red-data-book species and revealed that areas assumed to be floristically homogeneous for conservation planning purposes are, in fact, highly heterogeneous (Newton & Knight 2009). Consequently, we think it reasonable to expect that similar investment in inventory, as has occurred for Grootbos, in most other parts of the CFR would yield similar outcomes. Furthermore, the comprehensive inventory of plants and invertebrates in sites in most, if not all, of the other hotspots is likely to yield much higher species tallies than those derived from documented occurrences, for example, invertebrates on the Iberian Peninsula (Ramos et al. 2001), plants in Neotropical (Tobler et al. 2007) and African rainforests (Tchouto et al. 2006), lichens in Atlantic rainforests of Brazil (Cáceres et al. 2008), and plants in southwestern Australian Mediterranean scrub (Hopper 2009). So, what can be learned from the surprising results of the comprehensive plant inventory at Grootbos? First, although the CFR is renowned for the comprehensiveness of its spatial plant databases (Cowling & Heijnis 2001), these are likely to fail in identifying many local hotspots as conservation priorities. Grootbos, with its five new species and 106 red-data-book taxa, was overlooked in three spatial prioritizations. Second, as stated above, it is highly unlikely that Grootbos is unique: comprehensive inventory elsewhere in the CFR will certainly yield many new species occurrences, including species new to science. Third, inventory as comprehensive as that undertaken at Grootbos would be impossible to replicate throughout the CFR. The stark reality is that there is a huge uncertainty regarding species occurrences, meaning that interventions almost anywhere in hotspots will certainly yield unique gains for conservation. Or, to put it differently, habitat loss anywhere in a hotspot is likely to result in global extinctions of relatively cryptic groups, such as plants and invertebrates. Consequently, we suggest that conservation strategies in the CFR and other hotspots—especially in landscapes of high vulnerability—deploy limited conservation resources to areas displaying high opportunity by identifying and mapping localities where human and social capital are sufficient to kick-start actions (Knight & Cowling 2007; Polasky 2008). Restricting implementation to the strictly biological priorities identified by spatial prioritizations is likely to delay action because opportunity (e.g., willingness of landowners to participate in stewardship) and priority status may not often coincide (Gallo et al. 2009; von Hase 2009). Furthermore, investing in further inventory to improve the effectiveness of spatial prioritizations in hotspots is unwise, given the huge amount of money and effort required to achieve anything that vaguely approximates comprehensiveness, the escalating rate of habitat destruction, and the diminishing returns on the data gathered (e.g., Grantham et al. 2009). We thank H. Lutzeyer for his extraordinary effort in compiling the plant inventory at Grootbos. K. McKinnon and K. Redford provided comments that greatly improved this article. We would like to acknowledge the huge role that Grootbos Private Nature Reserve has played in catalyzing other conservation initiatives on the Agulhas Plain.