Biodiversity Hotspots: We're not mad, we're disappointed
"Biodiversity Hotspots" were first introduced to the world of conservation in 1988 by British environmentalist, Norman Myers. Biodiversity hotspots are geographic areas which contain a minimum of 1,500 endemic plant species and retain 30% or less of their primary vegetation (Myers et al. 2000). BDHs are beneficial in that they offer a more economically feasible prioritization scheme for protecting a large percent of Earth's biodiversity by condensing efforts to a small total area. BDHs are criticized for the limited nature of their data and criterion as well as their lack of ability to mitigate future impacts. Critics of the hotspot concept often emphasize "biodiversity coldspots." Coldspots are geographic areas which have been "left out in the cold" by strongholds of the hotspot effort, yet are still vital in maintaining healthy global ecological processes (Kareiva & Marvier 2003). The purpose of this paper is to examine why conservation efforts should not be primarily focused on identifying and protecting biodiversity hotspots.
Why conserve hotspots?
The magnitude of the current biodiversity crisis is overwhelming. Most conservationists, by nature, would like to save as many species as possible. This desire often leads to the diffusion of effort and resources across the globe despite a lack of funding and government attention. The hotspot strategy prioritizes conservation efforts to 36 hotspots which cover only 2.4% of Earth's land, but contain around half of endemic plants and 42% of terrestrial vertebrate endemics (Hrdina & Romportl 2017). Prior to extreme land-use change, these hotspots covered 16.7% of the land surface; this is an 85.5% reduction from their original size (Hrdina & Romportl 2017). This extreme loss of vegetation has concentrated about half of Earth's biodiversity to less than 3% of its surface, so the hotspot strategy focuses on this collective area as its top priority for conservation efforts. The prioritization scheme of the hotspot strategy has helped to alleviate some of the perplexity of where to begin in tackling the biodiversity crisis.
Prioritization of conservation efforts on protecting global biodiversity hotspots has been praised as both economically feasible and philanthropically enticing. Condensing conservation funding into 2.4% of the planet's land surface has allowed funds to be concentrated into areas in dire need of protection. Areas must meet strict standards to qualify as biodiversity hotspots to ensure that results are maximized through the scrupulous allotment of resources. The BDH strategy has brought in over $1 billion for conservation efforts (Marchese 2015). Protecting 25 hotspots would take $20 million per hotspot per year; totaling $500 million per year (Myers et al. 2000). Protecting all threatened species on Earth would cost about $4 billion per year, and conserving the areas containing species' habitats could cost more than $76 billion per year (Cressey 2012). Comparatively speaking, funneling conservation funding into BDHs is more economically feasible than diluting funds to save all species across the globe.
How are hotspots insufficient?
The data and criterion used to determine if an area meets BDH standard are quite limited and exclusive. Plants were chosen as the "focal taxa" because their available data are more complete, and species distribution is more easily measured (Kareiva & Marvier 2003; Stork & Habel 2014). While this approach is understandable, it is indeed one-dimensional as plants constitute only 6-8% of Earth's biodiversity (Stork & Habel 2014). It is uncertain if this strategy can protect all varieties of life despite its inherent bias for plants and vertebrates. Insects constitute a majority of Earth's biodiversity, but have been largely ignored by the hotspot strategy. Much is still unknown to science about invertebrates and fungi which explains their absence in may analyses. Further studies must be conducted in order to examine the relationships between insects, fungi, and their host plants (Stork & Habel 2014). Nonetheless, invertebrates and fungi are essential components in healthy ecosystems and thus must be given significantly more consideration by hotspot strategy.
Biodiversity hotspots are also criticized for their potential inability to mitigate land-use change and future encroachment from human civilization. Many BDHs are also hotspots for human population, but they were not selected for protection based on indication of future threat. The nature of the criterion upon which BDHs are based is that of past activity. However, previous destruction is not necessarily correlated to future threat. Hotspot advocates have attempted to correct for this oversight by adopting "high biodiversity wilderness areas." High biodiversity wilderness areas are geographic locations with high concentrations of biodiversity which have been left largely undisturbed (Hrdina & Romportl 2017). HBWAs must contain 1,500 endemic plant species, retain at least 70% of their original habitat, and have less than 5 people per square kilometer (Mittermeier et al. 2011). These areas are projected to face some of the greatest impact from future encroachment. Despite this, Conservation International dedicates much less funding and resources towards their protection (Kunzig 2008). In order to correct for a lack of forethought toward future mitigation, the hotspot concept needs to devote more resources toward protecting these vulnerable areas which have not yet been lost. Protection of high biodiversity wilderness areas in addition to biodiversity hotspots is necessary to bolster the strategy's foresight toward mitigation.
Climate change is another factor which makes not only new protection difficult, but also complicates the continued conservation of existing protections. Because much is still unknown of how organisms will attempt to adapt to climate change, it is extremely difficult to predict exact ecological responses to rising temperatures and precipitation change. Species may move up in elevation and/or latitude; without migration corridors, species may be prevented from finding suitable climatic conditions. If species migrate to higher latitudes, there must be suitable habitat and protected space available for them. Migrating species may move into biodiversity coldspots which have largely been overlooked by the hotspot strategy. Mitigation of climate change thus requires the conservation of biodiversity coldspots.
Why conserve biodiversity coldspots?
Biodiversity coldspots should be prioritized in conservation efforts as they provide ecosystem services and serve as a genetic library for evolutionary breakthroughs. 80% of the world's population lives outside of BDHs, so a majority of people are not directly affected by ecosystem services from hotspots (Stork & Habel 2014; Jepson & Canney 2001). Conserving ecosystems in BDHs encourages global processes such as climate regulation, but local ecosystem services only provide for 20% of the population. Valuable ecosystems with high human density are often overlooked due to their low species richness and rarity. For example, tidal marshes typically have no endemic species and low species richness, but are indispensable ecosystems which filter waste, regulate flooding, and encourage fishery yields (Kareiva & Marvier 2003). Biodiversity is also correlated with an increase in the resilience of ecosystems, so maintaining global ecosystem function should be a high priority for conservation efforts (Mittermeier et al. 2011). Neglecting temperate latitudes also leads to the loss of distinct evolutionary lineages. A greater wealth of evolutionary history is lost when a family or genus goes extinct rather than a subspecies with several close relatives (Kareiva & Marvier 2003). BDCs must be protected in order to preserve the genetic library carried by the higher taxonomic groups whose ranges fall outside of hotspots. Coldspots must also be preserved because the species they harbor are not less worthy of existence than those within hotspots. It is unethical for humans to select for the continued existence of certain species based solely upon economic feasibility and instrumental value. All species should be protected from the fallout of humanity's war on nature. Despite limited resources in the field of conservation, high centers of diversity should not be protected at the cost of other ecosystems around the world.
In conclusion, biodiversity hotspots provide an economically feasible starting point for intensive conservation efforts by prioritizing areas with high rates of endemism and vegetation loss. The strategy's enticing simplicity is both a strength and a weakness. While it allows for immediate and focused efforts, it often appears to agencies and politicians as the ultimate one-size-fits-all solution. Identifying and prioritizing hotspots must be viewed as a strategy, not a solution. Conserving concentrated areas of high biodiversity is a tactic which should be employed, but must be expanded to adequately protect high biodiversity wilderness areas. As stated by Kareiva and Marvier (2003), "Although biodiversity hotspots are indeed an academically appealing idea, blind adherence to this mantra runs the risk of leaving the world with a sizable collection of species in a few areas but with an environment that is otherwise largely degraded." Conservationists must not lose sight of biodiversity coldspots, for their ecosystems are vital for the survival of humanity and the organisms which they harbor. Global ecosystem function must not be compromised in order to protect a minute selection of species-rich areas. Conservation efforts must integrate both hotspot and coldspot strategies into a new paradigm which preserves biodiversity while protecting functional ecosystems across the globe.