Drivers of protected-area effectiveness in Africa

31 01 2018
Bowker_et_al-2017-Conservation_Biology. Fig. 1

Subtropical and
Tropical Moist Broadleaf Forest of
Africa with 224 parks surrounded
by a 10-km buffer area. ©
2016 Society for Conservation Biology.

I’ve just read an interesting paper published in late 2016 in Conservation Biology that had so far escaped my attention. But given my interest in African conservation recently (and some interesting research results on the determinants of environmental performance for that region should be coming soon out of our lab), the work caught my eye.

The paper by Bowker and colleagues asked a question that has been asked previously regarding the ‘effectiveness’ of protected areas — do they succeed in limiting forest loss? While forest loss itself is not necessarily indicative of biodiversity erosion in any given area (for that, you need measures of species trends, etc.), it is arguably one of the most important drivers of species loss today.

The first set out to differentiate ‘effective’ from ‘ineffective’ protected areas, which was a simple binary variable related to whether there was less deforestation inside the protected area relative to comparable points outside (effective), or greater than or equal to deforestation outside (ineffective). The authors then related this binary response to a series of biophysical and social indicators. Read the rest of this entry »

Giving a monkey’s about primate conservation

12 12 2017
Urban monkey living (Macaque, Gibraltar) small

Concrete jungle. A Barbary macaque sits in a human-dominated landscape in Gibraltar. Photo: Silviu Petrovan

Saving primates is a complicated business. Primates are intelligent, social animals that have complex needs. They come into conflict with humans when they raid rubbish bins and crops, chew power cables, and in some cases become aggressive towards people.

Humans, however, have the upper hand. While 60% of non-human primate species are threatened, humans grow in numbers and power, building roads through forests, hunting and trapping primates, and replacing their habitat with farms and houses.

To help primatologists choose the most effective conservation approaches to resolve these problems, researchers in the Conservation Evidence project teamed up with primate researchers to produce a global database on the effectiveness of primate conservation solutions. This free database, which can also be downloaded as a single pdf, summarizes the evidence for 162 conservation interventions — actions that conservationists might take to conserve primates. The data come from searches of over 170 conservation journals and newsletters, and each study is summarized in a single paragraph in plain English, making it possible for conservationists without access to scientific journals to read the key findings.

Front cover primate synopsisSo what works in primate conservation? Well, the picture is rarely straightforward — partly due to the lack of data — but there are some interesting trends. Reducing hunting is one area where there seem to be a range of potentially effective approaches. Community control of patrolling, banning hunting and removing snares was effective in the three studies in which it was tested, all in African countries.

Further emphasizing the importance of involving local communities, implementing no-hunting community policies or traditional hunting bans also appeared helpful in boosting primate numbers. In other places, a more traditional approach of using rangers to protect primates has proved a winning strategy. Training rangers, providing them with arms, and increasing ranger patrols all worked to protect primates from poachers. Identifying the circumstances in which community led approaches or ranger patrols work will be key to implementing the most appropriate response to each conservation challenge. Read the rest of this entry »

Microclimates: thermal shields against global warming for small herps

22 11 2017

Thermal microhabitats are often uncoupled from above-ground air temperatures. A study focused on small frogs and lizards from the Philippines demonstrates that the structural complexity of tropical forests hosts a diversity of microhabitats that can reduce the exposure of many cold-blooded animals to anthropogenic climate warming.

Luzon forest frogs

Reproductive pair of the Luzon forest frogs Platymantis luzonensis (upper left), a IUCN near-threatened species restricted to < 5000 km2 of habitat. Lower left: the yellow-stripped slender tree lizard Lipinia pulchella, a IUCN least-concerned species. Both species have body lengths < 6 cm, and are native to the tropical forests of the Philippines. Right panels, top to bottom: four microhabitats monitored by Scheffers et al. (2), namely ground vegetation, bird’s nest ferns, phytotelmata, and fallen leaves above ground level. Photos courtesy of Becca Brunner (Platymantis), Gernot Kunz (Lipinia), Stephen Zozaya (ground vegetation) and Brett Scheffers (remaining habitats).

If you have ever entered a cave or an old church, you will be familiar with its coolness even in the dog days of summer. At much finer scales, from centimetres to millimetres, this ‘cooling effect’ occurs in complex ecosystems such as those embodied by tropical forests. The fact is that the life cycle of many plant and animal species depends on the network of microhabitats (e.g., small crevices, burrows, holes) interwoven by vegetation structures, such as the leaves and roots of an orchid epiphyte hanging from a tree branch or the umbrella of leaves and branches of a thick bush.

Much modern biogeographical research addressing the effects of climate change on biodiversity is based on macroclimatic data of temperature and precipitation. Such approaches mostly ignore that microhabitats can warm up or cool down in a fashion different from that of local or regional climates, and so determine how species, particularly ectotherms, thermoregulate (1). To illustrate this phenomenon, Brett Scheffers et al. (2) measured the upper thermal limits (typically known as ‘critical thermal maxima’ or CTmax) of 15 species of frogs and lizards native to the tropical forest of Mount Banahaw, an active volcano on Luzon (The Philippines). The > 7000 islands of this archipelago harbour > 300 species of amphibians and reptiles (see video here), with > 100 occurring in Luzon (3).

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Four decades of fragmentation

27 09 2017


I’ve recently read perhaps the most comprehensive treatise of forest fragmentation research ever compiled, and I personally view this rather readable and succinct review by Bill Laurance and colleagues as something every ecology and conservation student should read.

The ‘Biological Dynamics of Forest Fragments Project‘ (BDFFP) is unquestionably one of the most important landscape-scale experiments ever conceived and implemented, now having run 38 years since its inception in 1979. Indeed, it was way ahead of its time.

Experimental studies in ecology are comparatively rare, namely because it is difficult, expensive, and challenging in the extreme to manipulate entire ecosystems to test specific hypotheses relating to the response of biodiversity to environmental change. Thus, we ecologists tend to rely more on mensurative designs that use existing variation in the landscape (or over time) to infer mechanisms of community change. Of course, such experiments have to be large to be meaningful, which is one reason why the 1000 km2 BDFFP has been so successful as the gold standard for determining the effects of forest fragmentation on biodiversity.

And successful it has been. A quick search for ‘BDFFP’ in the Web of Knowledge database identifies > 40 peer-reviewed articles and a slew of books and book chapters arising from the project, some of which are highly cited classics in conservation ecology (e.g., doi:10.1046/j.1523-1739.2002.01025.x cited > 900 times; doi:10.1073/pnas.2336195100 cited > 200 times; doi:10.1016/j.biocon.2010.09.021 cited > 400 times; and doi:10.1111/j.1461-0248.2009.01294.x cited nearly 600 times). In fact, if we are to claim any ecological ‘laws’ at all, our understanding of fragmentation on biodiversity could be labelled as one of the few, thanks principally to the BDFFP. Read the rest of this entry »

It’s not all about temperature for corals

31 05 2017


Three of the coral species studied by Muir (2): (a) Acropora pichoni: Pohnpei Island, Pacific Ocean — deep-water species/IUCN ‘Near threatened’; (b) Acropora divaricate: Maldives, Indian ocean — mid-water species/IUCN ‘Near threatened’; and (c) Acropora gemmifera: Orpheus Island, Australia — shallow-water species/IUCN ‘Least Concern’. The IUCN states that the 3 species are vulnerable to climate change (acidification, temperature extremes) and demographic booms of the invading predator, the crown-of-thorns starfish Acanthaster planci. Photos courtesy of Paul Muir.

Global warming of the atmosphere and the oceans is modifying the distribution of many plants and animals. However, marine species are bound to face non-thermal barriers that might preclude their dispersal over wide stretches of the sea. Sunlight is one of those invisible obstacles for corals from the Indian and Pacific Oceans.

If we were offered a sumptuous job overseas, our professional success in an unknown place could be limited by factors like cultural or linguistic differences that have nothing to do with our work experience or expertise. If we translate this situation into biodiversity terms, one of the best-documented effects of global warming is the gradual dispersal of species tracking their native temperatures from the tropics to the poles (1). However, as dispersal progresses, many species encounter environmental barriers that are not physical (e.g., a high mountain or a wide river), and whose magnitude could be unrelated to ambient temperatures. Such invisible obstacles can prevent the establishment of pioneer populations away from the source.

Corals are ideal organisms to study this phenomenon because their life cycle is tightly geared to multiple environmental drivers (see ReefBase: Global Information System for Coral Reefs). Indeed, the growth of a coral’s exoskeleton relies on symbiotic zooxanthellae (see video and presentation), a kind of microscopic algae (Dinoflagellata) whose photosynthetic activity is regulated by sea temperature, photoperiod and dissolved calcium in the form of aragonite, among other factors.

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Noses baffled by ocean acidification

18 04 2017

Clown fish couple (Amphiprion percula) among the tentacles of anemone Heteractis magnifica in Kimbe Bay (Papua New Guinea) – courtesy of Mark McCormick. Clownfish protect anemones from predators and parasites in exchange of shelter and food. The fish tolerates the host’s venom because its skin is protected by a mucus layer some 2-3× thicker than phylogenetically related species (12); clownfish fabricate the mucus themselves and seem to obtain anemone antigens through a period of acclimation (13), but whether protection is acquired or innate is still debated. Clownfish are highly social bony fish, forming groups with one reproductive pair (up to 11 cm in length each) and several smaller, non-reproductive males. Reproduction is protandrous (also known as sequential hermaphroditism), so larvae are born male and, as soon as the reproductive female dies, her widower becomes female and the largest of the subsidiary males becomes the alpha male. The IUCN lists clownfish, generically named ‘anemone fish’, as threatened by the pet-trade industry and habitat degradation, although surprisingly, only 1 species has been assessed (A. sandaracinos). The clown anemone fish A. ocellaris is the species that inspired Nemo in the 2003 Academy-Award fiction movie – contrary to the logical expectation that the Oscars Red Carpet would generate support for conservation on behalf of Hollywood, of the 1568 species represented in the movie, only 16 % of those evaluated are threatened (14).

Smell is like noise, the more scents we breathe in one sniff, the more difficult it is to distinguish them to the point of olfactory saturation. Experimental work with clownfish reveals that the increase in dissolved carbon dioxide in seawater, mimicking ocean acidification, alters olfactory physiology, with potential cascading effects on the demography of species.

Places such as a restaurant, a hospital or a library have a characteristic bouquet, and we can guess the emotional state of other people by their scents. Smell is critical between predators and prey of many species because both have evolved to detect each other without the aid of vision. At sea, the smell of predators dissolves in water during detection, attack, capture, and ingestion of prey, and many fishes use this information to assess the risk of ending up crunched by enemy teeth (1, 2). But predator-prey interactions can be modified by changes in the chemical composition of seawater and are therefore highly sensitive to ongoing ocean acidification (see global measuring network here). Experts regard ocean acidification as the ‘other CO2 problem’ of climate change (3) — just to emphasize that anthropogenic climate-change impacts terrestrial and aquatic ecosystems alike. Acidification occurs because the ocean absorbs CO2 at a rate proportional with the concentration of this gas in the atmosphere and, once dissolved, CO2 becomes carbonic acid (H2CO3), which in turn releases protons (H+) — in simple terms, pH is the concentration of protons (see video about ocean acidification): Read the rest of this entry »

Limited nursery replenishment in coral reefs

27 03 2017
Haemulon sciurus

blue-striped grunt (Haemulon sciurus)

Coral reef fishes are wonderfully diverse in size, form, and function, as well as their need for different habitats throughout the life cycle. Some species spend all of their life in the same kind of coral habitat, while others need different places to breed and feed.

Fishes requiring different habitats as they progress through life often have what we call ‘nurseries’ in which adults lay eggs and the subsequent juveniles remain, and these places are often dominated by mangroves or seagrasses (i.e., they are not part of the coral reef).

While we’ve known for quite some time that when these nursery habitats are not around, adjacent coral reefs have few, if any, of these nursery-dependent species. What we haven’t known until now is just how far the influence of nurseries extends along a coral reef.

In other words, if a nursery is present, just how many new recruits do different areas of a reef receive from it? Read the rest of this entry »