Tropical forest resilience depends on past disturbance frequency

16 07 2014

I’ve recently come across an interesting study that perfectly marries palaeo-ecological data with modern conservation philosophy. It’s not often that such a prehistorical perspective dating at least to the Last Glacial Maximum has been used so effectively to inform future conservation outlooks. I’m particularly interested in this sort of approach considering my own palaeo dabblings of late.

Published in Nature Communications this May, Lydia Cole and colleagues’ paper Recovery and resilience of tropical forests after disturbance is a meta-analysis of 71 studies covering nearly 300 disturbance events in tropical forests over the last 20,000 years or so. Using fossil pollen records as an index of vegetation change, they demonstrated the (somewhat intuitive) main result that the time to recovery following a disturbance generally decreases as the past disturbance frequency increased.

This appears to be a vindication of the idea that a system’s adaptive strategies evolve as a product of the local disturbance regime. More importantly, they found that recovery was faster following ‘large infrequent events’, which are natural perturbations such as cyclones and major fires. While most past disturbances were caused by humans clearing forest, the fact that tropical forest systems were most resilient to ‘natural’ events means that if we can’t stop human disturbances, at least we can attempt to emulate natural processes to maximise the rebound potential. Much like many modern forestry operations try to emulate natural disturbances to limit their damage, we should at least manage our impacts by understanding so-called ‘natural’ regimes as much as possible. Read the rest of this entry »





Toothed conflict

1 11 2012

Left: An Anatolian shepherd (a Turkish breed improved in the USA) guiding a herd of boer goats whose flesh is much appreciated by people in Namibia and South Africa. Right: A cheetah carrying a radio-transmitter, within a project assessing range movements of this feline for the Cheetah Conservation Fund. Cheetahs refrain from moving close to the herds when the latter are looked after by the guardian dogs. Photos courtesy of Laurie Marker.

Another corker from Salva. He’s chosen a topic this week that’s near and dear to my brain – the conservation of higher-order predators. As ConBytes readers will know, we’ve talked a lot about human-predator conflict and the inevitable losers in that battle – the (non-human) predators. From dingos to sharks, predator xenophobia is just another way we weaken ecosystems and ultimately harm ourselves.

Rural areas devoted to livestock are part of the natural landscape, so it is inevitable (as well as natural) that predators, livestock and humans interact in such a mosaic of bordering habitats. However, their coexistence remains an unresolved conservation problem. 

When two species, people, political parties, enterprises… want the same thing, they either share it (if possible) or one side eliminates the competitor. The fact that proteins are part of the diet of humans and other carnivore species has resulted in a trophic drama that goes back millennia. Nowadays, predators like eagles, coyotes, lions, wolves and raccoons are credited for attacks on cattle and poultry (and people!) in all continents. This global problem is not only economic, but interlaces culture, emotion, policy and sanitation (1-4). For instance, some carnivores are reservoirs of cattle diseases and contribute to pathogen dispersal (5, 6).

Management options

Managers of natural resources have implemented three strategies to handle these sorts of issues for livestock breeders in general (7). Those strategies can be complementary or exclusive on a case-by-case basis, and are chosen following cost-benefit assessments and depending on the conservation status of the predator species involved. (i) ‘Eradication’ aims to eliminate the predator, which is regarded as noxious and worthless. (ii) ‘Regulation’ allows controlled takes under quota schemes, normally for pre-defined locations, dates and killing methods. ‘Preservation’ is applied in protected areas and/or for rare or endangered species, and often requires monitoring and measures set to prevent illegal harvest or trade. Additionally, many livestock breeders receive money to compensate losses to predators (8).

Many experts now advocate non-lethal (preventive) measures that modify the behaviour of people, livestock or predators (2, 7). The use of livestock-guarding dogs is one of those preventive measures (9). As an example, Laurie Marker (director of the Cheetah Conservation Fund) et al. (10) studied the use of 117 Anatolian shepherds adopted by Namibian rangers between 1995 and 2002 (Fig. 1). In this African country, cheetahs (Acinonyx jubatus) selectively forage on small-sized cattle and juveniles. Despite this feline being protected nationally, Namibian laws authorise rangers to shoot cheetahs in situations of risk to people and their properties, with more than 6,000 cheetahs having been killed in the 1980s alone (11). Through face-to-face interviews, Marker found that since the arrival of the Anatolian shepherds, > 70 % of the rangers perceived a pronounced reduction in cattle mortality (10). Although, the use of livestock-guarding dogs has worked out fine in many places worldwide, it is no panacea. In many other instances, the dogs dissuade some predator species and not others from harassing the livestock, or are only effective in combination with other measures (7, 9). Read the rest of this entry »





Threats to biodiversity insurance from protected areas

26 07 2012

A red-eyed tree frog (Agalychnis callidryas) from Barro Colorado Island in Panama. This small island, just 1500 ha (3700 acres) in area, is one of the tropical protected areas evaluated in this study (photo © Christian Ziegler <zieglerphoto@yahoo.co>, Smithsonian Tropical Research Institute). Note: It is prohibited for any third party or agency to use or license this image; any use other then described above shall be subject to usage fees as determined solely by the photographer.

Much of conservation science boils down to good decision making: when, where and how we ‘set aside’ terrestrial or marine areas for specific protection against the ravages of human endeavour. This is the basis for the entire sub-discipline of conservation planning and prioritisation, and features prominantly in most aspects of applied conservation and restoration.

In other words, we do all this science to determine where we should emplace protected areas, lobby for getting more land and sea set aside so that we have ‘representative’ amounts (i.e., to prevent extinctions), and argue over the best way to manage these areas once established.

But what if this pinnacle of conservation achievement is itself under threat? What if many of our protected areas are struggling to insure biodiversity against human consumption? Well, it’d be a scary prospect, to say the least.

Think of it this way. We buy insurance policies to buffer our investments against tragedy; this applies to everything from our houses, worldly possessions, cars, livestock, health, to forest carbon stores. We buy the policies to give us peace of mind that in the event of a disaster, we’ll be bailed out of the mess with a much-needed cash injection. But what if following the disaster we learn that the policy is no good? What if there isn’t enough pay-out to fix the mess?

In biodiversity conservation, our ‘insurance’ is largely provided by protected areas. We believe that come what may, at least in these (relatively) rare places, biodiversity will persist despite our relentless consumerism.

Unfortunately, what we believe isn’t necessarily true.

Today I’m both proud and alarmed to present our latest research on the performance of tropical protected areas around the world. Published online in Nature this morning (evening, for you Europeans) is the 216-author (yes, that is correct – 216 of us) paper entitled “Averting biodiversity collapse in tropical forest protected areas” led by Bill Laurance. Read the rest of this entry »





Reforesting wealthy countries for the common good

29 06 2011

The Coalition of Financially Challenged Countries with Lots of Trees, known as ‘CoFCCLoT’, representing most of the world’s remaining tropical forests, is asking wealthy nations to share global responsibilities and reforest their land for the common good of stabilizing climate and protecting biodiversity.

“We are willing to play our part, but we require a level playing field in which we all commit to equal sacrifices,” a coalition spokeswoman says. “Returning forest cover in the G8 countries and the European Union back to historic coverage will benefit all of us in the long-term.”

Seventy-five per cent of Europe was once forested. Now it is 45 per cent. Some countries such as Ireland saw forest cover reduced to near zero. Most forest cover in the developed world is now often planted with stands of alien trees, turning them into deserts for biodiversity. Remaining natural forests are often highly fragmented and have few native species. Read the rest of this entry »





Blog Action Day 2010 – Water neutrality and its biodiversity benefits

16 10 2010

In my little bid to participate in Change.org’s Blog Action Day 2010 – Water, I’ve re-hashed a post from 2008 on ‘water neutrality’. This will also benefit my recently joined readers, and re-invigorate a concept I don’t think has received nearly enough attention globally (or even in parched Australia where I live). So here we go:

The world’s freshwater ecosystems are in trouble. We’ve extracted, poisoned, polluted, damned and diverted a large proportion of the finite (and rather small!) amount of freshwater on the planet. Now, most people might immediately see the problem here from a selfish perspective – no clean, abundant water source = human disease, suffering and death. Definitely something to avoid, and a problem that all Australians are facing (i.e., it’s not just restricted to developing nations). Just look at the Murray-Darling problem.

In addition to affecting our own personal well-being, freshwater ecosystems are thought to support over 10000 fish species worldwide (see also a recent post on Africa’s freshwater biodiversity’s susceptibility to climate change), and the majority of amphibians and aquatic reptiles. Current estimates suggest that about 1/3 of all vertebrate biodiversity (in this case, number of species) is confined to freshwater. As an example, the Mekong River system alone is thought to support up to 1700 different species of fish.

So, what are some of the ways forward? The concept of ‘water neutrality’ is essentially the wet version of carbon neutrality. It basically means that water usage can be offset by interventions to improve freshwater habitats and supply. Read the rest of this entry »





The lost world – freshwater biodiversity conservation

6 09 2010

Even the most obtuse, right-wing, head-in-the-sand, consumption-driven, anti-environment yob would at least admit that they’ve heard of forest conservation, the plight of whales (more on that little waste of conservation resources later) and climate change. Whether or not they believe these issues are important (or even occurring) is beside the point – the fact that this particular auto-sodomist I’ve described is aware of the issues is at least testament to growing concern among the general populace.

But so many issues in conservation science go unnoticed even by the most environmentally aware. Today’s post covers just one topic (I’ve covered others, such as mangroves and kelp forests) – freshwater biodiversity.

The issue is brought to light by a paper recently published online in Conservation Letters by Thieme and colleagues entitled Exposure of Africa’s freshwater biodiversity to a changing climate.

Sure, many people are starting to get very worried about freshwater availability for human consumption (and this couldn’t be more of an issue in Australia at the moment) – and I fully agree that we should be worried. However, let’s not forget that so many species other than humans depend on healthy freshwater ecosystems to persist, which feed back in turn to human benefits through freshwater filtering, fisheries production and arable soil accumulation.

Just like for the provision of human uses (irrigation, direct water consumption, etc.), a freshwater system’s flow regime is paramount for maintaining its biodiversity. If you stuff up the flow regime too much, then regardless of the amount of total water available, biodiversity will suffer accordingly.

Glen Canyon Dam

Image by James Marvin Phelps (mandj98) via Flickr

Thieme and colleagues focus specifically on African freshwater systems, but the same problems are being seen worldwide (e.g., Australia’s Murray-Darling system, North America’s Colorado River system). And this is only going to get worse as climate change robs certain areas of historical rainfall. To address the gap in knowledge, the authors used modelled changes in mean annual runoff and discharge to determine fish species affected by 2050.

The discharge/runoff results were: Read the rest of this entry »





Party with future conservation leaders

11 07 2010

I’ve just come back from the 2010 International Congress for Conservation Biology in Edmonton, Canada. I thought it would be good to tweet and blog my way through on topics that catch my attention. This is my third post from the conference, and a full conference ‘assessment’ post will follow in a few days.

I haven’t been a member of the Society for Conservation Biology for a very long time, and I’ve only now attended three annual meetings of the Society. I’ve been somewhat lukewarm about the social events at these conferences in the past, but this time I had much better experience.

After a less-than-inspiring barbecue meal and a general under-abundance of ethanol-based social lubricant, someone in our group whispered that we should ‘crash’ a party being held ‘secretly’ back at the conference venue. I had heard around the traps that the Conservation Leadership Programme (CLP) bashes were good, but I hadn’t attended one before. Well, not only was it a bloody good party, I’ve learned a little more about the programme and the kinds of people it promotes. Read the rest of this entry »








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