The bad green is threatening unique species to oblivion

In my last post, I shown that not all green is good. That some plant species are a threat and can even make other plant species disappear. The bad guys plants are what is called invasive alien plants, non-native plants or exotics plants.

Most people would know the problem that invasive alien animals can cause. For example, only one species of mosquito, the tiger mosquito, is responsible increasing cases of dengue, chikungunya and zika in the last decades.

aedes-albopictus-cdc-gathanysmall

A small non-native animal that causes a lot of trouble

 

But the impact of invasive alien plants is less known as fewer species can disrupt human life as quick as non-native animals. The famine weed, Parthenium hysterophorus, it is a small herb that is disrupting lives in Africa – it decreases crop yields, make meat unfit for consumption, causes health problems like asthma, among other problems.

Small herb with pretty flowers that behave like an evil outside its native environment

Small herb with pretty flowers that behave like an evil outside its native environment

 

But many invasive alien species are a slower trouble-maker. Well, slower just on our on perception of time. Large trees can survive for decades and centuries, so competition with invasive alien plants needs to be measure on larger time scales.

In the island of Mauritius, in the Western Indian Ocean, this process the very few best preserved and protected native forests are today dominated by alien species! In average, nearly 80% of the stems of these best preserved forest are of non-native species.

The main problem is that the levels of invasion is set to get worst. The invasion is progressing, slowly but surely. When comparing todays number of species, number of stems and basal area of forest on forest areas where surveys were done in 1930s and in 1980s, we see a clear tendency of the invasion getting worst making the native forest, little by little, be submerged under this tsunami of alien species.

Some endemic species have disappeared from these forests because of the invasion. The number of trees in one of these forests have more than halved in near 70 years. Also the biomass of native trees in this forest is less than half of it was in 1930s.

Once the commonest shurb in one of the studied sites, this Mauritian endemic plant, has vanished from that forest in less than 50 years

Once the commonest shrub in one of the studied sites, this Mauritian endemic plant, has vanished from that forest in less than 50 years

 

This high invasion is also seen in other forest on tropical oceanic islands around the world. The invasion is putting the planet on the way to lose many unique species, many unique interactions, many unique ecosystems. All these without even considering the effects that global warming (that is a fact and not a hoax) is and will cause.

 

 

References cited

Florens et al in press. Long term declines of native trees in a oceanic island’s tropical forests invaded by alien plants. Applied Vegetation Science. DOI: 10.1111/avsc.12273

Florens et al 2016. Invasive alien plants progress to dominate protected and best-preserved wet forests of an oceanic island. Journal for Nature Conservation 34: 93–100

When green vegetation is bad…

Being close to nature is for most of us city dwellers a free health medicine. It makes you relax, decreases anxiety, make your blood circulate better and sharpens your mind.

A peaceful sunny day in a restored forest of Mauritius

A peaceful sunny day in a restored forest of Mauritius

 

But for some, a walk in the woods can be very stressful indeed. The reason? Some plants around shouldn’t be there. The so called invasive alien plants, non-native species or exotics. Plants that we humans transported to places where they did not grow before, sometimes purposefully, sometimes accidentally. The alien plants behave like deadly diseases – a cancer killing the resident plants of the place. In turn, it reduces the resilience of the native ecosystems, which little by little will spiral out of control and collapse, bring other native species and its interactions to become rarer and rarer or to disappear altogether.

 

In the island of Mauritius, in the Western Indian Ocean, this process is happening in from of our eyes. The very few best preserved and protected native forests are today dominated by…alien species! If you are a good observer, you will realise that in most of the native forest left on the island you are surrounded by a ‘sea’ of strawberry guava (a species from the Atlantic forest of Brazil). Well, you don’t need to be a great observer as, in average, nearly 80% of the stems are of non-native species. Worrisome is that it does not stop here: the invasion is progressing.

Invasion can be extreme. All reddish stem are strawberry guava

Invasion can be extreme. All reddish stem are strawberry guava

Fruits of strawberry guava are disperse into the native forests by birds, alien pigs and alien monkeys

Fruits of strawberry guava are disperse into the native forests by birds, alien pigs and alien monkeys

 

Strawberry guava is also a major problem in other tropical islands around the world. It is considered the worst invasive species of Hawaii. To avoid the full destruction of unique species and its ecosystems, it is necessary to control alien invasive plants. Both on Mauritius and Hawaii, manual removal of stems of these alien plants are done on regular basis. But such approach can only be effective on small areas. Biocontrol, a much used tool for agriculture, when conducted carefully and well-studied is arguably the only way to reverse the fate of today invaded forest and bring it back to a more pristine state and to avoid extinctions of unique species. Luckily, an effective and specific biocontrol has been found for strawberry guava. It was introduced in some selected areas of Hawaii in 2011.

The biocontrol of strawberry guava affects the leaves

The biocontrol of strawberry guava affects the leaves weaking the plant

 

Understanding the problem is the beginning of the solution to bring back a world where all green is good for all.

 

 

Reference cited

Florens et al 2016. Invasive alien plants progress to dominate protected and best-preserved wet forests of an oceanic island. Journal for Nature Conservation 34: 93–100

Mitch Ladyman: What do mining companies do for the environment?

Mitch is out bush so he asked us to post this on his behalf.

 

I was in Bunnings the other day: Australia’s largest hardware warehouse chain with exceptionally large warehouses full of……….well, hardware (in-text footnote – I actually believe that all Bunnings stores function in a parallel universe on a different space/time continuum: men (and women) of all ages ‘pop’ in to quickly grab a hardware item and emerge three days later with a bunch of stuff they neither want nor need).

 

Accustom to the typically very friendly service I was rather taken aback by one young female employee who, upon seeing the company logo on my car and questioning me as to what I did for a living, unreservedly and assertively quipped about her ‘hatred for mining and mining companies’.

 

At this point, I had to make a choice: am I going to be dismissive of her or am I going to present her with an alternate view in an attempt to encourage her to reconsider her values. I had nothing to lose and very little to gain from either of the above.

 

I had to dig deep to muster any amount of my usual enthusiasm and effervescence. Within seconds I was waxing lyrical with countless personal experiences and examples of how the mining dollar underpins a lot of very valid ecological research and an endless array of conservation projects across this great state of ours. In a brief and fleeting display of cognizance about the subject matter this young lady rightly pointed out that mining companies are only funding said research and conservation projects because they are legally obliged to do so (though she did not put it quite so eloquently). She is correct, of course. But is it not better that the work get done out of obligation than not done at all? Moreover, there are many companies that contribute beyond their Ministerial requirements by choice. Often this results in recognition through industry environmental awards which are valued by the companies staff and shareholders.

 

The outcomes of this exchange have been threefold.

1) I may have actually influenced this young lady’s way of thinking and she has since embraced miners as conservation allies rather than enemies.

2) I have concluded that Bunnings would do well to educate their staff in communicating in a manner which is both warm and embracing, rather than abrasive, abject and affronting.

3) I am suddenly very concerned about what the nationwide slow down in mining means for conservation projects in Australia.

 

Mining companies in the Pilbara are delivering hundreds of thousands of dollars into the government coffers and that money will be used to fund many projects on Northern Quoll (a species under significant threat in W.A.), with the recent Cane Toad invasion, the Greater Bilby (threatened by feral predators), the Malleefowl (threatened by habitat loss and predation) etc etc etc.

 

Closer to home, at least for me, one of Animal Plant Mineral’s clients has spent tens and tens of thousands of dollars protecting and enhancing feeding and breeding habitat of the Gouldian Finch. That same client funded a regional helicopter survey to find new populations of a flora taxon that was thought to only exist in the Northern Territory. And while we are talking about KMG, it is worthwhile mentioning that they financed a survey to extend the known distribution of the Northern Leaf-nosed Bat, which is to this day the most exciting field survey I have ever designed and executed See this awesome clip to appreciate where I am coming from.

 

What will happen to the great work that is currently being done when the active mines shut down and no new mining proponents are seeking environmental approval for new mines. Quite simply, the research and conservation work will cease and we will see a return to the era that preceded the mining boom where the staff within government departments, such as the Department of Parks and Wildlife, are stranded at their desks sitting on their hands because they no longer have any money to go bush to do real work.

 

Taken years ago (2010) these photos capture some of the still ongoing work that APM and KMG are doing on the Gouldian Finch. But with the iron ore price in the gutter, who knows how much longer such projects will last?

 

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They are called Snappy Gums for a reason: best not lean the ladder on dead hollow limbs.

 

 

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If you were a finch, would you be happy to call this home?

 

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Yes – this looks bad. But no mine equals no money. Benefits outweigh costs.

Living a Double Life

 

Batrachochytrium dendrobatidis (Bd, or chytrid) is a fungal pathogen that causes chytridomycosis in some susceptible amphibians.  Not all amphibians are plagued by this infection, but those that are tend to show drastic population declines when exposed to chytrid.  This leaves a collection of individuals that can serve as carriers or vectors of disease, spreading it from one pond to another.  One of the interesting characteristics with chytrid is its specificity to tissues that is attacks.  Chytrid fungus only attacks keratinized tissues, thos with a certain chemical- keratin- that gives skin its waterproofing.

Since amphibians use cutaneous breathing, or getting oxygen through their skin, it should come as no surprise that amphibians’ skin is less keratinized than human skin and other organisms.  In fact, the areas of skin that are keratinized vary throughout an amphibian’s life, with tadpoles having little to no keratin outside of the mouthparts in most species.  Where we have teeth for chewing, tadpoles have rough fingernail-like ridges to scrape off their food.  Chytrid attacks on tadpoles often are not directly fatal but can lead to lower tadpole condition, smaller size, and longer time to metamorphosis.  In adults, chytrid infects far more of the skin, as there’s more keratin for chytrid to feed off of.  This leads to a more extensive infection, and more often than in tadpoles leads to death, and the skin can even slough off as the keratin is broken down so much.

For amphibians, their dual life cycle using both aquatic and terrestrial habitats can help to divide resources and lessen intra-specific competition, but it also exposes them to predators, pathogens, and pollutants in both habitats as well.  It also means that as researchers, we need to consider two functionally different groups- aquatic larvae that eat phytoplankton and detritus, and terrestrial adults who are carnivores.  Two sets of predators, two sets of prey, two sets of environmental conditions, and two sets of competitors.  We might talk about “amphibians,” but that’s not a homogeneous group by any means.

In ecology in general, organisms might be lumped into groups in different ways, either based on relationships or functional groups usually.  Our ability to construct those groups accurately plays a big role in our ability to best study the world around us.  Sometimes, we can put organisms in more than one group based on the type of study that’s being conducted and the questions that we’re asking.  With living things, there’s rarely simplicity, and making sense of that complexity helps us to find the answers as best we can.  For amphibians, that might mean treating a species as two different groups instead of one.