In any case, I've had time now to put something together, taking a look at the potential impact of invasive species on ecosystem services, using a recent example from Montserrat (Peh et al., 2015)
If you're thinking 'what is an ecosystem service?' it's a fairly straightforward concept, essentially referring to the benefits that an ecosystem provides to humans. A lot of these can be very important, both locally (like food provision) and on larger scales (such as carbon sequestration *painful memories*)
The term is being increasingly used in academic literature , having been popularised by the Millennium Ecosystem Assessment in the early 2000s. The Google Ngram graph below shows how it's usage has really taken off.
So, to Montserrat! Located in the sunny Caribbean, Montserrat may seem like a great place for a holiday. However, half the island is an 'exclusion zone' following a devastating volcanic eruption in 1995. The island also has a growing problem controlling invasive species, which is what the recent study is more concerned with.
In Montserrat, local stakeholders at the Central Hills forest area (Fig.1) are concerned that invasive feral goats and pigs may trigger a chain of events that causes native vegetation to by replaced by alien plum and guava trees.
|Fig.1 Map of Montserrat, highlighting the study area|
|A Montserrat oriole. Straight up 10/10 but critically endangered.|
In 2009, the reserve made an estimated $419,000 from nature based tourism. The survey revealed that only 54.3% of tourists said they would still visit the reserve if the invasion substantially altered the forest, representing a loss of income of $192,000 per year.
|Central Hills. Worth a visit I'd say.|
Taking a Carbon price of $83.61 per tonne, the benefit of maintaining current forest structure would be over $3,000,000, and of course, there would be a little less carbon dioxide in the atmosphere. The resolution of the study is low though, so there is little confidence in this statement.
|Trees: sucking up CO2, and savings|
In an attempt to manage the 'all-round loser' situation, hunting of livestock has been undertaken since 2009. However, long term funding for this endeavor has not yet been secured. From an economic viewpoint, Peh et al have shown that it needs to continue.
Montserrat has been devastated by a recent volcanic eruption and its ecosystem services in the north of the country are threatened by invasive species. Control needs to be undertaken, the only issue now is who is going to pay for it.
Finally, if invasive species are threatening services in Montserrat, it makes it more likely that services will suffer elsewhere if similar disruption to ecosystem functions occur. Another reason to be wary of invasive species then...
Over and out