- By J W
January 26, 2015
The mud grabbed at my over-sized rubber boots and splashed all over my clothes as I used my pick (picoto) to muck out the roots of Sium latifolum, an invasive semi-aquatic plant from Brazil that vaguely resembles celery, from one of the creeks flowing through the town of San Juan Bautista, Robinson Crusoe Island, Chile. Our work crew (cuadrilla) consisted of two local islanders, four mainlander Chileans, a Spaniard, and two gringos (me and Jessie). We were getting up close and personal with the front lines of biodiversity conservation, and, basically, it meant wallowing in the mud in a ditch under a bridge, whacking at plants and pulling up roots. Sium latifolium, our target, is an “incipient invasive plant,” meaning it has not yet become widespread on Isla Robinson Crusoe, but easily could if left unchecked. Our job was a very important one–to eradicate it before that happened.
Invasive species are a worldwide threat to biodiversity, and their impact is especially severe in island ecosystems, which often harbor high diversities of unique plants and animals. There are currently 154 species of native plants that have been described on Isla Robinson Crusoe and Isla Santa Clara in the Juan Fernández Islands. Of these, 61% are endemic, meaning they are found nowhere else on earth. This falls out to be one of the highest rates of endemism in the world, meaning that the islands are a world-hotspot for biodiversity.
Unfortunately, the native plants of the islands are nearly all considered by international bodies such as the International Union for the Conservation of Nature (IUCN) to be vulnerable, endangered, or critically endangered with extinction. The reasons for this are simple: human exploitation (mostly in the past), and introductions of invasive plant and animal species by people. Introductions of non-native plants and animals started with the discovery of the islands in 1574 (by the Spanish sailor Juan Fernández), and have continued ever since. There are now more non-native than native plant species on the islands (57% of the plant species are introduced, 43% are native), and over the years animals as varied as goats, cows, sheep, dogs, cats, rats, rabbits, toads, pigeons, yellow-jackets and more have been introduced. Some of these non-native plants and animals behave relatively well and have not become widespread invasive species, but others, released from the competition and disease in their native ranges, spread rampantly and become major problems for the native plants and animals.
In many areas of the islands, the grazing pressure from rabbits, cows, sheep, and goats has decimated the native vegetation, which evolved without defense mechanisms to deal with mammalian grazers. Absent are the thorns, spines, toxic compounds, and stump sprouting adaptations that so many continental plants have evolved to deal with grazing. In many lower-elevation areas of the island, most of the native vegetation has long-since disappeared, or where it persists, cattle and rabbit grazing keep it from regenerating. At higher elevations, and on inaccessible cliffs and crags, native forest persists, but faces yet another threat—the encroachment of invasive plant species. The biggest problems here are Zarzamora, a.k.a. blackberry, and maqui, a plant from mainland Chile that bears small, tasty fruits that stain your tongue dark purple when you eat them. Native and non-native birds (pigeons, house sparrows) also find the fruits tasty, and they often spread the seeds into the native forest.
Altogether, the situation for the islands’ endangered plants is pretty dire. On the bright side, there are many amazing groups and individuals who are working tirelessly to rescue the native plants (and, in doing so, the native animals such as the endemic Juan Fernández Firecrown hummingbird). Jessie and I have been very impressed this (austral) summer with the various conservation programs being implemented by CONAF (the Chilean park service), Oikonos, Island Conservation, and Rescatemos Juan Fernández (an organization founded by students that brings volunteers to the island each summer to work on conservation projects).
The first order of business is to make sure that the native plants are in cultivation so that they don’t go extinct, and CONAF runs an extensive greenhouse operation and an arboretum in town. The arboretum contains specimens of several species that are extinct or near-extinct in the wild, like the Juan Fernández Cabbage Tree and the giant Robinson Crusoe Chenopodium. The park and other organizations also encourage locals to plant natives in their yards; thus, we have a lovely specimen of Ajo Dulce (sweet garlic; Ochagavia elegans), classified as vulnerable by the IUCN, in the front yard of our rental-cabaña.
Oikonos and Island Conservation, with support from CONAF, work on the front lines of Maqui-Mora invasion, removing the plants from areas in and around the most pristine native forest habitat. Each year several locally-hired work cuadrillas carry out the exhausting business of chain-sawing the maqui trees and removing the blackberry, which has diabolical thorns. Great strides have been made in controlling the maqui-mora and this year the crews are moving into a new area, because control has been effective in the Plazoleta del Yunque where the project began in 2003.
Rescatemos Juan Fernández is another group that is working on plant conservation in the islands. Their name can be roughly translated to mean “We must rescue Juan Fernández”. The group was formed in 2011 year by Chilean students with the goal of protecting the ecosystem of the Juan Fernández Islands and educating locals and continental Chileans about the island’s environmental issues. One of the founders, Hector (Chipi) Gutierrez, is currently working as a coordinator for Oikonos, as well as running the summer volunteer program. This year, several volunteers are working with Rescatemos on the island, on projects including a plant control cuadrilla, an environmental education program, and an illustrated guide to the native ferns of the island.
Jessie and I have been occasionally helping with the Rescatemos cuadrilla, which is why we were mucking about in the mud under the bridge, helping with incipient invasive plant control. We have worked at the dump, which is a hotspot for invasive species, in the creek flowing through town, and in backyards and empty lots in town, removing problem plants or monitoring the prior removal sites. This is not your glamorous tourist experience, but on-the-ground conservation work is rarely glamorous. It’s hard, dirty, slow work, but in the end, you know you are helping to save one of the most unique ecosystems on earth. And that is a satisfying feeling.