Invasive Alien Plants: not from Mars, but controversy brews over source of introduction

Botanical gardens - those quiet sanctuaries where folks go to stroll amongst flower and trees, contemplating the fate of the world - or escaping from it for a few precious minutes. Not exactly a place that you would consider as a hotbed of invasive species activity, now would you?

Well, it may not be that extreme but Philip Hulme, a weed specialist at Lincoln University, New Zealand, claims that a large number of invasive plant species can be traced back to botanical gardens or arboretums. Hulme reviewed the history behind 34 of the top 100 invasive plant species as defined by the IUCN. Researching the origins of these plants, Hulme found that over half of them could be traced to botanical gardens. From a horticultural laboratory or garden, winds, temperature, and animals that can distribute seeds - all can play a role in allowing an alien species to gain a foothold.

Just what are we talking about when we say "invasive plant species"? Well, it casts a fairly broad net, ranging from weeds and vines to flowers all the way to large trees. In the right climate and soil environment, many have the ability to propagate quickly and literally push indigenous plants out of the way. This has often happened when exotic tropical plants have been brought into non-tropical forest environments - the tropical plant comes from an ecosystem where many different plant species are thrust together and battle it out for territory. In less competitive environments, these species can quickly dominate.

As expected, the botanical garden community is not particularly pleased with Hulme's research and conclusions. Stephen Blackmore, head of the Royal Botanic Garden Edinburgh, U.K., says that while botanical gardens may have been interested in introducing non-native species - but lax in protocols - in the past, today they are much more mindful of the consequences and that it is home gardeners and the horticultural trade that probably deserve greater inspection.

"I am not saying that that lets botanic gardens off the hook," says Blackmore, adding that botanical gardens today go to great lengths to quarantine new plants to guard against the spread of fungus or disease, and that they are very conscious of preservation and conservation of the local botanical ecology. Botanic Gardens Conservation International, a global network of botanical gardens, is beginning to develop a set of guidelines for how alien or non-native plants should be managed.

Home gardeners and commercial plant shops remain as a possible point of introduction of invasive species, much like the tropical fish stores and home aquarists who thrill at displaying tropical fish and seaweed species until they become to large or too aggressive for the tanks they are in and accidentally end up in local waters, disrupting the balance of an ecosystem. Case in point, the Caribbean invasion by the voracious lionfish, a Pacific Ocean species.

As mankind becomes more and more global in his curiosity and his movements, then the threat of disruption of ecosystems by invasive species - whether accidental or by design - remains high.

Read more about invasive plant species in NatureNews.

Plants At Risk: research catalogs potential extinction threat to one-fifth of all plants

There are several news agencies that are picking up on a recently released study that declares that one-fifth of the world's plants are faced with extinction. Animals or large-scale ecosystems seem to catch the attention of the general public more than plants, perhaps because we can relate to an animated polar bear, a wolf, or a shark better than we can to an orchid. And ecosystems catch our attention because their fate is often wrapped up in global implications.

However, plants, as much as they may be taken for granted or ignored altogether, play a significant role in not only the overall health of the planet but to mankind specifically.

Researchers at England's Royal Botanical Gardens at Kew, and the Natural History Museum, along with the International Union for the Conservation of Nature (IUCN) have analyzed over 4,000 plant species and determined that 22% should be considered threatened with possible extinction, while another 33% could not have their status determined because so little is known about them. Their research forms an important baseline by which future growth or loss can be measured.

With an estimated 380,000 plant species in the world today, what appears to be the greatest threat is habitat loss - areas of land that are being consumed and redirected towards agriculture. Tropical rain forests seem to be the greatest botanical areas at risk.

Now what might assume that the loss of some obscure orchid or weed is not a big deal; that as long as we have plenty of fruits and vegetables, we will be okay. Not so, according to the research. Many medicines have been first derived or can only be derived from plant extracts, and with the loss of botanical environments that can be a loss of an untold number of future medications. Ironically, developing countries, where much of the tropical forests and plant systems are being wiped out, are one of the main benefactors in plant-derived medicines for conditions ranging from malaria to leukemia.

In addition, focusing on plants that serve the greatest numbers of people as food is a limitation that can have profound effects on the very plants we depend on. It is reported that 80% of the calories consumed by the world come from only 12 different plant species. That can cause a precarious limitation in the DNA gene pool of plants which can have a negative impact on those 12 species we so much depend on. Imagine ridding the world of all animals except for cows, pigs, chickens and a few fish and you can see how precarious our situation would become in maintaining a healthy gene pool of feed animals.

The report on the ongoing botanical research comes in advance of next month's United Nations Biodiversity Conference. The future of plants on earth must be an important component of a more holistic approach towards biodiversity, realizing that every plant or animal plays a role and we must consider the implications when any species, plant or animal, is brought to the level of extinction.

Stephen Hopper, professor and director of the the Royal Botanical Gardens said, "We cannot sit back and watch plant species disappear - plants are the basis of all life on Earth, providing clean air, water, food and fuel. All animal and bird life depends on them and so do we. Every breath we take involves interacting with plants. They're what we all depend on."

Read more about it in the Royal Botanical Gardens' KEW News.