Botanical Gardens: Learning vs. Invasives

By Elizabeth Morison

When I was younger, trips to the botanical garden were my FAVOURITE way to spend the day. I was curious about the shapes and colours of the flowers, whether they stood tall, or spread out in clumps on the soil. I wanted to know whether the stems would snap if I tugged them, or bend and resist. The leaves, the roots, the spikes! Everything that made each plant different and unique was exactly what I wanted to witness.

As I’ve grown up, this curiosity has manifested in an intense desire to learn about botany and how plants work – particularly what makes them so good at surviving and thriving in their environments. Botanical gardens have been some of the most important resources I’ve had access to in my learning, in their exhibition of local native species as well as specimens from different regions and countries. Actually seeing plants from different places, with all of their different adaptations, is undeniably more informative than looking at a textbook. There is little dispute that botanical gardens are good for science – but are they good for ecosystems?

Over the last three weeks, we’ve been living and studying at Las Cruces biological station and botanical garden. The garden, nestled in a matrix of protected areas, is home to thousands of specimens, a large proportion of which are not local. This is essential to the diversity of the garden, and in most cases those non-native species don’t become introduced in the surrounding forests, because enough is known about each species for the gardeners to be able to contain them and monitor their reproduction. But sometimes – as is the case with invasive Zingiber spectabile – botanical garden specimens can become introduced.

For a species to be considered introduced, it has to go through a series of processes: transport, introduction, establishment, and spread. Ecosystems have resistance to non-native species at each of these stages, so most species that arrive in new territory don’t become a threat. However, in botanical gardens, the first three steps have already happened, very intentionally, and are being continually maintained for exhibition – so essentially, the only step remaining is to spread. And boy, Zingiber spectabile is good at it! These introduced gingers poke up through the leaf litter, like bright red torches lining our hiking trails, and outshining the other species in the understory. Zingiber spectabile particularly outcompetes native ginger Renealmia cernua, leading to its classification as an invasive species, as well as introduced. Invasive species have complex negative impacts on their ecosystems, altering the physical and community structure of the environment. It is when botanical species become invasive, that the question of the tradeoffs between the benefits to science and the threats to ecosystem functioning arises.

Overall, I think botanical gardens are great. I love being able to visit them, as someone who studies plants scientifically, but also simply as a human who enjoys experiencing nature. And even though there can be harmful consequences to curating introduced species, I will boldly suggest that botanical gardens are also one of the best ways we have to learn enough about plants to STOP them from becoming invasive! So I say kudos to growing plants and learning from mistakes.