Planned optimism

I can’t do everything everywhere, but I can still make a difference (5 minute read)

It’s supposed to be the middle of winter, and the frosts we’ve had for the last couple of days certainly suggest it is, but one plant hasn’t got the message. Donna and I were at Cashmere Reserve early on Saturday morning, and I was checking an area we cleared of weeds in the autumn. Despite my efforts to dig out all the roots of climbing dock, the area was covered with new shoots emerging from roots I had left behind. But Donna was happy.

Why was she happy? To explain, I have to tell you a little about the plant. Climbing dock is a cousin to the kind of dock plants which grow as garden weeds. If you’ve ever tried to dig one out, you’ve probably noticed how deep and tough the roots are. But those kinds of dock have nothing on climbing dock. It has three different types of roots, each with a different function and each adding to the difficulty of control. The first type of root is the rhizome. Strictly speaking, it’s actually a stem, but it appears to be a root because it creeps along just under the surface of the soil. Often, what looks like a dozen plants turns out to be many shoots of one plant, all connected under the ground. The second type of root is the tuber. These look rather like a small to medium kūmara, or sometimes a beetroot, although I haven’t found any information suggesting that they are edible. The tubers are found at various points along the rhizome, and can easily resprout new plants. The third type of root is just an ordinary root which grows off the tuber, but it goes deep into the ground and is as difficult to pull as any dock root.

When I dig up the roots of climbing dock, which is the best way to deal with a relatively small and accessible infestation, I toss them away from me for Donna to chase. She’s happy to take any twig or weed I’ve pulled out, but climbing dock tubers are so much better because I can throw them like balls. Donna loves balls, but she doesn’t bring them back like one of the retrieving breeds would. All she wants to do with a ball is chew it. Climbing dock tubers aren’t toxic, unless you consume a lot, and are easily broken apart by a dog’s teeth. So I pull out the tubers and Donna destroys them. She doesn’t always destroy them enough to prevent resprouting, but she certainly enjoys tearing them apart.

In Cashmere Reserve, climbing dock is one of the more abundant weeds on the edge of the wetland and in the main area where we are replanting to establish native species. As its name suggests, it’s a vine, and in the spring it sprouts rapidly and can smother native shrubs. It doesn’t grow as high as a vine like old man’s beard, but it can do a lot of damage in regenerating forest, coastal cliffs and wetland edges. In autumn it produces numerous seeds which can be carried by the wind, and in winter it dies back to its roots, leaving the mass of seeds to blow around in the storms.

In my weed plan for Cashmere Reserve, I’ve set an objective of eliminating climbing dock, although I’ve also noted that I’m not sure whether that is feasible. This doesn’t mean that I expect to get rid of it completely, but my goal is to prevent any seeds from being formed and to dig up enough tubers to knock the plants right back. It isn’t a species which grows well in the shade, so if we can get a native canopy established, we will be more than halfway there.

I have now written up most of my weed plan into a spreadsheet, but this will be of interest only to a few people who are directly involved with weed control planning. I’ve made another version of the plan which I thought I’d share here, because it was much more fun to do. I’ve drawn up my plan, by hand, on an A3 sheet of paper. I drew some pictures of plants and birds (and one moth) to show the forest being a habitat for native species and a wonky map which may not mean much to those who know the reserve, but does the job. I’ve also listed the weeds based on the objectives, and colour-coded them to show the kind of impact each weed has.

I’ve got a group of weeds which are barely established but could be very damaging, so I’m working to ensure they are eliminated as far as possible. I’ve a few which require substantial, sustained effort over the next few years - climbing dock, blackberry and tradescantia, and probably bindweed and montbretia, which also have stubbornly persistent roots. The rest will just need control in a few places.

So, here it is, the visual version of the plan.

Image credit: Melanie Newfield

When weed management used to be my job, people would often say to me that I must be a real optimist, because otherwise the job would get me down. And it’s true that weed problems are generally getting worse. Seeds and stem fragments are spread by birds, wind, water, footwear, gravity and the transport of soil and gravel. Weeds are moving further into our natural areas, and more and more species are beginning to spread from gardens. We aren’t doing enough to prevent the slow but irreversible alteration of important natural environments, such as some of our wetlands and shrublands. I accept that in future years, many of the forests around Wellington will be a mix of native and introduced species. I’d like to see more resources put into controlling weeds, but I know that there are always many competing priorities.

I knew that then, and I still know it, but I also know that it’s possible to make a difference. The way to do that is to plan and prioritise. I can’t do everything everywhere. But I can ensure that the effort I put in is worthwhile.