I’m not sure who first said, ‘the only constant, is change’, but whoever said it may have based the idea on plants. Plants, long-lived plants at least (trees) exist in a constant state of change. They can’t migrate or move, they sit where they have always sat, rooted to the ground while change happens all around them.

The oldest living tree is said to be the Methuselah tree* – a 4,500-year-old bristlecone pine living in the mountains of California. Change for Methuselah is bad. Against the odds and the elements he somehow survives, but at what cost – time has not been kind to him. Yet there is old, and there is really old. It all depends on when you start counting. There are groves (small forests) of quaking aspen (Populus tremuloides) that might have been around for more than 80,000 years. Ageing these bad boys is complicated – they are clonal trees regenerating from roots. There is not one tree to age, but a forest of trees all living, dying, sprouting, rotting, being old, being young and being everything in-between all at the same time. A single tree might make it to 150 but as it grows one or more new trees sprout up from its roots. The parent tree dies but the sprouts (clones of the parent) live on. From their roots sprout shoots, and those sprouts become trees which grow and die but before they do, more sprouts are produced. On and on it goes. There is one grove of quaking aspen called Pando, which extends for over 100 acres and consists of nearly 50,000 stems. Each stem is genetically the same as the first tree, it just exists 550 re-generations later.

So what does this tell us about survival in a constantly changing world? Holding onto the past isn’t the answer, and there is no future in standing still.

When you plant a tree, you are planning for the future. Not 4,500 years or even 450 years, let’s be realistic. The average tree would and should survive for 80 to 120 years in the urban environment. So with that in mind, the first thing that you should consider, as in the very first thing, is what will the growing conditions be like in 80 years’ time. What you should not do – and stop it if you are, is consider what once grew in the area. As tempting as it is, recreating the past isn’t a long-term solution.

Climate change aside, the growing conditions in downtown Auckland, Wellington, or even Morrinsville, or Mosgiel are not the same as they once were. The plains have been drained, forests felled and replaced with concrete, the rain that falls no longer falls onto foliage, and there is light long after the sun goes down – the children of Tanē Mahuta were never supposed to take a bus into town. And for those of you that don’t subscribe to natives over exotics, recreating the gardens of old is equally risky – there probably isn’t much future in planting ye olde English oak tree. Consider that and then add in climate change.

So what should we do and what should we plant?

We need to embrace the change, or at least accept it – change is and has been the only constant after all. We need to use science to build biological resilience into the future. There are climate change modelling websites all over the Net. It shouldn’t be too hard to work out what the expected average rainfall and temperature will be in your area in 80 years’ time. Find locations from around the world where your predicted climate currently exists and plant what grows there. If you live down south look at what grows up north and plant it. If you live up north… look further north. And yes, you can still plant natives, but just maybe not the ones that grew in your neck of the woods 100 years ago. Consider different species – there are many to choose from. And yes, you can recreate the look and feel of the gardens of old if you want to; but maybe with different species (there are over 500 species of oak – you will find one to fit the bill going forward).

There is much to learn from nature We can reinvent ourselves every 150 years to survive and thrive, or we can lock in the past and crumble away. Methuselah or quaking aspen? There are plenty of options going forward, but holding onto the past perhaps shouldn’t be one. 

• Written for NZ Landscaper Magazine

* apparently there is a bristlecone pine growing a few hundred metres from Methuselah that is said to be at least 500 years older than he (so around 5,000 years old). But in Europe, there is an olive tree called La sorella di Noè (The Sister of Noah) which is thought to be over 6,000 years old, and a Patagonian cypress called Alerce Milenario which is said to be at least 5,500 years old.