Tuesday, 21 July 2020

Back in the field: ash scanning in Wytham Woods

It's been a while, but y'know there's been stuff going on .... which is why it's been so nice to get back out into the field finally, collect some data, do something that feels a little bit 'normal', whatever that means now. Following a trip into the dept for the first time since March to pick up the kit, and getting our covid-19 risk assessment approved, Phil and I went out to Wytham Woods last week. We were collecting baseline TLS data from 15 plots as part of a NERC-funded project exploring the ecological impact of ash dieback. This is a large 4 year programme led by Yadvinder Malhi, with various colleagues from Oxford and elsewhere. It is fundamentally a manipulation experiment, assessing the response of high, medium and control (no ash) ash cover plots to the death of ash, which will be artificially facilitated by ring-barking in each plot. ADB is already widespread in Wytham and so this is just speeding up the process. The project is looking at the resulting impact on insects, small mammals, birds, bats, understory, soil composition and overstory including changes in light environment. We're using the TLS in a different way here - aiming to quantify the vertical structure and understory cover, rather than looking at tree structure.

To get at the vertical profiles and potentially very dense ground cover (some of the plots are just bramble apocalypse!) we rented a pump up 6m tower (see below). This enables us to get the TLS up into the canopy, and looking down on, and hopefully through the understory.

Looking up the pump-up tower into the ash canopy.
The pump-up tower worked really well, with the downside that carrying it through the plots was a pain - heavy and bulky, awkward to carry, sharp edges - gah! This meant longer days than planned, but hey after 4 months of lockdown and staying local, this felt like a bit of an adventure. After the dry weather there seemed to be a lot of mosquitoes and ticks - Phil seemed to be a particular delicacy for them, picking several off each day. It pays to be vigilant though as Lyme has been seen in Wytham although not this year, so far.
Daily tick check - put them in the tube, label them and put in the fridge. Someone's studying the ticks because of course they are - this is Wytham, someone's studying everything!
We stayed in the chalet in the woods - which has been refurbished into a really rather splendid, if slightly eccentric, field station. We didn't get as much done as we'd hoped - slowed down by the tripod, a single battery, and the terrain. And then the lidar had a disk read fail on the last day - nothing too serious we think, but we might lose a day's data which is always a pain. So we'll be back in September to finish off the leaf-on data, and then in January for the baseline leaf-off scans. But wow, it was good to be back doing some normal work again - long may it continue. Many thanks to the Oxford team, particularly Yadvinder for the lovely dinner, and Cecilia for showing us the plot locations - although you could've chosen ones with fewer brambles! :-) 

The only genuine Swiss chalet in Oxfordshire?