SAEON’s monitoring sites experience a key fynbos ecosystem driver - fire!

By Abri de Buys, Technician, SAEON Fynbos Node

As with several of South Africa’s biomes, fire is an important ecosystem driver in fynbos. Fire regimes are one aspect of the environment that is anticipated to change in future and something that SAEON pays attention to.

Changes in fire regimes and post-fire vegetation recovery in mountain catchments have implications for vegetation cover, composition and therefore water runoff. Climate is obviously an important factor in this equation.

Monitoring of temperature, humidity, wind, rainfall and other weather variables to understand the interactions of climate, vegetation and drivers such as fire is a staple of SAEON’s business in terrestrial ecosystems. We are thus taking calculated risks and mostly getting away with great results when we install sensor networks in fire-prone ecosystems to understand how they function.

With the Cape Peninsula fire grabbing headlines in early March 2015, the SAEON Fynbos Node, along with most other Capetonians, were following it as closely as we could with mixed feelings of awe and dread as we tried to ascertain if, or when, our equipment networks were going to be in trouble. First to be affected on the peninsula was our network of temperature and humidity sensors, part of a project led by Node Scientist Dr Jasper Slingsby to study the effects of fine-scale topographical differences on local climate.

Then, as the smoke started rising from Constantiaberg peak, we watched the live connection to our Constantiaberg weather station reach a maximum temperature of 74 degrees Celsius!

With the flames barely out on the Peninsula, we received the news that a fire had started at our main monitoring platform site, Jonkershoek. In the week that followed, all but five of our monitoring stations were badly damaged.

Below follows a series of photographs taken at Jonkershoek during the ten days after SAEON could regain access to the sites (16-25 March 2015).

Langrivier catchment, the fynbos "control" catchment for the historical Jonkershoek afforestation research and a site where SAEON and our supported students have been studying whether a denser network of rain gauges would better allow us to explain runoff measured at the weir below. It is also the site of the Fynbos Node’s fog collector transect across the elevation gradient.

Looking down the Langrivier catchment towards the valley floor, where fire went through the Langrivier riparian thicket. The transect of fog monitoring stations would be on the ridge to the right.

Near the upper reaches of the Langrivier catchment, the SAEON team is on their way to the fog station at 800 metres above sea level. Along the stream below some patches of riparian forest remain intact after the fire burnt on both slopes.

  Fynbos Node technical intern, Luvuyo Dlamini, looks down the valley from the top of Langrivier fog station.

Fire damage to the fog gauges. A similar sight was encountered at each of them.

Wind speed and direction sensors warped and stuck in position.

Some of the weir huts and water monitoring equipment had a narrow escape.

A layer of ash covers the inside of a weir hut. The domed grey object in the middle of the image is part of the water-level sensor’s data transmission system. The black cable to the underwater sensor can be seen at the bottom of the picture.

Other weir huts were not so lucky. Here Luvuyo Dlamini removes the remains of a melted data transmission antenna from the top of a hut.

Fynbos Node technicians Abri de Buys (left) and Luvuyo Dlamini try to prise a melted rain gauge funnel from its base to assess the damage inside. Strings of melted plastic hang suspended from the white radiation shield under the rain gauge platform where the temperature logger is housed.

All that remains of an automated rain gauge. A couple of these stations were still recognisable, with so little damage to their loggers that these could be downloaded. A maximum air temperature of 82 degrees Celsius was recorded at one. The one shown above sustained too much damage to be downloaded.

A howling Southeaster blows mist from the orographic cloud across the Dwarsberg down into the Jonkershoek valley and over the burnt landscape.

Swartboschkloof automated weather station (property of the Agricultural Research Council) sustained some fire damage. On the slopes in the background are some scorched and burnt pine plantations as well as some that were not affected.

An example of the remarkable fire adaptations to be found in fynbos - a protea cone that opened to release its seed after the fire. Vast amounts of seed can be seen where mature fynbos burnt, both in Jonkershoek and on the Cape Peninsula.