It’s the end of the dry season and the landscape at Mutinondo Wilderness is in limbo as it awaits the first rains. From up on the grey granite inselbergs, you can look out across the mosaic of miombo woodland flushing its new red leaves and dambo wetlands that are golden with dense dry grasses. Patches of blackened fire scars already show green signs of regrowth.
Our transect spanned the transition from miombo to the gentle grassy slopes and down to the dambo drainage line. We tested out a new ‘moving window’ design for the Global Grassy Group protocol for recording herbaceous species and trained researchers who are commencing projects in Zambia, Democratic Republic of the Congo, Zimbabwe and South Africa. Each circular subplot, 1m in diameter, is a snapshot of ground-layer plant community composition and is a way to track species that appear, persist, or vanish over space and time. We had expected most plants to be dormant at this time of year, but the data sheets told quite a different story - scattered forbs were in flower and many grasses were (surprisingly) identifiable.
Alongside the vegetation transect, we installed a series of sensors across three miombo/dambo transitions to calibrate microclimate models of waterlogging and frost. Soil moisture and temperature, at ground level and at 10cm deep, will be recorded over the year. We also measured other metrics such as tree cover and grass height, which will influence the localised conditions that the sensors detect. These data will be pooled with comparable transects in Bicuar National Park, Angola, where we sampled last year as part of our project ‘Mapping and Managing Africa’s Grasslands’.
One morning, we had a stark reminder that fire is also a predominant process in the Miombo landscape. Our plot burned with 6m high flames, but it was over quickly thanks to the tireless Mutinondo management team. Walking on the burned area, it was fascinating to see the trees unaffected despite a bit of scorching, unburned trails up and down the transect where we had trampled, and (most) microclimate sensors still functioning.
The fire spanned the whole shallow valley side, up to the opposite slope that was no longer flammable after a management burn 2 months ago. This previous burn already had regrowth and we set up vegetation plots out of curiosity to somewhat predict the near future of our transect. We found almost an entirely different species composition and many more flowers blooming - but the stars of the show were the especially well-prepared underground trees.
Monitoring vegetation through big fires and small variations in soil moisture helps explain how species composition and ecosystem function shift through cycles of disturbance and recovery. This field season in particular reminded us that grassy ecosystems are always in flux - something best considered from back up on the inselbergs at sunset.
Thank you to Prof. Sally Arichibald (University of the Witwatersrand, South Africa), Prof. Stephen Syampungani (Copperbelt University, Zambia), Dr. Mwale Chishaleshale (Copperbelt University, Zambia), Dr. Edouard Ilunga (Copperbelt University, Zambia), Mokwani Kaluwe (Division of Forest Research, Zambia), Jone Fernando Junior (University of the Witwatersrand, South Africa) and Dr. Theo Maponga (University of the Witwatersrand, South Africa) who made the fieldwork fun and efficient! Many thanks also to Steyl Prinsloo Heyns and Kyla Fick for facilitating our research at Mutinondo. This work was funded by South Africa’s National Research Foundation, the Oppenheimer Generations Research and Conservation program Future Ecosystems for Africa, and the European Commission.