Threatened plant species here include Indigofera rehmannii , Inezia speciosa , Merwilla plumbea and Aloe lettyae ( Figure 1 ). In recent years , SAEON ’ s Ndlovu Node has supported efforts to collect the baseline data necessary for the long-term monitoring and population assessment of this endangered flagship Aloe species , which is endemic to the critically endangered Woodbush Granite Grassland .
NEWS
Tackling a BIG problem in a SMALL grassland : Beating bracken for biodiversity ’ s sake
The Limpopo Province ’ s most threatened vegetation type is it ' s just over 2 000 km 2 of grassland . Mostly situated at the northern limit of the Great Escarpment , these grasslands constitute the Wolkberg Centre of Endemism , supporting high levels of often unique biodiversity , much of which are of conservation concern
Dr Dave Thompson
Current Address : SAEON Ndlovu Node Reprinted From : https :// bit . ly / 37Pw82t
In 2016 it was estimated that less than 6 % of this grassland type remained untransformed , restricted to just 10 isolated fragments . The largest of these includes the 126-hectare Haenertsburg Nature Reserve site of over a decade of vegetation fire-response monitoring by the SAEON Ndlovu Node ( Figure 2 ).
Figure 1 : Grasslands are hyperdiverse systems , often containing endemic and threatened forb taxa . Examples from Limpopo include ( from left ): Indigofera rehmannii , Inezia speciosa , Merwilla plumbea and Aloe lettyae . ( Photos : Sylvie Kremer-Köhne )
Findings from this show that even frequent application of fire as a management tool cannot prevent transformation of the diverse herbaceous layer , with indigenous ( and to a lesser degree exotic ) woody species rapidly taking hold . On the back of these findings , reserve management now prioritises burning and the ongoing assessment of woody encroachment .
Symptomatic of this encroachment is the presence of bracken fern – Pteridium aquilinum ( Figure 3 ), which is singled out in the Haenertsburg Nature Reserve management plan as needing to be closely monitored , and strategies to control its spread need to be investigated .
But why the special attention ?
Figure 2 : Dr Dave Thompson and Mightyman Mashele have been monitoring vegetation in permanent monitoring plots in the species-rich grasslands of the Haenertsburg Nature Reserve since 2009 . ( Photo : Sylvie Kremer-Köhne )
In 2011 the species occurred in 8 % of periodically burned permanent vegetation plots being monitored by SAEON ; in 2020 that figure had nearly doubled to 15 %.
Bracken is one of the most successful invasive plant species in the world – indeed it has the widest distribution of any plant taxa and occurs in woodlands and grasslands in subtropical and temperate regions the world over . Once
Grassroots Vol 20 No 4 December 2020 22