NEWS
We recorded and counted as many butterfly species as we could , allowing us to determine just how important natural grassland habitats are among plantation compartments . The results were clear – butterflies need grassland habitats to outlive human transformation .
Not that simple
There is a catch . Conserving only one or a few feature grassland types won ’ t protect all butterfly species .
Our results show that grasslands of similar types vary considerably . Each grassland has a set of characteristics that defines them such as availability of sunlight during the day , resistance to fire outbreaks and richness of flowering plants . These characteristics are important for attracting particular butterfly species that would avoid another type of grassland .
Butterflies are highly mobile insects . Many species rely on small elevation variations to complete their day-to-day tasks . In particular , butterflies move up and down the elevation gradient to avoid , or catch , more sun . This means it ’ s important for butterflies to have access to habitats at various elevations throughout the day .
Figure 2 . A Geranium bronze butterfly settles on some flowers in the study area . Charl Deacon
grassland types , in addition to flower diversity , is important for butterflies . When it ’ s not possible to conserve whole grassland areas , a variety of smaller grassland patches can help protect butterflies and other insects against environmental transformation . This means that effective insect conservation is possible in areas earmarked for largescale transformation – without sacrificing economic gain .
The landscape
Timber estates occupy a large proportion of the grassland landscape in the KwaZulu-Natal province , where we conducted our study . This leaves little habitat for grassland butterflies in some areas .
To ensure that the biological impact of plantation forestry is minimised , forestry practitioners have moved towards leaving at least a third of natural grasslands untouched among timber plantations . This provides butterflies and other insects with enough habitat to roam the landscape while timber production continues in other sections .
But this approach raises an important question : does it matter which grasslands are set aside for conservation ? Or is one grassland much the same as another ?
The butterflies Many butterfly species roam in high elevation habitats , like the Mistbelt Grasslands of KwaZulu-Natal province . The area also forms part of one of the world ’ s biodiversity hotspots .
Inconspicuous species such as the Natal spotted blue ( Azanus natalensis ) and the Meadow blue ( Cupidopsis cissus cissus ), along with large and showy species such as the Mountain pride ( Aeropetes tulbaghia ), frequent grasslands in the region .
A keen eye might even spot some magisterial species briefly darting over , like the Flying handkerchief ( Papilio dardanus cenea ). Strikingly , these species and their counterparts rarely enter timber plantation compartments ; they rely on grassland habitats .
Butterfly population levels are also highly variable between seasons and from one year to the next . During times when feeding and breeding resources are scarce , butterfly populations may be more concentrated in areas where resources are more reliable . Resources are often more reliable in nature reserves , meaning that butterflies need to access them .
When grassland patches among plantations are connected to nature reserves at the landscape level , they are more accessible to moving butterflies . This means that butterfly diversity is higher in grasslands that are close to , and connected to , neighbouring protected areas .
All of this is important information because it can help in guiding decisions about where to focus grassland conservation efforts in the region .
Next steps
Our study shows that landscape variety is best and that taking this landscapescale variety into consideration in conservation practices can greatly counteract human impact on natural systems .
In viewing butterflies as sentinels in conservation , we can use this information to decide which grasslands to conserve , or restore , to better protect all their insect residents .
17 Grassroots Vol 23 No 2 July 2023