Are Climate Changes and Extremes Responsible for Changes in Vegetation Phenology in South Africa?

ABSTRACT

Changes in vegetation density and phenology are widely attributed to rising temperatures and altered precipitation. In South Africa, however, recent climate change has been characterised primarily by increasing temperature extremes rather than shifts in mean conditions. We assessed vegetation greenness and phenology using enhanced vegetation index (EVI) data from 154 protected areas (> 100 km ² ; 2001–2024) and trends in climate extremes and seasonality at 42 weather stations (1980–2024). EVI showed few significant long‐term trends and no systematic shifts in phenology (start, peak or end of growing season) at individual reserves, despite strong seasonal cycles. Mixed‐effects models across all reserves, however, detected small but significant decadal increases in EVI and a possible delay in the end of the growing season—a subtle signal not apparent in individual reserves. Maximum temperatures increased by 0.52°C decade ⁻¹ and annual temperature range increased markedly, while mean annual precipitation showed no coherent national trend despite longer wet spells and higher extremes. These limited and spatially inconsistent changes suggest that increasing temperature extremes have not yet driven widespread or ecologically substantial vegetation responses in the protected areas examined. This is possibly because much of this vegetation is water‐limited, precipitation has changed little nationally, and photoperiod may constrain growing‐season timing shifts. A climate–EVI linkage analysis confirmed EVI responds to inter‐annual climate variability, with precipitation anomalies the dominant predictor and temperature anomalies also significant, though climate explained only a modest fraction ( R ²  = 12.4%) of reserve‐level EVI variation. Where sustained rainfall declines did occur, such as at Springbok (−46 mm decade ⁻¹ ), corresponding EVI declines were observed in adjacent protected areas, consistent with water availability as the dominant constraint in these systems. Overall, we found little evidence for systematic shifts in climate seasonality in contrast to reports for extratropical regions. Instead, recent climate change across most of South Africa has intensified extremes without yet producing widespread ecological responses in vegetation greenness or phenology.