Abstract
As an important bottom-up driver of ecosystem processes, rainfall is intrinsically linked to the dynamics of vegetation and species distributions through its effects on soil moisture content and surface water availability. Rainfall effects are thus spatially and temporally specific to different environmental role-players. Knowledge of its spatio-temporal pattern is therefore essential to understanding natural ecosystem flux and potential climate change effects. Climate change poses a serious threat to protected areas in particular, as they are often isolated in fragmented landscapes and confined within hard park boundaries. In consequence, a species' natural movement response to resulting climate-induced niche shifts is often obstructed. Long-term, accurate and consistent climate monitoring data are therefore important resources for managers in large protected areas like the Kruger National Park (Kruger). In this article we model local rainfall measurements as a function of global rainfall surfaces, elevation and distance to the ocean using a generalized additive mixed effects model to produce fine-scale (1 km 2) monthly rainfall surfaces from July 1981 to June 2015. Results show a clear seasonal cycle nested within an oscillating multi-decadal trend. Most noticeably, seasonality is shifting both temporally and spatially as rainfall moves outside of the typical dry/wet periods and areas. In addition, high-rainfall seasons are generally receiving more rainfall while low-rainfall seasons are receiving less. Northwestern regions of the park are experiencing more extreme annual rainfall differences, while far northern and southern regions show greater seasonality changes. The well-described north–south and east–west rainfall gradient is still visible but the spatial complexity of this pattern is more pronounced than expected. Taken together, we show that Kruger's spatio-temporal rainfall patterns are changing significantly in the short to medium term. The resulting raster data set is made freely available to promote holistic ecosystem studies and support longer-term climate change research (http://dataknp.sanparks.org/sanparks/).
Original language | English |
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Pages (from-to) | 2506-2519 |
Number of pages | 14 |
Journal | International Journal of Climatology |
Volume | 38 |
Issue number | 5 |
Early online date | 3 Jan 2018 |
DOIs | |
Publication status | Published - 2018 |
Funding
We are grateful to Benedikt Gräler for assistance with earlier attempts at spatio-temporal kriging with the gstat package, and Judith Botha for making data available on the SANParks Data Repository. We thank SAWS and SAN-Parks for access to rainfall station data. This project was supported by the National Research Foundation (NRF) of South Africa (grant nos. 89967, 109244 and 109683). Opinions expressed and conclusions arrived at, are those of the authors and are not necessarily to be attributed to the NRF.
Funders | Funder number |
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National Research Foundation | 109244, 89967, 109683 |