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Modelling the distribution of Aspalathus linearis (Rooibos tea): implications of climate change for livelihoods dependent on both cultivation and harvesting from the wild.

Lötter D, Maitre D - Ecol Evol (2014)

Bottom Line: Climate change predictions for the region indicate a significant warming scenario coupled with a decline in winter rainfall.Most of the areas where range expansion was indicated are located in existing conservation areas or include conservation worthy vegetation.These findings will be critical in directing conservation efforts as well as developing strategies for farmers to cope with and adapt to climate change.

View Article: PubMed Central - PubMed

Affiliation: CSIR, Natural Resources and the Environment P.O Box 320, Stellenbosch, 7602, South Africa.

ABSTRACT
Aspalathus linearis (Burm. f.) R. Dahlgren (rooibos) is endemic to the Fynbos Biome of South Africa, which is an internationally recognized biodiversity hot spot. Rooibos is both an invaluable wild resource and commercially cultivated crop in suitable areas. Climate change predictions for the region indicate a significant warming scenario coupled with a decline in winter rainfall. First estimates of possible consequences for biodiversity point to species extinctions of 23% in the long term in the Fynbos Biome. Bioclimatic modelling using the maximum entropy method was used to develop an estimate of the realized niche of wild rooibos and the current geographic distribution of areas suitable for commercially production. The distribution modelling provided a good match to the known distribution and production area of A. linearis. An ensemble of global climate models that assume the A2 emissions scenario of high energy requirements was applied to develop possible scenarios of range/suitability shift under future climate conditions. When these were extrapolated to a future climate (2041-2070) both wild and cultivated tea exhibited substantial range contraction with some range shifts southeastwards and upslope. Most of the areas where range expansion was indicated are located in existing conservation areas or include conservation worthy vegetation. These findings will be critical in directing conservation efforts as well as developing strategies for farmers to cope with and adapt to climate change.

No MeSH data available.


Related in: MedlinePlus

Marginal response curves of the most important predictor variables explaining wild tea suitability: (A) average winter rainfall, (B) land types rainfall, (C) average summer rainfall, (D) average minimum winter temperature, (E) slope derived from a digital terrain model, and (F) average maximum summer temperature.
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fig04: Marginal response curves of the most important predictor variables explaining wild tea suitability: (A) average winter rainfall, (B) land types rainfall, (C) average summer rainfall, (D) average minimum winter temperature, (E) slope derived from a digital terrain model, and (F) average maximum summer temperature.

Mentions: The potential distribution of A. linearis in geographic space (Fig. 3B) was predicted with reasonable success (test omission rate of 0.07) at the minimum training presence threshold. It exhibits a good match to the known distribution of A. linearis in the greater Cederberg region (Fig. 3B). The environmental variables used to define the bioclimatic envelope of A. linearis corresponded with the variables used in modelling cultivated tea, but differed in the contribution each variable made to define the envelope. According to the jacknife procedure, winter precipitation (31.2%), minimum temperatures (26%) during winter, and land types (18.6%) were the most important variables. Summer precipitation remained a significant variable, although to a lesser extent than for the cultivated tea. Land types of sandstone origin were still significant and also included soils with more rocky outcrops. In addition, slope increased a little in importance with an optimum between 3° and 10°. Both winter and summer precipitation displayed the same open-ended response curves as cultivated tea (Fig. 4A and B). They displayed a similar response of decreased suitability as rainfall increases above a certain value, indicated by the response curves generated using only the corresponding variable. The potential distribution of wild tea is similar to that of the cultivated tea, although more restricted to mountainous areas. The environmental space was also somewhat different. This can be seen in the different optima of the environmental variables and the shape of the response curves (Fig. 4). Minimum temperature during winter exhibits a narrower range of temperatures, which corresponds to the narrower elevation range of wild compared with the cultivated tea.


Modelling the distribution of Aspalathus linearis (Rooibos tea): implications of climate change for livelihoods dependent on both cultivation and harvesting from the wild.

Lötter D, Maitre D - Ecol Evol (2014)

Marginal response curves of the most important predictor variables explaining wild tea suitability: (A) average winter rainfall, (B) land types rainfall, (C) average summer rainfall, (D) average minimum winter temperature, (E) slope derived from a digital terrain model, and (F) average maximum summer temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4020683&req=5

fig04: Marginal response curves of the most important predictor variables explaining wild tea suitability: (A) average winter rainfall, (B) land types rainfall, (C) average summer rainfall, (D) average minimum winter temperature, (E) slope derived from a digital terrain model, and (F) average maximum summer temperature.
Mentions: The potential distribution of A. linearis in geographic space (Fig. 3B) was predicted with reasonable success (test omission rate of 0.07) at the minimum training presence threshold. It exhibits a good match to the known distribution of A. linearis in the greater Cederberg region (Fig. 3B). The environmental variables used to define the bioclimatic envelope of A. linearis corresponded with the variables used in modelling cultivated tea, but differed in the contribution each variable made to define the envelope. According to the jacknife procedure, winter precipitation (31.2%), minimum temperatures (26%) during winter, and land types (18.6%) were the most important variables. Summer precipitation remained a significant variable, although to a lesser extent than for the cultivated tea. Land types of sandstone origin were still significant and also included soils with more rocky outcrops. In addition, slope increased a little in importance with an optimum between 3° and 10°. Both winter and summer precipitation displayed the same open-ended response curves as cultivated tea (Fig. 4A and B). They displayed a similar response of decreased suitability as rainfall increases above a certain value, indicated by the response curves generated using only the corresponding variable. The potential distribution of wild tea is similar to that of the cultivated tea, although more restricted to mountainous areas. The environmental space was also somewhat different. This can be seen in the different optima of the environmental variables and the shape of the response curves (Fig. 4). Minimum temperature during winter exhibits a narrower range of temperatures, which corresponds to the narrower elevation range of wild compared with the cultivated tea.

Bottom Line: Climate change predictions for the region indicate a significant warming scenario coupled with a decline in winter rainfall.Most of the areas where range expansion was indicated are located in existing conservation areas or include conservation worthy vegetation.These findings will be critical in directing conservation efforts as well as developing strategies for farmers to cope with and adapt to climate change.

View Article: PubMed Central - PubMed

Affiliation: CSIR, Natural Resources and the Environment P.O Box 320, Stellenbosch, 7602, South Africa.

ABSTRACT
Aspalathus linearis (Burm. f.) R. Dahlgren (rooibos) is endemic to the Fynbos Biome of South Africa, which is an internationally recognized biodiversity hot spot. Rooibos is both an invaluable wild resource and commercially cultivated crop in suitable areas. Climate change predictions for the region indicate a significant warming scenario coupled with a decline in winter rainfall. First estimates of possible consequences for biodiversity point to species extinctions of 23% in the long term in the Fynbos Biome. Bioclimatic modelling using the maximum entropy method was used to develop an estimate of the realized niche of wild rooibos and the current geographic distribution of areas suitable for commercially production. The distribution modelling provided a good match to the known distribution and production area of A. linearis. An ensemble of global climate models that assume the A2 emissions scenario of high energy requirements was applied to develop possible scenarios of range/suitability shift under future climate conditions. When these were extrapolated to a future climate (2041-2070) both wild and cultivated tea exhibited substantial range contraction with some range shifts southeastwards and upslope. Most of the areas where range expansion was indicated are located in existing conservation areas or include conservation worthy vegetation. These findings will be critical in directing conservation efforts as well as developing strategies for farmers to cope with and adapt to climate change.

No MeSH data available.


Related in: MedlinePlus