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The impact of climate change on the distribution of two threatened Dipterocarp trees

View Article: PubMed Central - PubMed

ABSTRACT

Two ecologically and economically important, and threatened Dipterocarp trees Sal (Shorea robusta) and Garjan (Dipterocarpus turbinatus) form mono‐specific canopies in dry deciduous, moist deciduous, evergreen, and semievergreen forests across South Asia and continental parts of Southeast Asia. They provide valuable timber and play an important role in the economy of many Asian countries. However, both Dipterocarp trees are threatened by continuing forest clearing, habitat alteration, and global climate change. While climatic regimes in the Asian tropics are changing, research on climate change‐driven shifts in the distribution of tropical Asian trees is limited. We applied a bioclimatic modeling approach to these two Dipterocarp trees Sal and Garjan. We used presence‐only records for the tree species, five bioclimatic variables, and selected two climatic scenarios (RCP4.5: an optimistic scenario and RCP8.5: a pessimistic scenario) and three global climate models (GCMs) to encompass the full range of variation in the models. We modeled climate space suitability for both species, projected to 2070, using a climate envelope modeling tool “MaxEnt” (the maximum entropy algorithm). Annual precipitation was the key bioclimatic variable in all GCMs for explaining the current and future distributions of Sal and Garjan (Sal: 49.97 ± 1.33; Garjan: 37.63 ± 1.19). Our models predict that suitable climate space for Sal will decline by 24% and 34% (the mean of the three GCMs) by 2070 under RCP4.5 and RCP8.5, respectively. In contrast, the consequences of imminent climate change appear less severe for Garjan, with a decline of 17% and 27% under RCP4.5 and RCP8.5, respectively. The findings of this study can be used to set conservation guidelines for Sal and Garjan by identifying vulnerable habitats in the region. In addition, the natural habitats of Sal and Garjan can be categorized as low to high risk under changing climates where artificial regeneration should be undertaken for forest restoration.

No MeSH data available.


Graphs showing the marginal relationship between each bioclimatic variable and the probability of species occurrence: In the figures, the curves (red) and the mean ± standard deviation (blue) show the response of Shorea robusta and Dipterocarpus turbinatus to the two most important variables (i.e., keeping all other bioclimatic variables at their average sample value) annual precipitation, and annual mean temperature. The y‐axes indicate logistic output (probability of presence). The results suggest that there was an overall positive nonlinear response observed for annual precipitation for both species. The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models
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ece32846-fig-0002: Graphs showing the marginal relationship between each bioclimatic variable and the probability of species occurrence: In the figures, the curves (red) and the mean ± standard deviation (blue) show the response of Shorea robusta and Dipterocarpus turbinatus to the two most important variables (i.e., keeping all other bioclimatic variables at their average sample value) annual precipitation, and annual mean temperature. The y‐axes indicate logistic output (probability of presence). The results suggest that there was an overall positive nonlinear response observed for annual precipitation for both species. The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models

Mentions: The individual response curves (marginal responses obtained by keeping all other bioclimatic variables at their average sample value) of the two key variables (annual precipitation and annual mean temperature) portray the relationships between each bioclimatic variable and probability of species occurrence (Figure 2). In Figure 2a–f curves represent the response of annual precipitation and annual mean temperature for three Sal models, respectively. Curves (g–i) and (j–l) represent the response of annual precipitation and annual mean temperature for three Garjan models, respectively. The results exhibit complex but quadratic relationships between bioclimatic variables and the probability of species occurrence. In general, there was an overall positive nonlinear response observed for annual precipitation for both species (Figure 2). The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models (Figure 2). However, the curves showed a high probability of presence of the species at low temperatures (especially for Garjan; Figure 2 j–l). This might be due to the occurrence of the species in different forest ecosystems with a large range of temperature and elevation.


The impact of climate change on the distribution of two threatened Dipterocarp trees
Graphs showing the marginal relationship between each bioclimatic variable and the probability of species occurrence: In the figures, the curves (red) and the mean ± standard deviation (blue) show the response of Shorea robusta and Dipterocarpus turbinatus to the two most important variables (i.e., keeping all other bioclimatic variables at their average sample value) annual precipitation, and annual mean temperature. The y‐axes indicate logistic output (probability of presence). The results suggest that there was an overall positive nonlinear response observed for annual precipitation for both species. The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383467&req=5

ece32846-fig-0002: Graphs showing the marginal relationship between each bioclimatic variable and the probability of species occurrence: In the figures, the curves (red) and the mean ± standard deviation (blue) show the response of Shorea robusta and Dipterocarpus turbinatus to the two most important variables (i.e., keeping all other bioclimatic variables at their average sample value) annual precipitation, and annual mean temperature. The y‐axes indicate logistic output (probability of presence). The results suggest that there was an overall positive nonlinear response observed for annual precipitation for both species. The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models
Mentions: The individual response curves (marginal responses obtained by keeping all other bioclimatic variables at their average sample value) of the two key variables (annual precipitation and annual mean temperature) portray the relationships between each bioclimatic variable and probability of species occurrence (Figure 2). In Figure 2a–f curves represent the response of annual precipitation and annual mean temperature for three Sal models, respectively. Curves (g–i) and (j–l) represent the response of annual precipitation and annual mean temperature for three Garjan models, respectively. The results exhibit complex but quadratic relationships between bioclimatic variables and the probability of species occurrence. In general, there was an overall positive nonlinear response observed for annual precipitation for both species (Figure 2). The optimum annual mean temperature for the probability of both Sal and Garjan occurrence was approximately 28°C in all models (Figure 2). However, the curves showed a high probability of presence of the species at low temperatures (especially for Garjan; Figure 2 j–l). This might be due to the occurrence of the species in different forest ecosystems with a large range of temperature and elevation.

View Article: PubMed Central - PubMed

ABSTRACT

Two ecologically and economically important, and threatened Dipterocarp trees Sal (Shorea robusta) and Garjan (Dipterocarpus turbinatus) form mono‐specific canopies in dry deciduous, moist deciduous, evergreen, and semievergreen forests across South Asia and continental parts of Southeast Asia. They provide valuable timber and play an important role in the economy of many Asian countries. However, both Dipterocarp trees are threatened by continuing forest clearing, habitat alteration, and global climate change. While climatic regimes in the Asian tropics are changing, research on climate change‐driven shifts in the distribution of tropical Asian trees is limited. We applied a bioclimatic modeling approach to these two Dipterocarp trees Sal and Garjan. We used presence‐only records for the tree species, five bioclimatic variables, and selected two climatic scenarios (RCP4.5: an optimistic scenario and RCP8.5: a pessimistic scenario) and three global climate models (GCMs) to encompass the full range of variation in the models. We modeled climate space suitability for both species, projected to 2070, using a climate envelope modeling tool “MaxEnt” (the maximum entropy algorithm). Annual precipitation was the key bioclimatic variable in all GCMs for explaining the current and future distributions of Sal and Garjan (Sal: 49.97 ± 1.33; Garjan: 37.63 ± 1.19). Our models predict that suitable climate space for Sal will decline by 24% and 34% (the mean of the three GCMs) by 2070 under RCP4.5 and RCP8.5, respectively. In contrast, the consequences of imminent climate change appear less severe for Garjan, with a decline of 17% and 27% under RCP4.5 and RCP8.5, respectively. The findings of this study can be used to set conservation guidelines for Sal and Garjan by identifying vulnerable habitats in the region. In addition, the natural habitats of Sal and Garjan can be categorized as low to high risk under changing climates where artificial regeneration should be undertaken for forest restoration.

No MeSH data available.