Impacts of physiological characteristics and human activities on the
species distribution models of orchids taking the Hengduan Mountains as
a case
Abstract
The biogeography research of orchids through species distribution models
(SDMs), a vital tool in the biogeography field, is critical to
understanding the fundamental geographic distribution patterns and
identifying conservation priorities. The correspondence between species
occurrence and environmental information is crucial to the model’s
performance. However, ecological preferences unique to different orchid
species, such as their life forms, are often overlooked during the
modeling process. This oversight can introduce bias and increase model
uncertainty. Additionally, human activities, as an important potential
predictor, have not been quantified in any orchid SDMs. Taking the
Hengduan Mountains as an example, we preprocessed all orchid species’
occurrences based on physiological characteristics. Choosing five
spatial factors related to human activities to quantify the interference
and enter into models as HI factor. Using different modeling methods
(GLM, MaxEnt, and RF) and evaluation indices (AUC, TSS, and Kappa),
diverse modeling strategies have been constructed in the study. A
double-ranking method has been adopted to select the critical orchid
distribution regions. The results showed that classification models
based on physiological characteristics significantly improved the
model’s accuracy while adding the HI factor had the same effect but the
absence of enough significance. Suitability maps indicated that highly
heterogeneous mountainous areas were vital for the distribution of
orchids in the Hengduan Mountains. Different distribution patterns and
critical regions existed between various orchid life forms
geographically - terrestrial orchids were dominant in the mountain, and
mycoherterophical orchids were primarily located in the north, more
influenced by vegetation and temperature. Critical regions of epiphytic
orchids were in the south due to a greater dependence on precipitation
and temperature. These studies are informative for understanding the
orchids’ geographic distribution patterns in the Hengduan Mountains,
promoting conservation, and providing references for similar research
beyond orchids.