Distribution patterns and influencing factors of different parasitic angiosperm types in China

Abstract

Parasitic plants are widely distributed in major biomes. They can be categorized into root parasites and stem parasites in terms of parasitic sites or divided into hemiparasites and holoparasites according to the degree of nutritional dependence on their hosts via haustoria. However, little is known concerning distribution patterns of different parasitic plant types and their determinants, which may be helpful for effective management and ecological conservation. Here, we collated an updated checklist of parasitic angiosperms in China and examined the distribution pattern of the four types, and then performed multiple linear regression analysis and redundancy analysis of 22 influencing factors representing biotic, topographic, and climatic factors. There are 745 species of parasitic angiosperms in China, belonging to 50 genera and 12 families. Regarding root parasites, most appeared in the west of China than in the east; while stem parasites showed a broader north-south divide in distribution. Hemiparasites were fewer in the east and more in the southwest. However, holoparasites displayed a patchy distribution across China. The results of redundancy analysis (after eliminating multicollinearity effects) showed that explained variation of root parasites, stem parasites, and hemiparasites was 87.9%, 93.7%, and 87.0%, respectively; while that of holoparasites was only 57.8%. Therefore, the four types of parasitic angiosperms varied quite distinctly in terms of distribution patterns across China. Seed plant richness was one of the common leading factors affecting distributions of root parasites, stem parasites, and hemiparasites in China. Besides, the other major influencing factors were the maximum temperature of the warmest month (Bio5), temperature seasonality (Bio4) and precipitation of the warmest quarter (Bio18), and isothermality (Bio3), respectively. Additionally, the main factor affecting holoparasites’ distribution was the temperature (Bio3). We found that different parasitic angiosperm types in China were mainly affected by the biotic factor, temperature, and precipitation. In addition, the whole flora of parasites was similar to root parasites and hemiparasites in distribution; nevertheless, its leading factors were the same as those of hemiparasites. Our findings reveal the various responses of different parasitic angiosperm types to the environmental changes across China. It probably comes down to the evolutionary relationships and life strategies among these different types.