Abstract:

Aims: Herbarium specimens are important for taxonomic research. Analyses of these specimens are important for understanding their history, taxonomic status, and existing gaps in knowledge. In addition, such analyses allow for deeper insights into the distribution and classification of specific taxa using phylogenetic and niche modeling techniques. In most cases, identification of herbarium specimens is based on the reproductive traits. However, bamboo is a long-lived clonal plant that undergoes flowering followed by simultaneous death after a long-term growth period. As a result, most bamboo specimens only contain vegetative characters, and the information on reproductive traits remains sparse. As a result of this unique life history, bamboos are one of the most difficult taxa for taxonomic research. Here, we aim to examine the status of collection of bamboo herbarium specimens in China and document existing biases. Furthermore, we also aim to evaluate the main drivers for the distribution of the two major clades of bamboos (temperate woody bamboos, TWB; paleotropical woody bamboos, PWB).
Methods: Here, we used collection data from the major herbaria of China to analyze the current collection and preservation status of bamboo specimens. The completeness of the collection was evaluated by the ratio and slope methods with respect to geographical and group deviations. In combination with climate data from WorldClim, we used model simulations to identify the main factors affecting the distribution of bamboo.
Results: The results from the analysis on collection information indicate that there is a great unevenness in the collection and conservation of bamboo specimens in domestic herbaria. These aspects are highly dependent on the vigor of research teams. Second, variation in the collection of bamboo specimens is a clear reflection of the history of plant taxonomy research in China. Additionally, the results from the assessment of taxa and the completeness of geographic collection indicate that much work still remains for the collection and collation of bamboo specimens in China. The analysis of model simulations showed that the distribution of the two major clades of bamboos in China is mainly limited by a low temperature. Moisture had a greater effect on the distribution of TWB than on PWB, while the effect of temperature was higher for PWB. Results from niche modeling further indicate that the PWB and the TWB in China have diverged in area use with only some overlap in subtropical areas.
Conclusions: Our study highlights the geographic distribution and taxa collecting biases in herbarium specimens of bamboos in China, as well as the significance of climate variables for the distributions of temperate and paleotropical woody bamboos. Our findings also indicate some poorly sampled areas, which should be preferential targets for future biodiversity surveys. Furthermore, as millions of digitalized herbarium specimens become available online and will play an important role in revealing large-scale diversity patterns. Such effort can improve the forecasts of the impacts of climatic change on the biodiversity.

Key words: bamboo, herbarium specimens, collection status, completeness assessment, climate factors, geographical distribution