Differences in seed drop periods lay the foundation for forest species diversity Research reveals the dynamic influence mechanism of climate change on plant seed rain

Cork oak and golden snub-nosed monkey in Qinling Foping Conservation Area. Photography By Zhang Xingyong

Qinling shell bucket plant – chestnut. Courtesy of the author of the paper

Qinling shell bucket plant – Quercus sharpened. Courtesy of the author of the paper

Qinling shell bucket plant – short-stemmed oak oak. Courtesy of the author of the paper

Seeds are an important organ for sexual reproduction of plants, and when the seeds mature, they spread from the mother plant to the surroundings, thus forming a rain of seeds. Seed rain refers to the number of seeds that fall from the mother plant in a specific time and space, and is a visual description of the spread of seeds or propagators around. The dynamic changes of seed rain not only affect the predation, transmission and storage of animals, but also affect the storage and dynamics of soil seed banks, thus affecting the establishment of seedlings and plant renewal.

In nature, seed rain, as the beginning of species dispersal, is a key process node in forest structure and renewal. Therefore, it is of great significance to study the dynamics of the seed rain period to understand the renewal strategy of plant populations and communities and the mechanism of maintaining system balance.

The spatial distribution of seed rain is heterogeneous, usually with seasonal dynamics and interannual variation characteristics, biological factors such as plant species, plant height, seed weight, seed propagation mode, etc., topography, slope, aspect and other environmental factors and climate factors such as temperature, precipitation, and length of sunshine may significantly affect the seed rain dynamics. If plants bloom in large quantities in some suitable climate years to produce pollen, the use of wind pollinators or insects to improve pollination efficiency is conducive to the results; conversely, excessive precipitation during the flowering period may affect the pollination activities of insects, resulting in poor fertilization or even only flowering infertility and fruitlessness.

“Therefore, climatic factors may be an important cause of seed rain fluctuations.” Hou Xiang, assistant researcher of shaanxi institute of zoology, said.

“The Species of the Family Crustaceae are widely distributed and belong to the dominant tree species in the Qinling Mountains of China, which are an important part of the forest ecosystem, usually providing food and habitat for various animals and playing an important role in the function of the ecosystem.” Therefore, it is of great significance to study the response mechanism of seed rain dynamics to climatic factors of Chitinaceae. Chang Gang, an associate researcher at the Shaanxi Institute of Zoology, elaborated.

To this end, the Chang Gang research team of the “Hazardous Animal Monitoring and Prevention and Control Research Center” of the Shaanxi Institute of Zoology has monitored the rain of four species of chickophetaceae plants distributed in the same region in the Foping National Nature Reserve on the southern slope of Qinling for 10 consecutive years, and combined with the temperature and precipitation meteorological data of the study area in the past 10 years, the response of the dynamic changes of rain of these four plant seeds to climatic factors was discussed.

Chang Gang et al. found that the seed rain fall dynamics of the four species of Chitinaceae have different sensitivities and responses to temperature and precipitation, and may also promote the spread and renewal of the plants themselves by regulating the rain and fall dynamics of seeds, thereby avoiding the predatory risk of being eaten by rodents in large quantities. His research was recently published in Biology.

According to reports, the four species with the same domain distribution selected by the institute are the dominant species widely distributed in the Qinling Mountains and occupy an important position in the Qinling ecosystem. Based on the seed rain monitoring data of four species of chickaceae plants distributed in the same domain for 10 consecutive years from 2011 to 2020, they investigated the response of four plant seed rain dynamic changes to climatic factors. The results show that chestnuts of castanea and quercus of Quercus have significant differences in the duration of seed rain fall at the beginning and end of seed rainfall and the duration of the entire seed rain fall process, indicating that there are certain biological differences between chestnuts and other three oak plants, for example, the seeds of three oak plants are easy to germinate and germinate under appropriate conditions. But chestnuts have a dormant period and must pass through a dormant period before germination, which may reflect the adaptation strategies of different plants to their environment.

Chang Gang believes that this result also reflects the difference in the rainfall time of different tree species, especially the peak period is not consistent and not completely concentrated in the same period, which can promote the coexistence of dominant species to a large extent, alleviate competition between species, and lay the foundation for maintaining forest species diversity. It is also a reproductive or adaptive strategy for plants to their environment. It shows that different species, especially different genera of plants, have different reproductive strategies, and the flowering and fruiting without concentration and piling are conducive to their better coexistence in the same domain.

In addition, the study also found that most of the four seeds have a non-linear relationship with precipitation, indicating that suitable precipitation is conducive to the accumulation of plant nutrients and seed maturation, and too much or too little precipitation may affect the photosynthesis of plants.

“This is not conducive to seed maturation and may lead to early or late seed drop-off.” Hou Xiang explains, “The seed rainfall dynamics of the four plants have different responses and sensitivities to temperature and precipitation on different time scales, which may also be the adaptation strategies of different plants to the environment. It shows that they can avoid fierce competition for limited resources by adapting to the environment. ”

The seeds of these four species of Chitinaceae are important food resources for forest rodents in the study area, and they may promote the spread and renewal of the plants themselves by regulating the rain and fall dynamics of seeds, thereby avoiding the risk of predation by rats in large quantities. Chang Gang further explained.

Chen Yiping, vice president of the Xi’an Branch of the Chinese Academy of Sciences, Shaanxi Academy of Sciences, and expert on the ecological environment of Qinling Mountains, believes that studying the coexistence strategy of neighboring tree species and its small-scale interaction will help us to have a deeper understanding of the function of forest ecosystems and the mechanism of biodiversity maintenance.

The results of this study also further show that the vegetation restoration of a region should be matched according to the evolution results of plant community species, forming an ecosystem of benign and coordinated ecological development, rather than planting a dominant tree species in a large area. This is also a foundation for the construction of a high-quality biodiversity restoration system in Qinling Mountains from light green to dark green. Chen Yiping further emphasized. (Source: China Science Daily, Zhang Xingyong, Yan Tao)

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