Areas with moderate to high temperatures and abundant rainfall throughout the year are heavily forested unless humans have cleared the land for agriculture! Areas with somewhat less rainfall are mainly grasslands, which are called prairies in North America. Humans have converted grasslands into rich agricultural areas around the world. Even in areas with high yearly rainfall, trees are scarce if there is not much rainfall during the warm growing season.
If the variance of transformed data was still not homogenous, treatment differences were assessed using the Kruskal—Wallisnon-parametric test. Survival percentage, morphological characters plant height, leaf area, root length, branch length and number of branches, flowers, fruits and seeds , dry mass accumulation and allocation total dry mass and proportion allocated to roots, stems, leaves and reproductive organs and offspring seed germination were analysed as dependent variables with a two-way ANOVA.
Germination season and watering regime were considered as fixed effects. All data analyses were performed with the software SPSS Snow depth was Increase in precipitation delayed flowering, fruiting and withering of AG and SG plants about 1—2 days, but the difference was not significant Table 1. Effects of increased precipitation on life cycle phenology of spring-germinating SG and autumn-germinating AG plants of Erodium oxyrhynchum. Increased precipitation improved survival of SG plants significantly from Summary of a two-way ANOVA showing the effects of different germination seasons and increased precipitation treatments on life history traits.
However, there was no significant change in root length of SG with increased precipitation. Effects of increased precipitation on root length A , height B , leaf number C , leaf area D , branch number E and branch length F of spring-germinating SG plants and autumn-germinating AG plants of Erodium oxyrhynchum. Effects of increased precipitation on seed number A , dry mass B , dry mass allocation C and offspring seed germination D of spring-germinating SG and autumn-germinating AG plants of Erodium oxyrhynchum.
Total dry mass of AG 0 was 1. Similarly, dry mass of reproductive organs of AG 0 was 1. Total biomass per plant for SG was 0. Reproductive allocation did not differ significantly between SG and AG. Our hypothesis that the life history traits of SG plants of E. Increased precipitation increased seed production and total biomass more for SG than for AG plants, thus supporting our hypothesis.
Thus, root length data do not support our hypothesis. The overall percentage of survival to maturity of AG was lower than that of SG in the control, probably due to AG experiencing extremely low temperatures in winter Fig. This finding is consistent with the results for seedlings of Chamaecyparis nootkatnesis in which the exposure to freezing stress damaged the fine roots and foliar browning and mortality occurred after the onset of warming conditions Schaberg et al.
Plant death in April likely can be attributed to frost-damaged tissues not becoming metabolically active as temperatures increased in spring Fan et al. Also, there were some late freezes in April Fig. Further, the different effects of increased precipitation on survival of SG and AG are related to differences in phenology stage and size of SG and AG when precipitation was increased in spring.
SG were still in the seedling stage with only a few leaves, while AG were larger with more leaves and thus not as sensitive as SG to increased precipitation.
Therefore, future increased precipitation in early spring may especially improve the survival of SG. The morphological characteristics of AG and SG in response to increased precipitation only partly support our hypothesis.
That is, increased precipitation significantly increased all of the measured morphological characters of SG, except root length, while it increased some characters of AG and decreased others. The significant decrease in root length of AG 30 and AG 50 compared with AG 0 indicates that increased water in the upper soil profile stimulated roots to stop growing into the deeper layers.
However, the relatively dry soil of AG 0 stimulated roots to grow deeper into the soil. Studies on Stipa bungeana in the desertified grasslands of the Ordos Plateau in Inner Mongolia China also have found that root length increased as depth to moist soil in the soil profile increased Cheng et al. Thus, AG may have an advantage over SG in relatively dry springs.
When precipitation was increased, seed production of SG was significantly higher than that of AG, which supports our hypothesis that the response of SG is more sensitive to increased precipitation than that of AG. In Eremopyrum distans Wang et al. In the context of increased precipitation, the capability of SG and AG to produce more seeds that potentially remain viable in the soil allows them to form large persistent seed banks, thereby spreading germination risk over time.
This is similar to the increased seed production in wet vs. With an increase in precipitation, both SG and AG accumulated more biomass than the controls, which does not support our hypothesis. Increased precipitation promoted growth of stems and production of leaves, fruits, seeds and total biomass of both AG and SG, as has been shown in some hot Shem-tov and Gutterman and cold Yu et al. However, the increase in biomass of SG was significantly greater than that of AG, which supports our hypothesis.
This difference between AG and SG may have been caused by a combination of factors. First, the phenological stage strongly influences the responses of plants to the environment, and generally the earlier the phenological stages the more sensitive plants are to environmental changes Petraglia et al. Second, since AG were significantly larger than SG when water was added, the addition of water to AG may have been insufficient to elicit a strong response in growth and biomass accumulation.
This difference in biomass accumulation of SG and AG is also consistent with the response of the morphological traits height, leaf number and area and branch number and length of SG and AG to increased precipitation. Therefore, SG showed a more obvious growth plasticity response to increased precipitation than AG. With increased precipitation, the proportion of biomass allocated to stems and leaves of SG and AG increased, and the proportion allocated to reproduction and roots decreased.
According to the theory of optimal allocation, plants allocate more resources to aboveground than to belowground organs, which allows them to obtain additional space and light and consequently to increase their competitiveness and productivity Mccarthy and Enquist However, SG were more efficient than AG in increasing reproductive fitness.
However, increased precipitation did not have much effect on seed yield of AG via adjustment of reproductive allocation, while it promoted growth but not seed production of SG. Moreover, other environmental conditions especially, increased temperature in nature may accelerate entrance of SG into the reproductive stage before they reached a large size Espe et al.
As a result, the proportion of stems and leaves increased, and the proportion of reproduction decreased in SG. The significant differences of SG and AG in seed dormancy may provide two completely different directions for species evolution.
Nondormant seeds such as those of E. However, if drought follows seedlings may die. Dormancy ensures that there is a reserve of seeds that can germinate at some time in the future when seedlings potentially will be able to survive Baskin and Baskin However, if the soil is dry in autumn, germination of the ND seeds of E.
Thus, depending on how late in the growing season rain occurs, there could be an increase in AG or SG. With an increase in AG and SG, and thus an increase in seeds with PY and ND, respectively, and number of seeds in the seed bank and the number of plants in the standing vegetation will increase, respectively.
Thus, in the context of increased precipitation, the differences of SG and AG in seed dormancy not only avoid the risk of population extinction from a one-time germination event, but also enhance competitivenessof the species in the plant community. For both AG and SG, increased precipitation prolonged the life cycle; increased dry mass accumulation and seed production; increased the proportion of biomass allocated to stems and leaves; and decreased the proportion of reproduction and roots.
These results do not support our hypothesis that the response of SG is more sensitive to additional water than AG. In the context of climate change, the increase of biomass and seed production in SG and AG enhances the overall competitive advantage of E. The results on survival and morphological characteristics of AG and SG partly support our hypothesis. Thus, with increasing precipitation, SG accumulated proportionally more biomass and produced proportionally more seeds per plant than AG.
The effect of increased precipitation with climate change could modify the proportion of dormant and nondormant seeds produced by SG and AG. Since SG and AG produced both dormant and nondormant seeds when precipitation was increased, it seems likely that E.
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Learn more about how IoT sensors can monitor weather conditions. Learn More. Contact us. When to Water Knowing when to water, as well as how much to water, is skill backed by years of experienced for farmers. Growth from Seed Besides disease, rainfall can also determine how fast a crop will grow from seed, including when it will be ready for harvesting.
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