分类： 地球科学 >> 地理学 提交时间： 2021-11-10 合作期刊: 《干旱区科学》
XIANG Zeyu
Arvind BHATT
TANG Zhongbin
PENG Yansong
WU Weifeng
ZHANG Jiaxin
WANG Jingxuan
David GALLACHER
ZHOU Saixia
摘要： Mounds constructed by plateau zokors, which is widely distributed in alpine meadows significantly modified plant community structure. However, the variations of plant community structure under the disturbance of plateau zokor-made mound are less concerned. Therefore, we investigated the responses of plant community on zokor-made mound of different years (1 a and 3–4 a), and compared with undisturbed sites (no mound) in an alpine meadow in the eastern Qinghai-Tibetan Plateau (QTP), China. Species richness, coverage and Simpson diversity index were all significantly reduced by the presence of zokor-made mound, but plant heights were significantly increased, particularly in grasses and sedges. Several perennial forage species showed an increased importance value and niche breadth, including Koeleria macrantha, Elymus nutans and Poa pratensis. The effect of zokor-made mound on niche overlap showed that more intense interspecific competition produced a greater utilization of environmental resources. And this interspecific niche overlap was strengthened as succession progressed. The bare mound created by zokor burrowing activities provided a colonizing opportunity for non-dominant forage species, resulting in abundant plant species and plant diversity during the succession period. We concluded that presence of zokor-made mound was conducive to regeneration and vitality of plant community in alpine meadows, thus improving their resilience to anthropogenic stress.
分类： 地球科学 >> 地理学 提交时间： 2021-01-15 合作期刊: 《干旱区科学》
摘要： Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation. In deserts, the spatiotemporal distribution of plant-available water is highly episodic and unpredictable, making winter months more favorable for seed germination when other abiotic conditions co-occur. We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage. We assessed 21 annual and short-lived perennial species in the Arabian Desert to find (1) if seeds were dormant at maturity, (2) if in situ seed storage increased germination percentage compared with no storage, (3) if photoperiod and thermoperiod germination requirements were influenced by in situ storage, and (4) if a phylogenetic association in seed germination could be observed. Seeds of each species collected in early 2017 were divided into two batches. One was tested for germination within one week (fresh seeds). The other was stored in situ at the maternal location (stored seeds) until October 2017 and tested for seed germination in the first week of November. Seed germination was conducted in incubators at two thermoperiods (15°C/20°C and 20°C/30°C; 12 h/12 h), and two photoperiods (12 and 0 h light per day). Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage. A thermoperiod response was exhibited by stored, but not fresh seeds. Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds. Germination traits exhibited no phylogenetic correlation. This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2020-05-31 合作期刊: 《干旱区科学》
摘要： Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes. The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production. Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum (Gmel.) Henr. in the desert of Kuwait was evaluated in different populations in May 2017. Experiment of seed germination (25 seeds and 4 replicates) was conducted for each population at night/day temperatures of 15°C/20°C and 20°C/30°C under the following light condition: continuous darkness or 12 h/12 h light/dark. Results showed that seed masses of both species strongly varied according to their seed provenances, and both species produced heavier seeds in population with a higher soil electrical conductivity. Seed germination percentage considerably varied between two species, and the variation in P. turgidum was greater (17%–49%) than that of P. divisum (72%–93%). Germination percentage in P. turgidum was greater at high temperature (20°C/30°C) than at low temperature (15°C/20°C). However, temperature regimes had no effect on germination percentage of P. divisum seeds. Mean germination time of both species exhibited significant inter-population variability. This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species. Besides this, inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2020-04-23 合作期刊: 《干旱区科学》
摘要： Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes. The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production. Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum (Gmel.) Henr. in the desert of Kuwait was evaluated in different populations in May 2017. Experiment of seed germination (25 seeds and 4 replicates) was conducted for each population at night/day temperatures of 15°C/20°C and 20°C/30°C under the following light condition: continuous darkness or 12 h/12 h light/dark. Results showed that seed masses of both species strongly varied according to their seed provenances, and both species produced heavier seeds in population with a higher soil electrical conductivity. Seed germination percentage considerably varied between two species, and the variation in P. turgidum was greater (17%–49%) than that of P. divisum (72%–93%). Germination percentage in P. turgidum was greater at high temperature (20°C/30°C) than at low temperature (15°C/20°C). However, temperature regimes had no effect on germination percentage of P. divisum seeds. Mean germination time of both species exhibited significant inter-population variability. This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species. Besides this, inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.
分类： 生物学 >> 生态学 提交时间： 2019-01-17 合作期刊: 《干旱区科学》
摘要： With the aim to investigate if the halophyte Halothamnus iraqensis Botsch. can be suitable for re-vegetation and remediation of salt-affected lands, this study evaluated (1) the effects of photoperiod, thermoperiod, storage period and wings' presence on its seed germination, and (2) the ability of its seeds to have successful germination recovery after salt stress. Germination tests in different photoperiods (12 h light/12 h darkness and total darkness) and thermoperiods (15°C/20°C and 20°C/25°C) were conducted for seeds collected in 2012, 2013, 2014, 2015 and 2016. The seeds collected in 2016 were sown under different salinity levels (0, 100, 200, 400 and 600 mM NaCl) to assess the salinity tolerance during the germination. Wings' presence highly inhibited seed germination of this species in both photoperiods and thermoperiods under all salinity level treatments. In addition, the germination recovery occurred well when seeds were deprived of their wings. The photoperiod of 12 h light/12 h darkness and the thermoperiod of 15°C/20°C were the best conditions for seed germination. Germination percentages of H. iraqensis seeds decreased with the increasing storage duration, especially after three years of the collection. In addition, H. iraqensis seeds were able to germinate under different salinity levels, and their germination percentages decreased with increasing salinity levels. H. iraqensis seeds have the ability to recover their germination after alleviating the salt stress, irrespective of photoperiod, highlighting the halophilous character of this species.
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