We investigated characteristics （scales and composition） of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegeta...We investigated characteristics （scales and composition） of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m？2. A total of 23 plant species were found in soil seed banks, of which 63–80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0–5 cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the aboveground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.展开更多
Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ag...Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ages of the established Middle and Upper Proterozoic sequence stratigraphic framework in the Ming Tombs area lying in western Yanshan Mountain of Beijing. Besides, sketchy determination of δ13C and δ18O was also performed for other formations and members. The analytical results show the following: under the condition of clear-water carbonate sediments, δ13C and δ18O, featuring smaller variation of δ13C but larger variation of δ18O, can well delineate the relative change of sea level, which reflects the difference of primary sedimentary settings; in the presence of terrigenous substances, δ13C values vary greatly while δ18O slightly; the carbon and oxygen isotopes show marked changes at sequence boundaries. Besides, particular patterns can be found in regard to the distribution of carbon and oxygen isotopes within the sequences.展开更多
Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional tr...Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional traits and litter quality.However,at the community level,it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent.A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain,Beijing,North China,including six monodominant communities dominated by Juglans mandshurica,Populus cathayana,Betula dahurica,Betula platyphylla,Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla,Quercus mongolica and Tilia mongolica.The results showed that there were considerable differences in the litter decomposition rate(k-rate)among the different forest types.The community weighted mean(CWM)traits of green leaves and litter quality explained 35.60%and 9.05%of the k-rate variations,respectively,and the interpretation rate of their interaction was 23.37%,indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations.In the recommended daily allowance,leaf nitrogen content,leaf dry matter content,leaf tannin content and specific leaf area were the main factors affecting the k-rate variations.Therefore,we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.展开更多
基金supported by National Natural Science Foundation of China (31071817)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(PXM20090142076309)
文摘We investigated characteristics （scales and composition） of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m？2. A total of 23 plant species were found in soil seed banks, of which 63–80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0–5 cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the aboveground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.
文摘Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ages of the established Middle and Upper Proterozoic sequence stratigraphic framework in the Ming Tombs area lying in western Yanshan Mountain of Beijing. Besides, sketchy determination of δ13C and δ18O was also performed for other formations and members. The analytical results show the following: under the condition of clear-water carbonate sediments, δ13C and δ18O, featuring smaller variation of δ13C but larger variation of δ18O, can well delineate the relative change of sea level, which reflects the difference of primary sedimentary settings; in the presence of terrigenous substances, δ13C values vary greatly while δ18O slightly; the carbon and oxygen isotopes show marked changes at sequence boundaries. Besides, particular patterns can be found in regard to the distribution of carbon and oxygen isotopes within the sequences.
基金This work was supported by the National Natural Science Foundation of China(10300-210100218).
文摘Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional traits and litter quality.However,at the community level,it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent.A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain,Beijing,North China,including six monodominant communities dominated by Juglans mandshurica,Populus cathayana,Betula dahurica,Betula platyphylla,Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla,Quercus mongolica and Tilia mongolica.The results showed that there were considerable differences in the litter decomposition rate(k-rate)among the different forest types.The community weighted mean(CWM)traits of green leaves and litter quality explained 35.60%and 9.05%of the k-rate variations,respectively,and the interpretation rate of their interaction was 23.37%,indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations.In the recommended daily allowance,leaf nitrogen content,leaf dry matter content,leaf tannin content and specific leaf area were the main factors affecting the k-rate variations.Therefore,we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.
