Plant diversity has important ecosystem function in forest ecosystem. Forest restoration approaches can impact plant diversity, especially the understory plant diversity. We studied the floristic characteristics, plant community structure and diversity of three forest restoration approaches in red soil region of southern China, which included introduced species slash pine (Pinus elliottii) plantations, native species Masson pine (Pinus massoniana) plantations and natural secondary forests. For each forest restoration approach, a total of 15 independent plots were surveyed. On each plot, three 10 m 伊 10 m subplots of area were surveyed for trees忆 abundance, height and diameter at breast height. Within each tree subplot, one to two shrub quadrates (5 m 伊 5 m) and one to three herb quadrates (1 m 伊 1 m) were surveyed for plant species abundance. A total of 127 tree subplots, 238 shrub subplots and 357 herb subplots were effectively surveyed for plant community structure. The results showed that: (1) 155 species (which belong to 160 genera and 86 families) , 137 species (which belong to 97 genera, 59 families) and 226 species (which belong to 160 genera, 86 families) were identified in
With the fast increase of population and global environmental changes, it is a big challenge to ensure food security with shrinking cropland and limited resources in an environment鄄friendly way, which can maintain or even improve soil fertility, and protect environment. Recently, highlights have been shed on the integrated and efficient utilization of different cropping strategies including intercropping, which is on the edge of being abandoned in the farming systems. Intercropping, a land鄄use strategy of cultivating two or more crop species in the same pieces of land at the same time, is an old and traditional cropping practice. Generally, there are two main intercropping systems, i. e. , strip intercropping and relay intercropping, both of which are trying to make more efficient use of the available growth resources on the bases of the complementary utilization of growth resources by the component crops. These cropping strategies are still common practiced in the world especially in developing countries, such as China, India, Southeast Asia, Latin America, and Africa. The most common advantage of intercropping is the production of greater yield on a given piece of land by making more efficient use of the available growth resources using a mixture of crops of different rooting ability, canopy structure, height, and nutrient requirements based on the complementary utilization of growth resources by the component crops. More importantly, it also has other exclusive ecological functions, such as improving soil fertility through biological nitrogen fixation with the use of legumes, increasing soil conservation through greater ground cover than sole cropping, protecting more species by providing more habitats, and allowing lower inputs through reduced fertilizer and pesticide requirements, thus minimizing
Methane is the second most abundant greenhouse gas in the atmosphere. Methane metabolic microbial community in soil affect the production and oxidation of methane. Land use type significantly influence methane release from soil and methane metabolic microorganisms. China has the biggest plantation area in the world. In central and Southern China, Masson pine (Pinus massoniana) and slash pine (Pinus elliottii) plantations account for 59% of the forested areas. What effect of plantation, especially the introduced slash pine plantation, on methane metabolic microbial community deserves much concern. While little has been researched about effects of forest type on methane metabolism community in soil. Molecular technique is a good way to reveal the community of methane metabolic microorganisms. Functional gene
Maize鄄soybean relay intercropping pattern, with highly economic, ecological and environmental significance, is widely applied in southwestern China. However, growth of soybean seedlings may be depressed by maize shade in this cropping pattern. The objective of this paper was to study the photosynthetic responses of soybean seedlings to maize shading in relay intercropping system in terms of morphological plasticity and photosynthetic parameters compared with mono鄄 cropping system. A field experiment was conducted to compare gas exchange, chlorophyll fluorescence parameters, pigments contents, leaf carbon and nitrogen contents, leaf area index and dry matter accumulation of two soybean cultivars in two cropping patterns, i.e., soybean mono鄄cropping and maize鄄soybean relay intercropping. Compared with the mono鄄cropped seedlings, soybean seedlings intercropped with maize had significantly lower net photosynthetic rate (P n) (-37. 9%) , transpiration rate (T r) (-42.4%) and stomatal conductance (G s) (-54.2%) due to low available light, but there was non鄄significant difference in two soybean varieties. The intercellular carbon dioxide concentration (C i) and F v / F m were not http: / / www.ecologica.cn changed significantly, in comparison with the seedlings under mono鄄cropping. Additionally, reductions in photosynthetic rate induced by maize shading was correlated significantly with stomatal conductance. The maize shading鄄induced depressions of photosynthetic rate may be attributed to stomatal limitation and energy deficiency in CO 2 assimilation process. Leaf carbon contents, leaf weight, leaf area index, root dry weight, total biomass and root / shoot ratio was also reduced because of maize shading, and significant difference was found between the two soybean varieties, which indicated that Nangdou12 might be a better cultivar to be relay intercropped with maize in Southwest China. The correlation analysis indicated that the relative reduction in biomass was caused by the decline in leaf area index rather than P n. Although automatic regulation of light鄄harvesting efficiency in terms of total nitrogen contents, total chlorophyll contents and chlorophyll b contents was significantly improved in soybean seedlings in relay intercropping condition, it could not compensate the decline of light interception caused by the reduced light interception area. Therefore, the growth parameters may be more important index for assessing the adaptation of soybean cultivars to low light condition in intercropping system than ecophysiological parameters merely at unit leaf level.
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