Environmental Adaptability and Energy Investment Strategy of Different Cunninghamia lanceolata Clones Based on Leaf Calorific Value and Construction Cost Characteristics.

The calorific value and construction cost of leaves reflect the utilization strategy of plants for environmental resources. Their genetic characteristics and leaf functional traits as well as climate change affect the calorific values. This study explores the differences in energy investment strategies and the response characteristics of energy utilization in leaves to climate change among nine clones of Chinese fir (Cunninghamia lanceolata). Considering the objectives, the differences in the energy utilization strategies were analyzed by determining the leaf nutrients, specific leaf area, and leaf calorific value and by calculating the construction cost. The results showed a significant difference in the ash-free calorific value and construction cost of leaves among different Chinese fir clones (p < 0.05). There were also significant differences in leaf carbon (C) content, leaf nitrogen (N) content, specific leaf area, and ash content. The correlation analysis showed that leaves' ash-free calorific value and construction cost were positively correlated with the C content. Principal component analysis (PCA) showed that P2 is inclined to the "fast investment return" energy investment strategy, while L27 is inclined to the "slow investment return" energy investment strategy. Redundancy analysis (RDA) indicates that the monthly average temperature strongly correlates positively with leaf construction cost, N content, and specific leaf area. The monthly average precipitation positively impacts the ash-free calorific value and construction cost of leaves. In conclusion, there are obvious differences in energy investment strategies among different Chinese fir clones. When temperature and precipitation change, Chinese fir leaves can adjust their energy investment to adapt to environmental changes. In the future, attention should be paid to the impact of climate change-related aspects on the growth and development of Chinese fir plantations.

[Response of Topsoil Fungal Community Structure to Soil Improvement Measures in Degraded Forest of Red Soil Region].

Soil fungal community structure and diversity are highly sensitive to variations in the external environment, as well as soil improvement measures. In order to clarify the effects of soil improvement measures on topsoil fertility or quality, a field experiment was conducted in eroded forest of a red soil region. Organic fertilizer, biochar, and lime+microbial fertilizer were added to the topsoil, respectively. After four years, the chemistry properties and nutrients in the topsoil were measured, and the diversity and composition of fungi were analyzed. The results showed that the additions of organic fertilizer, biochar, and lime+microbial fertilizer reduced fungal richness in topsoil, compared to that with no fertilizer addition (CK). Among them, lime+microbial fertilizer had the most negative effect on fungal richness. The three soil improvement measures also affected the diversity of topsoil fungi, but the impacts were not significant. The dominant fungal phyla in the topsoil were Ascomycota (31.29%-46.55%) and Basidiomycota (30.07%-70.71%), and the dominant fungal genera were Amphinema and Archaeorhizomyces. The effects of soil improvement measures on fungal community structure in the topsoil were different; organic fertilizer increased the relative abundance of Ascomycetes and Archaeopteroides, and biochar enhanced the relative abundance of Basidiomycetes and Archaeopteroides, whereas lime+microbial fertilizer improved the relative abundance of Basidiomycetes and Archaeopteroides. Fungal diversity and community structure in the topsoil was affected by edaphic factors, and fungal richness was regulated by pH value, whereas fungal community structure was influenced by pH, total nitrogen, and organic carbon. This study provides scientific guidance for soil improvement and ecological restoration below the canopy in eroded forests of red soil regions.

Physiological Responses and Tolerance Mechanisms to Cadmium in Conyza canadensis.

Experiments were conducted to examine the effects of different concentrations of Cd on the performance of the Cd accumulator Conyza canadensis. Cd accumulation in roots and leaves (roots>leaves) increased with increasing Cd concentration in soil. High Cd concentration inhibited plant growth, increased the membrane permeability of leaves, and caused a significant decline in plant height and chlorophyll [chlorophyll (Chl) a, Chl b, and total Chl] content. Leaf ultrastructural analysis of spongy mesophyllic cells revealed that excessive Cd concentrations cause adverse effects on the chloroplast and mitochondrion ultrastructures of C. canadensis. However, the activities of antioxidant enzymes, such as superoxide dismutase, catalase, peroxidase, total non-protein SH compounds, glutathione, and phytochelatin (PC) concentrations, showed an overall increase. Specifically, the increase in enzyme activities demonstrated that the antioxidant system may play an important role in eliminating or alleviating the toxicity of Cd in C. canadensis. Furthermore, results demonstrate that PC synthesis in plant cells is related to Cd concentration and that PC production levels in plants are related to the toxic effects caused by soil Cd level. These findings demonstrate the roles played by these compounds in supporting Cd tolerance in C. canadensis.