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Quercus rehderiana Hand.-Mazz. belongs to Quercus sect. Heteroallenes' of the Fagaceae family. It is widely distributed in forests with rocky and non-rocky desertification in Guizhou Province of Southwest China. However, our knowledge of the adaptation strategies of Quercus in forests with rocky desertification is surprisingly lacking. In this study, 16 leaf traits (morphological, anatomical, and chemical) of Quercus rehderiana were investigated in 15 individuals in five 20 × 20 m quadrants of forests with rocky and non-rocky desertification. The aim was to analyze their strategies of adaptation to arid and poor-soil environments in forests with rocky desertification. The results showed that Quercus rehderiana leaves in forests with rocky desertification had a greater leaf thickness, specific leaf area, abaxial epidermis thickness, and sponge mesophyll thickness but a lower leaf area than in forests with non-rocky desertification. Quercus rehderiana leaves in forests with rocky desertification had higher calcium and magnesium concentrations and a higher N:P ratio but lower potassium and phosphorus concentrations than in forests with non-rocky desertification. The results of principal component analysis showed that forests with rocky desertification tended to show resource-conserving strategies with thicker leaf tissue and a lower nutrient concentration, while forests with non-rocky desertification tended to show resource acquisition strategies with a greater leaf area and potassium concentration. In resource-poor environments, species that adopt conservative resource strategies are more likely to survive; therefore, we forecasted that more conservative, slow-growing Quercus rehderiana will be more stable over time. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) play crucial roles in tea planting, but information on how the long-term excessive application of chemical N fertilizer affected N and P in subtropical tea plantations remains limited. In this study, soil and leaf samples were collected along a chronosequence of tea plantations (0-, 5-, 10-, 18- and 23-year-old plantations) with excessive N input but no P application to investigate the effects of planting age on N and P availability. Diverse soil N forms and P fractions, and the concentrations of leaf N and P were measured. The results showed that (1) N O 3 − -N and dissolved organic nitrogen (DON) concentrations in both topsoil and subsoil, and the N concentration of mature leaf showed significant upward trends with tea plantation age; (2) the concentrations of available phosphorus (AP), NaHCO3-Pi in labile P pool, NaOH-Pi and D.HCl-Pi in moderately labile P pool in both layers of soil and that the P concentration of mature leaf also increased with age; (3) the N concentration of mature leaves had closely significant logarithmic relations with N O 3 − -N concentration, while the TP (total P) concentration of mature leaves had significant positive correlations with AP; and (4) the ratio of N/P in tea leaves indicated a slightly P limitation in tea plantations. We concluded that the N O 3 − -N concentration, instead of TN (total N) of N H 4 + -N, would be a good indicator to reflect N availability for tea trees, and the increasing of N O 3 − -N concentration in soil has a diminishing promoting effect on the TN concentration of mature leaves. The long-term application of chemical N fertilizer had not lead to serious P limitation in subtropical tea plantations. Generally, our study could contribute to improving our understanding of N and P availability and optimizing fertilization management in subtropical tea plantations. [ABSTRACT FROM AUTHOR]

Rocky desertification (RD), a natural and human-induced process of land degradation in karst areas, has become the primary ecological disaster and one of the obstacles to sustainable ecological development in southwest China. Nevertheless, the variation of soil physical and chemical properties, bacterial and fungal communities, and their relationships in RD forests remains limited. Therefore, soil samples were collected from forests under four degrees of RD (NRD, non-RD; LRD, light RD; MRD, moderate RD; and SRD, severe RD) and subjected to high-throughput sequencing of 16S rRNA and ITS1 genes. The results showed a significant reduction in bacterial richness and diversity, while fungal richness and diversity decreased markedly and then showed a balanced trend with the increase in RD degree, indicating that bacteria and fungi did not present the same dynamics in response to the process of RD. The bacterial communities were dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, while the fungal communities were dominated by Basidiomycota, Ascomycota, and Mortierellomycota. The PCoA and NMDS demonstrated significant differences in microbial communities in study sites, among which the fungal communities in non-RD forest and LRD forest clustered together, suggesting that fungal communities were more stable than bacteria in RD forest. The db-RDA, Mantel test, and random forest model confirmed the important role of soil BD, pH, SOC, AN, and AP in driving microbial diversity and communities. The IndVal analysis suggested that Chloroflexi, Patescibacteria, Atheliales, and Cantharellales with high indicator values were identified as potential bio-indicators for RD forests. This study could not only improve our understanding of bacterial and fungal community dynamics across RD gradients, but also could provide useful information for the further use of microorganisms as indicators to reflect the environmental changes and ecosystem status during forest RD. [ABSTRACT FROM AUTHOR]

Priority conservation areas are the key areas of biodiversity maintenance and ecosystem conservation. Based on a Maxent model, this study predicted the potential distribution of Pseudotsuga sinensis under the current climate and future climate change scenarios in Guizhou province, and then, assessed three kinds of priority conservation area under climate change. The results were as follows: (1) The AUC (Area Under the Curve) values showed excellent prediction accuracy of the model. (2) The areas of the potential habitats of P. sinensis forests under the current climate and future climate change scenarios were 22,062.85 km2 and 18,395.92 km2, respectively. As for their spatial distribution, the potential habitats of P. sinensis forests were distributed in the Bijie, Zunyi, Tongren, Liupanshui and Xingyi regions under the current climate, and in the Kaili region, in addition to the above-mentioned cities, under future climate change scenarios. (3) The total area of priority conservation areas under climate change was 25,350.26 km2. The area of the predicted sustainable potential habitats was 15,075.96 km2, of the vulnerable potential habitats was 7256.59 km2 and of the derivative potential habitats was 3017.71 km2. [ABSTRACT FROM AUTHOR]

Long-term studies have revealed that forest species composition was shifting under environment change and disturbance induced by loss of large trees. Yet, few studies explicitly analyzed their impacts on composition concurrently. To learn more about impacts of environment change and disturbance on driving forest community, we investigated shifts in functional composition over past 24 years in an old-growth subtropical forest in southern China. We analyzed nine traits that are mainly related to leaf nutrients, photosynthetic capacity, hydraulic conductivity, and drought tolerance of plants and examined hypotheses: (1) The functional composition change over time was directional instead of random fluctuation, (2) drought-tolerant species increased their abundance under soil dryness, (3) both environmental change and disturbance related to changes of functional composition significantly, and (4) initial trait values of quadrats strongly influenced their subsequent change rates in quadrat level (10 × 10 m). We found that species composition had shifted to favor species with high leaf nutrient content, high photosynthesis rate, high hydraulic conductivity, low water-use efficiency, and high drought tolerance traits, which was due to soil dryness and disturbance. These two factors explained 47–58% of quadrats' trait value changes together. Considering rapidly increasing stem density, this pattern may indicate ecological processes of which disturbance provided numerous recruits of resource-acquisition strategy species and soil dryness conducted a selecting effect on shaping composition in the forest. Additionally, quadrats with initial trait values at the far end of change direction shifted faster in three traits, which also indicated that functional composition changes in quadrats were directional and homogenized. Our results implied that environment change and accompanied disturbance events possibly drove species composition change along a different trajectory in the subtropical forest that experienced high climatic variability. [ABSTRACT FROM AUTHOR]