scholarly journals Nitrogen Deposition and Leaching from Two Forested Catchments in Southwest China — Preliminary Data and Research Needs

2001 ◽  
Vol 1 ◽  
pp. 520-526 ◽  
Author(s):  
T. Larssen ◽  
J. Mulder ◽  
Y. Wang ◽  
X. Chen ◽  
J. Xiao ◽  
...  
Keyword(s):  
Nitrogen Deposition ◽  
Forest Soils ◽  
Southwest China ◽  
Nitrogen Retention ◽  
Agricultural Practices ◽  
Pinus Massoniana ◽  
Nitrogen Leaching ◽  
Forested Catchments ◽  
Humid Climate ◽  
Masson Pine

Increased nitrogen deposition has resulted in increased nitrogen pools and nitrogen leaching in European and North American forest soils. The development in Asia in general, and China in particular, suggests increased deposition of reduced nitrogen from changes in agricultural practices and of oxidized nitrogen from rapid growth of the transportation sector. Decreased nitrogen retention in forested areas in the future may cause increased NO3–leaching and, thus, acidification and eutrophication in surface waters. The differences in climate, ecosystems, land use, and deposition history make direct application of knowledge from studies in Europe and North America difficult. In Southwest China the potential for nitrogen mobilization from forest soils may be high because of the warm and humid climate, resulting in high decomposition rates of soil organic matter. However, there are very few data available for quantifying the suspected potential for increased nitrogen leaching in forest ecosystems. Here we present data from two forested catchments, dominated by Masson pine (Pinus massoniana), near Guiyang and Chongqing, respectively, in Southwest China. The present nitrogen deposition is moderate, estimated in the range from 10 to 40 kg N ha–1year–1. The C/N ratios of the soils are generally below 15. Nitrate concentrations in soil water are rather variable in space, with highest values of several hundred microequivalents per liter. The turnover rate of nitrogen in the forest ecosystem is quite high compared to the atmospheric deposition rate. At present, nitrate runoff from the catchments is low and intermediate in Guiyang and Chongqing, respectively. More research is needed to improve our ability to predict future nitrogen leaching from subtropical Asian coniferous forests.

scholarly journals Role of Suillus placidus in Improving the Drought Tolerance of Masson Pine (Pinus massoniana Lamb.) Seedlings

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 332
Author(s):  
Min Li ◽  
Haoyun Wang ◽  
Xizhou Zhao ◽  
Zhongke Lu ◽  
Xueguang Sun ◽  
...  
Keyword(s):  
Drought Stress ◽  
Defense Mechanism ◽  
Southern China ◽  
Dry Weight ◽  
Pinus Massoniana ◽  
Photosynthetic Performance ◽  
Ectomycorrhizal Fungus ◽  
Severe Drought ◽  
Masson Pine ◽  
Pine Seedlings

Masson pine is an important afforestation species in southern China, where seasonal drought is common. The present study focused on the effects of Suillus placidus, an ectomycorrhizal fungus, inoculation on the growth and physiological and biochemical performance of masson pine seedlings under four different watering treatments (well-watered, mild drought, moderate drought, and severe drought) to evaluate the symbiotic relationship between S. placidus and masson pine seedlings. Ectomycorrhizal-inoculated (ECM) and non-inoculated (NM) seedlings were grown in pots and maintained for 60 days using the weighing method. Results showed that seedlings’ growth, dry weight, RWC, chlorophyll content, PSII efficiency, and photosynthesis decreased as drought stress intensified in both ECM and NM plants. This suggests that drought stress significantly limits the growth and photosynthetic performance of masson pine seedlings. Nevertheless, increased An/gs and proline contents in both NM and ECM prevented oxidative damage caused by drought stress. In addition, increased peroxidase (POD) activity is an essential defense mechanism of ECM seedling under drought stress. Compared with NM, ECM seedlings showed faster growth, higher RWC, and photosynthetic performance, and lower lipid peroxidation in cell membranes under drought stress, as indicated by higher POD activity and lower proline and malondialdehyde (MDA). Our experiment found that S. placidus inoculation can enhance the drought resistance of masson pine seedlings by increasing antioxidant enzyme activity, water use efficiency, and proline content, thereby enhancing growth under water-deficiency conditions. S. placidus can be used to cultivate high-quality seedlings and improve their survival in regions that experience seasonal droughts.

Thinning effects on forest evolution in Masson pine (Pinus massoniana Lamb.) conversion from pure plantations into mixed forests

2020 ◽  
Vol 477 ◽  
pp. 118503
Author(s):  
Cheng Deng ◽  
Shougong Zhang ◽  
Yuanchang Lu ◽  
Robert E. Froese ◽  
Xiaojun Xu ◽  
...  
Keyword(s):  
Pinus Massoniana ◽  
Mixed Forests ◽  
Masson Pine ◽  
Pinus Massoniana Lamb

scholarly journals Agricultural practice negatively affects soil microbial diversity and nitrogen functional genes comparing to adjacent native forest soils

2021 ◽  
Author(s):  
Tiehang Wu ◽  
Michael Sabula ◽  
Holli Milner ◽  
Gary Strickland ◽  
Gan Liu
Keyword(s):  
Community Structure ◽  
Bacterial Diversity ◽  
Forest Soils ◽  
Agricultural Practices ◽  
Functional Genes ◽  
Agricultural Practice ◽  
Soil Bacterial Diversity ◽  
Soil Microbial Diversity ◽  
Soil Microbial ◽  
Soil Bacterial

Soil microbial diversity and community are determined by anthropogenic activities and environmental conditions, which greatly affect the functioning of ecosystem. We investigated the soil bacterial diversity, communities, and nitrogen (N) functional genes with different disturbance intensity levels from crop, transition, to forest soils at three locations in the coastal region of Georgia, USA. Illumina high-throughput DNA sequencing based on bacterial 16S rRNA genes were performed for bacterial diversity and community analyses. Nitrifying (AOB amoA) and denitrifying (nirK) functional genes were further detected using quantitative PCR (qPCR) and Denaturing Gradient Gel Electrophoresis (DGGE). Soil bacterial community structure determined by Illumina sequences were significantly different between crop and forest soils (p < 0.01), as well as between crop and transition soils (p = 0.01). However, there is no difference between transition and forest soils. Compared to less disturbed forest, agricultural practice significantly decreased soil bacterial richness and Shannon diversity. Soil pH and nitrate contents together contributed highest for the observed different bacterial communities (Correlations = 0.381). Two OTUs (OTU5, OTU8) belonging to Acidobacteriales species decreased in crop soils, however, agricultural practices significantly increased an OTU (OTU4) of Nitrobacteraceae. The relative abundance of AOB amoA gene was significantly higher in crop soils than in forest and transition soils. Distinct grouping of soil denitrifying bacterial nirK communities was observed and agricultural practices significantly decreased the diversity of nirK gene compared to forest soils. Anthropogenic effects through agricultural practices negatively affecting the soil bacterial diversity, community structure, and N functional genes.

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