Post-fire species recruitment in a semiarid perennial steppe on the Loess Plateau

2013 ◽  
Vol 61 (1) ◽  
pp. 29 ◽  
Author(s):  
Ling-Ping Zhao ◽  
Gao-Lin Wu ◽  
Zhi-Hua Shi
Keyword(s):  
Loess Plateau ◽  
Fire History ◽  
Seedling Recruitment ◽  
Western China ◽  
The Loess Plateau ◽  
Offspring Number ◽  
Significant Difference ◽  
Species Recruitment ◽  
North Western ◽  
Steppe Community

Offspring recruitment is an important part of population dynamics, as well as for plant-community structure and succession. One generality regarding grasses and fire is that clonal grasses tolerate fire extremely well and in most cases reach their maximum production in the immediate post-fire years. One qualification to this statement is that post-fire offspring, recruitment mode is very important. However, respective data are scare in the semiarid perennial steppe. We studied the relative importance of asexual v. sexual recruitment in the post-fire recovery in semiarid steppe on the Loess Plateau of north-western China. We observed differences in regeneration strategy after different times post-fire (burnt in 2008, burnt in 1999, and no fire history for at least 30 years). Results showed that fire significantly increased offspring recruitment numbers, but not species richness. The increase of asexual recruitment after a fire made a major contribution to the increase of total offspring number. Meanwhile, there was no significant difference for the ratio of asexual to sexual recruitment among sites with different times since fire. The asexual to sexual recruitment ratio was significantly different for different species, with some species not recruiting offspring via sexual recruitment. Our results indicated that seedling recruitment contributed little to post-fire recovery of the perennial-steppe community. Lack of sexual recruitment is not related to fire management but to inherent traits of the occurring plants.

scholarly journals Nitrogen Supply Affects Grain Yield by Regulating Antioxidant Enzyme Activity and Photosynthetic Capacity of Maize Plant in the Loess Plateau

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1094
Author(s):  
Kai Yue ◽  
Lingling Li ◽  
Junhong Xie ◽  
Setor Kwami Fudjoe ◽  
Renzhi Zhang ◽  
...  
Keyword(s):  
Grain Yield ◽  
Antioxidant Enzyme ◽  
Loess Plateau ◽  
Photosynthetic Capacity ◽  
Growth And Yield ◽  
Dry Matter Accumulation ◽  
The Loess Plateau ◽  
Area Index ◽  
Leaf Stage ◽  
Significant Difference

Nitrogen (N) is the most limiting nutrient for maize, and appropriate N fertilization can promote maize growth and yield. The effect of N fertilizer rates and timings on morphology, antioxidant enzymes, and grain yield of maize (Zea mays L.) in the Loess Plateau of China was evaluated. The four N levels, i.e., 0 (N0), 100 (N1), 200 (N2), and 300 (N3) kg ha−1, were applied at two timings (T1, one-third N at sowing and two-thirds at the six-leaf stage of maize; T2, one-third applied at sowing, six-leaf stage, and eleven-leaf stage of maize). The results show that N2 and N3 significantly increased the plant height, stem and leaf dry weight, and leaf area index of maize compared with a non-N-fertilized control (N0). The net photosynthetic rate, transpiration rate, stomatal conductance, and leaf chlorophyll contents were lower, while the intercellular carbon dioxide concentration was higher for non-fertilized plants compared to fertilized plants. The activities of peroxidase (POD) and superoxide dismutase (SOD) increased with N rate, but the difference between 200 and 300 kg ha−1 was not significant; further, the isozyme bands of POD and SOD also changed with their activities. Compared with a non-N-fertilized control, N2 and N3 significantly increased grain yield by 2.76- and 3.11-fold in 2018, 2.74- and 2.80-fold in 2019, and 2.71- and 2.89-fold in 2020, and there was no significant difference between N2 and N3. N application timing only affected yield in 2018. In conclusion, 200 kg N ha−1 application increased yield through optimizing the antioxidant enzyme system, increasing photosynthetic capacity, and promoting dry matter accumulation. Further research is necessary to evaluate the response of more cultivars under more seasons to validate the results obtained.

Natural Dust and Pneumoconiosis in High Asia

2003 ◽  
Author(s):  
Edward Derbyshire
Keyword(s):  
Loess Plateau ◽  
Yellow River ◽  
Western China ◽  
Human Populations ◽  
The Loess Plateau ◽  
The North ◽  
High Asia ◽  
Uplift Rates ◽  
Few Data ◽  
Tian Shan

High Asia, defined here as that great tract of land from the Himalaya- Karakoram in the south to the Tian Shan in the north and the Pamir in the west to the Qinling Mountains in the east, is a very dusty place. Whole communities of people in this region are exposed to the adverse effects of natural (aerosolic) dusts at exposure levels reaching those encountered in some high-risk industries. Outdooor workers are at particular risk. However, few data are available on the magnitude of the dust impact on human health. The effect of such far-travelled particles on the health of the human population in the Loess Plateau, and including major Chinese cities, has received relatively little attention to date. A combination of the highest known uplift rates, rapid river incision (up to 12 mm/yr: Burbank et al. 1996), unstable slopes, glaciation and widespread rock breakup by crystal growth during freezing (frost action), and by hydration of salts (salt weathering) makes the High Asia region the world’s most efficient producer of silty (defined as between 2 and 63 μm) debris. The earliest written records of the dust hazard come from China, most notably in the “Yu Gong” by Gu Ban (ca 200 BC) (Wang and Song 1983). Here, deposits of wind-blown silt (known as ‘loess’) cover the landscape in a drape that is locally 500 m thick. In North China, the loess covers an area of over 600,000 km², most of it in the Loess Plateau, situated in the middle reaches of the Huang He (Yellow River). The characteristic properties of loess include high porosity and collapsibility on wetting (Derbyshire et al. 1995, Derbyshire and Meng 2000).Thus, it is readily reworked and redistributed by water. This process concentrates silts in large alluvial fans (up to 50 x 50 km) in the piedmont zones of 6,000 m high glacier- and snow-covered mountain ranges of western China, including the Altai Shan (‘shan’ = mountains), Tian Shan, Kunlun Shan, Qilian Shan, and Karakoram. These zones are loci for human populations, and also a major source of wind-blown dust.

scholarly journals Soil Available Phosphorus Investigated for Spatial Distribution and Effect Indicators Resulting from Ecological Construction on the Loess Plateau, China

2021 ◽  
Vol 13 (22) ◽  
pp. 12572
Author(s):  
Shengdong Cheng ◽  
Ganggang Ke ◽  
Zhanbin Li ◽  
Yuting Cheng ◽  
Heng Wu
Keyword(s):  
Spatial Distribution ◽  
Loess Plateau ◽  
Soil Depth ◽  
Available Phosphorus ◽  
Land Uses ◽  
The Loess Plateau ◽  
Small Catchment ◽  
Soil Available Phosphorus ◽  
Significant Difference ◽  
Soil And Water

Soil phosphorus is a major determinant and indicator of soil fertility and quality, and is also a source of nonpoint-source pollution. In order to control soil and water loss in the Loess Plateau, a series of soil and water conservation measures have been taken, resulting in changes in land use and differences in spatial distribution. It is necessary to study soil available phosphorus (SAP) to evaluate land productivity and environmental quality. In this study, the spatial distribution of SAP in different land uses was investigated in a small catchment area of Loess Plateau, and the field-influencing factors were determined on five layers with soil depth of 20 cm. The results show the minimum and maximum SAP content occurred at 20–40 cm and 80–100 cm soil depth and reach a value of 27.26 mg/kg and 29.37 mg/kg at catchment scale, respectively. There is significant difference among the SAP of the five soil layers (p < 0.01). The SAP of different land uses is, in order: forestland < slope farmland < dam farmland < terrace < grassland. Different land uses’ topographies make a difference to the spatial distribution of SAP. Slope and soil texture are the domain factors influencing the SAP concentration at the catchment.

Relative contribution of photorespiration and antioxidative mechanisms in Caragana korshinskii under drought conditions across the Loess Plateau

2017 ◽  
Vol 44 (11) ◽  
pp. 1111 ◽  
Author(s):  
Juan Bai ◽  
Tai Kang ◽  
Hongdou Wu ◽  
Baiyan Lu ◽  
Xiaogang Long ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Reduced Glutathione ◽  
Photosynthetic Apparatus ◽  
Protective Role ◽  
The Loess Plateau ◽  
Sod Activity ◽  
Relative Contribution ◽  
Caragana Korshinskii ◽  
Drought Tolerant ◽  
Significant Difference

The drought-tolerant plant Caragana korshinskii Kom. was used to investigate the relative contribution of photorespiration and antioxidative mechanisms to water-stress adaptations across the Loess Plateau. The samples were collected from Shenmu, Yulin and Dongsheng along with the reduction of rainfall. The results showed the lower leaf water potential and the lower content of O2•– and malondialdehyde (MDA) were found in the plants in drier zone. H2O2 didn’t show a significant difference among these sampling sites. Both photorespiratory rate (PR) and net photosynthetic rate (PN) increased with the decrease of rainfall. Low rainfall upregulated the gene expression and activities of photorespiratory enzymes. In addition, ascorbate peroxidase (APX), glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity and reduced glutathione (GSH), ascorbic acid (AsA) contents increased with the decrease of rainfall, whereas catalase (CAT) activity decreased. These results indicate photorespiration could play a protective role for the photosynthetic apparatus from photoinhibition and photodamage under low rainfall levels, which could also act together with the antioxidation system to improve the tolerance to drought in C. korshinskii.

scholarly journals Increased precipitation enhances soil respiration in a semi-arid grassland on the Loess Plateau, China

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10729
Author(s):  
Yutao Wang ◽  
Yingzhong Xie ◽  
Gillian Rapson ◽  
Hongbin Ma ◽  
Le Jing ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Loess Plateau ◽  
Root Biomass ◽  
Western China ◽  
Shoot Biomass ◽  
Least Squares Regression ◽  
The Loess Plateau ◽  
Grassland Ecosystems ◽  
Arid Steppe

Background Precipitation influences the vulnerability of grassland ecosystems, especially upland grasslands, and soil respiration is critical for carbon cycling in arid grassland ecosystems which typically experience more droughty conditions. Methods We used three precipitation treatments to understand the effect of precipitation on soil respiration of a typical arid steppe in the Loess Plateau in north-western China. Precipitation was captured and relocated to simulate precipitation rates of 50%, 100%, and 150% of ambient precipitation. Results and Discussion Soil moisture was influenced by all precipitation treatments. Shoot biomass was greater, though non-significantly, as precipitation increased. However, both increase and decrease of precipitation significantly reduced root biomass. There was a positive linear relationship between soil moisture and soil respiration in the study area during the summer (July and August), when most precipitation fell. Soil moisture, soil root biomass, pH, and fungal diversity were predictors of soil respiration based on partial least squares regression, and soil moisture was the best of these. Conclusion Our study highlights the importance of increased precipitation on soil respiration in drylands. Precipitation changes can cause significant alterations in soil properties, microbial fungi, and root biomass, and any surplus or transpired moisture is fed back into the climate, thereby affecting the rate of soil respiration in the future.

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