[Effects of Short-Term Nitrogen and Phosphorus Addition on Soil Respiration Components in a Subalpine Grassland of Qilian Mountains].

In order to investigate the effects of short-term nitrogen and phosphorus addition on soil respiration and its components in a subalpine grassland located on the Qilian Mountains, a random block design of nitrogen[10 g·(m2·a)-1, N], phosphorus[5 g·(m2·a)-1, P], nitrogen and phosphorus addition[10 g·(m2·a)-1N and 5 g·(m2·a)-1P, NP], the control (CK), and complete control (CK') was conducted from June to August 2019, and total soil respiration and its component respiration rates were measured. The results showed that nitrogen addition reduced soil total respiration and heterotrophic respiration rates at a lower rate than P addition[-16.71% vs. -19.20%; -4.41% vs. -13.05%], but the rate of decrease in autotrophic respiration was higher than that of P addition (-25.03% vs. -23.36%); N and P mixed application had no significant effect on soil total respiration rate. The total soil respiration rate and its components were significantly exponentially correlated with soil temperature, and the temperature sensitivity of soil respiration rate was decreased by nitrogen addition (Q10:-5.64%-0.00%). P increased Q10 (3.38%-6.98%), and N and P reduced autotrophic respiration rate but increased heterotrophic respiration rate Q10 (16.86%) and decreased total soil respiration rate Q10 (-2.63%- -2.02%). Soil pH, soil total nitrogen, and root phosphorus content were significantly correlated with autotrophic respiration rate (P<0.05) but not with heterotrophic respiration rate, and root nitrogen content was significantly negatively correlated with heterotrophic respiration rate (P<0.05). In general, autotrophic respiration rate was more sensitive to N addition, whereas heterotrophic respiration rate was more sensitive to P addition. Both N and P addition significantly reduced soil total respiration rate, whereas N and P mixture did not significantly affect soil total respiration rate. These results can provide a scientific basis for the accurate assessment of soil carbon emission in subalpine grassland.

[Effects of nitrogen addition on tree root traits.] / æ°®æ·»åŠ å¯¹æ ‘æœ¨æ ¹ç³»ç‰¹æ€§çš„å½±å“.

Atmospheric nitrogen deposition has complex effects on individual plants and terrestrial ecosystems. We synthesized results from 39 published papers (16 papers in English and 23 papers in Chinese) and conducted a meta-analysis to evaluate the general responses of tree root traits to nitrogen addition, and further analyzed the difference of N-induced results between English papers and Chinese papers. Our results showed that N addition significantly increased fine root diameter (+6.7%), fine root N content (+8.9%), and root respiration rate (+17.5%), but did not affect fine root biomass, fine root length, specific root length, fine root C content, and fine root C:N ratio. Different climatic zone and fertilizer types had different effects on the experimental results. In addition, experimental results published in English papers were generally more significant than those in Chinese papers. We summarized the general effects of N addition on tree root systems, and further analyzed the mechanisms underlying the effects of N enrichment on forest ecosystem carbon cycle.

Influence of chronic kidney disease on the outcome of patients with chronic total occlusion.

OBJECTIVE: Chronic kidney disease (CKD) predicted a poor prognosis in patients with coronary artery disease. There is a paucity of data on outcomes after revascularization in patients with chronic total occlusion (CTO) and CKD. This study aims to investigate the impact of CKD on the revascularization of CTO. METHODS: This study enrolled 1,092 CTO patients received treatments in our hospital between February 2009 and January 2014. Major adverse cardiac and cerebrovascular events (MACCE) and all-cause mortality were compared to evaluate medium- and long-term outcomes. Median follow-up was 39 months (interquartile range, 27-52 months). RESULT: CKD decreased cumulative MACCE-free survival rate (54.4 ± 6.2% vs. 70.9 ± 2.5%, P < 0.001) and cumulative survival rate (68.6 ± 6.3% vs. 90.5 ± 1.6%, P < 0.001). Revascularization was associated with better outcomes among patients with (MACCE-free survival rate: 64.8 ± 5.7% vs. 20.1 ± 15.3%, P = 0.009; survival rate 78.4 ± 5.6% vs. 38.7 ± 17.4%, P = 0.006) or without CKD (MACCE-free survival rate 73.9 ± 2.7% vs. 61.0 ± 5.4%, P = 0.001; survival rate 92.9 ± 1.5% vs. 83.8 ± 4.0%, P = 0.009). The benefit from revascularization was attenuated by CKD. Compared with percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG) had similar cumulative survival rates among patients, whether with or without CKD, but was associated with a higher cumulative MACCE-free survival rate (80.5 ± 3.4% vs. 68.5 ± 4.0%, P = 0.017) among patients without CKD. CONCLUSION: CKD attenuated the benefit from revascularization for CTO. Moreover, CABG was not superior to PCI among CTO patients, but with a reduction in MACCE in patients without CKD.

[Distribution of fine root biomass of main planting tree species in Loess Plateau, China].

The distribution of fine roots of Pinus tabuliformis, Populus tomentosa, Prunus armeniaca, Robinia pseudoacacia, Hippophae rhamnoides, and Caragana korshinskii was investigated by using soil core method and the fine root was defined as root with diameter less than 2 mm. The soil moisture and soil properties were measured. The results showed that in the horizontal direction, the distribution of fine root biomass of P. tabuliformis presented a conic curve, and the fine root biomass of the other species expressed logarithm correlation. Radial roots developed, the fine root biomass were concentrated within the scope of the 2-3 times crown, indicating that trees extended their roots laterally to seek water farther from the tree. In the vertical direction, the fine root biomass decreased with the increasing soil depth. Fine root biomass had significant negative correlation with soil water content and bulk density, while significant positive correlation with organic matter and total N contents.

[Spatial distribution of aboveground biomass of shrubs in Tianlaochi catchment of the Qilian Mountains].

This study estimated the spatial distribution of the aboveground biomass of shrubs in the Tianlaochi catchment of Qilian Mountains based on the field survey and remote sensing data. A relationship model of the aboveground biomass and its feasibly measured factors (i. e. , canopy perimeter and plant height) was built. The land use was classified by object-oriented technique with the high resolution image (GeoEye-1) of the study area, and the distribution of shrub coverage was extracted. Then the total aboveground biomass of shrubs in the study area was estimated by the relationship model with the distribution of shrub coverage. The results showed that the aboveground biomass of shrubs in the study area was 1.8 x 10(3) t and the aboveground biomass per unit area was 1598.45 kg x m(-2). The distribution of shrubs mainly was at altitudes of 3000-3700 m, and the aboveground biomass of shrubs on the sunny slope (1.15 x 10(3) t) was higher than that on the shady slope (0.65 x 10(3) t).

[Canopy interception of Pinus tabulaeformis plantation on Longzhong Loess Plateau, Northwest China: characteristics and simulation].

Taking the Pinus tabulaeformis plantation in the Anjiagou catchment on Longzhong Loess Plateau as test object, an observation was made on the characteristics of throughfall, stemflow, interception, and canopy structure of P. tabulaeformi during its growth season (from May to September) in 2011. Based on the observed data, the revised Gash analytical model was adopted to simulate the canopy interception, aimed to understand the ecological hydrological processes of Pinus tabulaeformis plantation and related mechanisms. In the observation period, a total of 19 precipitation events were observed, with a total precipitation of 215.80 mm. The throughfall, stemflow, and canopy interception were 165.24 mm, 2.29 mm, and 48.27 mm, occupying 76.7%, 1.1%, and 22.4% of the total precipitation, respectively. The simulated canopy interception was 41.24 mm, being 7.13 mm lower than the observed value and with a relative error of 14.7%. There were 33.8% and 60.0% of interception were evaporated from the canopy during and after precipitation, respectively. The revised Gash analytical model was highly sensitive to the canopy storage capacity, forest coverage, rainfall intensity, and evaporation, but less sensitive to the stemflow rate and stem water holding capacity.

[Characteristics of rainfall interception by Caragana korshinskii and Hippophae rhamnoides in Loess Plateau of Northwest China].

From May to October 2011, an investigation was conducted on the effects of rainfall and its intensity on the canopy interception, throughfall, and stemflow of Caragana korshinskii and Hippophae rhamnoides, the main shrub species commonly planted to stabilize soil and water in the Anjiagou catchment of Loess Plateau. A total of 47 rainfall events were observed, most of which were featured with low intensity, and the total amount and average intensity of the rainfalls were 208.9 mm and 2.82 mm x h(-1), respectively. As a whole, the rainfall events of 2-10 mm and 0.1-2 mm x h(-1) had the highest frequency. The canopy interception, throughfall, and stemflow of C. korshinski were 58.5 mm (28%), 124.7 mm (59.7%), and 25.7 mm (12.3%), while those of H. rhamnoides were 17.6 mm (8.4%), 153. 1 mm (73.3%), and 38.2 mm (18.3%), respectively. Regression analysis showed that the canopy interception, throughfall, and stemflow of the two shrub species all had significant positive correlations with the rainfall amount, and had exponent or power correlations with the rainfall amount and the maximum rainfall intensity in 10 minutes.

[Water storage capacity of qinghai spruce (Picea crassifolia) forest canopy in Qilian Mountains].

By the methods of direct measurement and regression analysis, this paper estimated the water storage capacity of Picea crassifolia forest canopy in Guantan in Qilianshan Mountains, based on the observed throughfall and the laboratory experimental data about the water storage capacity of various canopy components in 2008. Due to the impacts of various factors, differences existed in the canopy water storage capacity estimated by the two methods. The regression analysis was mainly impacted by the measurement approaches of the throughfall, the maximum water storage capacity estimated being 0.69 mm, whereas the direct measurement was mainly impacted by tree height, diameter at breast height, plant density, and leaf area index, with the estimated maximum water storage capacity being 0.77 mm. The direct measurement showed that the maximum water storage capacity per unit area of the canopy components of the forest was in the order of barks (0.31 mm) > branches (0.28 mm) > leaves (0.08 mm).

[Spatial distribution characteristics of the biomass and carbon storage of Qinghai spruce (Picea crassifolia) forests in Qilian Mountains].

This paper estimated the biomass and carbon storage and their spatial distributions of Qinghai spruce (Picea crassifolia) forests in Qilian Mountains, based on the field investigation, forest map, and meteorological data, and with the help of GIS technology. In 2008, the biomass of the forests was averagely 209.24 t x hm(-2), with a total biomass of 3.4 x 10(7) t. Due to the difference of water and thermal condition, there existed great differences in the biomass of Qinghai spruce within the Mountains. The biomass increased by 3.12 t x hm(-2) with increasing 1 degrees longitude and decreased by 3.8 t x hm(-2) with increasing 1 degrees latitude, and decreased by 0.05 t x hm(-2) with the elevation increasing 100 m. The carbon density of the forests ranged from 70.4 to 131.1 t x hm(-2), averagely 109.8 t x hm(-2), and the average carbon density was 83.8 t x hm(-2) for the young forest, 109.6 t x hm(-2) for the middle age forest, 122 t x hm(-2) for the near-mature forest, 124.2 t x hm(-2) for the mature forest, and 117.1 t x hm(-2) for the over-mature forest. The total carbon storage of Qinghai spruce forests in the study area was 1.8 x 10(7) t.

[Spatial distribution of Tamarix ramosissima aboveground biomass and water consumption in the lower reaches of Heihe River, Northwest China].

Based on the field observation on the Tamarix ramosissima populations in the lower reaches of Heihe River, the relationship models between the aboveground biomass of T. ramosissima and its morphological features (basal diameter, height, and canopy perimeter) were built. In the mean time, the land use/cover of the study area was classified by the decision tree classification with high resolution image (QuickBird), the distribution of T. ramosissima was extracted from classification map, and the morphological feature (canopy perimeter) of T. ramosissima was calculated with ArcGIS 9.2. On the bases of these, the spatial distribution of T. ramosissima aboveground biomass in the study area was estimated. Finally, the spatial distribution of the water consumption of T. ramosissima in the study area was calculated by the transpiration coefficient (300) and the aboveground biomass. The results showed that the aboveground biomass of T. ramosissima was 69644.7 t, and the biomass per unit area was 0.78 kg x m(-2). Spatially, the habitats along the banks of Heihe River were suitable for T. ramosissima, and thus, this tree species had a high biomass. The total amount of water consumption of T. ramosissima in the study area was 2.1 x 10(7) m3, and the annual mean water consumption of T. ramosissima ranged from 30 mm to 386 mm.

[Dynamic changes of groundwater level and vegetation in water table fluctuant belt in lower reaches of Heihe River: coupling simulation].

Based on the 2006 investigation data in lower reaches of Heihe River, and by using logarithmic normal distribution model, the models about the vegetation cover of Populus euphratica and Tamarix ramossima and the groundwater level in study area were built, and the potential plant of the study area was simulated. The results showed that in the lower reaches of Heihe River, the optimal groundwater level and mean groundwater level for P. euphratica were 2.6 m and 3.6 m, and those for T. ramossima were 2.0 m and 3.0 m, respectively. The high cover P. euphratica distribution area was mainly concentrated in the near-banks of Donghe River and Xihe River, while higher cover T. ramossima was distributed in most parts of the study area. From the aspect of current groundwater level, T. ramossima should be the adaptive species in the study area. The similarities between the potential and actual spatial distribution of P. euphratica and T. ramossima were 43. 4% and 55. 6% , respectively, and the main reason for the lower similarity was that there existed a gypsum salt pan in soil, which blocked the vertical movement of soil water.