Afforestation in the Three North Region (TNR) of China has received wide concern due to the low survival rate and threats to water security associated with the lack of available precipitation for vegetation. It is crucial to provide a spatial layout for revegetation according to the available precipitation to achieve the vegetation cover target. This study investigated the spatial pattern of precipitation, determined the suitable vegetation distribution based on the ecological water requirements and precipitation, and proposed an optimized revegetation scheme by comparing the actual and suitable vegetation patterns. The results indicated that the actual vegetation that matched the pixel-level precipitation accounted for 67.24% of the total vegetation area in the TNR. However, 18.50% of the actual forest, 21.82% of the actual shrublands, and 19.95% of the actual grasslands were overloaded with respect to precipitation. The total suitable vegetation area was reduced slightly compared to the actual vegetation area. There is still some potential for the revegetation of forest and shrublands, mainly those in the eastern and south-eastern parts of the TNR. The optimized revegetation area in the TNR was 3.04 × 106 km2, including a maintenance management type of 2.19 × 106 km2, an upgrade type of 0.49 × 106 km2, and a degradation type of 0.37 × 106 km2. Maintenance management (natural restoration) and transformation to vegetation types with lower ecological water requirements were recognized as important revegetation practices in the TNR. This study provides guidelines to adjust the Three North Shelterbelt Project policies based on precipitation data to reduce the negative impact of revegetation on the hydrological cycle.
Based on the 7th forestry inventory data of Shandong Province, this paper estimated the carbon storage and carbon density of forest stands, and analyzed their distribution characteristics according to dominant tree species, age groups and forest category using the volume-derived biomass method and average-biomass method. In 2007, the total carbon storage of the forest stands was 25. 27 Tg, of which the coniferous forests, mixed conifer broad-leaved forests, and broad-leaved forests accounted for 8.6%, 2.0% and 89.4%, respectively. The carbon storage of forest age groups followed the sequence of young forests > middle-aged forests > mature forests > near-mature forests > over-mature forests. The carbon storage of young forests and middle-aged forests accounted for 69.3% of the total carbon storage. Timber forest, non-timber product forest and protection forests accounted for 37.1%, 36.3% and 24.8% of the total carbon storage, respectively. The average carbon density of forest stands in Shandong Province was 10.59 t x hm(-2), which was lower than the national average level. This phenomenon was attributed to the imperfect structure of forest types and age groups, i. e., the notably higher percentage of timber forests and non-timber product forest and the excessively higher percentage of young forests and middle-aged forest than mature forests.
Based on decade's located observation,the flow process of water conservation service in middle sub-tropical and south sub-tropical forests was studied,including five forest types.The results showed that intra-annual canopy interception curves in Liluo Chinese fir forest and Xijiangping evergreen broad-leaved forest were unimodal curves with larger variation,while that of the three forests in Longqiao were bimodal curves with smaller variation.The value cumulative process curves of monthly canopy interception in five forest types were basically identical.In terms of water regulation,Liluo Chinese fir forest and Xijiangping evergreen broad-leaved forest had larger variation than that of the other three forest types in Longqiao.The monthly mean water regulation was ranked in the descending orders as follows: Xijiangping evergreen broad-leaved forest(848.08 m3/hm2),Liluo Chinese fir(573.58 m3/hm2),Longqiao mixed plantation of Eucalyptus citrlodora with masson pine(397 m3/hm2),Longqiao masson pine forest(329.83 m3/hm2),and Longqiao Chinese fir forest(315 m3/hm2).The flow process of water supply appeared the basically identical shape as the water regulation curves.The monthly mean volume of water supply in Xijiangping evergreen broad-leaved forest,Liluo Chinese fir,Longqiao mixed plantation of Eucalyptus citrlodora with masson pine,Longqiao masson pine forest,and Longqiao Chinese fir forest was 751.92 m3/hm2,486.92 m3/hm2,332.08 m3/hm2,210.50 m3/hm2 and 65.92 m3/hm2,respectively.The monthly value of canopy interception,water regulation and water supply was estimated by means of shadow price method.Furthermore,the linear regression equation of monthly water regulation and monthly water supply on monthly precipitation was built,respectively.
Abstract Biochar supported nano-scale zerovalent iron (nZVI/BC) for persulfate (PS) activation has been studied extensively for the degradation of pollutants on the lab scale, but it was rarely applied in practical soil remediation in the field. In this research, we developed a facile ball-milling method for the mass production of nZVI/BC, which was successfully applied to activate persulfate for the remediation of organic polluted soil on an in-situ pilot scale. In-situ high-pressure injection device was developed to inject nZVI/BC suspension and PS solution into the soil with a depth of 0–70 cm. The removal efficiency of target pollutants such as 2-ethylnitrobenzene (ENB, 1.47–1.56 mg/kg), biphenyl (BP, 0.19–0.21 mg/kg), 4-(methylsulfonyl) toluene (MST, 0.32–0.43 mg/kg), and 4-phenylphenol (PP, 1.70–2.46 mg/kg) at different soil depths was 99.7%, 99.1%, 99.9% and 99.7%, respectively, after 360 days of remediation. The application of nZVI/BC significantly increased the degradation rates of contaminants by 11–322%, ascribed to its relatively higher efficiency of free radical generation than that of control groups. In addition, it was found that nZVI/BC-PS inhibited soil urease and sucrase enzyme activities by 1–61% within 55 days due to the oxidative stress for microbes induced by free radicals, while these inhibition effects disappeared with remediation time prolonged (> 127 days). Our research provides a useful implementation case of remediation with nZVI/BC-PS activation and verifies its feasibility in practical contaminated soil remediation. Graphical Abstract
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