Effects of forest regeneration types on phosphorus fractions of soil aggregates in subtropical forest.

Soil aggregates are important for the storage and availability of phosphorus in the soil. However, how forest regeneration types affect phosphorus fractions of soil aggregates remains unclear. In this study, we examined the composition of aggregate particle size, phosphorus fractions, phosphorus sorption capacity index (PSOR), legacy phosphorus index (PLGC) and degree of phosphorus saturation by Mehlich 3 (DPSM3) in bulk soils and soil aggregates of Castanopsis carlesii secondary forest (slight disturbance), C. carlesii human-assisted regeneration forest (moderate disturbance), and Cunninghamia lanceolata plantation (severe disturbance), aiming to explore the impact of forest regeneration types on phosphorus availability and supply potential of bulk soils and soil aggregates. The results showed that forest regeneration types significantly influenced the composition of soil aggregates. The proportion of coarse macroaggregates (>2 mm) in the soil of C. carlesii secondary forest and human-assisted regeneration forest was significantly higher than that in the C. lanceolata plantation, while the proportion of silt and clay fraction (<0.053 mm) showed an opposite trend. The composition of soil aggregates significantly affected the contents of different phosphorus fractions. The contents of soil labile phosphorus fractions (PSOL and PM3) decreased as aggregate particle size decreased. The contents of soil total phosphorus (TP), total organic phosphorus (Po), mode-rately labile phosphorus fractions (PiOH and PoOH), and occluded phosphorus (POCL), as well as PSOR and PLGC, exhibited a trend of decreasing at the beginning and then increasing as particle size decreased. The contents of TP, Po, and PiOH in coarse and silt macroaggregates was significantly higher than that in fine macroaggregates (0.25-2 mm) and microaggregates (0.053-0.25 mm). Forest regeneration types significantly influenced the contents of phosphorus fractions of bulk soils and soil aggregates. The contents of TP, Po, PSOL, and PM3 in the soil of C. carlesii secondary forests was significantly higher than that in C. carlesii human-assisted regeneration forest and C. lanceolata plantation. The contents of PSOL and PM3 in different-sized aggregates of C. carlesii secondary forests were significantly higher than that in the C. lanceolata plantation. Forest regeneration types significantly influenced the composition and supply potential of phosphorus fractions in soil aggregates. The proportions of PSOL, and PM3 to TP in different-sized soil aggregates were significantly lower in C. carlesii human-assisted regeneration forest compared with C. carlesii secondary forest. PSOR and DPSM3 in different-sized soil aggregates were significantly lower in C. lanceolata plantation than that in C. carlesii secondary forest. Overall, our results indicated that natural regeneration is more favorable for maintaining soil phosphorus availability, and that forest regeneration affects soil phosphorus availa-bility and its supply potential by altering the composition of soil aggregates.

[Characteristics of phosphorus fractions and their driving factors in forest soils with different parent materials in the mid-subtropics, China]. / ä¸­äºšçƒ­å¸¦ä¸åŒæ¯è´¨å‘è‚²æ£®æž—åœŸå£¤ç£·ç»„åˆ†ç‰¹å¾åŠå ¶å½±å“å› ç´ .

With the aim to understand the influence degree and mechanism of parent material and forest type on soil phosphorus component, we analyzed soil P fractions, iron and aluminum oxides, microbial biomass, and phosphatase activity in Castanopsis carlesii and Cunninghamia lanceolata forest soils developed from two types of parent materials, sandstone and granite, in Sanming, Fujian Province. The results showed that both parent material and forest type significantly affected the contents of different P fractions. The contents of total P, labile inorganic/organic P, moderately labile inorganic/organic P, and non-labile P from sandstone-developed soils were significantly higher than those from granite-developed soils. Moreover, soil labile organic P, moderately labile inorganic/organic P and non-labile P fraction in sandstone-developed soils of C. carlesii forest were significantly higher than those of C. lanceolata forest, while the corresponding soil P fractions in granite-deve-loped soils had no significant difference between the two types of forests. The activity of acid phosphatase (ACP) in granite-developed soils was significantly higher than that in sandstone-developed soils under two types of forest, while soil microbial biomass carbon (MBC) and P (MBP) in sandstone-developed soils were significantly higher under C. carlesii forest than under C. lanceolata fo-rest. The content of soil P fractions was significantly positively correlated with the content of different forms of iron and aluminum oxides, MBP, and MBC, but negatively correlated with soil pH and acid phosphatase activity (ACP). Our results indicated that parent material and forest types might affect soil P fractions and characteristics mainly through altering soil iron and aluminum oxides, ACP, MBP in mid-subtropical forest soils.

[Clinical effects of qianggan capsule on the liver tissue pathology and PDGF-BB, TGF-beta1, TIMP-1, and MMP-1 factors in patients with chronic hepatitis B].

OBJECTIVE: To study the therapeutic efficacy of Qianggan Capsule (QC) in treating patients Seventy pa-with chronic hepatitis B fibrosis from the pathological aspect and serum fibrosis markers. METHODS: patients with chronic hepatitis B were randomly assigned to two groups, the treated group (45 cases) and the control group (25 cases). QC was given to patients in the treated group, while glucurone and compound vitamin B were given to those in the control group. The therapeutic course for both groups was 6 months. The therapeutic effect was assessed by determination of fibrosis markers including serum levels of platelet-derived growth factor-BB (PDGF-BB), transforming growth factor beta 1 (TGF-beta1), matrix metalloproteinases-1 (MMP-1), tissue inhibitors of metalloproteinases-1 (TIMP-1) and serum levels of alanine transaminase (ALT), total bilirubin (TBIL), albumin (ALB), and prothrombin time (PT) were completed 1 month before treatment and at the end of the trial respectively. RESULTS: (1) Serum levels of ALT, TBIL, PT decreased obviously and the serum ALB level obviously increased in both groups (all P<0.05), showing no significant difference between the two groups (P>0.05). (2) Hepatic fibrosis markers: Serum levels of PDGF-BB, TGF-1P3, and TIMP-1 significantly decreased, and serum MMP-1 level markedly increased in the treated group more than before treatment (all P<0.05). No significant difference was shown between before and after treatment in each index of the control group (P>0.05). Serum levels of PDGF-BB, TGF-beta1, and TIMP-1 were obviously lower and the serum MMP-1 level was obviously higher in the treated group than in the control group after treatment (all P<0.05). (3) Hepatic histopathological results: The hepatic inflammatory necrosis activity and the hepatic fibrosis degree in the treated group were significantly improved (P<0.05), with the total effective rate of the hepatic necrosis activity improvement being 40.00% and that of the hepatic fibrosis degree being 57.78%. But there was no obvious improvement in the hepatic inflammatory necrosis activity or the hepatic fibrosis degree in the control group (P>0.05). CONCLUSIONS: QC could effectively improve serological indices and pathological indices of chronic hepatitis B fibrosis patients, showing better therapeutic effect in reversing hepatic fibrosis and alleviating hepatic inflammatory necrosis.