Tanshinone I induces ferroptosis in gastric cancer cells via the KDM4D/p53 pathway.

INTRODUCTION: Tanshinone I (Tan I) is one of the bioactive components of Salvia miltiorrhiza. Whether it inhibits gastric cancer through ferroptosis has not been reported. This study aimed to confirm the effect of Tan I on ferroptosis in gastric cancer cells. METHODS: AGS and HGC27 cells were treated with Tan I. First, oxidative stress-related parameters and the expression of ferroptosis-related proteins were examined. Combined with a ferroptosis inhibitor, Tan I was found to inhibit gastric cancer cells via the ferroptosis pathway. Finally, with bioinformatics analysis, the target protein of Tan I was identified. RESULTS: Tan I significantly inhibited the expression level of GPX4. This molecule also increased ROS, MDA, and Fe2+ contents and decreased GSH enzyme activity. Therefore, we hypothesized that Tan I may inhibit gastric cancer cells by inducing ferroptosis. Western blotting results showed that Tan I inhibited the expression levels of the ferroptosis resistance-related proteins GPX4, SLC7A11, and FTH1, while the pro-ferroptosis-related proteins TFR1 and ACSL4 were significantly upregulated. A ferroptosis inhibitor effectively reversed these regulatory effects of Tan I in gastric cancer. With these data combined with the bioinformatics analysis, KDM4D was identified as a key regulatory target of Tan I. Mechanistically, Tan I induced positive regulation of ferroptosis resistance-related indicators by inhibiting KDM4D to upregulate p53 protein expression. Overexpression of KDM4D significantly reversed the effect of Tan I-induced ferroptosis resistance in gastric cancer cells. CONCLUSIONS: Tan I induced ferroptosis inhibition in gastric cancer by regulating the KDM4D/p53 pathway.

Variations in soil phosphorus fractionations in different water-stable aggregates under litter and inorganic fertilizer treatment in Korean pine plantation and its natural forest.

Soil aggregation in forest ecosystem is considered as a significant physical process mainly influenced by manure, fertilizers or combination. This aggregation may directly alter the soil nutrient and their fractions in soil. So, soil samples were collected from two types of forests i.e. Natural Korean pine forests (NKPF) and Korean pine plantation (KPP) in order to know the quantities of organic and inorganic Phosphorus (P) amounts in different aggregate sizes viz. >5 mm, 2-5 mm, 0.25-2 mm, <0.25 mm under forest litter and synthetic fertilizer application below the treatments as undisturbed soil (CK), removed litter (RL), altered litter (AL) while the fertilizer treatments were as control; C: (No added N and P,), L: low (5 g N m-2 a-1 + 5 g P m-2 a-1), M: medium (15 g N m-2 a-1 + 10 g P m-2 a-1) and H: high concentration (30 g N m-2 a-1 + 20 g P m-2 a-1), respectively. The results showed that H2O-Pi, NaHCO3-Pi, Residual Pi, SOC were highest retained in larger soil aggregates (>5 mm) and decreased with the decreasing aggregate size, while other variables, i.e., NaOH-Pi, NaHCO3-Po, pH and T-N were not affected in aggregate size. H2O-Pi (48 ppm), NaHCO3-Pi (68 ppm), NaHCO3-Po (80 ppm), NaOH-Po (623 ppm), HCL-Po (67 ppm), SOC (20.36 ± 1.6) was estimated in medium fertilizer treatment. PCA analysis showed that spread/variance of data points on F1 (62.90%) is more than spread/variance of data points on F2 (57.74%) in NKPF and KPP, respectively, while correlation matrix showed high correlation between H2O-Pi and NaOH-Pi (0.63) and H2O-Pi and NaHCO3-Pi (0.63) while a strong negative correlation was present between Res-Pi and Po (-0.61). Moreover, litter inputs increased the organic-P fractions in soil particularly at medium treatment.

Value of the Prognostic Nutritional Index in Surgery for Crohn Disease in China and the Effects on Outcome: A Retrospective Study.

PURPOSE: To investigate the value of the Prognostic Nutritional Index (PNI) in the surgery of Crohn Disease and examine the ability of PNI to predict poor outcomes with surgery. METHODS: One hundred fifty-seven patients were divided into a good nutrition group (PNI ≥40) and a poor nutrition group (PNI <40). The retrospective univariate analysis, logistic regression multivariate analysis, and receiver operating characteristic (ROC) curve analysis were used to screen out independent risk factors for postoperative complications and postoperative recurrences that required reoperation. RESULTS: Penetrating behavior was an independent risk factor for postoperative complications. Emergency surgery, penetrating behavior, hypoalbuminemia, and low PNI were independent risk factors for reoperation. By the receiver operating characteristic analysis, low PNI was superior to hypoproteinemia in predicting postsurgical recurrence. CONCLUSIONS: PNI is a good marker for predicting surgical recurrence, but it cannot predict postoperative complications. The nutritional status in patients before elective surgery can be modified to improve PNI. It can reduce surgical recurrence to a minimum level.

[Effects of canopy density on understory plant diversity in Robinia pseudoacacia plantations on the Loess Plateau of China]. / é»„åœŸé«˜åŽŸåˆºæ§äººå·¥æž—éƒé—­åº¦å¯¹æž—ä¸‹æ¤ç‰©å¤šæ ·æ€§ç‰¹å¾çš„å½±å“.

To solve the problems of understory plant shortage and biodiversity reduction caused by high tree density of Robinia pseudoacacia plantations on the Loess Plateau in northwest China, we analyzed the data collected by field survey and from literatures. We used the upper boundary line method to examine the impacts of canopy density on understory plant diversity. Based on field survey at the Guanshan Forest Farm of Jingchuan County of Gansu Pro-vince, the species number of understory plants in R. pseudoacacia plantations was higher than that in natural grassland (91 vs. 78). The dominant species varied with canopy density, which was completely different from that of natural grassland. A comprehensive analysis of both literature data and field survey data showed that, when mean annual precipitation (MAP) <550 mm or >550 mm, the increases in canopy density first led to a stable understory plant coverage and then a sharp or slight decrease, and understory plant biomass showed a sharp and continuous decrease or a slight increase and then decrease. Understory plant species richness and other diversity indices (Shannon, Simpson, and Pielou indices) first increase and then decrease, with bigger variation range under lower MAP. In all, the characteristics (coverage, biomass and species diversity, etc.) of understory plant community in R. pseudoacacia plantations were strongly affected by canopy density, with higher sensitivity under lower MAP. There was a general threshold range of canopy density of 0.45-0.6. When canopy density was above or below this thre-shold range, it would lead to a rapid decrease of the most characteristics of understory plant community. Therefore, keeping canopy density within the rational range of 0.45-0.6 in the management of R. pseudoacacia plantations is the key to make all the above-mentioned understory plant characteristics at relatively high level.

Knockdown of CENPU inhibits cervical cancer cell migration and stemness through the FOXM1/Wnt/ß-catenin pathway.

Currently, the clinical outcome of cervical cancer (CC) is still undesirable, and it is urgent to explore more treatment strategies for CC. In this study, the effects of CENPU on migration and stemness of CC was studied. The CENPU expression were retrieved from The Cancer Genome Atlas (TCGA). The effects of CENPU on the viability and proliferation of cells were evaluated by CCK-8 assay and colony formation assay. Wound healing assay and invasion assay were chosen to assess migration and invasion of cells. Tumorsphere-forming assay was applied for testing the stemness. Western blot analysis was applied for assessing the level of CENPU, Nanog, Oct4, FOXM1, ß-catenin, c-myc and MMP-7. The tumor sizes and volumes were also measured. The TCGA data and WB assay suggested that CENPU was upregulated in CC. CENPU knockdown would inhibit the viability of CC cells and prohibit the migration and invasion of cells. Tumorsphere-forming assay and WB results suggested that CENPU silencing decreased the sphere formation rate and the expression of Nanog and Oct4. Moreover, CENPU knockdown suppressed the expression of FOXM1, ß-catenin, c-myc and MMP-7 by WB. In vivo study demonstrated that CENPU knockdown inhibited the growth of CC, indicated by reduced sizes and volumes of CC. In summary, our results suggested that knockdown of CENPU inhibited CC migration and stemness through the FOXM1/Wnt/ß-catenin pathway.

Nintedanib Induces the Autophagy-Dependent Death of Gastric Cancer Cells by Inhibiting the STAT3/Beclin1 Pathway.

BACKGROUND: Tyrosine kinase inhibitors are currently the most widely studied targeted therapies for gastric cancer. As a triple tyrosine inhibitor, nintedanib can alleviate the progression of a variety of cancers, but it is poorly studied in gastric cancer. AIMS: To investigate the effect of nintedanib on gastric cancer. METHODS: This study investigated nintedanib's effect on gastric cancer autophagy in vivo and in vitro, and the activity and morphological changes of gastric cancer cells were detected by MTT and HE staining. Proliferation, migration, invasion, and EMT-related marker proteins of AGS and MKN-28 cells were detected. The effects of nintedanib on autophagy in gastric cancer cells were detected by acridine orange, immunofluorescence, and Western blotting assays. The regulation of nintedanib on STAT3 and Beclin1 was detected by qPCR and Western blotting assays. Subsequently, the effects of nintedanib on the tumor STAT3/Beclin1 pathway were verified by stably overexpressing STAT3 in gastric cancer cell lines and tumor-bearing experiments in nude mice. RESULTS: The results showed that nintedanib could inhibit gastric cancer cells' proliferation and EMT process. Meanwhile, autophagy was induced in AGS and MKN-28 cells, and the expression of autophagy-related protein Beclin1 was upregulated, and the phosphorylation level of STAT3 was downregulated. Nintedanib inhibited STAT3 phosphorylation and upregulated Beclin1 to inhibit tumor growth in gastric cancer cell lines with stable STAT3 overexpression and tumor-bearing experiments in nude mice. CONCLUSIONS: By inhibiting STAT3, nintedanib upregulated Beclin1 and caused autophagic death in gastric cancer cells.

Correlation of Serum IGF-1R, VEGF, and ET Levels with Bone Mineral Density in Type 2 Diabetic Mellitus Patients Treated with Metformin Plus α-Glucosidase Inhibitors.

Diabetes mellitus is a common chronic disease. This study aimed to investigate the correlation between serum insulin-like growth factor 1 receptor (IGF-1R), vascular endothelial growth factor (VEGF), endothelin (ET) levels, and bone mineral density (BMD) in type 2 diabetic mellitus (T2DM) patients treated with metformin plus α-glucosidase inhibitors and evaluate the predictive value of serum factors in the prognosis of osteoporosis in these patients. It was a prospective study that enrolled 142 patients with T2DM treated in Dinghu District People's Hospital from March 2019 to May 2020. All enrollments were randomized (1 : 1) to receive either metformin (control group) or metformin plus α-glucosidase inhibitors (study group). After 12 weeks of treatment, metformin plus α-glucosidase inhibitors were associated with significantly lower levels of 2 hPG, FPG, HbA1c, and HOMA-IR versus metformin alone (P < 0.05). After treatment, the BMD was positively correlated with IGF-1R and negatively correlated with VEGF and ET. Alpha-glucosidase inhibitors plus metformin for primary T2DM can effectively manage blood glucose and reduce insulin resistance in patients, but the prediction of osteoporosis development remains to be further explored in large sample studies.

Jatrorrhizine can improve nerve cell injury induced by Aß 25-35, acting through miR-223-3p/HDAC4 axis.

OBJECTIVE: The purpose of this research is to probe the mechanism of Jatrorrhizine (JAT) improving Aß 25-35-induced nerve cell injury through the miR-223-3p/HDAC4 axis. METHODS: SH-SY5Y cells were treated with Aß 25-35 to simulate nerve injury in the pathogenesis of Alzheimer's disease (AD), and JAT-treated SH-SY5Y cells were assessed for HDAC4 and miR-223-3p. The HDAC4 and miR-223-3p levels were tested by qRT-PCR. Proliferation was determined through MTT. Apoptosis was assessed by flow cytometry, and the related indexes of oxidative stress (OS) were examined by an OS kit. RESULTS: Compared with AD group, OD value increased, apoptosis rate decreased, and OS was inhibited in the AD+JAT group (all P<0.05). In SH-SY5Y cells, miR-223-3p can specifically inhibit the HDAC4 expression. The miR-223-3p expression increased and HDAC4 decreased after JAT acted on SH-SY5Y cells stimulated by Aß 25-35 (all P<0.05). The addition of over-expression HDAC4 vector or miR-223-3p inhibitor could inhibit proliferation, and promote apoptosis and OS on the basis of JAT (all P<0.05). In addition, over-expressing miR-223-3p can suppress over-expressed HDAC4's effects on proliferation, apoptosis, and OS of SH-SY5Y cells (all P<0.05). CONCLUSION: JAT can improve the nerve injury induced by Aß 25-35 by up-regulating miR-223-3p and inhibiting the HDAC4 expression, suppress apoptosis and OS, and induce proliferation. This research further clarified the mechanism of JAT in AD.

Tumor suppressor role of hsa_circ_0035445 in gastric cancer.

Circular RNAs (circRNAs) are closely related to the occurrence and development of cancers. However, the roles of circRNAs in gastric cancer are largely unknown. Total 104 pairs of gastric cancer tissues and non-cancer tissues, fasting plasma of 42 healthy people and 42 gastric cancer patients' one day before operation and 10 days after operation were collected. Quantitative reverse transcription-polymerase chain reaction was used to detect the expression level of hsa_circ_0035445. The receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) were used to analyze its diagnostic value. Small interfering RNA and overexpression vector were used to downregulate and upregulate the expression of hsa_circ_0035445, respectively. Cell Counting Kit-8 and colony formation assays were used to detect the proliferation ability. Trans-well assay and scratch assay were used to detect the migration ability. Finally, flow cytometry was used to detect the changes of cell cycle distribution and apoptosis. Hsa_circ_0035445 was lowly expressed in gastric cancer tissues, plasma of gastric cancer patients, and gastric cancer cells. The expression level of hsa_circ_0035445 in gastric cancer tissues was relationship with tumor size and distant metastasis. The AUC of hsa_circ_0035445 in tissues and plasma was 0.68 and 0.86, respectively. Upregulation of hsa_circ_0035445 suppressed the proliferation and migration, promoted apoptosis, and blocked cells at G0/G1 phase. Downregulation of hsa_circ_0035445 promoted the proliferation and migration, suppressed apoptosis, and blocked cells at S phase. In conclusion, hsa_circ_0035445 may become a new target for the treatment of gastric cancer.

Biglycan Expression Promotes ß-Amyloid-Induced Microglial Activation via TLR2 in Mouse Cell Culture Model.

BACKGROUND: Alzheimer disease (AD) is one of the most frequent neurodegenerative disorders that results in the progressive loss of memory and severe impairments and death. The experimental results showed that the neuroinflammation involving microglia and cytokines, especially the neuritic plaques composed of aggregates of ß-amyloid protein, also play a major risk in AD. Biglycan (BGN) is involved in the regulation of neuronal cell division that could induce the expression of proinflammatory factors. Furthermore, BGN also exerts effects on ß-amyloid-induced microglial dysfunction and contributes to AD pathogenesis. However, the mechanisms underlying the regulatory role of BGN on ß-amyloid-induced microglial activation remain unclear. This study intended to investigate whether BGN could promote ß-amyloid induced microglial activation through TLRs in immortalized murine microglial (BV2) cells. METHODS: The levels of tumor necrosis factor α (TNF-α) and interleukin 1ß (IL-1ß) were detected by enzyme-linked immunosorbent assay (ELISA). The Cell Counting kit-8 (CCK8) assay was performed to detect cell viability. The expression level of a microglia marker (CD11b) was detected by immunofluorescence. The mRNA and protein expression levels of BGN and Toll-like receptor 2 (TLR2) were determined by quantitative RT-PCR and western blotting. RESULTS: BGN was upregulated in activated microglial cells. Knockdown of BGN efficiently attenuated ß-amyloid-induced microglial activation and expressions of proinflammatory factors. Furthermore, the present findings provided evidence showing that BGN could regulate ß-amyloid-induced microglial activation through TLR2 in BV2 cells. CONCLUSIONS: Our results suggested that TLR2 signaling may be involved in the regulatory role of BGN in ß-amyloid-induced microglial activation.

[Composition and fractal features of soil micro-aggregates in microsites of different types of treefall gaps]. / ä¸åŒæž—åž‹æ ‘å€’æž—éš™å† å¾®ç«‹åœ°ç±»åž‹çš„åœŸå£¤å¾®å›¢èšä½“ç»„æˆåŠå ¶åˆ†å½¢ç‰¹å¾.

Through field survey and laboratory analysis, we examined the composition and fractal features of soil micro-aggregates in different types of treefall gaps and microsites (pit bottom and mound top) in broad-leaved Korean pine forest and spruce-fir-Korean pine forest. Results showed that the contents of soil microaggregates under the classes of 0.25-2 mm and 0.05-0.25 mm were higher in both forest types, ranging from 25.7% to 50.7% and from 27.0% to 42.8%, respectively, and that of <0.002 mm was the lowest, ranging from 4.4% to 8.9%. In the pit bottom and mound top of gaps, soil bulk density was higher in both forest types. Soil nutrient content in mound top was higher than that in pit bottom and was higher in broad-leaved Korean pine forest than spruce-fir-Korean pine forest. Soil microaggregates of <0.002 mm had no correlation with soil physical and chemical properties, whereas that of 0.25-2 mm and 0.002-0.02 mm had significantly positive and negative correlation with soil non-capillary porosity, total porosity, aeration porosity, organic matter, total phosphorus, total nitrogen and organic carbon, respectively. On the whole, soil fractal dimension (D) and the proportion of characteristic soil micro-aggregates (PCM) in broad-leaved Korean pine forest were larger than those in spruce-fir-Korean pine forest, and the ratio of soil microaggregates diameter (RMD) in mound top and pit bottom was increased in two forest types. Soil D and PCM had no significant correlation with soil physical and chemical properties, while RMD was negatively correlated with capillary porosity, total porosity, soil bulk density and aeration porosity. In two forest types, the formation of mound and pit microsites could decrease the larger size micro-aggregates and the stability of soil micro-aggregate, increase soil D and PCM, and signifi-cantly increase RMD. RMD could be used as a quantitative index of soil physical and chemical properties in pit and mound microsites of forest.

Global and Geographically and Temporally Weighted Regression Models for Modeling PM2.5 in Heilongjiang, China from 2015 to 2018.

Objective: This study investigated the relationships between PM2.5 and 5 criteria air pollutants (SO2, NO2, PM10, CO, and O3) in Heilongjiang, China, from 2015 to 2018 using global and geographically and temporally weighted regression models. Methods: Ordinary least squares regression (OLS), linear mixed models (LMM), geographically weighted regression (GWR), temporally weighted regression (TWR), and geographically and temporally weighted regression (GTWR) were applied to model the relationships between PM2.5 and 5 air pollutants. Results: The LMM and all GWR-based models (i.e., GWR, TWR, and GTWR) showed great advantages over OLS in terms of higher model R2 and more desirable model residuals, especially TWR and GTWR. The GWR, LMM, TWR, and GTWR improved the model explanation power by 3%, 5%, 12%, and 12%, respectively, from the R2 (0.85) of OLS. TWR yielded slightly better model performance than GTWR and reduced the root mean squared errors (RMSE) and mean absolute error (MAE) of the model residuals by 67% compared with OLS; while GWR only reduced RMSE and MAE by 15% against OLS. LMM performed slightly better than GWR by accounting for both temporal autocorrelation between observations over time and spatial heterogeneity across the 13 cities under study, which provided an alternative for modeling PM2.5. Conclusions: The traditional OLS and GWR are inadequate for describing the non-stationarity of PM2.5. The temporal dependence was more important and significant than spatial heterogeneity in our data. Our study provided evidence of spatial-temporal heterogeneity and possible solutions for modeling the relationships between PM2.5 and 5 criteria air pollutants for Heilongjiang province, China.

LncRNA SNHG6 promotes the migration, invasion, and epithelial-mesenchymal transition of colorectal cancer cells by miR-26a/EZH2 axis.

Objective: Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Small nucleolar RNA host gene 6 (SNHG6) was reported to function as an oncogene in a number of cancers. Here, we aimed to further explore the roles and molecular mechanism of SNHG6 in CRC metastasis. Methods: The expression levels of SNHG6, miR-26a, and enhancer of zeste homolog 2 (EZH2) mRNA were assessed by quantification real-time PCR in CRC tissues and cell lines. Western blot analysis was performed to determine the levels of E-cadherin, Snail, Vimentin, N-cadherin, and EZH2. Cell migration and invasion capacities were detected by transwell assay. Dual-luciferase reporter assay or RNA Immunoprecipitation assay was employed to verify the interaction between SNHG6 and miR-26a, or EZH2 and miR-26a. Results: Our data indicated that SNHG6 and EZH2 mRNA were upregulated, and miR-26a was downregulated in CRC tissues and cell lines. SNHG6 knockdown suppressed the migration, invasion, and epithelial-mesenchymal transition (EMT) of CRC cells. Moreover, SNHG6 binded to miR-26a and repressed miR-26a expression. EZH2 was a direct target of miR-26a, and it was regulated by SNHG6/miR-26a. MiR-26a inhibitor undermined the effect of SNHG6 knockdown on cell migration, invasion, and EMT. Additionally, EZH2 antagonized the effect of miR-26a on cell migration, invasion, and EMT in CRC cells. Conclusion: SNHG6 knockdown suppressed cell migration, invasion, and EMT at least partly by sponging miR-26a and regulating EZH2 expression in CRC cells, providing a strategy for blocking CRC metastasis.

Jatrorrhizine Protects Against Okadaic Acid Induced Oxidative Toxicity Through Inhibiting the Mitogen-Activated Protein Kinases Pathways in HT22 Hippocampal Neurons.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by deposit of amyloid plaques and neurofibrillary tangles and oxidative stress plays an essential role in the pathogenesis of AD. Jatrorrhizine (JAT), a Coptidis Rhizome, has multiple biological functions such as anti-oxidation and anti-inflammation. Herein, we investigated the neuroprotective effects of JAT on okadaic acid (OA)- induced cytotoxicity and apoptosis in HT22 cells. Following the exposure to 80 nmol/L OA for 12h, the reduction in cell survival, activities of superoxide dismutase, glutathione peroxidase and mitochondria membrane potential has been shown in HT22 cells. In contrast, OA increased levels of lactate dehydrogenase, malondialdehyde production and intracellular reactive oxygen species. OA also enhanced the expression of Bax but decreased the levels of Bcl-2, OA also upregulated the expression of cleaved caspase-3, phosphorylated extracellular signal-regulated kinases 1/2, phosphorylated c-Jun N-terminal kinases, phosphorylated p38 and NF-kappa B p65 subunit in HT22 cells and this up-regulation was attenuated by JAT which was pre-incubated for 12h in the cells prior to OA exposure. In conclusion, our data present the protective role of JAT in OA induced cytotoxicity, via its antioxidant and anti-apoptotic properties by inhibiting the mitogen-activated protein kinases pathways in HT22 hippocampal neurons. These results indicate that JAT may be the potential target to treat AD induced by oxidative stress and apoptosis.

[Spatial distribution pattern of main populations and gap makers in Picea koraiensis and Abies nephrolepis forest of Xiaoxing' an Mountains, Northeast China].

Species composition and diameter class structure were investigated in 1.5 hm2 (100 m x 150 n) permanent plot in Picea koraiensis and Abies nephrolepis forest of Xiaoxing' an Mountains. The spatial distribution pattern and spatial association of main populations and gap makers were analyzed by using point pattern analysis. The results showed that there were a total of 13 species with diameters at breast height greater than 2 cm in tree layer, and great differences were observed in the densities of main populations. The importance values of A. nephrolepis, P. koraiensis, Betula platyphylla and Acer ukurunduense were ranked in the first 4 in the plot. The diameter class structure of their populations presented an inverse 'J' curve. The spatial distribution patterns for A. nephrolepis and P. koraiensis were similar, which changed from aggregated, random to uniform distribution with the spatial scale. For B. platyphylla, the distribution was aggregated at ≤40 m scale, and random at >40 m scale, whereas A. ukurunduense presented an aggregated distribution pattern at the whole research scale. Except that the negative correlation between B. platyphylla and A. ukurunduense existed at the whole research scale, positive correlation between the other populations at small scale and negative correlation at large scale were observed. Only A. nephrolepis and B. platyphylla had significant positive correlation, and generally no significant correlation existed between other populations. Spatial distribution pattern of gap makers was characterized as aggregated distribution at small and middle scales, and random distribution with increasing scale. Spatial point pattern of gap makers formed by uprooting exhibited unimodal type distribution, and random, aggregated, and uniform distribution also occurred. Spatial point pattern of gap makers formed by breaking overall presented a little fluctuation, random and aggregated distributions alternatively appeared at small scale, and random distribution happened at large scale. Their spatial correlation analysis indicated that significant positive correlation existed at ≤32 m scale, and non-significant negative correlation at >32 m scale.

[Microclimate dynamics of pit and mound complex within different sizes of forest gaps in Pinus koraiensis-dominated broadleaved mixed forest].

An investigation was conducted in a 2.25 hm2 plot of Pinus koraiensis-dominated broad-leaved mixed forest to study basic characteristics of 7 small gaps, 5 middle gaps, 3 large gaps and 7 closed stands within 38 pit and mound complexes caused by treefall in May 2012. From June to September 2012, the soil temperature, soil water content and relative humidity at five microsites (pit bottom, pit wall, mound top, mound face and undisturbed closed stands) were measured in six sunny days each month. The results showed that among the five microsites in every month, the mound top had the highest soil temperature and the lowest water content and relative humidity, and vice versa for the pit bottom. Mostly, the differences in the above indicators among the five microsites were significant. From June to September, the mean soil temperatures for all microsites at pit and mound complex in the various gaps and closed stands were in the order of large gap>middle gap >small gap>closed stand; but the soil water content ranked differently every month. In June, August and September, the mean relative humidities for all microsites in the various gaps and closed stands were in the order of closed stand>small gap>middle gap>large gap. Mostly, the differences in the above indicators between all microsites in the various gaps and closed stand were significant. The mean monthly soil temperature and relative humidity were highest in July, but lowest in September. The maximal mean monthly soil water content occurred in July and the minimal one in September for each microsite except the undisturbed closed stands, where the maximal mean monthly soil water content occurred in July. The variation of the microclimate at the pit and mound complex was mainly influenced by gap size, microsite, and time.

[Dimensional characteristics and spatial distribution patterns of pit and mound complexes in Pinus koraiensis-dominated broadleaved mixed forest].

Characteristics of pit and mound complexes in different sizes of forest gaps and closed stands and their distribution patterns were compared and analyzed. The results showed that mean mound width, mound height, mound thickness of all pit and mound complexes were larger than corresponding mean pit length, pit width, pit depth in large, medium and small gaps as well as in closed stands. Mound width, mound height, mound thickness, pit length, pit width, pit depth were the largest in large gap, being 2.85, 0.37, 2.00, 2.99, 2.10, 0.39 m, respectively, and the smallest in closed stands, being 2.35, 0.19, 1.60, 2.66, 1.65, 0.21, respectively. Mean mound volume (1.66 m3) was larger than mean pit volume (1.44 m3). The difference in characteristic values between the most of pit and mound complexes was significant for the same size of forest gap, not significant for closed stands, significant for different sizes of forest gaps and closed stands. Most of characteristic values for pit and mound complexes within the plot in 2012 were significantly less than those in 2011. 89.5% and 60.5% of type and shape of pit and mound complexes were hinge and semiellipse, respectively. Their distribution was relatively centralized.

[Effects of forest gap size and light intensity on herbaceous plants in Pinus koraiensis-dominated broadleaved mixed forest].

1 m x 1 m fixed quadrats were parallelly arranged with a space of 2 m in each of six forest gaps in Pinus koraiensis-dominated broadleaved mixed forest, taking the gap center as the starting point and along east-west and south-north directions. In each quadrat, the coverage and abundance of herbaceous plants at different height levels were investigated by estimation method in June and September 2011, and the matrix characteristics within the quadrats were recorded. Canopy analyzer was used to take fish-eye photos in the selected overcast days in each month from June to September, 2011, and the relative light intensity was calculated by using Gap Light Analyzer 2.0 software. The differences in the relative light intensity and herbaceous plants coverage and richness between different gaps as well as the correlations between the coverage of each species and the direct light, diffuse light, and matrix were analyzed. The results showed that in opening areas and under canopy, the relative light intensity in large gaps was higher than that in small gaps, and the variation ranges of diffuse light and direct light from gap center to gap edge were bigger in large gaps than in small gaps. The direct light reaching at the ground both in large gaps and in small gaps was higher in the north than in the south direction. In the Z1, Z2, Z3, and Z4 zones, both the coverage and the richness of herbaceous plants were larger in large gaps than in small gaps, and the differences of species richness between large and small gaps reached significant level. The coverage of the majority of the herbaceous plants had significant correlations with diffuse light and matrix, and only the coverage of a few herbaceous plants was correlated with direct light.

[Microsite characteristics of pit and mound and their effects on the vegetation regeneration in Pinus koraiensis-dominated broadleaved mixed forest].

Abstract: An investigation was conducted in a 2.55 hm2 plot of Pinus koraiensis-dominated broad-leaved mixed forest to study the microsite characteristics of pit and mound formed by 42 treefalls and the status of vegetation regeneration on the microsites. The soil water content, soil temperature, relative air humidity, and photosynthetically active radiation (PAR) on five microsites (mound top, mound face, pit wall, pit bottom, and intact forest floor) were measured. Among the five mirosites, mound top had the highest PAR (527.9 micromol.m-2.s-1 ) while intact forest floor had the lowest one (58.7 micromol.m-2.s-), mound top had the highest soil temperature (16.0 degrees C) but pit bottom had the lowest one (13.3 degrees C), pit bottom had the highest soil water content (34.6%) but mound face had the lowest one (0.5%), and intact forest floor had the highest relative air humidity (75.9%) but mound top had the lowest one (68.0%). The frequency of forming pit/ mound complex by the tree species was decreased in the order of Pinus koraiensis (42. 9%) >Picea asperata (31.0%) > Betula platyphylla (16.7%) > Abies fabri (7. 1%) > Prunus padus (2.4%). Among the 42 treefalls, two-thirds of them were in northwest direction. The treefalls volume had significant positive correlations with pit depth, pit length, mound height, and mound width, but negative correlation with mound thickness. The treefall mean diameter at breast height had significant positive correlations with pit width (r=0.328, P=0.017) and pit length (r=0.527, P= 0). The tree species richness at the microsites decreased in the order of intact forest floor > pit > mound, and the tree species coverage was in the sequence of intact forest floor > pit > mound.

[Effects of gap size on the spatial heterogeneity of soil water in Pinus koraiensis-dominated broad-leaved mixed forest].

In August-October 2011, the soil water content (SWC) at different depths in different sized gaps in Pinus koraiensis-dominated broad-leaved mixed forest of Xiaoxing' an Mountains, Northeast China was continuously measured by grid nesting method and time domain reflectometry (TDR), and the spatial heterogeneity of the SWC was analyzed by the principles and approaches of geostatistics. The SWC was most abundant in medium gap, followed by in large gap and in small gap whereas the maximum difference of SWC was the biggest in large gap, followed by in medium gap, and in small gap. The variation range of the nugget of SWC at different depths in the large, medium, and small gaps was 0.001-0.404, 0.001-0.273, and 0.001-0.261, respectively. The SWC heterogeneity resulted from random part and the total system SWC spatial heterogeneity were decreased in the order of large gap > medium gap > small gap. The spatial distribution pattern of SWC was most complicated in medium gap, while the spatial dependence in the variation of the SWC pattern was the strongest in large gap. High-grade patches (SWC was 50%-60%) occupied the largest area in medium gap, followed by in large gap, and there was no high-grade patch in small gap. As for the SWC at same depths and in same months, its grade distribution was most simple in small gap, but relatively complicated in large and medium gaps. The maximum value of SWC increased with increasing gap size.