Magnesium fertilizer application increases peanut growth and pod yield under reduced nitrogen application in southern China

This study investigated the effect of magnesium application on peanut growth and yield under two nitrogen(N)application rates in acidic soil in southern China.The chlorophyll content,net photosynthetic rate and dry matter accumulation of the N-sensitive cultivar decreased under reduced N treatments,whereas no effect was observed on the relevant indicators in the N-insensitive variety GH1026.Mg application increased the net photosynthetic rate by increasing the expression of genes involved in chlorophyll synthesis and Rubisco activity in the leaves during the pegging stage under 50%N treatment,while no effect on the net photosynthetic rate was observed under the 100%N treatment.The rate of dry matter accumulation at the early growth stage,total dry matter accumulation and pod yield at harvest increased after Mg application under 50%N treatment by increasing the transportation of assimilates from stems and leaves to pods in both peanut varieties,whereas no effect was found under 100%N treatment.Moreover,Mg application increased the NUE under 50%N treatment.No improvement of NUE in either peanut variety was found under 100%N treatment,while Mg application under the 50%N treatment can obtain a higher economic benefit than the 100%N treatment.In acidic soil,application of 307.5 kg ha^(-1)of Mg sulfate fertilizer under 50%reduced nitrogen application is a suitable fertilizer management measure for improving carbon assimilation,NUE and achieve high peanut yields in southern China.

Impact of the red imported fire ant Solenopsis invicta Buren on biodiversity in South China: A review

The red imported fire ant, Solenopsis invicta, is a problematic invasive species in China since at least 2003. Over the past 15 years, a numerous studies were published on the impacts of this species on flora, fauna, and ecosystem function in natural and agricultural systems. We reviewed the literature on S. invicta invasion biology and impacts on biodiversity in South China. Both monogyne and polygyne colonies of S. invicta were introduced to China and polygyne colony is the dominant type. The range expansion rate of S. invicta may reach 26.5–48.1 km yr–1 in China. S. invicta forage activities occur year-round, peaking in the summer and fall in South China and show a preference for insects and plant seeds. We describe the ecological impacts of S. invicta on various habitats in South China, including arthropod community structure disruption and decreases in diversity and abundance of native ant species. S. invicta can replace the role of native ants in mutualisms between ants and honeydew-producing Hemiptera, which results in loss of important food resources for native ants and natural enemies of hemipterans. Further research is required to assess the complex ecosystem-level impacts of S. invicta in introduced areas.

Nitrogen and Phosphorus Runoff Losses from Orchard Soils in South China as Affected by Fertilization Depths and Rates

Fertilizers are heavily applied in orchards of the hilly and mountainous topography of South China and may increase nutrient loadings to receiving waters.A simple runoff collecting system was used to measure the effects of different fertilization treatments on total N and P concentrations of surface runoff in a Chinese chestnut (Castanea mollissima Blume) orchard in Dongyuan County,Guangdong Province,China.In such orchards,fertilizer was typically applied in two short furrows or pits on either side of each tree.Treatments included three application depths (surface,10cm and 20 cm),and three application rates (low,median and high).Results showed that 90.5% of the runoff water samples had a total N concentration higher than 0.35 mgL^(-1) and 54.2% had a total P concentration higher than 0.1 mgL^(-1).Fertilizer application at all depths and at all but the lowest rate significantly increased total N and P concentrations in runoff water.Fertilization with chemical compound fertilizer at a soil depth of 20cm produced significantly lower (P<0.05) total N concentration in runoff than both surface and 10-cm depth fertilization,and significantly lower (P<0.05) total P concentration in runoff than surface fertilization.Total N and P concentrations in runoff significantly increased with the application rate of organic fertilizers.With the exception of total P concentrations,which were not significantly different between the control and fertilization at a rate of 119 kg P ha-1 in organic form,all the other fertilization treatments produced significantly higher total N and total P concentrations in runoff than the control.A fertilization depth≥20cm and an application rate≤72 kg N ha^(-1) or 119 kg P ha^(-1) for compound organic fertilizer was suggested to substantially reduce N and P runoff losses from hillslope orchards and to protect receiving waters in South China.

Soil Organic Carbon Content and Distribution in a Small Landscape of Dongguan, South China

Global warming has become an increasing concern, and using soil as a carbon sink to sequester carbon dioxide has attracted much attention in recent years. In this study, soil organic carbon (SOC) content and organic carbon density were estimated based on a soil survey of a small landscape in Dongguan, South China, with spatial heterogeneity of SOC distribution and the impacts of land-use patterns on soil organic carbon content assessed. Field sampling was carried out based on a 150 m×150 m grid system overlaid on the topographic map of the study area and samples were collected in three 20-cm layers to a depth of 60 cm. Spatial variability in the distribution of SOC was assessed using the Kruskal-Wallis test. Results showed that SOC in the topsoil layer (0-20 cm) was not much higher or even lower in some sites than the underlying layers, and except for the two sites covered with natural woodland, it did not exhibit a pronounced vertical gradient. The difference in both horizontal and vertical distribution of SOC was not statistically significant. However, in the topsoil layer among land-use/land-cover patterns, significant differences (P≤0.05) in SOC distribution existed, indicating that management practices had great impact on SOC content. SOC storage in the study area to a depth of 20, 40, and 60 cm was estimated as 2.13×106 kg, 3.46×106 kg, and 4.61×106 kg, respectively.

Impact of fertilization on chestnut growth, N and P concentrations in runoff water on degraded slope land in South China

Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake （peanut oil pressing residue）, on chestnut （Castanea mollissima Blume） growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.

Detection and Characterization of β-Lactam Resistance in Haemophilus parasuis Strains from Pigs in South China

To characterize the β-lactam resistance in veterinary clinical isolates of Haemophilus parasuis, 115 isolates were examined for the β-lactam resistance, the possession of β-lactamase, and the presence of β-lactamase genes. The genetic relationship among isolates was evaluated by pulsed-field gel electrophoresis （PFGE）. Overall, the commonly detected resistance phenotypes were resistant to ampicillin （26.09%）, penicillin （22.61%）, amoxicillin （21.74%）, cefazolin （14.78%）, cefaclor （12.17%）, and cefotaxime （6.96%）. These strains showed high minimal inhibitory concentration （MICs） to oxacillin. 20.87% strains produced β-lactamase, and 4.35% strains showed extended-spectrum b-lactamase （ESBL） phenotype. Moreover, 19 strains harboured bla genes including TEM-1 （n=5）, TEM-116 （n=10）, and ROB-1 （n=5）. Significantly, one strain possessed both TEM-1 and ROB-1, and displayed resistance to cefotaxime （MIC=8 mg L-1）. The epidemiological analysis of PFGE revealed high genetic diversity among bla-positive isolates. This work shows that TEM- and ROB-type β-lactamases are prevalent in H. parasuis isolates in China.

Roles of fishing and climate change in long-term fish species succession and population dynamics in the outer Beibu Gulf,South China Sea

A prevailing,controversial hypothesis is that fishing pressure has played a greater role than climatic and environmental drivers,in changing fish species succession and biomass fluctuation in the South China Sea(SCS).Based on otter trawl survey data from 1959 to 2010 in the outer Beibu Gulf(OBG),northern SCS,large seasonal and interannual variation is reported for fish species composition,the proportional abundances of dominant taxa,and fish biomass.Generalized additive models are developed to quantify relationships between fish biomass and the external factors of fishing pressure and climate change.Fishing pressure proved to be the main driver of sharp declines in demersal fish stocks,with high-value species being replaced by low-value ones over time.Abrupt decreases in fish biomass during the years of 1993 and 1998 correspond to El Nino events,with climate change possibly the main driver of proportional representation of pelagic species in fisheries trawl catch.The need to differentiate impacts of fishing and environmental drivers on fish species with different life history strategies is stressed to better understand fish community dynamics.

Characteristics of Tropical Sea Surface Temperature Anomalies and Their Influences on the Onset of South China Sea Summer Monsoon

The characteristics of sea surface temperature anomalies(SSTAs)in the tropical oceans and their influences on the onset of South China Sea summer monsoon(SCSSM)have been studied.The anomaly of SST in tropical Pacific Ocean exerts persistence impact for one to three months on atmospheric circulations.If the warm pool becomes anomalously warmer during an earlier period from February to April,the SCSSM breaks out earlier,and vice versa.Singular value decomposition(SVD)and composite analysis have shown that,in La Ni a pattern,the convection over Western Pacific will occur earlier and be stronger than normal,which favors the convergence at a lower layer over Western Pacific,as well as the strengthening of upwelling branch of Walker circulation,leading to an earlier burst of westerly in the southern South China Sea.Moreover,the convection in Sumatra appears earlier than normal and favors the westerly evolution in eastern Indian Ocean,resulting in the splitting of the subtropical high belt and an early onset of SCSSM.However,the atmospheric circulation anomaly is reversed in El Nio pattern.

Plant Ideotype at Heading for Super High-Yielding Rice in Double-Cropping System in South China

The newly released super high-yielding hybrid rice combinations, Yueza 122, Fengyou 428, Peiza 67, and the super high-yielding conventional cultivars, Guangchao 3 and Shengtai 1, were grown in both early and late seasons. The morphological characters of each population were investigated at the heading stage, and the data were analyzed by using ANOVY and other statistic methods. The plant ideal morphological characters at the heading stage were established as follows： 1 ） for the early-season cropping, 90-105 cm plant height; 11-12 tillers per plant; 35-40 em length and 2.1-2.2 cm width of flag leaf; 46-50 cm length and 1.8-2.1 cm width of the second leaf from the top （L2）; 59-64 cm length and 1.4-1.9 cm width of the third leaf from the top （L3）; 7°-14°, 18° and 200-33° for the ideal leaf angles of the flag leaf, L2 and L3, respectively; 2） for the late-season cropping, 90-100 cm plant height; 9-15 tillers per plant; 30-41 cm length and 1.8-2.0 cm width of flag leaf; 53-61 cm length and 1.3-1.8 cm width of L2; 52-58 cm length and 1.2-1.5 cm width of L3; 9°-19°, 15°-37° and 16°-49° for the ideal leaf angles of the flag leaf, L2 and L3, respectively. The main physiological characteristics of these varieties were also analyzed.

Genetic Diversity of Wild Soybeans from Some Regions of Southern China Based on SSR and SRAP Markers

There are rich annual wild soybean (Glycine soja) resources in Southern China, which are the progenitor of cultivated soybean. To evaluate the genetic diversity and differentiation of G. soja in Southern China, we analyzed allelic profiles of 141 annual wild soybean accessions from Southern China and 8 core wild soybean accessions fromNorthern Chinaby using 41 simple sequence repeat (SSR) markers and 18 Sequence-related amplified polymorphism (SRAP) primer combinations. The 41 SSR markers produced a total of 421 alleles (10.27 per locus) with a mean of gene diversity of 0.825 (Simpson index) and 1.987 (Shannon-weaver index). The 18 SRAP primer combinations detected a total of 90 polymorphism bands (5 per primer combination) with a mean of gene diversity of 0.918 (Shannon-weaver index). SSR and SRAP markers detected 43 and 5 rare alleles in 149 wild soybeans, respectively. The wild soybeans from Fujian province showed the highest genetic diversity with Shannon-weaver index of 1.837 (by SSR) and 0.803 (by SRAP), and the highest allelic richness with an average of 8.8 alleles per locus and the most number of rare alleles of 0.68 per locus based on SSR data. An analysis of Molecular Variance (AMOVA) analysis showed that significant variance did exist amongHunan,Fujian, Guangxi andNorthern Chinasubpopulations based on SSR and SRAP data. The unweighted pair-group method of the arithmetic average (UPGMA) cluster analysis indicated that the wild soybeans fromFujianprovince occurred in different clusters based on both SSR and SRAP data. The above results indicated thatFujianprovince could be the major center of genetic diversity for annual wild soybean inSouthern China. In addition, Mantle test showed there was a weak positive linear correlation (r = 0.25) between SSR and SRAP analysis in the study.

Effects of different culture media on the growth of Indian sandalwood(Santalum album L.) seedlings in Zhanjiang,Guangdong,southern China

We studied the effects of different culture media on the growth of India sandalwood （Santalum album L.） seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subsoil, burnt soil, agricultural soil, peaty soil and coconut dust, were used as the basic culture materials and seven different treatments of composition were used as potting media. Kuhnia rosmarinifolia Vent. was used as a primary host plant for all treatments. Statistically significant differences were found between treatments in respects of survival rate （p 〈 0.001）, height （p 〈 0.001）, ground diameter （p 〈 0.001） and biomass （p = 0.002）, as well as for quality index （p 〈 0.001） of S. album seedlings after 6-month growth in containers with different culture media. Among all treatments, the treatment combining burnt soil, peat and coconut dust in a weight ratio of 1：1：1 plus 2% calcium super-phosphate as basal manure achieved the best performance for most of the seedling growth parameters, including survival rate （98%）, height （35.81 cm）, ground diameter （0.56 cm）, biomass （4.46 g） and quality index （0.65）, followed by the treatment using only burnt soil plus 2% calcium super-phosphate as the culture medium （survival rate 86%, height 29.23 cm, ground diameter 0.48 cm, biomass 3.36 g and quality index 0.52）, while the treatment using only lateritic subsoil plus the basal manure as the medium obtained the poorest results in survival rate （38%）, height （12.04 cm）, ground diameter （0.19 cm）, biomass （0.26 g） and quality index （0.043）. Increasing the proportion of lateritic subsoil in the medium when mixed with peat and coconut dust did not show statistically significant differences in survival, height, ground diameter, biomass nor in quality index. In consideration of cost, using burnt soil plus 2% calcium super-phosphate as basal manure may be the optimum culture medium for large-scale production of Indian sandal- wood seedlings in Guangdong, southern China.

Exploring the genetic features and signatures of selection in South China indigenous pigs

To explore the genetic features and signatures of selection in indigenous pigs from South China and Duroc pigs,259 pigs from six populations were genotyped using single-nucleotide polymorphism(SNP)BeadChips.Principal component analysis(PCA),effective population size(Ne),linkage disequilibrium(LD),and signatures of selection were explored and investigated among the six pig populations.The results showed the Ne of five South China indigenous pig populations has been decreasing rapidly since 100 generations ago.The LD between pairwise SNP distance at 100 kb ranged from 0.16 to 0.20 for the five indigenous pig populations,while it was 0.32 for the Duroc population.However,the LD of all six pig populations showed the opposite order at long distances(>5 Mb).Furthermore,15 potential signatures of selection associated with meat quality and age at puberty were exclusively detected in South China indigenous pigs,while eight potential signatures of selection associated with growth traits were detected in Duroc pigs.Our work provides valuable insights for the utilization and conservation of South China indigenous pigs.

Effects of gap size on diversity of soil fauna in a Cunninghamia lanceolata stand damaged by an ice storm in southern China

Cunninghamia lanceolata （Lamb.） Hook. is economically the most important tree species in southern China and has been cultivated in plantations on a large scale. This species is widely used in construction, furniture, utensils and shipbuilding. Soil fertility of C. lanceolata stands affects soil structure, porosity and nutrient availability, which causes changes in fauna activity. During January to February 2008, an ice storm caused extensive damage to C. lanceolata stands. Despite the environmental importance of soil fauna, basic information on the distribution and diversity of soil fauna in C. lanceolata stands after ice storm damage is lacking. To assess the response of soil fauna diversity and distribution to forest gaps following the ice storm, five small gaps （each 30-40 m^2）, five large gaps （each 80-100 m^2） and five canopy cover plots were selected within a 2-ha C. lanceolata stand. Soil samples were collected from 0 to 10 cm depth in March 2011 to measure soil fauna diversity and abundance. The abundance and community composition of the soil fauna varied with gap size. In canopy cover sites, the number of individuals was 2.0 and 5.2 times greater than in the small gaps and large gaps. Three taxa （Nematoda, Oribatida and lnsecta） of soil inver- tebrates occurred commonly, and Nematoda dominated the communities in all three habitat types. The Shannon-Wiener diversity index, Margalef diversity index, and Pielou evenness index were high in the small gaps, indicating that they harbored the most species, with the most even distribution, and the highest diversity. Our results indicated that gap size apparently affected abundance and community composition of the soil fauna.

Grain Yield, Quality and 2-Acetyl-1-Pyrroline of Fragrant Rice in Response to Different Planting Seasons in South China

Climate conditions is an important factor affected the fragrant rice growth and development.In order to study the effects of different planting seasons on fragrant rice performance in South China,present study was conducted with three planting seasons(early season(April to July),middle season(June to September)and late season(August to November))and three fragrant rice cultivars,‘Basmati-385’,‘Meixiangzhan-2’and‘Xiangyaxiangzhan’.The results showed that the highest grain yield and grain 2-acetyl-1-pyrroline(2-AP,key component of fragrant rice aroma)content were both recorded in late season treatment while the fragrant rice in middle season treatment produced the lowest grain yield,grain filling percentage,1000-grain weight and gain 2-AP content.The highest contents of precursors(proline,pyrroline-5-carboxylic acid and 1-pyrro-line)which related to 2-AP biosynthesis were recorded in late season treatment compared with early season treatment and middle season treatment.The highest activities of enzymes(proline dehydrogenase,pyrroline-5-carboxylic acid synthetase and ornithine transaminase)which involved in 2-AP biosynthesis were also observed in late season treatment.Moreover,the fragrant rice cultivars in late season possessed the lowest chalk rice rate,chalkiness as well as the highest brown rice rate,head rice and protein content.Thus,the optimal season for fragrant rice production in South China is the late season.

Long-term changes of water acidity in an intact forested watershed in south China

Acid rain is a global environmental issue and causes serious adverse impacts on natural ecosystems and human health.The acid rain and its subsequent impacts have been extensively studied in temperate regions and in big cities globally,but the monitoring of acid rain in non-urban areas in subtropical region is still limited.Here,we analyze 18 years of water acidity observations from a non-urban site in western Pearl River Delta region,south China.From 2000 to 2018,annual mean precipitation pH values in the study site showed a marked increase(P<0.0001)from 4.96 in 2000 to 6.88 in 2018.This 18-year dataset of precipitation acidity shows a clear recovery from acid deposition over the annual period,dry seasons and wet seasons.Within a year,precipitation pH was relatively lower in dry seasons(5.46±0.95)than in wet seasons(5.80±0.89)during the whole study period,and the seasonal pattern of precipitation pH was amplified during drier years as a strong dilution effect was detected between precipitation amount and its acidity.The pH of surface runoff water(4.74±0.70)was significantly lower than that of precipitation as a result of the regulating effects of the highly acidified soil and the rich humus on the forest floor.The groundwater pH(6.32±0.63)was significantly higher than the precipitation pH especially during dry seasons.The results of the present study indicated that the groundwater has a strong acid buffer and neutralizing effects and thus plays an important role in supplies of clean water.

Current Status and Thermal Performance of Traditional Rural Residence in Chaoshan Area,South China(Ⅱ):A Case Study of Pashi House

Pashi house(climbing-lion-type house) is an important residence type in Chaoshan rural area evolved from its traditional rural dwellings,and study on such houses provides effective support for the energy-saving designs of rural buildings.Three typical Pashi houses in Jinpu Town,Shantou City were selected,specifically,onestorey Pashi house,multi-storey Pashi house with Tianjing(small courtyard enclosed by rooms) and multi-storey Pashi house without Tianjing.Ecotect was applied to simulate indoor light environment,and indoor light and thermal environments of 3 typical Pashi houses were compared.The results showed that(a) Grey spaces such as open hall should be maintained;(b) Cooler outdoor air should be introduced into indoor spaces at night to reduce the indoor air temperature;(c) The tradition that Pashi House never has a window facing north should be broken to improve the indoor lighting,and heat insulation structure can be applied for the roof;(d) Top of the Tianjing in a multi-storey Pashi house influences the indoor thermal environment,and plays a less effective role than onestorey Pashi house does in adjusting micro climate of the house.

Changes in soil properties under Eucalyptus relative to Pinus massoniana and natural broadleaved forests in South China

The ecological effects of eucalypt plantations（EPs） have garnered increasing attention.To understand their effect on soil quality at a landscape scale,and to determine whether soil quality parameters differ due to different stand types,we evaluated soil characteristics in twenty-one groups of EPs,Pinus massoniana Lamb.plantations（PMPs） and natural broadleaved forests（NBFs）across Guangdong Province,China.Both the physical characteristics of soil hydrology and the properties of soil nutrients in A and B horizons were determined.Results showed that,compared to NBFs,EPs and PMPs produced a shallower litter layer,reduced canopy density,higher soil bulk density,significantly lower total porosity,non-capillary porosity,total water volume,and hygroscopic water in the A horizon（P〈0.05）.Moreover,total N,available K,and soil organic carbon（SOC） in EPs and PMPs were significantly lower than in NBFs.EPs and PMPs did not differ significantly in N,P or K content,but PMPs had significantly lower SOC and boron in the A horizon than EPs.Low p H and poor capacity to buffer acidification generally occurred in all cover types.Both EPs and PMPs showed a decline in soil properties relative to NBFs,but EPs and PMPs exhibited no significant difference.These results indicate that actions are needed to ameliorate the potential negative effects on soil quality in forestry plantations.

Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy ffelds in southern China

Agricultural sustainability has benefited from the broad adoption of conservation agriculture(CA)practices for decades,in which the reduction of mechanical disturbances to soil(also known as reduced tillage,RT)is one of the most essential principles for CA implementation.Many studies have recommended the advantages of CA practices in the promotion of biodiversity,but the integrated impacts on crop productivity and biodiversity remain unclear.Since CA has been applied in rice production in the subtropical area of southern China for several years,the effects of CA,particularly the RT methods,need to be evaluated for the local and long-term adoption.In this study,we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates(such as rice pests and their predators),pathogens and weeds,and then led to an impact on rice yield.The two-year study demonstrated that major rice pests,such as rice planthoppers,stem borers and apple snails,were effectively controlled by RT practice.Similarly,the occurrence of common diseases declined with less tillage.Compared to the conventional tillage(CT)treatment,the density of weeds in paddy fields deceased significantly in the RT treatment.In addition,the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied,which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem.More importantly,the rice yield gradually increased after the two-year reduction of tillage.Taken together,our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests,and facilitates the sustainability of the agroecosystem and rice yield,which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

Effect of Lime Application to Acidic Soils on Oleoresin Yield Tapped from Pine Plantations in South China

Oleoresin is a major non-forest product collected from commercially mature or near mature pine trees. Efforts have been made to increase oleoresin yield, but basically limited to the genetic improvement of planting materials and the application of chemical stimulants to tapping surface of trees. Nutrition management may play a role, particularly for pine stands suffering from soil acidification and degradation. We set up a field experiment including application of water retainer, NPK complex fertilizer, lime and borax in different combinations to pine stands for oleoresin tapping with extremely low soil pH value and nutrition. Lime significantly affected the annual yield of oleoresin tapped from two pine species studied (P < 0.05). Among 3 levels of lime applied (0, 100, 200 g/tree), the oleoresin yield increased as the dose increased in slash pine, but was highest at 100 g/tree in masson pine. The doses of 167 g and 133 g of lime per tree were optimal or close to be optimal for slash pine and masson pine, respectively. The effects of other three matters applied were statistically insignificant (P > 0.10). In addition, all of the four matters applied did not influence the growth of both pine species. We concluded that proper use of lime alone may generate 15% to 35% of gain in oleoresin production for pine plantations with similar soil conditions in the region. We also discussed the potential of comprehensive soil or site management, and proposed further research for improvement of pine oleoresin production.

Detecting Droughts in Southwest China from GPS Vertical Position Displacements

The solid Earth responds elastically to terrestrial water storage(TWS)changes.Here global positioning system(GPS)vertical position data at 31 stations from the crustal movement observation network of China(CMONOC)from August 2010 to December 2016 are used to detect droughts in Southwest China.Monthly GPS vertical position displacements respond negatively to precipitation changes and TWS changes observed by gravity recovery and climate experiments(GRACE)as well as river water level variations.GPS vertical position anomalies(the non-seasonal term)are well correlated negatively(correlations of about-0.70)with the commonly used meteorological composite index(CI)in China and the GRACE drought severity index(GRACE-DSI),but less correlated with the standardized precipitation evapotranspiration index(SPEI).Compared to CI,GPS vertical position anomalies have the advantage of detecting droughts caused by abrupt precipitation deficits in a short time.GRACE-DSI is less accurate in drought monitoring for some periods due to the missing data,while the severity of abrupt precipitation absent in some cases can be overestimated from SPEI with big variability.This study shows the reliability and advantages of GPS data in drought monitoring.