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2023, 45(3): 1-10.
doi:10.12171/j.1000-1522.20220007
Abstract:
ObjectiveThe variation characteristics of soil nitrogen of
Pinus tabuliformisnatural secondary forest in Pingquan County, Hebei Province of northern China were analyzed in different years after fire, and the influencing factors of soil nitrogen were explored in combination with stand factors, site factors and fuel factors, so as to provide a scientific basis for nutrient circulation and vegetation restoration after fire.
MethodStudy sites were burnt areas located in Liuxi Town of Pingquan County. Soil samples were collected in 2015(the year after the fire, 0 year), 2016 (1 year after the fire, 1 year) and 2021 (6 years after the fire, 6 years), respectively. We analyzed the tendency of content of soil total nitrogen (TN), alkali-hydrolysable nitrogen (AN), ammonium nitrogen (NH
4
+-N) and nitrate nitrogen (NO
3
∑/sup>-N) under different years (0 year, 1 year and 6 years), different fire intensities (CK, control test plots which is unburnt area; L, low intensity burnt area; M, moderate intensity burnt area; H, heavy intensity burnt area), and different soil layers (0?0 cm and 10?0 cm). Correlation analysis (Pearson) and redundancy analysis (RDA) were used to explore the potential impact of stand factors (tree height, DBH, canopy density), site factors (slope position and slope gradient) and fuel factors (1 h, 10 h, 100 h fuel load, 1 h,10 h,100 h fuel water content) on soil nitrogen.
Result(1) Fire intensity, soil layer and years had significant influence on 4 types of soil nitrogen (
P< 0.05). Fire intensity and soil layer had an interaction with all kinds of soil nitrogen (
P< 0.05) in 2015. Fire intensity and years had an interaction with all kinds of soil nitrogen (
P< 0.05). Fire intensity, soil layer and years showed no three-factor interaction with all kinds of soil nitrogen (
P> 0.05). (2) Total nitrogen content, ammonium nitrogen content and nitrate nitrogen content increased in 2016 (1 year), especially in heavy intensity areas (H), and the amplification was 464.67%, 397.97%, 185.63%, respectively. But alkali-hydrolysable nitrogen content decreased in each sample plot, especially in M-plot (52.48%). Total nitrogen content, ammonium nitrogen content and alkali-hydrolase nitrogen content increased in 2021 (6 years), especially in moderate intensity areas (M), and the amplification was 368.78%, 209.00%, 427.51%, respectively. But nitrate nitrogen content decreased by 14.31% and 14.34% in low intensity areas (L) and moderate intensity areas (M), respectively. (3) RDA results showed that fuel water content had the most contribution to the change of soil nitrogen content. 1 h fuel water content had an effect on alkali-hydrolase nitrogen content. 100 h fuel water content had an effect on nitrate nitrogen content. Both of them had a positive relationship between fuel factors and soil nitrogen. Stand factors and site factors had little explanatory on soil nitrogen content, which was the indirect effect.
ConclusionThe change of soil nitrogen content decreases first and then raises up, which is the common action with fire intensity, soil and years. At the early stage after burning (2015, 0 year; 2016, 1 year), fire intensity plays a significant role in affecting soil nitrogen content. However, the influence power of fire intensity decreased in 2021 (6 years). The direct impact of fire intensity on soil nitrogen content is reduced, and the mediation between fire intensity and soil continues to affect the change of soil nitrogen content through soil moisture content, temperature, pH and other indicators. The regeneration and development of vegetation in burnt areas is also affected by mediating effects. The differences in nutrient utilization strategies at different growth stages and the accumulation of vegetation litter are also important reasons for the significant changes of soil nitrogen content in 1 year and 6 years after fire.
2023, 45(3): 11-20.
doi:10.12171/j.1000-1522.20210317
Abstract:
ObjectiveThe population of
Populus euphraticarecovered to a certain extent following the ecological water conveyance project, but its restoration result was far less significant than for
Tamarix ramosissima, which overlaped its ecological niche. To provide scientific reference for protecting and managing
P. euphraticaforests and developing ecological water conveyance projects in oases, this study explored whether the adaptability advantages of
P. euphraticapopulation were affected by symbiosis with
T. ramosissimain different soil water and salinity environments.
Method
P. euphraticaand
T. ramosissimaforests in the arid area in northwestern China were selected as the key constructive species of riparian forest communities, and two common soil water and salinity habitats with high and moderate soil moisture and salinity were established as a means of analysing the spatial distribution of both species and their relationships with saline water.
Result(1) In an environment with relatively high water and salt content, the
P. euphraticapopulation demonstrated a declining trend, with relatively few young woods and a limited amount of regeneration, whereas the
T. ramosissimapopulation was stable. The population structure of
P. euphraticawas found to be stable with little difference between each age class, whereas
T. ramosissimawas found to have a growing population. (2) In different salt and water environment, both species were mainly distributed in aggregation as a means of resisting the stress of an adverse environment, and
P. euphraticaseedling growth was inhibited by
T. ramosissima.(3) Different soil water and salinity environments resulted in differences in the abundance of both species. The ratio of
T. ramosissimato
P. euphraticawas found to have a positive correlation with salinity, but as the water content increased, the number of
T. ramosissimadecreased and
P. euphraticaincreased with lower salt content.
ConclusionThe results further verify that competition is an important factor for the decline of
P. euphraticaduring the succession process, with the exception of environmental filtering.
T. ramosissimawill gradually replace
P. euphraticain high-salt habitats, but the improvement of water conditions could slow down the occurrence of this trend.
2023, 45(3): 21-33.
doi:10.12171/j.1000-1522.20220138
Abstract:
ObjectiveThis paper aims to analyze the current and future potential distributions of four common tree species (
Pinus sylvestris,
Pinus tabuliformis,
C
aragana korshinskiiand
Larix gmeliniivar.
principis-
rupprechtii) in the Loess Plateau region of northern China, and to reveal the effects of climate change on spatial distribution patterns of plants.
MethodFour dominant species on the Loess Plateau were studied based on 19 climate factors and 5 indicators from Holdridge life zone model and Kira index system: bio-temperature (ABT), potential evapotranspiration rate (PER), warmth index (WI), coldness index (CI) and humidity index (HI). The Maxent model was used to predict the potential geographical distribution of the four tree species under current and future scenarios (2041?060, 2061?080) SSP126, SSP245 and SSP585. The Jackknife method was used to analyze the main environmental factors affecting its distribution, and the predicted results were tested by the area under receiver operating characteristic curve (AUC).
Result(1) Maxent model can well simulate the potential geographical distribution range of major established species in the Loess Plateau, and the average AUC of each species was greater than 0.8. (2) For
Pinus sylvestris,
Pinus tabuliformisand
Caragana korshinskii, both temperature and precipitation limited their distribution, while for
Larix gmeliniivar.
principis-rupprechtii, precipitation was the main factor affecting their distribution. Temperature seasonality, potential evapotranspiration rate, precipitation of the driest month and precipitation of the wettest quarter were the main environmental factors affecting the distribution of
Pinus sylvestris. Temperature annual range, temperature seasonality, minimum temperature of the coldest month, precipitation of the warmest quarter and potential evapotranspiration rate were the main factors affecting the distribution of
Pinus tabuliformis. The main factors affecting the distribution of
Caragana korshinskiiare maximum temperature of the warmest month, warmth index, isotherm, potential evapotranspiration rate and precipitation of the coldest season. The main factors affecting the distribution of
Larix gmeliniivar.
principis-rupprechtiiwere mainly related to precipitation, which were precipitation of the wettest month, precipitation of the wettest quarter, variation coefficient of precipitation, and potential evapotranspiration rate. (3) The potential suitable areas of
Pinus tabuliformis,
Caragana korshinskiiand
Larix gmeliniivar.
principis-rupprechtiiwill migrate to the northwest, while that of
Pinus sylvestriswill migrate to the southwest. The potential suitable areas of
Pinus tabuliformisand
Larix gmeliniivar.
principis-rupprechtiishowed a trend of expanding first and then decreasing, while the potential suitable areas of
Caragana korshinskiiand
Pinus sylvestriswould continue to expand, especially the proportion of highly suitable areas of
Pinus sylvestriswould expand to 50.97% in 2070s.
ConclusionClimate change will deprive
P
inus tabuliformisand
Larix gmeliniivar.
principis-rupprechtiiof some of their highly suitable areas, but at the same time, the highly suitable areas of
Caragana korshinskiiand
Pinus sylvestriswill expand significantly.
Caragana korshinskiiand
Pinus sylvestrisare preferred in the project of converting farmland to forest land on the Loess Plateau.
2023, 45(3): 34-47.
doi:10.12171/j.1000-1522.20210364
Abstract:
ObjectiveUsing the method of extracting vegetation phenology by remote sensing,taking Xiaoxing’an Mountains of northeastern China as the study area, this paper analyzes the temporal and spatial changing characteristics of forest vegetation phenology and the response of forest vegetation phenology change to climate change.
MethodBased on GIMMS NDVI 3g image, the forest vegetation growth curve was fitted by univariate sixth order polynomial, and the phenological parameters of forest vegetation SOS, vegetation EOS and vegetation LOS in Xiaoxing’an Mountains from 1982 to 2015 were extracted by pixel dynamic threshold method. Using ArcGIS software, the temperature, precipitation and sunshine duration data were analyzed pixel by pixel with vegetation phenological parameters to obtain partial correlation coefficients between phenological parameters and meteorological factors.
Result(1) The characters in spatial distribution of multi-year mean value of vegetation phenology showed a kind of gradual change from northwest to southeast, including the advance of vegetation SOS, the delay of vegetation EOS and the extension of vegetation LOS. (2) The SOS of forest vegetation in Xiaoxing’an Mountains was concentrated among 112.1th?28.3th day of the year, with an abrupt change around 1998. Before 1998, it showed a significant advancing trend (
R
2= 0.284,
P= 0.028), and after 1998, it showed a non-significant delaying trend (
R
2= 0.002,
P= 0.86), resulting in a non-significant change during the whole analysis period (1982?015), with a rate of change at 0.12 d per ten years (
R
2= 0.001,
P= 0.872). The forest vegetation EOS was concentrated among 277.3th?94.8th day of the year, and showed a significant delaying trend during the whole analysis period, with a rate range of 2.33 d per ten years (
R
2= 0.294,
P< 0.01). The LOS of forest vegetation was concentrated among 149.5?67.5 days, and showed a significant extension trend during the whole analysis period, with a rate of change at 2.45 d per ten years (
R
2= 0.231,
P< 0.01). (3) The forest vegetation SOS was correlated with the April temperature of current year, followed by the February temperature of current year. The vegetation EOS was correlated with the precipitation in August of current year, followed by the June temperature in current year.
Conclusion(1) The multi-year average value of forest vegetation phenology and the multi-year average value of hydrothermal conditions in Xiaoxing’an Mountains show relatively consistent spatial characteristics. (2) The change of vegetation EOS during the study period is mainly driven by the change of precipitation in August. The decline of precipitation in August is the main reason for the significant delay of vegetation EOS. (3) The stagnation of global warming at the end of the 20th century causes the temperature in February to change from a significant increase to a non-significant decrease around 1998, causing a sudden change in the trend of vegetation SOS around 1998, leading to a non-significant change in vegetation SOS during the whole period.
2023, 45(3): 48-57.
doi:10.12171/j.1000-1522.20220279
Abstract:
ObjectiveThis study aimed to theoretically support the scientific assessment of the carbohydrate-water coupling connection of
Cryptomeria japonica.
MethodThe water use efficiency (WUE) of
Cryptomeria japonicawas calculated using the tree-ring stable carbon isotope method in this study. Additionally, average temperatures (
T), precipitation (
W), average wind speeds (Ws), solar radiation (Rs), the drought index (SPEI, SPI, WI), and other climate change-related indicators were used to analyze the WUE of
Cryptomeria japonicaand its adaptation to climate change.
Result(1) From 1969 to 2018, the sequence of
13C values of
Cryptomeria japonicatree rings in Lushan Mountain, Jiangxi Province of eastern China showed a downward trend; the variation range was ?3.09 to ?5.67? and the annual average was ?4.55? the inter-annual value of
Cryptomeria japonicaWUE showed an upward trend; the variation range was 91.06 to 118.89 μmol/mol, with an annual average of 102.37 μmol/mol. (2) Correlation analysis revealed that the WUE of
Cryptomeria japonicain Lushan Mountain was significantly correlated with the temperature in July, September to November of the previous year, February to June, and September to November of the current year, and significantly negatively correlated with the wind speed in July to December of the previous year and January to December of the current year. However, the solar radiation, precipitation, SPEI, WI, and SPI of each month had no significant impact on the WUE of
Cryptomeria japonicaon Lushan Mountain. (3)The multiple regression model analysis showed that the WUE of
Cryptomeria japonicaon Lushan Mountain was mainly related to Ws
1(wind speed in January of the current year),
T
3(average temperature in March of the current year),
T
9(average temperature in September of the current year),
T
?(average temperature in September of the previous year), and Ws
12(wind speed in December of the current year).
Conclusion
Tand Ws are the primary climatic variables affecting WUE of
Cryptomeria japonica. The WUE of
Cryptomeria japonicaon Lushan Mountain is not significantly affected by
W, Rs, or the drought indicators (SPI, SPEI and WI).
2023, 45(3): 58-67.
doi:10.12171/j.1000-1522.20210334
Abstract:
ObjectiveThis paper aims to investigate the important founction of CaM-like proteins in Chinese jujube in resistance to cold stress and identify the key
ZjCML, which could provide theoretical basis for cold breeding in Chinese jujube by using them.
MethodThrough using bioinformatics technology, the number and related structural information of
CMLin Chinese jujube were analyzed comprehensively in the current study. And then, we used RNA-seq and real-time fluorescence quantitative PCR technology to analyze its expression pattern in response to low temperature stress, laying a foundation for screening key cold resistance genes.
ResultA total of 23
ZjCMLgenes were identified in Chinese jujube genome. All of them distributed unevenly on 12 chromosomes. In addition,
ZjCMLcan be divided into 12 subgroups, and protein interaction network prediction showed that 16 ZjCML existed in the network and they had mutual interaction relationships. Moreover, RNA-seq analysis showed that the expression patterns of
ZjCML13 and
ZjCML6 in response to cold stress between ‘Dongzao and its autotetraploids were significantly different. The expression level of
ZjCML13 in response to cold stress in ‘Dongzao was significantly higher than that in its autotetraploid at 6 and 24 h. External CaCl
2and melatonin treatments could significantly induce the expression of
ZjCML13 in autotetraploids ‘Dongzao under cold stress at 6 and 24 h, indicating that it may regulate cold resistance of autotetraploid ‘Dongzao by inducing the expression of
ZjCML13.
ConclusionThe
ZjCMLgene family have specific characteristics and expression patterns,
ZjCML13 might play important role in regulation of cold difference between ‘Dongzao and its autotetraploids.
2023, 45(3): 68-78.
doi:10.12171/j.1000-1522.20210465
Abstract:
ObjectiveThis paper aims to research the coupling effects of furrow irrigation and nitrogen fertigation on the growth and stand productivity of high-density and short-rotation triploid
Populus tomentosaS86 pulp plantations, in order to provide scientific theoretical basis for selecting efficient furrow irrigation-fertilization technology system suitable for the local area.
MethodThe plant materials were triploid
P. tomentosaS86 in Gaotang County, Shandong Province of eastern China. A completely random block experiment design was adopted to monitor three irrigation levels, i.e. irrigation started when the soil water potential reached ?0 kPa (W1), ?3 kPa (W2) and ?5 kPa (W3), and four fertigation levels (N1, 120 kg/(ha·year); N2, 190 kg/(ha·year); N3, 260 kg/(ha·year); N4, 0 kg/(ha·year)), and the control treatment was with no irrigation and no fertigation set (CK).
ResultIt took a long time for the fast-growing period of DBH growth of triploid
P. tomentosaS86. The DBH growth of different stand ages in the growing season conformed to the Logistic function (
R
2> 0.99), and the difference of furrow irrigation and fertilization treatments was mainly manifested in June. Nitrogen application in furrow irrigation significantly affected the DBH increment and relative growth rate of 2-year-old
P
. tomentosaS86 plantations (
P< 0.05), but had no significant effect on 3?-year-old
P. tomentosaS86 plantations. The coupling measures of water and fertilizer had a strong promotion effect on the average volume and average productivity of 2?-year-old trees, but had no significant promotion effect on 4?-year-old
P
. tomentosaS86 plantations. The average annual productivity of triploid
P. tomentosaS86 stands was 19.65?5.31 m
3/(ha·year) in four years, among which, W1N1 had the highest annual productivity, which was significantly higher than CK by 28.41% (
P< 0.05). Under the treatment of 5-year-old stand W1N1, the tree growth was optimal, with unit area volume and average productivity reaching 104.39 m
3/ha and 27.42 m
3/(ha · year), respectively, which were 28.15% and 11.74% higher than CK treatment, respectively.
ConclusionThe furrow irrigation and fertilizer coupling measures have different degrees of improvement on the unit area storage and annual productivity of 2?-year-old triploid
P. tomentosaS86
stand, but have no significant effect on the unit area storage and annual productivity of 4?-year-old
P. tomentosaS86 plantation. Among them, W1N1 furrow irrigation and nitrogen application treatment has the best growth. Under similar climatic and soil conditions, maintaining sufficient water (irrigation threshold of ?0 kPa) and a lower nitrogen application rate (120 kg/(ha · year) is most conducive to the growth of high-density short-rotation triploid
P
. tomentosatargeting pulp forests.
2023, 45(3): 79-92.
doi:10.12171/j.1000-1522.20220121
Abstract:
ObjectiveThe
Parashorea chinensisis an endemic and endangered species in China, and it is classified as a class protected wild plant. Plantation cultivation is an important means to expand its populations. Phosphorus (P) supply is a major influence on tree growth and development, and P dissolving bacteria plays an important role in P transformation. This research aimed to screen high-efficient phosphate-solubilizing bacteria (PSB) from the rhizosphere soil of
P. chinensisplantations of different ages, and explore its P-solubilizing characteristics, so as to provide bacterial resources and culture conditions for the development of microbial fertilizer suitable of
P. chinensis.
Method(1) PSB was isolated and screened from the rhizosphere soil of
P. chinensisin different ages by inorganic P solid medium. The physiological and biochemical tests and 16S rDNA gene sequence were used to further identify 4 strains of PSB. (2) The relationship between the amount of P dissolved by PSB and the pH of the bacterial solution was studied by detecting the dynamics of P solubilization. (3) A single factor experiment was conducted to investigate the P-solubilizing characteristics of high efficiency PSB under different environmental and nutritional factors.
Result(1) A total of 18 strains of phosphorus solubilizing bacteria were isolated and screened, and the 4 strains with the strongest P-solubilizing capacity were P4, P8, P12 and P30 (P-solubilizing capacity was 552.87, 559.78, 548.53 and 598.89 mg/L, respectively). (2) Strain P8 was identified as
Burkholderia gladioli, P4 and P12 as
Burkholderia cepacia, and P30 as
Bacillus cereusby physiological, biochemical identification and combined with phylogenetic tree analysis. (3) There was a highly significant (
P< 0.01) negative correlation between the pH of the cultures and the amount of phosphorus dissolved by the P4, P8, P12 and P30 strains, with correlation coefficients of ?.995, ?.990, ?.985 and ?.997, respectively. (4) The results of single factor test showed that the PSBs had the preferable P-solubilizing effects at a temperature of 30?5 ? the pH of 5.5?.5, the NaCl mass fraction was 0?.5%, the carbon (C) sources were sucrose, lactose and glucose, and the nitrogen (N) sources were ammonium oxalate and ammonium sulfate. The optimal C∶N of strain P30, P12 and P4 was 20?, and that of P8 was 40?. The optimal P source for strain P12 was FePO
4, and Ca
3(PO
4)
2for P30, P8 and P4.
ConclusionThe P-solubilizing ability of PSBs can be significantly affected under different culture conditions. The 4 strains of high efficiency PSB have preferable P-solubilizing ability, which can dissolve a variety of insoluble inorganic phosphates. Therefore, it is expected to provide germplasm resources for the development of high-efficiency microbial phosphate fertilizers with a good application potential.
2023, 45(3): 93-103.
doi:10.12171/j.1000-1522.20220028
Abstract:
ObjectiveIn this paper, the host preference and selectivity of
Perina nudato different
Ficusspecies were investigated to provide scientific basis for the control of
Perina nuda.
Method4 species of host trees (
Ficus macrocarpa,
F. altissima,
F. benjaminaand
F. concinna) in Guangzhou City, Guangdong Province of southern China were selected to feed
P. nudaand the growth, development and feeding amount of
P. nudaafter feeding on different leaves of banyan were analyzed.
ResultThere were differences in the larval instars of
P. nudareared by different banyan trees. During larval instar,
P. nudafed on
F.
microcarpawas 5th to 7th instar, that fed on
F. altissima,
F. concinnaand
F. benjaminawere 6th to 8th instar. The development period of larval of
P. nudafed on
F. benjaminawas longest while the shortest period was the
P. nudafed on
F. microcarpa. Additionally, body length, body mass and fecal mass of
P. nudalarval fed on
F.
microcarpawere at the top among 4 banyan species. In the meanwhile, the 2nd to 7th instar larvae reared by
F. microcarpahad the widest head capsule (the 1st instar larvae fed on
F. altissimahad the widest head capsule). Besides, the survival rates of
P. nudalarvae reared by
F.
microcarpaand
F. altissimawere significantly higher than those of
F. benjaminaand
F. concinna. Furthermore, the female adults of
P. nudalarvae feeding on the
F.
microcarpahad the longest lifespan, while the male adults feeding on
F. altissimahad the longest lifespan. It was also showed that the female adult had the shortest pre-ovulation period, and the single female laid the most eggs. Finally, it was found that the larvae fed on
F.
microcarpaat the 1st to 4th instars preferred to feed on
F. altissimaat the 5th instar, while the host preferences of 5th instar
P. nudalarvae fed on other three banyan species were not obvious.
ConclusionThere are significant differences in the preference and selectivity of
P. nudato the four banyan species.
F. microcarpaand
F. altissimaare more suitable for the growth and development of
P. nudathan
F. benjaminaand
F. concinna.
2023, 45(3): 104-112.
doi:10.12171/j.1000-1522.20210254
Abstract:
ObjectiveThis paper aims to select Asiatic lilies with strong resistance to
Botrytis elliptica, the resistance of some Tiger and Pearl series Asian lilies and
Lilium davidiivar.
unicolorto
B. ellipticawas evaluated, and the physiological mechanism of resistance was preliminarily explored.
MethodThe disease resistance of different cultivars or species was evaluated by ex vivo leaf inoculation. On this basis, the physiological changes of selected disease-resistant and susceptible cultivars after inoculation were determined.
ResultThe comprehensive evaluation results showed that: (1) the resistance of Tiger, Pearl lilies and
L. davidiivar.
unicolorto
B. ellipticawas different. Relatively strong resistance to
B. ellipticawas ‘Pearl Melanie? which belonged to the medium resistance level. The weakest resistance materials were ‘Pearl Justin?
L. davidiivar.
unicolor, ‘Pearl White and ‘White Twinkle? (2) There was no significant correlation between resistance level and stomatal density, stomatal size. (3) The physiological responses of the resistant cultivar ‘Pearl Melanie and susceptible cultivar ‘Pearl Justin were obviously different after inoculation. The content of MDA showed an increasing trend with the extension of inoculation time, while the activities of oxalate oxidase and chitinase gradually increased, and the activities of β-1,3-glucanase decreased with time. The MDA content of the resistant cultivars was relatively lower than susceptible cultivar, and the activities of oxalate oxidase and chitinase were higher than susceptible cultivar.
ConclusionThere is no significant correlation between stomatal characteristics and disease resistance, the physiological mechanism of lillies with distinct disease resistance is different. During the physiological response, MDA content, oxalate oxidase activity and chitinase activity can be used as evaluation indexes for evaluating Asiatic lilies for resistance to
B. elliptica.
2023, 45(3): 113-126.
doi:10.12171/j.1000-1522.20220129
Abstract:
ObjectiveGreenspace is the ecological foundation of urban and rural development, and a good greenspace system is an important guarantee for coordinating urban development and nature conservation. Comprehensive measurement and investigation of the spatio-temporal evolution pattern of city-wide greenspace in the lower reaches of the Yellow River can help the planning for the construction of ecological corridors in the lower reaches and ecological improvement in the floodplain.
MethodFour cities in the lower reaches of the Yellow River, Jinan, Heze, Zhengzhou, and Xinxiang, were used as the study objects, and year 1990, 2000, 2010, and 2020 were taken as the time nodes. Using vegetation cover density and the secondary classification of land use, the city-wide green space types were classified, and then the transfer matrix, landscape pattern indices, urban-to-rural trajectory and geo-detector were used to conduct quantitative research on the spatio-temporal patterns and mechanism of city-wide evolution greenspace.
Result(1) In the past 30 years, the greenspace had transferred 3 223 km
2to the bare surface, and the bare surface had transferred 181 km
2to all kinds of greenspace; 735 km
2of greenspace was transferred to each other, of which 466 km
2was transferred from higher density to lower density greenspace, and 269 km
2was transferred from lower density to higher density greenspace. (2) The decrease of percentage of landscape (PLAND) and area-weighted mean shape index (AWMSI) of sparse greenspace, the decrease of number of patches (NP) of all kinds of greenspace, and the increase of mean patch size (MPS) and functional connectivity (PC) were the general rules of landscape pattern indices. (3) On the urban-rural gradient, the peaks and valleys of low density greenspaces moved significantly, while high and medium density greenspaces were relatively fixed. (4) The influence of natural environmental factors on the geographical distribution of greenspace in Jinan, Shandong Province of eastern China, Zhengzhou and Xinxiang, Henan Province of central China was dominant, and the cumulative influence of socio-economic factors in each city increased by 3.1%?.4%, showing an increasingly obvious non-linear enhancement with natural environmental factors. influence of socio-economic factors in each city increased by 3.1%?.4%, showing an increasingly obvious non-linear enhancement with natural environmental factors.
ConclusionDuring the 30 years, the total amount of regional greenspace is lost, and the internal transfer of greenspace is mainly from higher density to lower density, with more transfers along the edges of built-up areas and along the wide floodplain; the overall trend of landscape pattern changes from obvious fluctuation to nearly stable, from fragmentation and dispersion to integration and connectivity, and the improvement trend is more obvious in regional central cities; the urban-to-rural trajectory characteristics differ greatly between cities and greenspace types; the synergistic effect among influencing factors is gradually increasing, and greenspace gradually becomes the result of natural-social interconfiguration. In the future, the city-wide greenspace should be transformed from a “barrier to a “hub according to the needs of the city.
2023, 45(3): 127-136.
doi:10.12171/j.1000-1522.20220360
Abstract:
ObjectiveThis paper aims to further improve the high value-added utilization of culm resources of
Chimonobambusa utilis, the chemical components, physical and mechanical properties were investigated, and the variation regularity with age and axial part of bamboo culm were also revealed.
MethodIn this study, the natural plants of
Chimonobambusa utiliswere used as raw materials to determine the chemical component (mass fraction in this article) content and physical and mechanical properties, such as density, dry shrinkage, compressive strength parallel to grain, modulus of rapture (MOR), modulus of elasticity (MOE) and hardness according to the national standards. The crystallinity of cellulose and microfibril angle was calculated from the results of X-ray diffraction.
ResultThe content of each chemical component of
Chimonobambusa utilisvaried slightly with the age and axial part, and the variation pattern was not significant. The crystallinity increased with the age of bamboo and then decreased gradually, with a maximum of 50.39% at 2 years old, and increased gradually with the increase of axial part. The microfibril angle decreased and then increased with increasing age and axial part, and the smallest angle was 9.10° in the middle of 2 years old. The basic density ranged from 0.513 to 0.693 g/cm
3, the oven-dried density ranged from 0.535 to 0.725 g/cm
3, and the air-dried density ranged from 0.556 to 0.756 g/cm
3. All densities showed an increasing trend with increasing age and axial part, and increased significantly between 1 and 2 years, and then increased steadily to stabilize. The oven-dried and air-dried shrinking ratio showed a decreasing trend with the increasing age and axial part, and decreased significantly between 1? years, and then decreased steadily, the latter fluctuating relatively more. The compressive strength parallel to grain ranged from 50.73 to 64.58 MPa, MOR ranged from 114.09 to 134.26 MPa, and MOE ranged from 8.45 to 12.42 GPa, all of which showed an increasing-decreasing-increasing trend with increasing age, and an increasing trend with increasing axial part; the mean values of inner and outer hardness ranged from 60.00 to 72.70 HD, which showed an increasing trend with increasing age and axial part. The dry shrinkage, compressive strength parallel to grain, MOE and hardness of
Chimonobambusa utiliswere significantly affected by anatomical index and major chemical components.
ConclusionBoth bamboo age and axial part of culm affected the basic properties, but the effect of bamboo age was more significant. The culm material of
Chimonobambusa utiliswas basically mature over 2 years old, which could be the optimized cutting age of
Chimonobambusa utilis. In addition, there were some significant correlations between physical-mechanical properties and anatomical structure index.
2023, 45(3): 137-144.
doi:10.12171/j.1000-1522.20220432
Abstract:
ObjectiveIn order to enrich the color system of wood products, this paper discusses the construction and color performance of SiO
2photonic crystals on the surface of wood.
MethodIn this paper, SiO
2microspheres with different particle diameters were prepared by the Stöber method, and the SiO
2photonic crystal structure color was constructed on the wood substrate by the gravity deposition self-assembly method. The chemical composition and structure of SiO
2microspheres were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The morphology of the microspheres and their arrangement on the wood substrate were characterized by scanning electron microscopy, and the particle diameter distribution of the microspheres under different treatment processes was analyzed. The color parameters and UV-visible reflectance of SiO
2structure on the wood surface were analyzed by digital camera and UV-visible absorption spectrometer.
ResultX-ray diffraction, Fourier transform infrared spectroscopy confirmed that the reaction products prepared in this paper were pure amorphous SiO
2, suitable for constructing well-colored structural color coating. The preparation formula only controlled the amount of ethanol added, and the addition amount was 80, 85, 90, 95, 100, and 105 mL, respectively. The monodisperse nano-SiO
2was generated, and their particle diameters were 294, 246, 226, 214, 194, and 181 nm, respectively. As the particle diameter of SiO
2involved in self-assembly decreased in turn, the color of the film gradually changed from red to green, blue-green, and finally to deep purple, purple, and lavender. The ultraviolet reflection wavelength gradually decreased and the color blue shifted. The SiO
2microspheres showed a three-dimensional ordered face-centered cubic structure on the surface of the wood substrate. Due to environmental disturbances, assembly defects such as cracks and missing will occur, but will not affect the overall color.
ConclusionOnly by controlling the amount of ethanol added, six different particle diameters of nano-SiO
2particles suitable for constructing photonic crystal structure color can be prepared. Silica microspheres of various particle diameters formed bright structural colors after self-assembly on the wood substrate, and the color of the structural color coating would blue shift due to the particle diameter reduction of the self-assembled microspheres. The above research content provides a simple and novel method for the large-scale preparation of wood surface structural color coatings, which can enrich the color system of wood products.
2023, 45(3): 145-152.
doi:10.12171/j.1000-1522.20220471
Abstract:
ObjectiveThis study aimed to analyze the main chemical constituents and environmental influencing factors of cork from
Quercus variabilisthrough a wide range of samples in China, which would be helpful to provide scientific reference for the oriented selection and scientific utilization of cork resources.
MethodCork from
Q. variabiliswas collected from 12 regions in China for the determination of cork resin, lignin and other major chemical components, and the chemical components of cork from different locations were compared by LSD multiple comparison, principal component analysis and cluster analysis.
ResultThe average contents of main chemical constituents (the chemical composition content in this paper refers to the mass fraction) of the cork were: the total extractable matter was (13.94 ± 0.54)%, the suberin was (41.63 ± 1.44)% and the lignin was (23.03 ± 2.26)%. According to the content of suberin and lignin, the 12 provenances could be clustered into three groups, among which Lincheng (Hebei Province of northern China), Yongxiu (Jiangxi Province of eastern China), Jinzhai (Anhui Province of eastern China), Nanjing (Jiangsu Province of eastern China) and Neixiang (Henan Province of central China) had relatively high suberin content, while Jiyuan (Henan Province of central China), Meixian (Shaanxi Province of northwestern China) and Tianshui (Gansu Province of northwestern China) belong to the groups with high lignin content. The left provenances, Shangluo (Shaanxi Province of northwestern China), Chengbu (Hunan Province of southern China), Pinggu (Beijing of northern China) and Tianlin (Guangxi of southern China) belong to the middle group. The correlation analysis showed that the content of dichloromethane extract and total extractable matter was negatively correlated with latitude, while the suberin content increased with longitude and soil nitrogen content. The annual mean temperature had little effect on chemical composition content, but mean annual precipitation had significant positive correlation with the suberin, the dichloromethane extract and total extractable content.
ConclusionOn the whole, there are certain geographical differences in the chemical composition content of cork from
Quercus variabilisin China, and they are mainly affected by latitude, mean annual precipitation, and soil nitrogen content.
2023, 45(3): 153-159.
doi:10.12171/j.1000-1522.20220345
Abstract:
ObjectiveIn order to reduce the influence of human factors on the log sizing results and improve the work efficiency, a log sizing method based on mask region instance segmentation model and edge fitting algorithm was proposed.
MethodThe method used monocular camera as the acquisition equipment, and the end face images of eucalyptus with three different diameter classes and rectangular scaleplate were taken as the research objects. Firstly, the image was collected at different distances to make a data set, and the training set, verification set and test set were divided at the ratio of 8??, and the log end face recognition experiment database was established. Secondly, the instance segmentation model was used to extract the end face part to generate the mask, the edge fitting algorithm was used to obtain the pixel size of the rectangular scaleplate and the log end face, combined the actual size of the scaleplate to obtain the actual size of the log end face. Finally, the error of fitting size of the algorithm and the error of different national standard volume calculation formulas were compared.
ResultIt was found that the example segmentation model in this paper can achieve more accurate mask segmentation of log end face, and the accuracy and recall rate were 99.89% and 99.41%, respectively. Compared with the one-stage algorithm, F1 scores and mean average precision were significantly improved. By fitting the end face to an ellipse using a least square edge fitting algorithm, the short diameter of the ellipse was obtained as the log diameter. Compared with the real value, the average percentage error was about ?.00%, which was slightly smaller than the real value. Comparing the error of logs with different sizes, the measurement error of 100% small size logs, 98% medium size logs and 95% large size logs was ?%?%. By comparing the log end face images collected at different distances, it was found that the best effect was to collect images within 50?00 cm, the average relative error didn’t exceed ?.22%, and the error gradually increased when the distance was greater than 100 cm. By comparing the calculation standards of log volume in different countries, the volume error was ?.5% according to the calculation formula of wood volume in China, which was the lowest among the four national standards of China, America, Russia and Japan.
ConclusionCompared with manual measuring, the measuring method proposed in this paper is more efficient, less affected by human factors, and can more accurately measure the log size, and achieve the goal of replacing manual log sizing operations.
