Retrieving chlorophyll content and equivalent water thickness of Moso bamboo(Phyllostachys pubescens) forests under Pantana phyllostachysae Chao-induced stress from Sentinel-2A/B images in a multiple LUTs-based PROSAIL framework

Biochemical components of Moso bamboo(Phyllostachys pubescens)are critical to physiological and ecological processes and play an important role in the material and energy cycles of the ecosystem.The coupled PROSPECT with SAIL(PROSAIL)radiative transfer model is widely used for vegetation biochemical component content inversion.However,the presence of leaf-eating pests,such as Pantana phyllostachysae Chao(PPC),weakens the performance of the model for estimating biochemical components of Moso bamboo and thus must be considered.Therefore,this study considered pest-induced stress signals associated with Sentinel-2A/B images and field data and established multiple sets of biochemical canopy reflectance look-up tables(LUTs)based on the PROSAIL framework by setting different parameter ranges according to infestation levels.Quantitative inversions of leaf area index(LAI),leaf chlorophyll content(LCC),and leaf equivalent water thickness(LEWT)were derived.The scale conversions from LCC to canopy chlorophyll content(CCC)and LEWT to canopy equivalent water thickness(CEWT)were calculated.The results showed that LAI,CCC,and CEWT were inversely related with PPC-induced stress.When applying multiple LUTs,the p-values were<0.01;the R2 values for LAI,CCC,and CEWT were 0.71,0.68,and 0.65 with root mean square error(RMSE)(normalized RMSE,NRMSE)values of 0.38(0.16),17.56μg cm-2(0.20),and 0.02 cm(0.51),respectively.Compared to the values obtained for the traditional PROSAIL model,for October,R2 values increased by 0.05 and 0.10 and NRMSE decreased by 0.09 and 0.02 for CCC and CEWT,respectively and RMSE decreased by 0.35μg cm-2 for CCC.The feasibility of the inverse strategy for integrating pest-induced stress factors into the PROSAIL model,while establishing multiple LUTs under different pest-induced damage levels,was successfully demonstrated and can potentially enhance future vegetation parameter inversion and monitoring of bamboo forest health and ecosystems.

Experimental Study of Moso Bamboo to-Steel Connections with Embedded Grouting Materials

Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.

Effect of Steam Explosion Technology Main Parameters on Moso Bamboo and Poplar Fiber

One of the large-scale industrial applications of Moso bamboo and poplar in China is the production of standardized fiberboard.When making fiberboard,a steam blasting pretreatment without the addition of traditional adhesives has become increasingly popular because of its environmental friendliness and wide applicability.In this study,the steam explosion pretreatment of Moso bamboo and poplar was conducted.The steam explosion pressure and holding time were varied to determine the influence of these factors on fiber quality by investigating the morphology of the fiber,the mass ratio of the unexploded specimen at the end face,the chemical composition,and the tensile strength.The following conclusions were drawn:As the steam burst pressure and holding time increased,more cellulose and hemicellulose degradation occurred(the degradation of hemicellulose was greater than that of cellulose),the lignin content rose,and the fiber bundle strength decreased.The degradation of bamboo cellulose was slightly higher than that of poplar,and the degradation of poplar hemicellulose was significantly faster than that of bamboo.Furthermore,increasing the steam explosion pressure and pressure holding time could not effectively increase the lignin content.It is recommended to use a steam blasting pressure of 2.5 MPa or 3.0 MPa and a holding time of 180 s to perform steam blasting on bamboo and poplar specimens.

Study on the Bonding Performance of the Moso Bamboo Dowel Welded to a Poplar Substrate Joint by High-Speed Rotation

The wood friction welding technique with its high bonding strength,low cost,high efficiency,and without any adhesive has been increasing concern in China.Moso bamboo(Phyllostachys pubescens)and poplar(Populus sp.)are widely planted and used in the furniture industry,interior decoration,and wood structure construction in China.The aim of this work was to investigate the bonding performance of moso bamboo dowel rotation welded joints with different dowel/receiving hole diameter ratios.The results indicated that the ratio of dowel/receiving hole diameter was an important parameter that influenced the welding performance.The bonding strength of the bamboo-to-poplar welded joints at the optimal ratio of 10/7 was as high as 7.50 MPa,which was higher than that of the beech(Fagus sylvatica,L.),schima(Schima superba)dowels and PVAc glued joints.The temperature measurement results showed a peak temperature of bamboo dowel welding as high as 350–360°C.Some differences in the temperature curves between each dowel/hole diameter ratio group were observed at the three different hole depths,such as the friction time,peak temperatures,and stabilization time at the maximum temperature,which could explain the differences in welding strengths between different ratios.The SEM results showed the temperature-induced softening,melting and flowing of cell-interconnected polymer material in the wood and bamboo structure.In addition,the bamboo fibers(mainly vascular bundles)were wrapped to form a dense continuous bonding layer,similar to the reinforced concrete,thus producing a good bonding effect.The Fourier transform-infrared spectroscopy(FT-IR)analyses showed that the high temperature resulted in the increase of the lignin relative content due to the degradation reaction of cellulose in the welding zone,which improved the bonding properties.

Study on the Tangential Tensile Mechanical Properties of Moso Bamboo

In this work,we used tensile tests to analyze the tangential failure forms of raw bamboo and determine a relationship between tangential tensile strength,elastic modulus,position,density,and moisture content.We found that the tangential mechanical properties of the culm wall were mainly dependent on the mechanical properties of the basic structure of the thin wall.Formulas for calculating the tangential tensile strength of moso bamboo and adjusting the moisture content were also determined.The tangential tensile strength and the tangential tensile modulus of elasticity(TTMOE)followed:outer>middle>inner,and diaphragm>bamboo node>culm wall.Below the fiber saturation point,the tangential tensile strength and TTMOE values of the bamboo gradually decreased with increasing moisture content.When the moisture content was 15%,the tangential tensile strengths of the inner,middle,outer,culm wall,bamboo node,and diaphragm samples of the five-year-old moso bamboo were 3.17,3.29,3.31,3.24,3.67,and 8.85 MPa,respectively.Furthermore,their TTMOE values were 215.09,227.98,238.45,224.04,267.21,and 559.27 MPa,respectively.Hence,this study provides a theoretical basis for future research on bamboo cracking.

Mechanical Properties of Moso Bamboo Connections with External Clamp Steel Plates

The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of Moso bamboo connections with external clamp steel plates,the 16 specimens were designed by changing the bolt diameters and the end distances of the bolt holes.Their static tension tests were conducted to investigate bearing capacities and failure modes of different connection configurations.Based on test results,three failure modes of these connections were obtained,including the shear failure of bolt shank,bearing failure of bolt hole and punch-ing shear failure of the Moso bamboo.The influence of bolt diameters and end distances of bolt holes on bearing capacities of the connections was quantitatively analyzed.Based on a simplified mechanical model,the analytical models were deduced for the bolt shear failure and the bearing failure of bolt holes.The results showed that the predictive values are in substantial agreement with the experimental results.Finally,the design and manufacturing suggestions are recommended for this Moso bamboo connections.

Climate Warming-induced Upward Shift of Moso Bamboo Population on Tianmu Mountain,China

Although increasing attention has been paid to upward shift of plant species in altitude as a response to global warming,research on this phenomenon at low altitudinal and low latitudinal zones did not receive enough attention.In this study,an investigation was carried out to test the relationship between the upward spread of Moso bamboo(Phyllostachys pubescens) along altitudinal gradient and the increasing air temperature over the past decade within the Tianmu Mountain region,situated in southeastern China.Results showed that the peak elevation of Moso bamboo population establishment rose by an average of 9.8 m(±2.7 m) during the past decade and significant correlation existed with mean annual temperature(P < 0.0001,n = 339) but not with annual precipitation(P = 0.7,n = 339),indicating that the upward shift of Moso bamboo along altitudinal gradients was driven primarily by warming temperatures.This upward shift could potentially reduce biodiversity by altering the species composition of the ecosystem.However,there is also the potential for increased carbon sequestration capacity of local forest systems,which would produce an additional carbon sink to combat rising atmospheric CO 2 concentrations and future global warming.

Silicon’s organic pool and biological cycle in moso bamboo community of Wuyishan Biosphere Reserve

Biomineralization of Si by plants into phytolith formation and precipitation of Si into clays during weathering are two important processes of silicon’s biogeochemical cycle. As a silicon-accumulating plant, the widely distributed and woody Phyl-lostachys heterocycla var. pubescens (moso bamboo) contributes to storing silicon by biomineralization and, thus, prevents eu-trophication of nearby waterbodies through silicon’s erosion of soil particles. A study on the organic pool and biological cycle of silicon (Si) of the moso bamboo community was conducted in Wuyishan Biosphere Reserve, China. The results showed that: (1) the standing crop of the moso bamboo community was 13355.4 g/m2, of which 53.61%, 45.82% and 0.56% are represented by the aboveground and belowground parts of moso bamboos, and the under-story plants, respectively; (2) the annual net primary production of the community was 2887.1 g/(m2·a), among which the aboveground part, belowground part, litterfalls, and other fractions, accounted for 55.86%, 35.30%, 4.50% and 4.34%, respec-tively; (3) silicon concentration in stem, branch, leaf, base of stem, root, whip of bamboos, and other plants was 0.15%, 0.79%, 3.10%, 4.40%, 7.32%, 1.52% and 1.01%, respectively; (4) the total Si accumulated in the standing crop of moso bamboo com-munity was 448.91 g/m2, with 99.83% of Si of the total community stored in moso bamboo populations; (5) within moso bamboo community, the annual uptake, retention, and return of Si were 95.75, 68.43, 27.32 g/(m2·a), respectively; (6) the turnover time of Si, which is the time an average atom of Si remains in the soil before it is recycled into the trees or shrubs, was 16.4 years; (7) the enrichment ratio of Si in the moso bamboo community, which is the ratio of the mean concentration of nutrients in the net primary production to the mean concentration of nutrients in the biomass of a community, was 0.64; and lastly, (8) moso bamboo plants stored about 1.26×1010 kg of silicon in the organic pool made up by the moso bamboo forests in the subtropical area of China.

The Effect of Lignification Process on the Bioconversion Efficiency in Moso Bamboo

Recalcitrance of lignocellulosic biomass is closely related to the presence of lignin in secondary cell walls,which has a negative effect on enzyme digestibility,biomass-to-biofuels conversion,and chemical pulping.The lignification process and structural heterogeneity of the cell wall for various parts of moso bamboo were investigated.There were slight differences among three different column parts of moso bamboo in terms of chemical compositions,including cellulose,hemicelluloses,and lignin.However,the detailed analysis of the fractionated lignin indicated that the acid-soluble lignin was first biosynthesized,and the largest molecular weight value was detected from the bottom part of the moso bamboo,as well as the highest syringyl-to-guaiacyl ratio.Although the main b-O-4 aryl ethers and resinol structures were clearly present in all lignin samples examined by NMR analysis,the relatively small lignin biomacromolecule in the top part of the moso bamboo lead to poor thermal stability.For the bioconversion process,no significant difference was found among all the moso bamboo samples,and the relatively higher hydrolysis efficiency was largely dependent on the low crystallinity of cellulose rather than the degree of lignin biosynthesis.

Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites

The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.

Research on Physical and Mechanical Properties of Moso Bamboo

With the increase of the utilization of bamboo, we must find out more in bamboo properties. According to the national standard GB/T15780 -1995, this paper analyzed the air-dried density and mechanical properties of Moso bamboo in different ages and stalk parts. The results showed that both the age and the stalk part have remarkable effects on air-dried density and mechanical properties. The effect of age is much more prominent than that of stalk part. The performance shows: upper > middle > down, which increases with the age, and reaches to the peak values at the age of 4 and show a downward trend at the age of 6. According to the tests, the optimum age of bamboo for cutting is about at 4. Moreover, there is a positive correlation between air-dried density and mechanical properties. The correlation coefficients between air-dried density and crushing strength parallel to the grain, bending strength, modulus of elasticity and tensile strength parallel to the grain are 0.917 3, 0.783 9, 0.745 8 and 0.507 4, respectively. In addition, there is a good relativity among mechanical properties, δt: δc: MOR: MOE = 2.79: 1.00: 2.40: 0.15.

Research on Air-dried Density and Mechanical Properties of Moso Bamboo from Different Plantations

In order to further research bamboo cultivation and expand its application field, air-dried density and mechanical properties of Moso bamboo from the 2 plantations under the same site condition were measured and analyzed by using the national standard The Testing Methods for Physical and Mechanical Properties of Bamboo (GB / T 15780-1995). And the single linear regression analysis was carried out. The results showed that air-dried density and mechanical properties of the 2 kinds of Moso bamboo increase with the age increasing, and at the same age, those of Moso bamboo from the seedling plantation are much higher than those from the common plantation afforested by transplanting, in other words, Moso bamboo from the conventional plantation reaches a stabilization the at age of 4, while that from the seedling plantation reaches a stabilization at the age of 6 or more. There is a positive correlation between air-dried density and mechanical properties of the 2 kinds of bamboo.

Research on the Bending Impact Resistance and Transverse Fracture Characteristics of Bamboo under the Action of Falling Weight

Drop weight impact tester was used to accurately measure the bending impact resistance of various parts of Phyllostachys edulis,commonly known as moso bamboo,with a growth cycle of 3–8 years.Cellulose crystallinity in the bottom(B),middle(M)and top(T)of bamboo at different ages was calculated using peak height analysis in X-ray diffraction.Heatmap of Spearman correlation analysis was used to represent the correlation between chemical composition and impact mechanics.The breaking load(BL),fracture energy(FE)and impact deflection(ID)of 3–8-year-old bamboo were found to be in the range of~670–2120 N,~5.17–15.55 J,and~3.60–~17.76 mm,respectively.As the growth period of bamboo rises,the cellulose crystallinity at the B and T decreases first and then increases,while that for the M increases first and then remains stable.Similarly,the bending impact performance of bamboo was found to become stable with its growth and age.The flexural impact and toughness of the 4-year-old bamboo base material were better than other specimens.The enhancement in the bending impact properties of bamboo at different growth periods was influenced by the lignin content,while the value of FE was mainly positively correlated with ash,cold and hot water extracts and benzyl alcohol content.However the content of holocellulose and pentosan,air-dry density and,base density negatively influenced the FE.With the change in the height of the bamboo,the correlation between its impact mechanical properties and chemical composition gradually decreased.This study provides data support and theoretical basis for the age-appropriate thinning and application of moso bamboo.

Field Trial of Copper Treated Moso Bamboo in Southern China

The field trial of Moso bamboo treated with 9 copper preservatives was conducted in Guangzhou, China. The result showed that two formulations of ammonia-based copper azole (F17 and F18 ) and a formulation of amine copper added with boron (F10), as well as 2 kinds of ammonia-based ACQ, at the copper retention of 3.2 kg/m3 or over, were very resistant to decay and termites after the 5- year field test. And the durability of ACQ-B treated Moso bamboo was similar to that of treated Masson pine and slash pine at the same copper level.

Survey Study of Moso Bamboo Management Techniques Dissemination in Zhejiang

By PRA survey to 1 245 farmer households of 10 key Moso bamboo (Phyllostachys pubescens) production counties, the source and demand of the management techniques in Zhejiang were studied. The conducted principal factor analysis revealed that experience and traditional knowledge are currently major technical sources of farmer households' Moso bamboo forest management techniques and that the demonstrative household is a highly expected technical source, in which the prime factor is interpersonal dissemination with the variable information making up 21.5% of the total. The paper thus suggests that following the nationwide collective forest tenure reform and forest land allocation to the households, the technical sources available to the households should be diversified, that technical training with site expert instruction be taken as priority in establishing demonstrative households for extension and that the current technical extension mode await improvement.

毛竹扩张对幕阜山区森林土壤碳氮磷含量及生态化学计量特征的影响

以幕阜山区同一片毛竹林向两侧杉木林和阔叶林扩张形成的连续生态界面为研究对象,分析不同林型土壤有机碳(SOC)、全氮(TN)、全磷(TP)、硝态氮(NO_(3)^(−)−N)、铵态氮(NH_(4)^(+)−N)含量及其生态化学计量比,探讨毛竹不同扩张模式对森林土壤碳(C)、氮(N)、磷(P)的影响。结果表明:在2种扩张模式下,随土壤层次的增加,除NO_(3)^(−)−N呈不规律变化外,SOC、TN、TP、NH_(4)^(+)−N含量均呈逐渐降低趋势。在毛竹向杉木林扩张过程中,杉木林、竹杉混交林、毛竹林同一土层SOC、TN、TP含量均无显著差异;在毛竹向阔叶林扩张过程中,毛竹林0~10 cm土层SOC和TN含量较阔叶林和竹阔混交林分别降低了27.71%、30.45%和36.67%、31.11%,而在10~20 cm和20~30 cm土层则无显著差异;毛竹扩张对杉木林和阔叶林各土层TP含量无显著影响;毛竹向杉木林扩张增加了0~10 cm和20~30 cm土层NH_(4)^(+)−N含量,毛竹向阔叶林扩张增加了10~20 cm土层NH_(4)^(+)−N含量及20~30 cm土层NO_(3)^(−)−N含量;毛竹向杉木林扩张对土壤C/N、C/P、N/P无显著影响,毛竹向阔叶林扩张导致0~10 cm土层N/P明显降低、10~20 cm土层C/N显著增加。综上,毛竹向杉木林扩张对土壤SOC、TN、TP影响不显著,但提升了表层和深层土壤NH_(4)^(+)−N含量,毛竹向阔叶林扩张造成表层土壤SOC、TN含量显著降低,并导致中层土壤NH_(4)^(+)−N含量和深层土壤NO_(3)^(−)−N含量明显增加。

竹笋采挖下克隆整合对毛竹林发笋成竹规律的影响

【目的】为研发毛竹林高产高效生态经营技术提供一定参考。【方法】调查浙西南地区采挖毛竹林竹笋后的笋-幼竹生长过程,通过存活曲线分析毛竹林挖笋后的发笋成竹规律,探讨挖笋对竹笋中单宁、粗脂肪、粗蛋白等品质指标的影响。【结果】竹笋采挖提高了毛竹林地的发笋能力,挖笋样地的发笋数比未挖笋样地增加了12.8%(P<0.05),而挖笋后选留竹笋的存活率也显著高于未挖笋样地;与未挖笋样地相比,挖笋样地内毛竹新分株的平均胸径并未发生显著改变(P>0.05),挖笋不会降低新分株胸径而使林分衰退;竹笋间的非对称性竞争有利于竹笋地径的径级为Ⅰ-Ⅲ级竹笋的生长与存活,随着地径的提高竹笋死亡率显著降低,而径级Ⅳ级以上竹笋则有着较高的死亡率。盛笋早期以后,径级相对较小(Ⅳ级以上)的竹笋开始大量萌发,这类竹笋若不及时采挖,大部分会出现退笋,造成资源浪费;挖笋和未挖笋样地竹笋的含水率、蛋白质和粗脂肪含量在各笋期均未见显著差异(P>0.05),尽管挖笋样地竹笋的单宁含量在末笋期显著高于未挖笋样地,但两种样地其他笋期单宁含量均未见显著差异。【结论】毛竹林竹笋的采挖,可缓解竹笋间的非对称性的资源竞争,有效避免大量退笋导致的毛竹母株营养消耗,实现母株资源的克隆整合,增加竹笋产量。因此,合理的竹笋采挖有利于毛竹笋用林的高效生产及可持续性经营。

“六力”驱动破解湖南毛竹下山难题

湖南省竹资源丰富,竹产业发展具有良好基础。近年来,湖南省竹产业发展取得了显著成绩,但仍然面临许多困难,其中首要问题是毛竹下山难,使得资源优势无法转化为经济优势。文章分析了湖南省毛竹下山难的根源,并从推动"以竹代塑"激发毛竹下山动力、培育竹林资源提升毛竹下山内力、打通竹林通道消除毛竹下山阻力、组建采伐队伍减轻毛竹下山压力、推广全竹利用增加毛竹下山引力、创新经营模式增强毛竹下山活力等6个方面提出了对策,期望破解毛竹下山难题,助推湖南竹产业高质量发展。

不同肥料种类对毛竹材物理力学性质的影响

为探讨不同肥料种类对毛竹材物理力学性能的影响,于2021—2022年以福建省建瓯市房道镇埂尾村长期失管状态下的毛竹林为研究对象,以不施肥为对照,探讨施用有机肥、无机复合肥、有机肥+无机复合肥(简称复混肥)后不同年龄毛竹材气干密度、全干密度、基本密度、体积气干干缩率、体积全干干缩率、抗弯强度、抗弯弹性模量和顺纹抗压强度等8个物理力学性质相关指标的差异。结果表明,施用复混肥和有机肥后毛竹材密度大于施用无机肥的毛竹材密度,施肥的毛竹材密度均高于对照组。施用复混肥和有机肥的毛竹新竹材抗弯强度和抗弯弹性模量均高于施用无机肥和对照组。施用不同肥料类型均一定程度上提高Ⅰ—Ⅲ度毛竹材的顺纹抗压强度,其中施用复混肥和有机肥显著提高毛竹竹材顺纹抗压强度。相关性分析和主成分分析表明,竹材密度和体积干缩率是所调查竹材物理力学性质指标中的典型特征指标。综合分析可知,施用有机肥和含有机肥的复混肥的竹材具有更优良的物理力学性质。

立竹密度对不同发笋期毛竹叶片功能性状的影响

【目的】探究长周期母竹留养模式下毛竹叶片功能性状对立竹密度的响应及在不同发笋期的变化,并筛选出适宜的经营密度。【方法】以漳平市长周期母竹留养经营模式下笋用毛竹林为研究对象,设置(1350±100)、(1950±100)、(2550±100)、(3150±100)株·hm^(-2)4个不同立竹密度处理组,选用传统经营模式下生产效益较优的笋用毛竹林作为对照组,分析立竹密度对不同发笋期毛竹叶片功能性状的影响。【结果】毛竹林的叶面积指数、叶平均倾角、全氮含量、全磷含量、全钾含量和叶绿素含量均在立竹密度为(2550±100)株·hm^(-2)时达到最高,且不同处理组间差异显著(P<0.05);各处理组的叶面积指数、叶平均倾角及全氮含量均在发笋前期达到最高,冠层开度和叶绿素含量在发笋盛期达到最高,全磷和全钾含量则在发笋后期达到最高;毛竹叶片各功能性状间存在显著相关性。【结论】在长周期母竹留养经营模式下,当立竹密度为(2550±100)株·hm^(-2)时,毛竹林的冠层结构得到显著改善,叶片的空间分布更加合理,且叶片养分及叶绿素含量显著提高。