黄土高原刺槐林生长适宜生态区划

对黄土高原刺槐林生长及分布状况的调查,分析了刺槐林生长与环境气候条件的关系,提出刺槐林适宜生态区划分级,将黄土高原划为3个一级区和8个二级区。3个一级区分别是刺槐林生长适宜生态区,次适宜生态区及非适宜生态区。     

不同林分枯落物的持水性能及对表层土壤理化性状的影响

对刺槐林、麻烁林、五角枫林、黄连木林、油松林、赤松林、侧柏林、刺槐麻烁混交林的枯落物持水性能及枯落物层下的表层土壤理化性状进行了研究。结果表明：枯落物的持水性能大小顺序为刺槐林＞黄连木林＞刺槐麻烁混交林＞五角枫林＞麻烁林＞侧柏林＞赤松林＞油松林;表层土壤理化性状的优劣顺序为黄连木林＞刺槐林＞刺槐麻烁混交林＞五角枫林＞麻烁林＞侧柏林＞赤松林＞油松林。     

晋西黄土丘陵沟壑区刺槐林适宜性评价

晋西黄土丘陵沟壑区水土流失严重,气候干旱,生态环境恶劣,适应性和抗逆性很强的刺槐是该区重要的优良造林树种。建国以来,该区营造了大面积的刺槐林,但由于各立地类型的光、热、水、气、肥等条件不尽一致,其生长状况相差悬殊,有的甚至形成"小老树"。为了研究刺槐林的生态适宜性,在对不同立地条件下刺槐林生长状况调查的基础上,应用Verhanlst生长预测模型和模糊最优局势决策法进行了分析,发现刺槐林的生长状况与各立地条件的土壤水分变化基本一致,不同立地条件下刺槐林生长差异显著,同时筛选出适宜于营造刺槐林的最佳立地条件类型是梁峁阴坡和阴沟坡。     

三里庄水库上游水源涵养林不同林分枯落物水容量研究

通过对诸城市三里庄水库上游的刺槐林、麻栎林、油松林、刺槐麻栎混交林等主要林分类型的枯落物现存量及其持水性能的研究，总结出不同林分类型的枯落物的持水特征。结果表明枯落物的积蓄量为刺槐林〉刺槐麻栎混交林〉麻栎林〉油松林，枯落物的最大持水量为刺槐林〉刺槐麻栎混交林〉麻栎林〉油松林，枯落物的有效拦蓄量为刺槐林〉刺槐麻栎混交林〉麻栎林〉油松林，研究结果还表明，枯落物的粗糙度越大，截留径流的能力也越强，枯落物的水容量越大。     

晋西黄土丘陵沟壑区刺槐林适宜性调查研究

晋西黄土丘陵沟壑区水土流失严惩，气候干旱，生态环境恶劣，适应性和抗逆性很强的刺槐是该区的优良造林树种，多年来，该区营造了大面积的刺槐林，但由于骆立地条件类型的光，热，水，气，肥等条件不尽一致，其生长状况相差悬殊，有的甚至形成“小老树”，为了研究刺槐林的生态适宜性，在对不同立地条件下刺槐林生长状况调查的基础上，应用Verhanlst生长预测模型和模糊最优局势决策法进行了分析，发现刺槐林的生长状况与各立地条件的土壤水分变化基本一致，不同立地条件下刺槐林生长差异显著，同时筛选出适宜于营造刺槐林的最佳立地条件类型是梁峁阴坡和阴沟坡。     

晋西黄土区不同密度刺槐林对土壤水分的影响

在晋西黄土区蔡家川流域刺槐林地调查的基础上,选择密度为1 400株/hm2与2 200株/hm2的刺槐林地分别代表研究区低密度和高密度的刺槐林,并以裸地作为对照。通过设立固定样地,定位观测样地0—150cm土层的土壤水分,研究不同密度刺槐林地土壤水分状况及时空变化规律,并以土壤水分亏缺度和补偿度研究试验区降雨对刺槐林地土壤水分补偿与恢复效应。结果表明:(1)低密度刺槐林年平均土壤储水量比高密度刺槐林年平均土壤储水量绝对值高7.49mm,且低密度刺槐林达到土壤适宜储水量的天数比高密度刺槐林多60d;(2)从土壤剖面的垂直方向看,高密度和低密度刺槐林对30—150cm土层土壤水分消耗量无明显差异,但高密度刺槐林对表层土壤(0—30cm)的消耗远大于低密度刺槐林;(3)综合考虑不同降雨强度下土壤水分恢复程度、降雨补偿土壤深度等指标,研究区高密度刺槐林地土壤水分亏缺相对较大,研究区自然降雨不足以充分补给土壤水分,而低密度刺槐林地土壤水分经降雨补给可恢复到较高的水平。总体来看,研究区低密度刺槐林地土壤水分状况较好,建议研究区刺槐林种植密度以不超过1 400株/hm2为宜。     

黄土高原不同林龄刺槐林土壤水分亏缺程度

通过定点监测刺槐林土壤水分含量,探究不同林龄刺槐林土壤水分分布与亏缺程度。采用空间代替时间的研究方法,选择10,15,25,40年人工刺槐林为研究对象,农地(0年)为对照,调查分析0—200 cm土层土壤水分分布情况。结果表明：各样地平均土壤含水量大小顺序为农地(18.80%)>10年刺槐林(16.43%)>15年刺槐林(15.47%)>40年刺槐林(13.87%)>25年刺槐林(13.38%);不同林龄刺槐林土壤水分均处于亏缺状态,随着林龄增加,土壤水分亏缺呈增大趋势,平均土壤水分亏缺程度为19.38%,25年刺槐林土壤水分亏缺程度最大(27.76%),40年时略有恢复(25.80%);表层土壤水分变异程度最大,变异程度随林龄增加呈增大趋势,速变层、活跃层、次活跃层和相对稳定层4个层次只在40年刺槐林均有出现。研究结果可为黄土高原植被生态恢复和科学经营人工林提供一定的理论基础。     

黄土高原沟壑区人工刺槐林的建设、更新与演替

通过对王东沟小流域人工刺槐林生产现状、更新和演替过程进行分析,提出黄土高原沟壑区林草植被建设中应把人工刺槐林的培育与更新结合起来,通过皆伐萌蘖、择优间伐等措施进行人工刺槐林的更新;应根据二代刺槐林的生长和对水分的利用情况,对刺槐林进行合理采伐利用,不宜培育第三代刺槐林;应尽量保留草本和灌木植物,使之先被天然草本群落代替,继续发挥植被防止土壤侵蚀的作用,改善生态环境.     

黄河三角洲退化人工刺槐林地土壤特征

 黄河三角洲大面积人工刺槐林出现了衰退现象,表现为树木梢头出现不同程度的枯稍。为了揭示该地区刺槐林衰退的原因,对不同退化程度刺槐林的土壤特征进行研究。结果表明:随着刺槐林退化程度的增加,土壤密度(全层)逐渐增大,土壤多项养分指标有不同程度的下降趋势,土壤含盐量随退化程度的加重逐渐增大;在不同退化程度的刺槐林分中,基本趋势是随着退化程度的加重,脲酶、多酚氧化酶、过氧化氢酶和过氧化物酶的活性呈现降低的趋势;不同退化程度刺槐林的土壤中微生物总量随退化程度的加重而减少。     

刺槐萌生林与实生林的生长比较

刺槐是我国重要用材树种和生态公益林树种。针对刺槐萌生林生长状况出现下降等问题,在山东省沂山林场(E 118°36’,N 36°10’)和泰山药乡林场(E 117°19,N 36°17’),选取具有代表性的刺槐实生一代林和萌生二代林林分为研究对象,对林分结构特征、立木生长进程、干形等因子进行调查分析。结果表明:1)刺槐萌生二代林树高在前22年、材积总生长量和材积平均生长量在前17年、材积连年生长量在前14年均大于实生一代林,但随后各个指标生长量均小于实生一代林。2)刺槐实生一代林树干通直,而刺槐萌生二代林绝大部分树干弯曲,难以成材。3)提出用树干弯曲指数描述干形弯曲程度,并根据干形弯曲指数大小,将刺槐萌生二代林立木干形弯曲程度划分为无弯曲、极小弯曲、轻度弯曲、中度弯曲、重度弯曲5级。发现,刺槐萌生二代林中,树干中度和重度弯曲林木约占整个刺槐林的34.8%;树干无弯曲的树木极少,只占0.86%;树干极小弯曲的树木占33.8%。通过分析讨论刺槐连续无性更新林分生长迟缓、干形不良、不能成材成林的原因,认为刺槐无性更新问题是一个值得引起关注和研究的重要问题。     

Decomposition of black locust and black pine leaf litter in two coeval forest stands on Mount Vesuvius and dynamics of organic components assessed through proximate analysis and NMR spectroscopy

Litter quality is an important determinant of soil organic matter formation. Changes of organic components were investigated along decomposition of black locust (Robinia pseudoacacia L.) leaf litter and black pine (Pinus nigra Arn.) needle litter in the native adjacent coeval forest stands. To this purpose, data from proximate analyses were compared with those from CPMAS ¹³C NMR. Newly shed leaf litter of black locust had significantly higher concentrations of ADSS (acid detergent soluble substances) as well as lower concentrations of cellulose and AUR (acid unhydrolyzable residues that include lignin) and higher AUR-to-Cellulose ratio than that of black pine. The ¹³C CPMAS NMR spectra of newly shed leaf litter of black locust and black pine revealed that O-Alkyl-C components (including cellulose and hemicelluloses) accounted, respectively, for 53.8% and 61.4% of the total area of the spectra. All other C fractions were relatively more abundant in black locust than in black pine. Within individual sampling periods, relationships between residual litter mass and concentrations of ADSS, cellulose and AUR were examined, as were relationships between residual litter C and NMR fractions. Four periods were defined based on the slopes of the decomposition curve, with the length of period I defined by the start of a net decrease of AUR. Proximate analyses and NMR data showed changes in chemical composition over the decomposition process, as well as changes in decay rates of the residues, following different paths in the two litters. ADSS decayed faster in black locust litter; in contrast cellulose and AUR decayed faster in that of black pine. AUR concentration increased in both litters during decomposition; however, compared to black pine, the remaining litter of black locust was richer in AUR, despite the lower initial concentration, and had a higher AUR-to-Cellulose ratio. Phenol-C and Aryl-C decayed faster in black locust litter, while Alkyl-C decayed faster in that of black pine. In both litters, mass loss in periods was negatively correlated to concentration of AUR at the start of the periods. C loss in periods was negatively correlated to the concentration at the start of the periods of MC-to-PC (an index of lignin content) in black locust litter and positively correlated to Alkyl-C and O-Alkyl-C in that of black pine. Phenol-C, O-Alkyl-C and Aryl-C were the most decomposable C fractions in black locust. O-Alkyl-C and Alkyl-C were the most decomposable C fractions in black pine. Limit value was lower in black pine than in black locust. Consequently the different pattern of litter decomposition can affect the size of C sequestration in the forest floor and the quality of accumulated organic carbon.     

窟野河、秃尾河、孤山川流域主要水土保持树种造林密度的探讨

通过对窟野河、秃尾河、孤山川流域主要乔、灌木水土保持林的随机抽样调查分析,建立了林分保存密度与郁闭度的相关模型,并以此模型为基础,结合当地水保林经营现状,提出该地区刺槐、柠条、沙柳、踏郎和花棒的造林密度(株或丛/hm~2)分别以2571、4000、2400、3000和3000较为合理。这样的造林密度,在该地区既有较好的水土保持效益,又有较高的经济效益。     

基于模糊模式的蝗虫图像识别方法

蝗灾是中国农业病虫害防治的重点,采用低空机载蝗虫预警系统技术,对拍摄图像中蝗虫识别和计数,实现蝗虫监测,可以弥补蝗虫地面人工监测的不足。以广东省清远市英德区域农田为试验区,采用数码相机采集蝗虫图像,对蝗虫区域和背景的RGB分量平均值进行对比分析,选用超G绝对值法进行灰度转换,实现蝗虫与背景分离。通过面积统计对比,确定单个蝗虫的面积和周长特征,建立单个蝗虫模糊集和粘连重叠蝗虫区域模糊集,采用最大隶属度原则可以判定蝗虫连通区域为单个蝗虫或是存在图像粘连重叠。用模糊识别方法对单个和粘连重叠的区域分别计算数量,准     

黄河三角洲不同刺槐混交林的土壤持水能力

在黄河三角洲盐碱地,以无林地作为对照,调查刺槐臭椿混交林、刺槐白榆混交林、刺槐白蜡混交林、刺槐纯林4种林分不同土壤层的盐碱度、容重和孔隙度、枯落物层和土壤持水能力等指标。结果表明:(1)除刺槐白蜡混交林土壤表层有一定的返盐现象外,其余林分均具有一定的压盐抑盐效果,且pH值多随土壤深度的增加而升高;(2)不同混交林的枯落物层总蓄积量范围为2.03～12.15t/hm2,半分解层大于未分解层,表现出造林地显著高于无林地,但是刺槐混交林略小于刺槐纯林;(3)不同林分的枯落物最大持水量与其蓄积量的趋势基本一致,在3.79～19.59t/hm2之间,有效持水量在2.74～13.48t/hm2之间,二者的变化趋势并不完全一致;(4)与无林地相比,林地的土壤容重显著减小,而土壤孔隙度增加,其中混交林好于纯林,其土壤饱和蓄水量、毛管蓄水量从大到小依次为刺槐白蜡混交林、刺槐白榆混交林、刺槐臭椿混交林、刺槐纯林、无林地。因此,为发挥刺槐在黄河三角洲盐碱地的改良土壤、涵养水源等方面的作用,建议营造混交林。     

基于遥感的新疆蝗虫灾害渐进式修正预测方法

蝗灾是新疆的主要生物灾害之一,对新疆农牧业生产造成严重威胁。该文利用遥感技术在新疆范围内对蝗灾风险进行预测,以期为治蝗部门及早采取生物、化学治蝗措施提供参考。该文基于蝗虫种群发育的产卵、孵化与生长3个重要阶段,利用MODIS数据定量反演影响蝗虫种群发育的关键生境因子,进而提出一种基于卫星遥感的渐进式草原蝗灾风险评估模型,并以2010年与2014年为实例,对新疆地区草原蝗灾风险进行了预测与评估:野外实测得到的蝗灾严重程度分级和模型预测的风险等级完全一致的样本点占74.4%,误差在一个等级以内的样本点占94.9%。结果表明,该文所提出的渐进式蝗灾风险预测模型能较好地反映温度、植被、土壤、水分等关键生态因子对蝗虫种群发育的影响,避免了一次性预测的不准确,预测结果与历史灾情数据和地面实测数据一致性较好。该模型可用于新疆治蝗部门对蝗灾的早期预警,以增强防灾减灾的能力。     

晋西黄土区刺槐林种植密度对植被生长状况的影响

通过对山西省方山县土桥沟流域刺槐人工林植被生长指标的比较研究,分析了不同密度刺槐人工林的生长状况,以期为该区刺槐人工林的经营管理提供理论依据和技术支持.研究结果表明,同是林龄为20 a的刺槐人工林,高密度林分内林木的树高、冠幅等生长指标值,均比低密度林分内的低,但郁闭度要比低密度林分高;密度大的林分胸径普遍较小,随着林分密度的降低,胸径逐渐增大.刺槐林下灌木层和草本层植被的平均高度、盖度、生物量、物种丰富度都随着林分密度的降低而升高;各林分林下植被层的含水量也存在着随林分密度的降低而升高的趋势.从人工林的生长状况来看,晋西半干旱黄土丘陵沟壑区刺槐人工林的适宜密度为1667株/hm2.     

Catabolic and genetic microbial indices,and levels of nitrate,ammonium and organic carbon in soil from the black locust (<Emphasis Type="Italic"> Robinia pseudo-acacia</Emphasis>) and tulip poplar (<Emphasis Type="Italic"> Liriodendron tulipifera</Emphasis>) trees in a Pennsylvania forest

Soil samples were collected from the upper soil horizon within 4 m of black locust ( Robinia pseudo-acacia) and tulip poplar trees ( Liriodendron tulipifera) from the same mixed forest in south-central Pennsylvania. The soil samples were analyzed for organic C levels, pH, NO₃ ^-, NH₄ ⁺, catabolic diversity (Shannon diversity index; catabolic H), catabolic evenness (Simpson-Yule index; catabolic E), genetic H, and genetic E. The catabolic H and genetic H of microbes in these soils were found to correlate well with the levels of mineralized N, organic C, and pH. Significant variations in these parameters were found between the soils from near black locust and tulip poplar trees. Conditions in the soil near the black locust trees were more favorable to nitrification as indicated by the elevated pH, organic C, NO₃ ^-, and total mineral N levels, along with lower NH₄ ⁺ levels. The microbial genetic H and E were greater and the catabolic H and E were lower in the black locust soils than in the tulip poplar soils. This suggests that a more specialized environment exists in the soil near the black locust trees which selects for enhanced nitrification and the use of fewer, but preferred catabolic pathways by a more genetically diverse group of microbes that grow to a greater biomass. Conversely, the soils from near the tulip poplar trees are such that they do not select for some dominant catabolic pathways, rather they allow for the use of a greater variety of catabolic pathways by a less diverse microbial population, which appear to grow to a lower biomass. We believe that the combined application of the microbial genetic and catabolic diversity analyses, microbial biomass estimates, and traditional physico-chemical characteristics in soil studies provides information not easily available that can be useful during assessment of soil processes in different terrestrial habitats.     

Effect of Hydrophilic Gums on Frozen Dough. I. Dough Quality

Disadvantages of frozen doughs are their variable performance and loss of stability over long‐term frozen storage. Changes in rheological properties of frozen doughs have been reported to be due to the physical damage of the gluten network caused by ice crystallization and recrystallization. The objective of this study was to determine the effect of hydrophilic gums on ice crystallization and recrystallization for improvement of the shelf‐life stability of frozen dough. The present research involved use of the Hard Red Spring wheat cultivar Grandin and hydrophilic gums such as carboxymethyl cellulose (CMC), gum arabic, kappa carrageenan (κ‐carrageenan), and locust bean gum at three different levels each on doughs stored frozen for up to 16 weeks. The dough characteristics were analyzed after day 0, day 1, and after 4, 8, 12, and 16 weeks of frozen storage using data from differential scanning calorimetry (DSC), water activity, extensigraph, and proof time. The ΔH value of freezable water endothermic transitions obtained using DSC increased with storage time for all treatments. However, addition of different levels of the four gums lowered the ΔH value, indicating a decrease in freezable water. Doughs with locust bean gum gave a higher peak force, measured using the Kieffer dough extensibility rig of the texture analyzer, and lower proof time, indicating better retention of baking quality. Maximum resistance to extension increased upon addition of 1 and 3%; CMC; 1 and 3%; κ‐carrageenan; and 1, 2, and 3% locust bean gum as compared with the control. The various periods of storage or gum treatments did not affect the water activity of the thawed frozen doughs. Doughs with locust bean gum gave significantly lower proof time compared with the other treatments and the control. CMC gave the second lowest values, followed by gum arabic treatment. Addition of κ‐carrageenan increased the proof time compared with the control. In summary, locust bean gum, gum arabic, and CMC improved the dough characteristics to varying degrees. κ‐Carrageenan was the only gum that showed a detrimental effect on frozen dough.     

河北省夏蝗大发生的气象预报

分析影响夏蝗大发生的关键气象因子,预报夏蝗的发生程度,对夏蝗防治决策起着十分重要的作用.利用秩相关系数法,筛选出影响河北省洼淀和沿海两个类型区夏蝗大发生的关键气象因子.根据贝叶斯判别准则,确定了两类蝗区夏蝗大发生关键气象因子的最佳临界距平值;利用灾变规律的关键时预报方法,对两个蝗区因子数确定的关键年进行敏感性分析,确定了两个类型蝗区最佳的预报因子数.在此基础上,对河北省不同生态类型区夏蝗大发生进行模拟和预报,结果拟合率达到99%以上,2004和2005年延伸预报结果与实际一致.     

气扰刺激与波谱光源耦合作用下蝗虫的诱导捕集试验

灾害蝗虫光电诱导捕集技术中,致使蝗虫产生良好趋光效率的诱导光源是获取该技术高效应用的关键。为给诱导光源的研制提供最优设计参数,利用自行设计的发光二极管(light emitting diode,LED)阵列波谱光源与光电诱导蝗虫滑移捕集机分别进行了蝗虫趋光行为的对比试验和诱导捕集试验。结果表明:与其他诱导光源相比较,蓝色(465 nm)波谱光源和白色(395~720 nm)波谱光源均能促使蝗虫产生较为明确的趋向选择行为且具有相对较高的趋向运动速度,最终诱使较多的蝗虫集聚于诱导光源区域;气扰刺激能够激发处于栖息状态蝗虫的生理活性,促使蝗虫对波谱光源产生较强的趋向行为并表现出较高的趋向运动速度。气扰刺激与波谱光源的耦合作用可使蝗虫的趋光行为同时具有明确的方向选择性、较强的趋向运动持续性和较高的趋向运动速度,能够显著提高波谱光源对灾害蝗虫的诱导率,并能提高光电诱导蝗虫滑移捕集机对灾害蝗虫的捕集效率和捕集总量。研究结果为光电诱导蝗虫捕集技术中诱导光源的研制提供了设计参数方面的参考。