枫香半同胞家系早期选择的研究

为筛选适应湖北及相似环境条件生长的枫香优良家系,以132个枫香半同胞家系为实验材料,以7年生的胸径、树高、冠幅、分枝角度等为指标进行综合评价。发现枫香半同胞家系间差异较大,材积、胸径、树高、冠幅、分枝角度受中度的遗传控制。表明枫香半同胞家系可以进行优良家系选择,通过筛选得到43个生长表现较好的优良家系。     

42个牡丹品种叶部抗病性选育试验

为选择适应宜昌市丘陵岗地栽培的观赏牡丹品种,探索合适的栽培措施,从山东菏泽引进了42个观赏牡丹品种。采取搭棚和根部覆膜两种不同栽培措施,以无覆盖露天栽培措施作为对照,在7、8、9月分别调查牡丹叶部感病程度,并对牡丹不同品种间、不同栽培措施间、不同月份间的病情指数进行方差分析。牡丹不同品种间、不同栽培措施间、不同月份间抗病性均有显著性差异,其中"岛锦"等18个牡丹品种抗病性良好;采取搭棚栽培措施能显著降低牡丹叶部感病程度;随着高温高湿天气持续,牡丹叶部病害由轻到重不断发展。     

几种宿根花卉抗寒性研究

以重瓣金鸡菊、黑心菊等8种宿根花卉为试验对象,利用电导率法测定抗寒性,同时以可溶性蛋白质和脯氨酸含量的变化为辅助依据,从生理方面解释8种宿根花卉抗寒性的强弱。结果表明,随着低温胁迫温度逐渐降低,各品种花卉的细胞膜透性均逐渐升高,而不同品种之间增加的幅度有明显差异。通过运用隶属函数法结合植物体内可溶性蛋白质和脯氨酸含量的变化算出8种宿根花卉抗寒性顺序为:重瓣金鸡菊黑心菊飞燕草宿根福禄考射干肥皂草堆心菊地被菊。     

松沫蝉若虫药剂防治试验

以辽宁章古台地区樟子松人工林松沫蝉(Aphrophora flavipes Uhler)若虫为对象,采用人工喷洒乙酰甲胺磷、氟氯氰菊酯、毒死蜱、丙溴辛硫磷等4种化学药剂进行该虫防治试验。结果表明:氟氯氰菊酯5.7%水乳剂1500倍液防治效果最佳。     

辽河三角洲盐碱地覆膜措施对土壤物理性质的影响

采用覆膜措施在辽河三角洲腹地原地土壤修筑台田造林试验,结果表明:覆盖地膜能有效改善土壤理化性状,提高土壤孔隙度,降低土壤容重,改善土壤通透性,提高土壤养分含量,覆膜措施使小胡杨保存率高达92%,增加了0~40cm土层的孔隙度,提高了0~60cm土层的最大持水量,为小胡杨树木生长提供了良好的立地条件。     

张广才岭不同类型林分碳密度分布规律研究

采用干烧法对张广才岭7个主要林型的碳密度分布规律进行了研究。结果表明:五角槭林碳密度为83.015t hm~(-2),三大硬阔林为117.563t hm~(-2),榆树林为124.853t hm~(-2),蒙古栎林为179.323t hm~(-2),落叶松林为95.803t hm~(-2),白桦林为153.354t hm~(-2),椴树林为139.322t hm~(-2);林分的平均碳密度是126.346t hm~(-2),在平均碳密度中,乔木层占97.6%,凋落物层占2%,林下植被层占0.6%。     

祁连山排露沟流域青海云杉林生物量和净生产力研究

选择祁连山排露沟流域青海云杉林为研究对象,按海拔、坡向、坡度、坡位等设置青海云杉林固定样地共10块,开展青海云杉林生物量和净生产力研究。结果表明:青海云杉林乔木层平均生物量分别为116.19t hm~(-2),平均净生产力为1.36t hm~(-2)a~(-1)。海拔2 800m段是青海云杉林生长的最佳地段,生物量和年净生产力均为最大;从海拔2 800m开始,随着海拔梯度的增加,生物量和净生产力呈降低趋势;海拔3 300m林线处,生物量和净生产力达到最低。青海云杉林生物量及净生产力与林分树高和林龄显著相关(P0.05),与胸径相关性不显著(P0.05)。     

Studies on pre-treatment by compression for wood drying III: the reduction of moisture content,the recovery rate,and mechanical properties of wood compressed at different moisture content conditions

As a follow-up report, the pre-treatment by compression for wood drying was systematically studied in terms of the reduction of moisture content (MC), the recovery rate (RR), and mechanical properties of wood compressed at different MC conditions. The results showed that MC after compression on water-saturated wood determined the critical value of MC before compression which were about 84 and 105% at a compression ratio of 60 and 40% for Poplar and Chinese fir, respectively. Beyond the critical value, MC after compression remained constantly at about 84% and decreased slightly from 105% for Poplar and Chinese fir, respectively. The MC reduction decreased with the decrease of MC before compression. The MC reduction was rather effective when the MC before compression was higher than the critical value and was recommended to pre-treat for the effectiveness of MC reduction. In addition, after the recovery, the wood volume and mechanical properties were well retained for the wood compressed at all MC conditions which were above fiber saturation point (FSP) before and after compression. Therefore, the pre-treatment by compression is viable in terms of the RR and mechanical properties at rather broad MC conditions above FSP. Moreover, the compression force needed for treatment was almost same at these MC conditions.     

Soil aggregate characteristics and stability of soil carbon stocks in a <Emphasis Type="Italic">Pinus tabulaeformis</Emphasis> plantation

Pinus tabulaeformis has been widely planted in order to conserve soil and water and improve the ecological environment in China. This study aimed to unravel how soil aggregates and soil carbon (C) stock stability of a P. tabulaeformis plantation change after 60 years of natural development and was performed in Vitex negundo var. heterophylla and Ziziphus jujuba var. spinosa shrub (shrub), a P. tabulaeformis forest (pine), and a coniferous broadleaf P. tabulaeformis mixed forest (pine-oak). Afforestation increased the stability of soil aggregates in the 0–10 cm soil layer but resulted in a decrease in the 10–20 cm soil layer. However, the presence of deciduous broadleaf species in the pine plantation improved the stability of soil aggregates. The total soil C stock was increased by afforestation, especially in the pine-oak forest, where it reached a significant level. The mineral soil C stock in the shrub stand was higher than that in pine and lower than that in pine-oak forests, but the C fractions had a different change. Afforestation increased the C fraction of macroaggregates in the 0–10 cm soil layer but decreased it in the 10–20 cm soil layer. This result suggested that afforestation could improve soil C stabilization in deeper soil. However, the pine-oak forest had a higher C fraction of macroaggregates than the pine forest in the 10–20 cm soil layer, indicating that soil C stabilization of the P. tabulaeformis plantation decreased when deciduous broadleaf species were present and thus formed the coniferous broadleaf mixed forest.     

Separating component parts of soil respiration under <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> plantation in the Taihang Mountains,China

Partitioning the respiratory components of soil surface CO₂ efflux is important in understanding carbon turnover and in identifying the soil carbon sink/source function in response to land-use change. The sensitivities of soil respiration components on changing climate patterns are currently not fully understood. We used trench and isotopic methods to separate total soil respiration into autotrophic (R _A ) and heterotrophic components (R _H ). This study was undertaken on a Robinia pseudoacacia L. plantation in the southern Taihang Mountains, China. The fractionation of soil ¹³CO₂ was analyzed by comparing the δ¹³C of soil CO₂ extracted from buried steel tubes with results from Gas Vapor Probe Kits at a depth of 50 cm at the preliminary test (2.03‰). The results showed that the contribution of autotrophic respiration (fR _A ) increased with increasing soil depth. The contribution of heterotrophic respiration (fR _H ) declined with increasing soil depth. The contribution of autotrophic respiration was similar whether estimated by the trench method (fR _A , 23.50%) or by the isotopic method in which a difference in value of ¹³C between soil and plant prevailed in the natural state (RC, 21.03%). The experimental error produced by the trench method was insignificant as compared with that produced by the isotopic method, providing a technical basis for further investigations.