紫色土桤柏混交模式研究

桤柏混交林是紫色土的主要人工混交类型,在长江防护林建设中有重要作用。根据1983年营造的8种混交模式林分,研究了桤柏混交改良土壤、促进柏木生长的效果,用模糊综合评判方法,提出了不同立地类型的混交模式。     

绵阳新桥镇防护林体系桤柏混交林光合作用日变化研究

本文利用美国产ＬＩ—６２００便携式光合作用分析系统、ＬＩ—３０００叶面积仪配合照度计、通风干湿球温湿度计、土壤湿度计等测定了绵阳新桥防护林体系生长季节中桤柏混交林树种南、北面叶片光合作用每小时日变化进程，探讨了桤木和柏木光合作用率及其变动程度，指出了它们的光合作用日变化类型，从日射量、温度、ＣＯ２浓度等外界条件及内生节奏方面阐述了光合作用日变化机理，同时计算和分析了桤柏混交林平均光合作用率日变化类型和量子产额。结果表明桤木光合作用日变化为中午降低型，柏木为正规型曲线，桤木上午光合作用率高于下午，柏木为上午低于下午，它们都具有较高的量子产额，其光合作用日变化不存在着时间效应，为防护林功能研究提供依据。     

绵阳新桥镇防护林系桤柏混交林光合作用日变化研究

本文利用美国产ＬＩ－６２００便携式光合作用分析系统，ＬＩ－３０００叶面积仪配合照度计，通风干湿球温湿度计，土壤湿度计等测定了绵阳新桥防护林体系生长季节中桤柏混交林树种南，北面叶片光合作用每小时日变化进程，探讨了桤木和柏木光合作用率及其变动程度，指出了穴们的光合作用日变化类型，从日射量，温度，ＣＯ２浓度等外界条件及内生节奏方面阐述了光合作用日变化机理，同时计算和分析了桤柏混交林平均光合作用率日变化类     

桤柏混交幼林群落特征及生物量调查

桤柏混交林是川中盆地钙质紫色土区主要造林模式之一。因其群落稳定、生产力高,深受群众喜爱。对7年生桤柏混交林进行群落特征及生物量调查的结果表明:7年生桤柏人工幼林已郁闭成林,形成复层林冠层,垂直结构明显;桤木高4.37m,覆盖度32％;柏木高1.19m,覆盖度30％;草被均高0.5m,覆盖度95％;桤木根深30cm,柏木根深15cm。桤柏混交林群落植物种类为18种,总生物量14.794t/ha。纯柏林群落植物种类7种,总生物量3.583t/ha。柏木根系侧根发达,主根不明显.<0.2cm根量占总根量的23.1％。桤木根系主根明显,垂直根系发达,水平根少、<0.2cm根量占总根量的3.4％。桤柏混交幼林群落植物体内含水量与总生物量大致相等。乔木层各器官水分系数排序为:叶>枝 根>干。     

诺丽的光合生理特性研究

为了解诺丽的光合生理特性及为其丰产栽培提供科学依据,应用LI-6400便携式光合作用测定仪对诺丽的光合生理特性进行观测,分析与诺丽光合参数相关的环境因子日变化及光合生理特征的日变化,计算诺丽光能利用效率和水分利用效率。结果表明:诺丽Pn日变化呈双峰曲线,具有明显的"光合午休"特征;影响诺丽Pn日变化的主要生理因子是气孔导度和胞间CO_2浓度,主要生态因子是光合有效辐射;诺丽光能利用效率呈"V"型,早上8:00-10:00点最高,达到0.022%。诺丽水分利用效率早上8:00点左右最高,达到2.039μmol/mmol。     

四川盆地丘陵区主要森林群落结构特征研究

本文对四川盆地丘陵区主要森林群落--人工柏木纯林、次生栎柏混交林和桤柏混交林的群落结构特征进行了研究.结果表明：在群落的物种组成、生活型、层片结构以及Shannon-Wiener多样性指数、Pielou均匀度指数和Simpson生态优势度指数表征的群落综合特征上,次生混交林与人工林具有很大差异.人工柏木纯林物种数量少,乔、灌、草层的物种多样性和均匀度较低,生态优势度较高;次生栎柏混交林和桤柏混交林物种数量较多,乔、灌、草层有较高的物种多样性和均匀度,较低的生态优势度.     

柏木混交林类型分布立地条件的研究

本项研究应用主成分排序方法研究四川盆地4种天然柏木混交林分布与立地条件的关系,结果表明:区域内影响柏木混交林类型分布的主导立地因子是地形、土层厚度、水湿状况、土壤碳酸钙含量、pH值等。桤柏混交林主要分布在山中下部平缓的台阶低洼地带,水湿条件较好,土层深厚的地方;栎柏混交林主要分布在山中上部干燥瘠薄的立地上,生产力低;桤栎柏混交林介于二者之间;松柏混交林要求土壤中碳酸钙含量低,土壤呈微酸性至中性反应。林下灌木树种分布与立地条件因子无明显规律性。     

格木光合日变化及生理生态因子对光合作用的影响

对格木（Erythrophleum fordii）1年生营养杯苗的叶片光合作用和环境因子动态变化进行了测定,探索格木苗木光合日变化规律,分析光合作用与生理生态因子间的相互关系及影响光合作用的主要决策因子。结果表明：净光合速率（Pn）日变化呈现＂双峰＂曲线,有明显的光合＂午休＂现象;叶片温度（Tl）、蒸腾速率（Tr）、水汽饱和压亏缺（Vpdl）的日变化与光合有效辐射（PAR）一致,峰值在中午;空气相对湿度（RH）的谷值在中午;气孔导度（Gs）的日变化随时间的变化而变化,全天出现＂三峰＂值,最高峰值在16：00;胞间CO2浓度（Ci）的日变化呈＂双峰＂曲线;水分利用效率（WUE）、光能利用率（LUE）的日变化呈明显＂U＂型。影响格木苗木Pn的生理生态因子主要有PAR、Ca（大气CO2浓度）、Ta（空气温度）、RH、Gs、Tr、Tl和Vpdl,其中PAR、Ca、Tl和Vpdl为影响Pn日变化程度最高的因子,PAR为主要决策因素,Tl为主要限制性因素。由此可见,格木的光合日变化有一定的规律,同时生理生态因子对光合作用的影响及影响程度也各不相同。     

马尾松老头林混交杨梅后叶绿素含量和光合特性分析

通过比较分析紫色土侵蚀区马尾松老头林混交杨梅后混交树种的生长状况、叶绿素含量及光合特性的差异,试图揭示混交的营林模式对混交树种生理生态的影响。结果表明：马尾松老头林混交杨梅后,马尾松的胸径和树高分别增加45.55%和35.90%,其叶片叶绿素 a、b 和叶绿素 a+b 表现为略有增加,而叶绿素 a/b 比值从2.246减少到2.181;马尾松老头林混交杨梅后,马尾松的最大净光合速率和量子效率均表现为显著增加,光的补偿点表现为略为减少,而光的饱和点表现为略为增加,表明混交杨梅后增强了马尾松的光合能力。     

杉桤混交林生长效果与林分小气候特征研究

对桤木纯林及其与杉木混交林进行造林试验 ,研究了 6年生杉桤混交林的生长效果及林分小气候特征 ,结果表明 :杉桤 (2 :1)行间混交种间关系协调 ,能充分利用营养空间 ,具有改善林分生态环境条件、明显提高林分生产力和材质等效果 ,经济、生态、社会效益显著 ,是种理想的混交组合 ,应用前景广阔     

桤柏混交林能量代谢中能量吸收,固定,积累和损耗研究

本文通过桤柏混交林气体交换测定研究了能量代谢基本过程。结果表明：桤柏混交林吸收的太阳辐射能大部分损耗子蒸腾作用中，桤木和柏木用于生长呼吸中损耗的能量最多．其中桤木南面时则用于维持呼吸中损耗能量最多，其能量固定建立在内部节律基础上，柏木能量积累大于桤木．     

桤柏混交林的效益探讨

桤柏混交林是川中丘陵区的主要造林类型。本文对不同年龄阶段的桤柏混交林进行了对比研究。结果表明：２６年生的混交林中其柏木在单位面积上的蓄积最比纯柏木林大８０．６％，地上中分生物量比纯林高４７．２％；混交林柏木的Ｎ，Ｐ，Ｋ，Ｃａ等营养元素含量分别 比纯柏林高６５．４７％，５０．４３％，７．７０％和１７．９６％；混交林内空气相对湿度比纯柏木林大９．４－１０．５％，混交林能改善生态环境，提高土壤肥力。     

Linear programming approach for optimal forest plantation

The aim of this research was to identify species suitable for plantation. We first identified species for potentially suitable for plantation based on ecological capabilities regarding soil properties. We determined the area of plantation for different species based on ecological capabilities. Then, we collected relevant data such as growth patterns of different species, labor requirements for plantation and plantation cost. A linear programming model and two integer linear programming models were used for optimization. The appropriate species based on ecological capabilities were ash, elm, maple, oak and bald cypress. A linear programming model was used based on ecological capabilities classification to determine the land area of different species for plantation. Then, two integer linear programming models were employed to select the species for plantation. We set ecological properties unequal for all of the species in the first run of the integer programming model. Two groups were classified: group one included maple and ash; group two included bald cypress, oak and elm. The second integer programming model assumed equal ecological properties for all the species. Results of linear programming showed that maple and bald cypress were appropriate for plantation at the site and their plantation areas should be 151.3 and 355.3 ha, respectively. Results of the first integer linear programming model showed that maple and bald cypress would be economically profitable for plantation. The results of the second integer linear programming model showed that only bald cypress would be appropriate for plantation.     

Effects of root zone trenching on soil nitrogen dynamics in Japanese cedar and cypress plantations

The effects of root exclusion and planted tree species on soil nitrogen (N) dynamics were examined at two plantations, one planted with Japanese cedar and the other with Japanese cypress. We set up ten 1 × 1 × 0.2-m-deep trenched sites and ten untrenched control sites at each plantation. We measured the pool size and leaching of inorganic N at each site for 2 years and the net N mineralization 1 and 2 years after trenching. Despite similar soil conditions, the cedar plantation showed higher net N mineralization than the cypress plantation. Stopped tree uptake of N was expected to cause an increased pool size and leaching of inorganic N at the trenched sites. Nevertheless, we found no significant increase in those variables at both plantations. The trenched cypress sites showed no decrease in the net N mineralization during the 2 years after trenching. However, the net nitrification at the trenched cypress sites increased remarkably at the deeper horizons in comparison with that at the control sites. Enhanced nitrification might result from improved ammonium availability through root exclusion. Net N mineralization at the trenched cedar sites decreased more than 60% compared with that at the control sites 2 years after trenching. Higher nitrification potential at the cedar plantation and enhanced nitrification potential at the trenched cypress sites never resulted in increased leaching of N, due to added fine root litter which acted as an immobilization agent for excess N, thus preventing N loss.     

Productivity of European black alder (Alnus glutinosa) interplanted with black walnut (Juglans nigra) in illinois,U.S.A.

Fast-growing woody nurse crops planted among high value hardwoods can produce merchantable biomass early in the life of the plantation. On a productive site in south-central Illinois (U.S.A.), experimental interplantings of European black alder (Alnus glutinosa (L.) Gaertn.) and black walnut (Juglans nigra L.) were established and maintained under a factorial combination of two initial densities and two thinning regimes. This study evaluated the growth response of the alder component of this system. Although alder consistently overtopped walnut, alder mortality began to increase dramatically during the seventh growing season and was nearly complete following the nineteenth growing season. Mean alder cumulative dry mass through year 14 ranged from 19.05 to 58.62 Mg/ha among initial density and thinning treatments. Carbon sequestered in useable bolewood constituted approximately 25 of total biomass. The productivity of the interplanted alder was comparable to that of native forests while constituting only a portion of the stand and without negatively impacting walnut growth or bole quality. These results suggest that, if marketed, alder has the potential to partially offset costs associated with walnut plantation establishment and maintenance.     

米老排林下黄藤的生长表现和光合特征

米老排林下种植6年的黄藤主茎长为0．28±0．04m,产生萌茎的植株占48％,平均拥有萌茎1．3±0．2条,远远低于相邻间伐50％的马尾松林下的黄藤;黄藤植株晴天全天得到的有效光合辐射和相应的净光合速率最高为0．6μmol·m^-1·s^-1和0．05μmolCO2·in^-1·s^-1,远远低于空旷地上的1539μmol·m^-1·s^-1和3．11μmolCO2·m^-2·s^-1,表明米老排林下黄藤生长缓慢,可能与其得到的有效光合辐射较低有关,若在米老林下间种黄藤需进行间伐以增加透光。     

Ecophysiological characteristics of Taiwan alder (Alnus formosana) seedlings adapted to the subtropical region

We investigated several ecophysiological characteristics of seedlings of a low-elevation (100-200 m) and a high-elevation (2000-2400 m) population of Taiwan alder (Alnus formosana Makino) from subtropical Taiwan. Both populations had a wide optimal temperature range for photosynthesis, and there was little difference in the optimal temperature range for photosynthesis between populations. Photosynthetic rate (P(N)) was near maximal from 20 to 35 degrees C when seedlings of both the low-elevation and the high-elevation populations were acclimated at a day/night temperature of 30/23 degrees C. When seedlings were acclimated at a day/night temperature of 20/10 degrees C, P(N) was near maximal over the range 15-35 degrees C in the low-elevation population and 15-30 degrees C in the high-elevation population. Compared with nine other tree species native to Taiwan, Taiwan alder had a high P(N) and stomatal conductance (g(s)) under well-watered conditions. Reflecting its higher transpiration rate, Taiwan alder had a significantly greater leaf-air temperature difference than camphor (Cinnamomum camphora (L.) J. Presl), a co-occurring lowland tree species with leaves similar in shape and size to those of Taiwan alder. Despite higher g(s), high root and shoot hydraulic conductances enabled Taiwan alder to maintain higher leaf water potentials than camphor under well-watered conditions. We conclude that both photosynthetic characteristics and water relations are important factors enabling Taiwan alder to adapt to a wide temperature range, thereby ensuring its success at both high and low elevations in subtropical Taiwan.     

Comparison of two coniferous plantations in central Japan with respect to forest productivity, growth phenology and soil nitrogen dynamics

Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) are common species for plantation forestry in Japan. Cypress is conventionally planted on sites of low fertility whereas for cedar high fertility sites are used. Objectives of this study were to compare the productivities of cypress and cedar plantations grown on adjacent sites where common properties of soils, such as pH values and C and N contents, were similar, and to relate the N cycling at their site with productivities. The stem diameter of trees, aboveground litter production and fine root biomass were measured as indices of forest productivity. Parameters of N cycling included pools of total N and mineral N (ammonium + nitrate), annual N leaching, and potentially mineralizable N. The radial stem increment of the two tree species was similar. However, cedar site had higher total basal area and annual basal increment than cypress site reflecting higher tree density on the cedar site. Aboveground litter, fine root biomass, soil organic matter, and N turnover were higher on the cedar site than on the cypress site. However, litter production and fine root biomass per unit basal area was greater at the cypress site. Phenological pattern of stem growth and periodical litter production were similar for both species during the study period (1992–2000), but showed distinct annual variations caused by the fluctuation in the ambient temperature and precipitation. Mineral N content and the N mineralization potential were greater on the cedar site, indicating greater N availability and higher total tree productivity at the cedar site than those at the cypress site. When provided with more space in the canopy to expand more needles and in the soil to develop more fine roots to exploit sufficient resources, the individual cypress trees have the potential to grow faster. On fertile site and at lower tree density, thicker logs of cypress might be yielded.