黑龙江省主要阔叶树种绿枝扦插试验

在带岭林科所落叶松种子园大棚内进行了10个树种、3个采条时期、3种插穗处理和15种基质1350个组合的绿枝扦插试验。结果表明，同一树种的不同采条时期、不同插穗处理、不同基质和不同树种的同一采条时期、同一插穗处理、同一基质的生根效果不同，并有明显的交互作用。各树种最佳组合的生根率：刺五加80％、五味子70％、紫椴40％、花楸30％、水曲柳20％、黄菠萝20％、山槐20％、山梨10％、春榆10％、胡桃楸0。     

干热河谷和干旱山地人工混播造林试验

干热河谷和干旱山地的人工混播造林试验，于１９９１～１９９２年在永胜大龙潭、猫猫山和水平水泄３个造林困难的地区进行。选用车桑子、山毛豆、银合欢、滇合欢、银荆、黑荆等树种进行人工混播造林试验。还分别进行了云南松与车桑子、银荆、黑荆、滇合欢、红木荷、金合欢的混播造林试验。经３、４年的试验，通过对各参试树种的种质评价，落种状况、出苗率、成苗率和各成苗期，苗木生长状况的观测。得出以车桑子、山毛豆、银合欢作为干热河谷和干旱山地的混播造林种较好。可在今后形成多树种，多层次的林分环境。     

沙漠地区飞播沙拐枣种子丸粒化研究

针对飞播种子丸粒化存在的不足,本文选择沙拐枣为研究对象,通过各种原料配比对崩解时间的影响,确定了种子丸粒化的配方。该配方使种子重量增加了4～6倍,不仅解决了种子随风漂移的问题,而且也解决了种子崩解、营养、供水的问题,从而提高了种子的发芽率和成活率。     

观光木播种苗生长规律及育苗技术研究

用有序样本聚类分析法将观光木1年生播种苗生长过程划分为4个时期:出苗期(2月26日-5月20日)、幼苗期(5月21日-7月20日)、速生期(7月21日-10月20日)和生长后期(10月21日-11月20日)。不同播种期的试验表明:冬播观光木比春播提早16 d萌发,苗高、地径生长量和总生物量分别比春播提高13.3%、15.1%和18.8%。采用沙藏可促进种子提早萌发和提高场圃发芽率。不同密度试验表明,观光木育苗采用60株.m-2的密度较好。     

Long-term changes in forest floor processes in southern Appalachian forests

Soil nutrient concentrations decreased in an aggrading southern Appalachian forest over a 20-year period. Construction of nutrient budgets showed significant nutrient sequestration aboveground including increased forest floor mass. We hypothesized that the changes in forest floor mass resulted from decreased litter decomposition rates because of decreased litter quality. In 1992 and 1993, we repeated a litter decomposition experiment conducted in 1969 and 1970 to test this hypothesis. In addition, we examined microarthropod populations and functional groups as litter decomposed. For four of the five species tested, first-year decomposition rates were about the same in both experiments. Initial litter nutrient concentrations of P were lower in all tree species in the most recent sampling. N, Ca, and Mg concentrations also declined in some species. These declines often resulted in decreased nutrient release rates during decomposition. Microarthropod populations differed significantly among litter species, as well as between years (probably resulting from differences in growing-season rainfall). For some litter species we found significant relationships between microarthropod populations and nutrient concentration (primarily C and N); however, most r²-values were low. Data suggest that changes in forest floor mass probably resulted from decreased litter quality and that those changes may have an effect on microarthropod populations.     

杜仲栽培技术

从苗木培育(包括播种育苗、根扦插法育苗和嫁接育苗)及丰产林(包括皮用丰产林和叶用丰产林)的营造、抚育管理、病虫害防治、采收等方面叙述了杜仲的栽培管理技术。     

黄波罗育苗中混雪层积时间及保留密度研究

对辽宁东部山区黄波罗播种育苗的混雪层积时间和保留密度进行了研究。结果表明:随混雪层积时间增加,黄波罗种子发芽率和出苗率呈上升趋势,混雪层积145d的发芽率和出苗率最大,分别达到81.35%、64.59%;1年生幼苗保留密度为100株·m-2时,Ⅰ级苗单位产量达到最高。     

覆土厚度对油松出苗的影响

为了解不同覆土厚度对油松出苗率和出苗指数的影响,进行了油松育苗随机区组试验。结果表明:当播种深度为0.5cm时,出苗率和出苗指数最高;随着覆土厚度的增大,幼苗出苗率也相应降低,当覆土厚度超过2.5cm时,几乎不能出苗。建议生产中油松播种覆土厚度保持在0.5~1.0cm。     

播种时期对蒙古栎不同类型苗木出苗和生长的影响

以蒙古栎种子为材料,研究播种时期对蒙古栎不同类型苗木出苗和生长的影响,结果表明:蒙古栎在秋季不同时间播种的出苗率均在60%以上,但以早期(9月下旬)播种的出苗率最高(大于80%),早期播种的苗木在苗高、地径、侧根数、根体积和根生物量等指标上都明显要高于其它播种时期,蒙古栎在秋播裸根育苗时应适时早播;秋季播种的容器苗在所有观测的形态指标上均好于春季播种的容器苗,秋季容器育苗质量更高。     

N tracing models with a Monte Carlo optimization procedure provide new insights on gross N transformations in soils

¹⁵N tracing studies in combination with analyses via process-based models are the current “state-of-the-art” technique to quantify gross nitrogen (N) transformation rates in soils. A crucial component of this technique is the optimization algorithm which primarily decides how many model parameters can simultaneously be estimated. Recently, we published a Markov chain Monte Carlo (MCMC) method which has the potential to simultaneously estimate large number of parameters in ¹⁵N tracing models [Müller et al., 2007. Estimation of parameters in complex ¹⁵N tracing models by Monte Carlo sampling. Soil Biology & Biochemistry 39, 715-726].Here, we present the results of a reanalysis of datasets by Kirkham and Bartholomew [1954. Equations for following nutrient transformations in soil, utilizing tracer data. Soil Science Society of America Proceedings 18, 33-34], Myrold and Tiedje [1986. Simultaneous estimation of several nitrogen cycle rates using ¹⁵N: theory and application. Soil Biology & Biochemistry 18, 559-568] and Watson et al. [2000. Overestimation of gross N transformation rates in grassland soils due to non-uniform exploitation of applied and native pools. Soil Biology & Biochemistry 32, 2019-2030] using the MCMC technique. Analytical solutions such as the ones derived by Kirkham and Bartholomew [1954. Equations for following nutrient transformations in soil, utilizing tracer data. Soil Science Society of America Proceedings 18, 33-34] result in gross rates without uncertainties. We show that the analysis of the same data sets with the MCMC method provides standard deviations for gross N transformations. The standard deviations are further reduced if realistic data uncertainties are considered. Reanalyzing data by Myrold and Tiedje [1986. Simultaneous estimation of several nitrogen cycle rates using ¹⁵N: theory and application. Soil Biology & Biochemistry 18, 559-568] (Capac soil) resulted in a model fit similar to the one of the original analysis but with more precise estimates of gross N transformations. In addition, our analysis showed that small N transformations such as heterotrophic nitrification, which was neglected in the original analysis, could be quantified for this soil. Watson et al. [2000. Overestimation of gross N transformation rates in grassland soils due to non-uniform exploitation of applied and native pools. Soil Biology & Biochemistry 32, 2019-2030] provided evidence of a non-uniform exploitation of applied and native N that led to an overestimation of gross N transformations. Reanalyzing the data (CENIT soil, low N application) with the Müller et al. [2007. Estimation of parameters in complex ¹⁵N tracing models by Monte Carlo sampling. Soil Biology & Biochemistry 39, 715-726] model where oxidation was set to Michaelis-Menten kinetics resulted in a satisfactory fit between modeled and observed data, indicating that the observed artifact by Watson et al. [2000. Overestimation of gross N transformation rates in grassland soils due to non-uniform exploitation of applied and native pools. Soil Biology & Biochemistry 32, 2019-2030] was mainly due to inappropriate kinetic settings. Our study shows that the combination of a MCMC method with ¹⁵N tracing models is able to consider more complex and possibly more realistic models and kinetic settings to estimate gross N transformation rates and thus overcomes restriction of previous ¹⁵N tracing techniques.