三种鹿血清乳酸脱氢酶同功酶的电泳研究

采用聚丙烯酰胺凝胶电泳法对26头白唇鹿、41头马鹿和11头梅花鹿的血清乳酸脱氢酶（LDH）同功酶谱及其多态性进行了研究。结果发现：三种鹿的LDH都有LDH1、LDH2、LDH3和LDH5四种同功酶;LDH3同功酶具有1～3条亚带,LDH5具有显现酶活性和不显现酶活性两种表型而呈现多态性;白唇鹿的LDH同功酶酶谱及其多态性有较明显的种的特征。     

Effects of Clear‐Cutting Alder Coppice on Surface Soil Properties and Aboveground Herbaceous Plant Biomass

The purpose of this investigation was to evaluate the effects of clear‐cutting and skidding impacts on surface soils in an alder coppice and aboveground herbaceous biomass. For this purpose, experimental sites used in the study were a randomized complete block with four replications. Some soil properties were measured at 60 pits at 0 to 5 cm and 5 to 10 cm deep in control, normal harvest, and main skid trail sites. In the main skid trail site, as compared to the control and normal harvest site, the bulk density increased from 0.90 to 1.52g cm^?3, the soil organic‐matter content decreased from 4.77% to 1.65%, and saturated hydraulic conductivity decreased from 86.34 to 9.6 cm h^?1 at 0 to 5 cm deep. Optimization of harvesting time and rehabilitation of skid roads needed to be done to prevent and minimize negative impacts of the skid roads on soils.     

延川县红枣产业发展现状及对策

从自然生态环境、生产条件、枣树品种、栽培技术等方面分析了延川县红枣产业发展优势、限制因素及存在问题,提出了红枣产业发展对策与建议。     

Rootstock influence on ‘delicious’ and ‘golden delicious’ apple fruit quality at harvest and after storage

The influence of 9 rootstocks (M2, M7, M25, M26, MM104, MM106, MM109, MM111 and seedling) on fruit quality at harvest and after storage of ‘Wellspur Delicious’ (WS) and ‘Goldspur’ (GS), and of 3 rootstocks (M7, M26 and MM106) on fruit quality of ‘Red King Delicious’ (RK) and ‘Golden Delicious’ (GD) apple (Malus domestica Borkh.) was evaluated during a 4-year period. Fruits from trees on M26 were larger, developed earlier color and soluble solids (SS), and maintained higher levels of acidity (at harvest and during storage) in comparison with other rootstocks. Fruit from trees on M2 tended to have high SS. Fruit color from trees on MM104, MM106 and MM109 tended to be comparatively poor. There were significant rootstock effects on SS, starch, acidity, color, circumference, weight and box size.     

“红富士”不同树形冠层微生态对果实品质的影响

以"红富士"苹果为试材,研究了不同树形冠层微生态环境变化规律及其与果实品质的关系.结果表明:不同树形冠层微生态环境存在差别,高干开心形冠层光照强度、昼温、昼夜温差显著高于小冠疏层形和纺锤形,而空气相对湿度最低.由于不同树形冠层微生态环境对果实生长发育影响不同,高干开心形果实较其它两种树形单果重显著增加,着色较好,可溶性固形物含量较高,收获时单果重较小,冠疏层形增加了31.96%,而较纺锤形增加了31.28%.     

圆叶决明添加量对红壤可溶性氮及酶活性的影响

为了探明圆叶决明(Chamaecrista rotundifolia)降解后红壤可溶性氮及氮水解酶活性的变化规律,本研究采用室内好气恒湿培养法,研究占红壤质量0.5%(T1),1%(T2)和2%(T3)的圆叶决明添加至红壤中,培养7~88d内红壤硝态氮(NO^-₃-N)、铵态氮(NH⁺₄-N)和可溶性有机氮(Soluble organic nitrogen,SON)及脲酶、蛋白酶和天冬酰胺酶的变化。结果表明：添加圆叶决明后,红壤NO^-₃-N和NH⁺₄-N含量在培养前期降低,培养中期增加;而整个培养期SON含量及脲酶、蛋白酶和天冬酰胺酶活性均增加,且圆叶决明添加量越大,效果越显著。NO^-₃-N和SON含量及脲酶、蛋白酶和天冬酰胺酶活性可用2次或3次函数方程拟合;而NH⁺₄-N含量可用线性函数拟合。氮水解酶与NO^-₃-N负相关,与NH⁺₄-N和SON正相关,且相关性从大到小的顺序为蛋白酶>天冬酰胺酶>脲酶。综上,添加圆叶决明提高了红壤供氮水平和红壤氮转化能力。     

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。     

A variance-covariance structure to take into account repeated measurements and heteroscedasticity in growth modeling

This study proposes a within-subject variance-covariance (VC) structure to take into account repeated measurements and heteroscedasticity in a context of growth modeling. The VC structure integrates a variance function and a continuous autoregressive covariance structure. It was tested on a nonlinear growth model parameterized with data from permanent sample plots. Using a stand-level approach, basal area growth was independently modeled for red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] in mixed stands. For both species, the implementation of the VC structure significantly improved the maximum likelihood of the model. In both cases, it efficiently accounted for heteroscedasticity and autocorrelation, since the normalized residuals no longer exhibited departures from the assumptions of independent error terms with homogeneous variances. Moreover, compared with traditional nonlinear least squares (NLS) models, models parameterized with this VC structure may generate more accurate predictions when prior information is available. This case study demonstrates that the implementation of a VC structure may provide parameter estimates that are consistent with asymptotically unbiased variances in a context of nonlinear growth modeling using a stand-level approach. Since the variances are no longer biased, the hypothesis tests performed on the estimates are valid when the number of observations is large.     

Allometric model of the Reineke equation for Japanese cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>) and red pine (<Emphasis Type="Italic">Pinus densiflora</Emphasis>) stands

An allometric model that explains the mechanism of the difference in the slope of the Reineke equation (A) among species was proposed based on the allometric relationships of mean tree height (H) to quadratic mean diameter D (H ∝ D ^θ ) and stand density N (H ∝ N ^δ ), i.e., A = θ/δ. The proposed model was fitted to Japanese cypress (Chamaecyparis obtusa Endl.) and red pine (Pinus densiflora) stands. The allometric exponents θ and δ were, respectively, 0.8995 and −0.5000 for cypress and 0.8612 and −0.6619 for pine. The difference between cypress and pine was significant for δ but not for θ. Inserting the exponents into the model resulted in predicted slopes of −1.7991 for cypress and −1.3011 for pine. The difference in the slope of the Reineke equation between the two species was produced by characteristics related to the tree crown, rather than characteristics related to stem slenderness. The proposed model enables us to estimate the slope of the Reineke equation from commonly measured stand attributes, such as mean tree height and quadratic mean diameter. Therefore, the proposed model is expected to be practical and convenient for estimating the slope of the Reineke equation and for explaining the mechanism of its variation among species. The model should be also accepted as a generalized model of the stand density versus quadratic mean diameter relationship, whereas the original Reineke equation should be seen as a specific case of this model.     

Annualized diameter and height growth equations for Pacific Northwest plantation-grown Douglas-fir, western hemlock, and red alder

Simulating the influence of intensive management and annual weather fluctuations on tree growth requires a shorter time step than currently employed by most regional growth models. High-quality data sets are available for several plantation species in the Pacific Northwest region of the United States, but the growth periods ranged from 2 to 12 years in length. Measurement periods of varying length complicate efforts to fit growth models because observed growth rates must be interpolated to a common length growth period or those growth periods longer or shorter than the desired model time step must be discarded. A variation of the iterative technique suggested by Cao [Cao, Q.V., 2000. Prediction of annual diameter growth and survival for individual trees from periodic measurements. Forest Sci. 46, 127–131] was applied to estimate annualized diameter and height growth equations for pure plantations of Douglas-fir, western hemlock, and red alder. Using this technique, fits were significantly improved for all three species by embedding a multi-level nonlinear mixed-effects framework (likelihood ratio test: p < 0.0001). The final models were consistent with expected biological behavior of diameter and height growth over tree, stand, and site variables. The random effects showed some correlation with key physiographic variables such as slope and aspect for Douglas-fir and red alder, but these relationships were not observed for western hemlock. Further, the random effects were more correlated with physiographic variables than actual climate or soils information. Long-term simulations (12–16 years) on an independent dataset using these annualized equations showed that the multi-level mixed effects models were more accurate and precise than those fitted without random effects as mean square error (MSE) was reduced by 13 and 21% for diameter and height growth prediction, respectively. The level of prediction error was also smaller than an existing similar growth model with a longer time step (ORGANON v8) as the annualized equations reduced MSE by 17 and 38% for diameter and height growth prediction, respectively. These models will prove to be quite useful for understanding the interaction of weather and silviculture in the Pacific Northwest and refining the precision of future growth model projections.