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1.
马尾松飞播间伐抚育研究 总被引：1，自引：0，他引：1
以下层木为主的综合疏伐法对马尾松进行间伐，通过８年标准地的观测表明，经过１次间伐的林木直径可提高３４．９４％，主要材种的出材率可提高１５．６６％，２次间伐的标准地林木直径生长可提高６４．１６％，主要材种出材率可提高２７．５３％。 相似文献
2.
林木多样性模型及生长模拟 总被引：2，自引：0，他引：2
林木生存环境复杂多变,导致林木形态千差万别,为了准确描述林木的形态多样性特征,提出了一种基于模型分解的林木生长模拟方法。首先构建多样性林木三维模型,使用林木形态的实际测量数据,基于B样条函数约束树干、树冠形态,依据削度方程模拟树干直径的变化趋势,利用Direct3D实现林木形态的三维建模;其次,按林木形态特征进行林木模型分解,将林木模型分为9个子模型;最后,使用场景节点按照拓扑结构关系对子模型进行动态组织,基于胸径、树高、枝下高、冠高和冠幅生长模型,使用多核CPU多线程并行的计算方式,获得各年龄阶段林木东、南、西、北方向形态参数,从而对子模型生长状态进行控制,实现林木不同方向生长变化的可视化模拟。结果表明：该方法可将林木三维模型与生长模型紧密结合起来,林木各方向的枝下高、冠高和冠幅严格按照生长模型进行生长,可有效模拟出林木各方向生长状态的多样性;三维场景渲染帧率（FPS）保持在25以上,平均FPS可以达到50,实现林木生长的方向异质性模拟。 相似文献
3.
研究了外源性蜕皮激素对凡纳滨对虾生长和表观消化率的影响，实验时在基础饲料中分别添加0．1％、0．2％、0．4％的两种市售蜕壳素产品，制成6种外源性脱壳素配合饲料，不添加的基础饲料作为对照组，试验在260L玻璃钢循环水养殖系统中，每个剂量组设3个重复，8周生长试验结果表明：市售蜕壳素产品能有效地促进对虾生长，试验结束时，试验组虾体增重分别较对照组增加16．8％、7．52％、5．9％、11．4％、29．07％、16．53％，但是凡纳滨对虾对饲料粗蛋白的表观消化率没有明显地提高，凡纳滨对虾对脂肪的表观消化率较低。推算凡纳滨对虾饲料中最佳蜕皮酮添加量为60mg/kg。 相似文献
4.
在异育银鲫基础日粮中分别添加质量分数0．01％、0．02％、0．03％、0．04％的地衣芽孢杆菌，测定了鱼体的生长及食糜植酸酶活性等。结果表明：与对照组相比，添加量0．01％、0．02％、0．03％组的增重率分别显著提高了12．46％、18．59％、18．84％：添加量0．02％、0．03％组的磷表观消化率分别提高37．63％、35．03％（P〈0．05）；饵料系数降低了0．52、0．57（P〈0．05），其他组差异不显著。与对照组相比，0．03％组食糜植酸酶活性提高50．79％、0．04％组肝体比降低20．91％（P〈0．05），其他组差异不显著。因此在异育银鲫日粮中添加地衣芽孢杆菌提高了机体酶活性，促进了鱼体生长。 相似文献
5.
林向阳 《广东海洋大学学报》2004,24(1):15-19
研究了2002-2003年双棘黄姑鱼(Nibea diacanthus)的人工繁殖、育苗过程。成熟亲鱼注射LRH-A HCG就可产卵，产卵率55．6％～83．3％，受精率71．0％～87．1％，孵化率77．9％～89．3％。苗种培育期间加强水质管理、饵料生物的营养强化和病害防治工作，在水温24．5～29℃、盐度26～32条件下，仔、稚、幼鱼生长迅速。 相似文献
6.
李林锋 《广东海洋大学学报》2004,24(1):68-72
以尾叶桉U6无性系为研究材料，盆栽于土壤含水量分别为田间持水量的100％(Ⅰ)、80％(Ⅱ，CK)、60%，(Ⅲ)和40％(Ⅳ)条件下30d，研究不同土壤含水量对桉树幼苗生长和生物量分配的影响。结果表明：不同土壤含水量显著影响桉树幼苗的生长和生物量分配。与对照组相比，60%，和40%，土壤含水量下桉树幼苗的株高、地径、叶片数、叶面积、根长和侧根数分别减少37．8％、33．6％、52．1％、68．9%、44．0％、37．5％和44．4％、40．4％、60．8%，、77．5％、51．6％、48．9％；总生物量、根、茎、叶生物量分别减少53．5%，、22．4％、57．9％、62．0％和63．9%，、26．2%，、59．7％、78．9％。100%，土壤含水量下上述各项指标值均有所增加，说明桉树幼苗仍有一定增长潜力，然其水分利用效率不高，生产上不实用。水分亏缺使桉树幼苗倾向于将更多的资源分配给根系生长，增大根／茎比，降低其利用价值。 相似文献
7.
谷氨酰胺对肉仔鸡早期生长和组织器官发育的影响 总被引：5，自引：0，他引：5
黄冠庆 《广东海洋大学学报》2003,23(1):69-73
在肉仔鸡基础日粮中添加谷氨酰胺进行21d的试验，观察了其对肉仔鸡早期生长性能和组织器官发育的影响。试验表明，在肉仔鸡饲料中添加适宜的谷氨酰胺，有利于提高肉仔鸡的体重、日增重、饲料报酬和成活率，添加量为0．8％时效果最好，且谷氨酰胺添加量为0．8％时可明显提高21日龄时法氏囊、脾脏、肝脏和胰腺的重量以及法氏囊指数。 相似文献
8.
9.
提高鲮鱼鱼糜弹性的方法 总被引：3，自引：0，他引：3
研究了影响鲮鱼鱼糜弹性的主要因素和加工工艺条件。研究时采用漂洗鱼肉、添加谷氨酰胺转氨酶以及二段加热方法等工艺来提高鲮鱼鱼糜的弹性。结果表明：将鲮鱼鱼肉漂洗2次，添加质量分数0．2％的谷氨酰胺转氨酶作为弹性增强剂，采用在40℃温度缓慢凝胶化3h后加热至90℃保持30min的二段加热方式，可明显提高鲮鱼鱼糜的弹性。 相似文献
10.
去噪小波包能量法在水声信号识别中的应用 总被引：1，自引：0，他引：1
对小波包能量法进行改进，提出了一种新的方法——去噪小波包能量法，该算法对信号小波去噪后，再用小波包能量法提取信号的特征；应用去噪小波包能量法研究了不同的小波去噪方法对水声信号分类识别率的影响，在实测信号样本集上用BP神经网络进行了识别实验。结果显示软阈值、硬阈值、弹性阈值3种标准的小波去噪方法均能明显提高信号识别率，其中最为显著的是软阈值标准去噪，信号的识别率可由未去噪的53．3％提高到98．3％，表明算法的有效性。 相似文献
11.
单木参数对当前的森林资源管理、生态研究以及生物多样性保护等具有重要意义。无人机立体影像数据与单木识别算法为单木参数的低成本、自动化获取提供了基础。现有研究表明,常用的基于局部最大值搜索的单木识别算法面对密集林分时存在严重的漏识别问题,影响了参数提取的精度,因此本文提出了顾及单木三维形态的无人机立体影像单木识别新算法。算法首先综合利用无人机立体影像的高程与RGB光谱信息,通过随机森林分类进行林冠区的提取;然后利用形态学的多层腐蚀、膨胀与连通区标记进行树冠相连单木的分离与树冠中心点的提取,从而实现单木自动化识别。本文选取内蒙古大兴安岭林区和四川王朗林区的4块样地进行验证,以目视解译数据为参考,分别与基于高程值的局部最大值搜索算法（算法A）、基于RGB光谱亮度值的局部最大值搜索算法（算法B）进行比较。结果显示：本文提出的算法在4个样地的平均F1-score为94.17%,与算法A和算法B相比分别提高了15.85%和9.37%;而对于密集样地,本文提出的算法在查全率上相比算法A和算法B分别提高51.79%和35.64%。结果表明本文提出的算法在不同林区均能够实现较好的单木识别效果,特别是能够有效避免密集林分下的漏识别问题,为基于无人机立体影像的单木识别研究提供了一种新的思路。 相似文献
12.
Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, 10-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, China. Optimal nonlinear equations were applied to model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and 20-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, respectively. Also, it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages (p < 0.05) but not soil temperature (p > 0.05). Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at 10-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity (Q 10) increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets. 相似文献
13.
Thomas M.HINCKLEY Phillip CHI Keala HAGMANN Stevan HARRELL Amanda Henck SCHMIDT Lauren URGENSON Zong-yong ZENG 《山地科学学报》2013,10(5):824-832
This paper examines human impact on stands and individual trees of Pinus yunnanensis growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province,China.In an effort to assess whether use of these forests was sustainable,we examined the effects of human use in two ways.First,we directly measured the effect of cutting branches,for fuel and fodder,on tree growth.We hypothesized that branch cutting would negatively impact tree growth.We established 12 plots on four hills and compared 14 pairs of trees,one tree in each pair with an apparently full crown and the other with a considerable portion of the crown removed.Second,we assessed stand and tree properties over a 500 m elevation gradient above the villages where we hypothesized that as elevation increases,stand and tree properties should show fewer human impacts.Although extensive branch cutting reduced the live crown,tree height and diameter,compensatory processes likely enabled trees to recover and to add basal area increments(BAIs) similar to those added by trees with full crowns.Trees and stands close to villages showed less growth and lower basal areas,respectively,than stands and trees at intermediate or distant elevations from villages.Areas relatively close to the villages showed considerable effects of human-related disturbances such as branch cutting,grazing,tree and shrub removal,losses of litter,and human and animal trails.Such areas had increased soil erosion and often loss of the ‘A’ horizon.Stands close to villages had younger trees,lower stand basal areas,smaller basal area increments,and more stumps.Our results suggest an increasingly vulnerable interface between occupants of these two villages and their surrounding forests. 相似文献
14.
Labile organic matter content and distribution as affected by six-year soil amendments to eroded Chinese mollisols 总被引：2，自引：0，他引：2
Yueyu Sui Xiaoguang Jiao Wenting Chen Xiaobing Liu Xingyi Zhang Guangwei Ding 《中国地理科学(英文版)》2013,23(6):692-699
Labile organic carbon （LOC） is a fraction of soil organic carbon （SOC） with rapid turnover time and is affected by soil fertilization. This investigation characterized the SOC content, LOC content and LOC distribution in the treatment plots of surface soil erosion at five levels （0-, 5-, 10-, 20- and 30-cm erosion）. The soil had received contrasting fertilizer treatments （i.e., chemical fertilizer or chemical fertilizer ＋ manure） for 6 years. This study demonstrated that both SOC and various LOC fractions contents were higher in the plots with fertilizer ＋ manure than in those with fertilizer alone under the same erosion conditions. The SOC and LOC contents de- creased as the erosion depth increased. Light fraction organic carbon, particulate organic carbon, easily oxidizable organic carbon （KMnO4-oxydizable organic carbon）, and microbial biomass carbon were 27% 57%, 37%-7%, 20%-25%, and 29%-33% higher respectively in the fertilizer ＋ manure plots, than in the fertilizer alone plots. Positive correlations （p 〈 0.05） between SOC content and different fractions contents were observed in all plots except the correlation between total SOC content and water-soluble organic carbon content in the different fertilization treatments. Obviously, fertilizer ＋ manure treatments would be conducive to the accumulation of LOC and SOC in the Black soil of Northeast China. 相似文献
15.
Peiqing Xiao Wenyi Yao Zhenzhou Shen Chunxia Yang Xizhi Lyu Peng Jiao 《中国地理科学(英文版)》2017,27(4):589-599
Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic characteristics.In these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/h.The average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub plots.Average soil loss rates varied from 44.19 to 114.61 g/(min·m~2) for bare soil plots and from 5.61 to 84.58 g/(min·m~2) for shrub plots.There was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/h.Runoff and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and rills.The unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion mechanisms.The soil loss rate increased linearly with the unit stream power on both shrub and bare soil plots.Critical unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots. 相似文献
16.
Post-fire field measurements of sediment and run off yield were undertaken in natural rainfall event-basis during five rainy months in Korea on a total of 15 small plots: four replica burned unseeded plots, six replica burned seeded plots, and five replica unburned plots. The main aim was to evaluate the effects of vegetation recovery and spatial distribution patterns on sediment and runoff response between and within the treatment replica erosion plots. Six-years after the wildfire, total sediment and runoff yield in the burned unseeded plots with 20%-30% vegetation cover was still 120.8 and 20.6 times higher than in the unburned treatment plots with 100% ground cover, 8.3 and 6.7 times higher than in the burned seeded plots with 70%-80% vegetation cover, while only 1.6 and 2.0 times higher than in the burned seeded plots with 50%-60% vegetation cover, respectively. The differences in sediment and runoff yield between the treatment plots was proportional to total vegetation cover, distance of bare soil to vegetation cover, magnitude of rainfall characteristics and changes in soil properties, but not slope gradient. Three out of the six within-treatment pairs of two replica plots showed large differences in sediment and runoff yield of up to 6.0 and 4.2 times and mean CV of up to 99.1% and 62.2%, respectively. This was due to differences in the spatial distribution patterns of surface cover features, including aggregation of vegetation and litter covers, the distance of bare soil exposed to vegetation cover closer to the plot sediment collector and micro topographic mounds and sinks between pairs of replica plots. Small differences in sediment and runoff of only 0.9-1.4 folds and mean CV of 8.6%-25% were observed where the within-treatment pairs of replica plots had similar slope, total surface cover components and comparable spatial distribution pattern of vegetation and bare soil exposed surface covers. The results indicated that post-fire hillslopes undergoing effective vegetation recovery have the potential to reduce sediment and runoff production nearer to unburned levels within 6-years after burning while wildfire impacts could last more than 6-years on burned unseeded ridge slopes undergoing slow vegetation recovery. 相似文献
17.
YU Fei WANG De-xiang SHI Xiao-xiao YI Xian-feng HUANG Qing-ping HU You-ning 《山地科学学报》2013,10(5):845-853
Natural seedling regeneration and tree establishment are affected by various environmental factors.In this study,we established eight,eight,six,and four independent forest stands(each stand was further divided into five subplots) respectively based on the altitudinal gradient,stand density,slope location,and slope aspect to investigate the effects of environmental factors on tree seedling regeneration in a pine-oak mixed forest.The results indicated that the seedling density was significantly higher at altitudes of 1,283 m to 1,665 m,whereas the sapling density did not differ with altitudes.The seedling and sapling density decreased significantly at 1,835 m.The seedling densities on the upper slopes were much higher than those on the middle and lower slopes,whereas the sapling density had no difference.The sapling density decreased gradually from the southwest(20°-75°) whereas it increased on the shady slopes to the northeast(40°).The seedling density increased from southwest(20°) to northeast(40°).The seedling and sapling densities increased with the stand density(850 trees ha-1to 1,525 trees ha-1) whereas the sapling density was significantly lower in stands(1,900 trees ha-1).Principal components analysis showed that the slope aspect and stand density had more important roles in tree regeneration in this study region compared with the other two factors.Therefore,our findings suggest that it will be beneficial to keep stands at a moderate density on shady slopes.Appropriate thinning of higher density stands is also expected to promote the natural regeneration of pine-oak mixed forest. 相似文献
18.
Azyleah Cañizares Abino Sung Yong Kim Roscinto Ian Canicosa Lumbres Mi Na Jang Ho Joong Youn Ki Hyung Park Young Jin Lee 《山地科学学报》2016,13(5):822-830
This study was carried out to determine the performance of percentile-based Weibull diameter distribution model for Pinus thunbergii stands thriving along the eastern coast of South Korea. The parameter recovery technique was used to estimate the three parameters of the Weibull model. The analysis demonstrated satisfactory results based on the following test statistics for the principal percentile models: fit index (FI) range from 0.501 (minimum diameter) to 0.932 (50th diameter percentiles) and root mean square error (RMSE) range from 0.112 (quadratic mean diameter) to 3.572 (minimum diameter). The developed model was further evaluated by determining the mean bias (ē) in trees per ha (TPH) for each diameter class, and the results showed highest over-prediction in the 20 cm, and under-prediction in the 16 cm and 24 cm diameter classes. The goodness of fit tested by Kolmogorov-Smirnov (KS) test showed no significant differences (p>0.05) between the observed and predicted diameter distributions for almost all plots. Using site index and aboveground biomass (AGB) models developed for P. thunbergii in South Korea, a model to predict the AGB per ha for each diameter class and subsequently the total AGB of the stand was created. An application guide was also created, which will serve as a decision-support tool for forest managers in quantifying the future total AGB in P. thunbergii stands located in the eastern coast of South Korea and, subsequently, the quantification of potential carbon stocks aside from being a vital input in designing efficient management and protection strategies for these stands. 相似文献
19.
The study intended to describe the alpine vegetation of a protected area of the northwestern Himalaya and identify the important
environmental variables responsible for species distribution. We placed random plots covering different habitats and altitude
to record species composition and environmental variables. Vegetation was classified using hierarchical cluster analysis and
vegetation-environment relationships were evaluated with Canonical Correspondence Analysis. Four communities, each in alpine
shrub and meadows were delineated and well justified in the ordination plots. Indicator species for the different communities
were identified. Maximum species richness and diversity were found in community IV among shrub communities and community II
among the meadows. Studied environmental variables explained 61.5% variation in shrub vegetation and 59.8% variation in meadows.
Soil variables explained higher variability (∼35%) than spatial variables (∼21%) in both shrubs and meadows. Altitude, among
the spatial variables and carbon/nitrogen ratio and nitrogen among the soil variables explained maximum variation. About 40%
variations left unexplained. Latitude and species diversity among the other variables had significant correlation with ordination
axes. Study showed that altitude and C/N ratio played a significant role in species composition. Extensive sampling efforts
and inclusion of other non-studied variables are also suggested for better understanding. 相似文献
20.
Comparative Analysis of Fractional Vegetation Cover Estimation Based on Multi-sensor Data in a Semi-arid Sandy Area 总被引：1，自引：0，他引：1
《中国地理科学(英文版)》2019,(1)
The estimation of fractional vegetation cover(FVC) is important for identifying and monitoring desertification, especially in arid and semiarid regions. By using regression and pixel dichotomy models, we present the comparison of Sentinel-2A(S2) multispectral instrument(MSI) and Landsat 8(L8) operational land imager(OLI) data regarding the retrieval of FVC in a semi-arid sandy area(Mu Us Sandland, China, in August 2016). A combination of unmanned aerial vehicle(UAV) high-spatial-resolution images and field plots were used to produce verified data. Based on a normalized difference vegetation index(NDVI) regression model, the results showed that, compared with that of L8, the coefficient of determination(R2) of S2 increased by 26.0%, and the root mean square error(RMSE) and the sum of absolute error(SAE) decreased by 3.0% and 11.4%, respectively. For the ratio vegetation index(RVI) regression model, compared with that of L8, the R2 of S2 increased by 26.0%, and the RMSE and SAE decreased by 8.0% and 20.0%, respectively. When the pixel dichotomy model was used, compared with that of L8, the RMSE of S2 decreased by 21.3%, and the SAE decreased by 26.9%. Overall, S2 performed better than L8 in terms of FVC inversion. Additionally, in this paper, we develop a verified scheme based on UAV data in combination with the object-based classification method. This scheme is feasible and sufficiently robust for building relationships between field data and inversion results from satellite data. Further, the synergy of multi-source sensors(especially UAVs and satellites) is a potential effective way to estimate and evaluate regional ecological environmental parameters(FVC). 相似文献