印楝实生苗年生长规律研究   总被引：10，自引：0，他引：10       下载免费PDF全文

郑益兴  彭兴民  赵保荣  张燕平 《林业科学研究》2006,19(2):182-187

研究了1年生印楝实生苗生长动态、苗木生物量积累与分配模式以及苗木生长与气象因子的关系,结果表明:印楝苗的年生长规律符合Logistic曲线特征,据此方程可以建立苗高、地径与生长时间的拟合模型,结合二次多项式对苗木连日生长量的动态模拟,可将苗木生长划分为4个阶段:出苗期、生长初期、速生期和生长后期,其中处于速生阶段苗木的高和地径生长量均超过全年总量的70%,地径处于生长初期阶段的时间短于苗高,但生长量占全年总量之比是苗高的2倍;苗木生物量积累与苗高和地径的相关性极为密切,其中地上部分生物量占全株的69.1%,全株含水量是干质量的1.58倍;在制约苗木生长节律的气象因子中,偏相关分析表明:温度是苗木生长的主导因子.  相似文献   

Pilot Study to Examine Radial Variation in Annual Ring Width, Density and Shrinkage     

URAKAMI Hiroyuki  HIRAKAWA Yasuhiko  YAMASHITA Kana 《中国林业科技(英文版)》2003,(4)

The annual ring width, density and shrinkage variation from pith to bark in Chinese fir (Cunninghamia lanceolata) and Boka sugi (Cryptomeria japonicd) were studied and compared. The results show that the ring width decreased sharply from pith to bark for Chinese fir. However, the ring width variation pattern for Boka sugi followed a different way, i.e., the ring width decreased to the fifth ring, increased to the tenth ring, decreased again to the fifteenth, and then increased to the twentieth, where it became constant. The large variations of Boka sugi appeared to show the maintenance of fast growth for many years. The annual ring mean density of Chinese fir increased gradually from pith to bark. However, the density changes for Boka sugi indicated the opposite trend, i.e., the mean density decreased gradually from pith to bark. The former showed a pattern as the same as a pine and a larch, and the latter was often found in a cedar and a cypress. The longitudinal shrinkage in juvenile wood was much hig  相似文献   

杉木幼林年生长节律划分和相关气候因素分析     

魏国衡  邓佑荣 《四川林业科技》1991,12(1):15-22

杉木幼林年生长规律及气候因素对生长的影响,是合理制订杉木产区区划,改善杉木造林规划设计布局,正确实施经营管理措施的基础。 本项研究,将全国杉木西部试区的四川高县作为试验点,从1985～1988年,连续4年在5～8年生不同密度林分中,作了胸高直径及树高生长的旬期定期观测。经对这些实验数据作均值处理,聚类分析,关联分析和多元回归分析结果表明:对生长在中国杉木中带西部产区,处于中亚热带湿润气候区环境条件下的杉木幼林年生长规律的论证及对影响生长的主要气候因子的分析判断和预测,具有可靠性和区域代表性。  相似文献   

Annual net production of the five Sargassaceae species in Yoro,western Wakasa Bay,Sea of Japan   总被引：1，自引：0，他引：1  

Kousuke?YatsuyaEmail author  Tomokazu?Nishigaki  Akio?Douke  Yozo?Wada 《Fisheries Science》2005,71(5):1098-1106

ABSTRACT:   Annual net production of the five Sargassaceae species was investigated in Yoro, western Wakasa Bay, Sea of Japan. The Sargassaceae species were collected at a depth of 2.0–2.5 m and subjected to stratified clipping for 13 months. Annual net production was estimated at 2407 g dry wt/m² for Sargassum patens , 2132 g dry wt/m² for Sargassum macrocarpum , 1458 g dry wt/m² for Sargassum siliquastrum , 1197 g dry wt/m² for Myagropsis myagroides , and 1471 g dry wt/m² for Sargassum piluliferum . The ratio of annual net production to maximum biomass (P/B_max) for these species ranged between 1.3 and 1.7, being higher than in previous studies which used the same method. Winter storms with strong wave exposure and relatively calm condition in Yoro were considered to augment P/B_max. The total losses estimated from the different units of stratified clipping were compared. If larger and less segregated units were applied, the total loss would decrease. It was suggested that a 50 cm stratum would be applicable to the larger species (3 m or longer) and a stratum of 20 cm or less would be applicable to mid-sized or smaller species (less than 3 m).  相似文献   

长江口刀鲚汛期特征及其资源状况的年际变化分析   总被引：3，自引：2，他引：1  

田思泉  田芝清  高春霞  戴小杰 《上海海洋大学学报》2014,23(2):245-250

刀鲚是长江水域重要的洄游性经济鱼类。根据2008-2011年捕捞汛期长江口刀鲚的观测数据,对刀鲚汛期特征及汛期体长、体重以及渔获量的年变化进行研究。研究结果表明:2008-2011年各年调查汛期内长江口刀鲚的体长分布均呈显著差异,2008年的优势体长组为26~38 cm,2009年的优势体长组为22~32 cm,2010、2011年的优势体长组为24~34 cm,2008年优势叉长组较其他年份大,2011年的体长均值小于其他年份;调查的汛期样本中,150 g以上的大规格刀鲚在群体中所占比例逐年下降,而50 g以下的小规格刀鲚比例逐年增加,刀鲚个体小型化趋势明显;汛期内长江口刀鲚单船每网的渔获量(CPUE)不断减少,2011年最低,相较2010年,其单船每网渔获量下降了95.5%;2008-2011年各年刀鲚的汛期特征基本表现一致,3月下旬至4月中旬进入刀鲚的旺汛期,捕捞产量较大。  相似文献   

The cytochrome P450 system of Atlantic salmon (Salmo salar): II. Variations in hepatic catalytic activities and isozyme patterns during an annual reproductive cycle     

Håvard E. Larsen  Malin Celander  Anders Goksøyr 《Fish physiology and biochemistry》1992,10(4):291-301

A group of Atlantic salmon (Salmo salar) was followed through their first year of maturation and spawning. At monthly intervals, starting with juvenile fish in December, 5–7 fish of each sex were killed, and liver and plasma were sampled. The last sampling point was of spawning fish in November a year later. Variables in the cytochrome P450 (P450) system were studied in hepatic microsomes, and estradiol 17 was measured in the plasma of females to assess the maturational status. The P450 1A1-mediated 7-ethoxyresorufin O-deethylase (EROD) started at high levels in winter, but decreased to non-detectable activities in pre-spawning females. Decreases, but not to the same extent, were also observed during this period in total cytochrome P450, cytochrome b₅, NADPH-cytochrome P450 reductase, and in the content of two immunochemically determined P450 isozymes. At the same time, LSI levels increased in maturing females (starting in July), and GSI levels increased in both sexes (starting in May). Sex specific differences were observed in pre-spawning fish in September and October, with levels of total P450, b₅, NADPH-cytochrome P450 reductase, EROD and P450 isozymes significantly lower in females. At the same time, plasma estradiol-17 levels reached peak values in females. The results point to the important role of sex steroids such as estradiol-17 as major factors in the regulation of final sexual maturation. However, this study also indicates that there may be estradiol-17 independent events of equal importance in the early stages of gonadal maturation that may involve the P450 system. The changes observed in the P450 system (as a major drug and steroid metabolizing system) of Atlantic salmon during sexual maturation may be of importance both in the endogenous transduction of hormonal signals, and as a pharmacological basis for designing therapeutic treatment of diseases in the aquaculture industry.Parts of this work were presented at the 5th International Symposium on Responses of Marine Organisms to Pollutants, April 1989 in Plymouth, United Kingdom (Larsen and Goks\/oyr 1989).  相似文献   

Forage chain arrangement for sustainable livestock systems in a Mediterranean area     

S. L. Cosentino  F. Gresta  G. Testa 《Grass and Forage Science》2014,69(4):625-634

Mediterranean forage systems suffer from limited availability of fresh forage because of water deficits and extreme temperatures. Consequently, fresh forage is unavailable for at least 6–7 months a year, and farmers must buy feed to support livestock production. With the aim of overcoming these limitations, a 2‐year trial was conducted on three distinct sites in Sicily (at 10, 600 and 1200 m elevation) with thirty‐four varieties of forage species belonging to nine biennial/perennial and thirteen annual species. Results showed that by integrating grasses and legumes, species from environments with different climatic conditions enable the season of forage production to be extended from mid‐April to mid‐November. Quality traits of forage in different areas varied in relation to species and varieties. In general, the sown‐forage quality was better than in pastures and fallows in the same areas commonly used to feed animals. This also leads to a reduction in the use of supplementary feeds. Among the tested species, Lolium multiflorum and Medicago sativa emerged as the most promising for filling the forage‐deficit periods, and Trifolium spp. and Vicia sativa were found to be superior for increasing forage quality. The results are discussed in the context of adapting Mediterranean forage supplies for ensuring greater sustainability of livestock production in mountain, hill and plain areas. The proposed forage chain arrangement represents part of local potential adaptation to climate limitations and climate change.  相似文献   

基于SWAT模型的清水河流域年径流侵蚀功率空间分布     

杨光  鲁克新  李鹏    柳海亮  刘桂华  曹峰华  马天文  王得军  文妙霞  孙景梅 《水土保持研究》2022,29(6):90-96,103

为了从能量学的角度解释流域水力侵蚀的空间分布情况,选取可以更好表示流域下垫面条件、降雨及其产生的径流对水力侵蚀综合作用的径流侵蚀功率,以宁夏回族自治区水土流失严重的清水河流域为研究对象,基于SWAT模型模拟研究了清水河流域年径流侵蚀功率的空间分布特征及其空间尺度效应。结果表明:(1)清水河流域多年平均径流侵蚀功率在流域内呈现“支流大,干流小; 东部大,西部小”的空间分布规律;(2)当子流域出口断面控制面积小于4 000 km²时,子流域多年平均径流侵蚀功率与子流域出口断面集水面积间呈显著的幂函数关系; 当子流域出口断面集水面积大于4 000 km²时,子流域多年平均径流侵蚀功率稳定在1.56×10^-5 m⁴/(s·km²)左右;(3)优先选择处于清水河上中游区域且出口断面集水面积小于84.85 km²的小流域进行生态治理,可取得良好的水土流失治理效果。因此径流侵蚀功率具有一定空间分布规律且与流域集水面积间具有显著相关关系,掌握这一规律和相关关系可为流域生态治理提供理论支持。  相似文献   

Growth and thinning effects during a rotation period of hybrid aspen in southern Sweden     

Lars Rytter  Lars-Göran Stener 《Scandinavian Journal of Forest Research》2014,29(8):747-756

Hybrid aspen is an interesting tree species for wood production in northern Europe. In this study we examined growth dynamics over the whole rotation period. Height and diameter development, as well as annual growth of stem volume and stem biomass, were repeatedly recorded in 14 planted and 2 root sucker stands, aged up to 26 years, in southern Sweden. A main aim was to study the productivity level for hybrid aspen forestry with an expected rotation period of about 25 years. The study verified earlier prognoses, showing a mean annual increment (MAI) of 19.5 m³ of stem wood ha^?1 yr^?1 after 25 years. This corresponds to a dry weight of stem biomass of 7.2 tons dry matter (DM) ha^?1 yr^?1. Maximum MAI was still not reached after 25 years, although the growth curve was flattening out. If branch biomass is included, MAI is estimated to about 9 tons DM ha^?1 yr^?1 and further improvements in growth is expected by using the best genotypically selected clones available. Results from three different thinning regimens showed that thinning intensity provided significantly larger diameter growth, while no significant yield effects were seen among the thinning regimens.  相似文献   

一年生黑麦草与不同密度饲料玉米轮作对比试验     

杨琼  罗宗礼  白洪清  田志刚 《饲料博览》2014,(10):40-42

为解决湘西地区湘西黄牛养殖中饲草短缺的问题,试验通过不同密度饲料玉米与一年生黑麦草轮作将试验分为5个处理组,即试验组1:45 000株·hm-2饲料玉米与一年生黑麦草轮作;对照组1:直播45 000株·hm-2饲料玉米;试验组2:60 000株·hm-2饲料玉米与一年生黑麦草轮作;对照组2:直播60 000株·hm-2饲料玉米;试验组3:75 000·hm-2饲料玉米与一年生黑麦草轮作;对照组3:直播75 000株·hm-2饲料玉米。结果发现,试验组2,即60000株·hm-2饲料玉米与一年生黑麦草轮作的播种模式在湘西地区最具推广价值。  相似文献