共查询到20条相似文献，搜索用时 93 毫秒
1.
5.
9.
10.
11.
P.L. Mafongoya R. Chintu T.S. Chirwa J. Matibini S. Chikale 《Agroforestry Systems》2003,59(3):279-288
Seeking an alternative to Sesbania spp. tree fallows, a Tephrosia species and provenance trial was conducted at Msekera Research Station, Chipata (Zambia) to evaluate eleven Tephrosia vogelii and three Tephrosia candida provenances. They were tested for biomass production, quality of biomass, resistance to root-knot nematodes, nitrogen release,
and for their effects on soil nitrogen dynamics. At the end of 1.5 years, the T. candida provenances 02970, 02971 and 02972 from Madagascar produced two times greater amount of aboveground biomass than the T. vogelii provenances. There was little variability among the T. vogelii provenances in terms of litter and biomass production. Weed growth was significantly greater under T. vogelii than T. candida provenances. While Tephrosia vogelii provenance 98/02 from Zambia and T. candida 02972 were highly tolerant to the Meloidogyne incognita nematodes, T. vogelii provenances 02977, 98/03, 02973 from Kenya, Zambia and Malawi, respectively, were highly susceptible to the nematodes. The
Tephrosia species and provenances showed a wide variability in terms of N, lignin and polyphenol concentration in their foliage. Mineralization
of N in the foliage of T. candida provenances 02970 and 02971 and T. vogelii provenances 98/04 and 02974 from Malawi occurred rapidly within 14 weeks of incubation. At the end of the 2-year growth period,
there was significantly greater total inorganic N under T. candida provenance 02972 (12.5 mg kg−1) than T. vogelii (5 mg kg−1) provenance Mungwi 98/02. Maize (Zea mays L.) yields after T. candida provenances were greater than those after T. vogelii provenances. Further testing of the most promising provenances is needed for their effects on subsequent maize yields under
a range of farm conditions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
Kana Yamashita Yasuhiko Hirakawa Hiroshi Nakatani Motoyoshi Ikeda 《Journal of Wood Science》2009,55(3):161-168
The transverse shrinkage variation within trees was examined for five sugi cultivars. The within-tree trends of tangential
shrinkage (α
T) were different by cultivar, whereas radial shrinkage (α
R) increased from pith to bark in most cultivars. The tangential/radial shrinkage ratio (α
T/α
R) decreased from pith to bark in most cultivars, because the radial variation of α
R was larger than that of α
T. The cultivars showed significant differences among cultivars in α
T, α
R, and α
T/α
R, but the difference among cultivars for α
T/α
R was smaller. The relationships between transverse shrinkage and microfi bril angle (MFA), basic density (BD), tree ring parameters,
and modulus of elasticity were examined. The α
T and α
R showed positive relationships with BD, latewood percentage, latewood density, and modulus of elasticity, and negative relationships
with MFA and ring width. The relationships with earlywood density were weak. Sugi exhibited variation in transverse shrinkage
within stem and among cultivars, with the variation affected by MFA, density, and tree ring parameters.
Part of this article was presented at the 56th Annual Meeting of the Japan Wood Research Society, Akita, Japan, August 2006,
and the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, Japan, August 2007 相似文献
13.
A simple HPLC method was developed to quantify rabbit plasma tetrandrine (Tet) with propranolol (Pro) as internal standard. Based on the established method Tet and Pro were eluted at 7.1 and 12.0 min, respectively. It was shown that the concentration-time data of Tet fit the classical two-compartment model, no matter the drug was administered intravenously or orally to rabbits. The values of AUC0 → ∞, clearance (Cl0 → ∞), volume of distribution (Vd), and elimination half-life (t1/2β) of Tet were 59861.149 ± 26962.196 μg/L ? min, 0.503 ± 0.173 L/min/kg, 179 ± 76.185 L/kg, and 283.808 ± 162.937 min for intravenous injection of 5 mg/kg, or 18986.217 ± 7462.308 μg/L ? min, 0.805 ± 0.267 L/min/kg, 110.284 ± 94.176 L/kg, and 732.919 ± 847.32 min for gavage administration of 10 mg/kg , respectively. The results indicate that Tet displays a limited absorption in intestinal tract, even though it has a favorable pharmacokinetic profile after oral or intravenous administration. 相似文献
14.
Reaction behavior of lignin in supercritical methanol as studied with lignin model compounds 总被引：2，自引：0，他引：2
The reaction behavior and kinetics of lignin model compounds were studied in supercritical methanol with a batch-type supercritical
biomass conversion system. Guaiacol, veratrole, 2,6-dimethoxyphenol, and 1,2,3-trimethoxybenzene were used as model compounds
for aromatic rings in lignin. In addition, 5-5, β-1, β-O-4, and α-O-4 types of dimeric lignin model compounds were used as representatives of linkages in lignin. As a result, aromatic rings
and 5-5 (biphenyl)-type structures were stable in supercritical methanol, and the β-1 linkage was not cleaved in the β-1-type structure but converted rapidly to stilbene. On the other hand, β-ether and α-ether linkages of β-O-4 and α-O-4 lignin model compounds were cleaved rapidly, and these compounds decomposed to some monomeric compounds. Phenolic compounds
were found to be more reactive than nonphenolic compounds. These results indicate that cleavages of ether linkages mainly
contribute to the depolymerization of lignin, whereas condensed linkages such as the 5-5 and β-1 types are not cleaved in supercritical methanol. Therefore, it is suggested that the supercritical methanol treatment effectively
depolymerizes lignin into the lower-molecular-weight products as a methanol-soluble portion mainly by cleavage of the β-ether structure, which is the dominant linkage in lignin.
Received: December 19, 2001 / Accepted: April 30, 2002
Acknowledgments This research has been done under the research program for the development of technologies for establishing an ecosystem
based on recycling in rural villages for the twenty-first century from the Ministry of Agriculture, Forestry and Fisheries,
Japan; by a Grant-in-Aid for Scientific Research (B)(2) (no.12460144, 2001.4–2003.3) from the Ministry of Education, Culture,
Sports, Science and Technology, Japan; and under the research program from Kansai Research Foundation for Technology Promotion,
Japan. The authors thank them for their financial support.
This study was presented in part at the 45th Lignin Symposium, Ehime, Japan, October 2000 and the 52nd Annual Meeting of the
Japan Wood Research Society, Gifu, Japan, April 2002
Correspondence to:S. Saka 相似文献
15.
William R. Cobb Rodney E. Will Richard F. Daniels Marshall A. Jacobson 《Forest Ecology and Management》2008,255(12):4032-4039
We quantified the effect of water and nutrient availability on aboveground biomass and nitrogen accumulation and partitioning in four species from the southeastern United States, loblolly pine (Pinus taeda), slash pine (Pinus elliottii), sweetgum (Liquidambar styraciflua), and sycamore (Platanus occidentalis). The 6-year-old stands received five levels of resource input (control, irrigation with 3.05 cm water week−1, irrigation + 57 kg N ha−1 year−1, irrigation + 85 kg N ha−1 year−1, and irrigation + 114 kg N ha−1 year−1). Irrigation significantly increased foliage, stem, and branch biomass for sweetgum and sycamore, culminating in 103% and 238% increases in total aboveground biomass. Fertilization significantly increased aboveground components for all species resulting in 49, 58, 281, and 132% increases in total aboveground biomass for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Standing total aboveground biomass of the fertilized treatments reached 79, 59, 48, and 54 Mg ha−1 for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased foliar nitrogen concentration for loblolly pine, sweetgum, and sycamore foliage. Irrigation increased total stand nitrogen content by 6, 14, 93, and 161% for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased total nitrogen content by 62, 53, 172, and 69% with maximum nitrogen contents of 267, 212, 237, and 203 kg ha−1 for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Growth efficiency (stem growth per unit of leaf biomass) and nitrogen use efficiency (stem growth per unit of foliar nitrogen content) increased for the sycamore and sweetgum, but not the loblolly or slash pine. 相似文献
16.
S. Marañón-Jiménez J. Castro A.S. Kowalski P. Serrano-OrtizB.R. Reverter E.P. Sánchez-Cañete R. Zamora 《Forest Ecology and Management》2011,261(8):1436-1447
After a wildfire, the management of burnt wood may determine microclimatic conditions and microbiological activity with the potential to affect soil respiration. To experimentally analyze the effect on soil respiration, we manipulated a recently burned pine forest in a Mediterranean mountain (Sierra Nevada National and Natural Park, SE Spain). Three representative treatments of post-fire burnt wood management were established at two elevations: (1) “salvage logging” (SL), where all trees were cut, trunks removed, and branches chipped; (2) “non-intervention” (NI), leaving all burnt trees standing; and (3) “cut plus lopping” (CL), a treatment where burnt trees were felled, with the main branches lopped off, but left in situ partially covering the ground surface. Seasonal measurements were carried out over the course of two years. In addition, we performed continuous diurnal campaigns and an irrigation experiment to ascertain the roles of soil temperature and moisture in determining CO2 fluxes across treatments. Soil CO2 fluxes were highest in CL (average of 3.34 ± 0.19 μmol m−2 s−1) and the lowest in SL (2.21 ± 0.11 μmol m−2 s−1). Across seasons, basal values were registered during summer (average of 1.46 ± 0.04 μmol m−2 s−1), but increased during the humid seasons (up to 10.07 ± 1.08 μmol m−2 s−1 in spring in CL). Seasonal and treatment patterns were consistent at the two elevations (1477 and 2317 m a.s.l.), although respiration was half as high at the higher altitude.Respiration was mainly controlled by soil moisture. Watering during the summer drought boosted CO2 effluxes (up to 37 ± 6 μmol m−2 s−1 just after water addition), which then decreased to basal values as the soil dried. About 64% of CO2 emissions during the first 24 h could be attributed to the degasification of soil pores, with the rest likely related to biological processes. The patterns of CO2 effluxes under experimental watering were similar to the seasonal tendencies, with the highest pulse in CL. Temperature, however, had a weak effect on soil respiration, with Q10 values of ca. 1 across seasons and soil moisture conditions. These results represent a first step towards illustrating the effects of post-fire burnt wood management on soil respiration, and eventually carbon sequestration. 相似文献
17.
Shanchun Yan Yingsheng Liu Qi Wang Hong Cheng Jian Zhang Defu Chi 《Frontiers of Forestry in China》2008,3(2):237-242
Dendrolimus superans is one of the important pests feeding on the needles of Larix gmelinii. Six standard compounds, (1R)-(−)-α-pinene, (1S)-(−)-α-pinene, ocimene, (1S)-(−)-β-pinene, R(−)-α-phellandrene and camphene, the main volatiles of L. gmelinii were used to test the electroantennogram (EAG) responses of moths. The results show that the order of the EAG responses of
moths to seven concentrations of these six compounds were as follows: mated females > virgin females > unmated males, except
for 0.1 μL/μL R(−)-α-phellandrene, where the order was: virgin females > mated females > unmated males. There are statistically significant differences
between the EAG responses of virgin females and unmated males (p < 0.05), and also between mated females with virgin females and mated females and unmated males (p < 0.01), which suggests that the mated females are more sensitive to the volatiles of host plant. The results of EAG responses
of the mated females, virgin females and unmated males indicate that they are more sensitive to R(−)-α-phellandrene than to the other volatile components. The active time for the EAG responses of both mated females and unmated
males occurs during the night, i.e., from 20:00 to 04:00 hours. This is consistent with their eclosion, mating and oviposition
periods.
__________
Translated from Scientia Silvae Sinicae, 2007, 43(7): 55–60 [译自:林业科学] 相似文献
18.
We investigated the temporal dynamics of large woody debris (LWD) in five headwater streams before and after the 2001 Dogrib fire in the foothills of Alberta. The density of LWD varied from 5 to 41 logs per 50 m of stream reach and accounted for 19.4 ± 5.1 m3 ha−1 (mean ± standard error) of wood in the riparian zones and 114.1 ± 30.1 m3 ha−1 of wood in the bankfull margins of the stream channel. Individual logs averaged 18.9 ± 1.15 cm in diameter, 5.5 ± 0.7 m in length, and 0.2 ± 0.02 m3 in volume. Logs became significantly shorter in decay classes II–IV. Bridges were longer than partial bridges, which were longer than loose and buried LWD. Individual log volume was greatest for bridges, but not significantly different among other position classes. Bridges and loose LWD contributed little to stream morphology and function; however, 55% of partial bridges and all buried logs contributed to sediment storage, channel armouring, or riffles and pools in the stream channel. 相似文献
19.
Weiqiang Zhang Kangning He Yunqi Wang Baitian Wang Juntao Deng Yi Zhou Xijun Zhong Zhaoqing Li 《Frontiers of Forestry in China》2007,2(2):192-197
In order to offer a scientific basis for cultivation and management of forests, effects of light radiation intensity on photosynthetic
characteristics and water use efficiency of Platycladus orientalis and Pinus tabulaeformis were studied under different soil moisture contents. By adopting artificial control methods to soil moisture, and under simulated
photosynthetic radiation (SPR), the net photosynthetic rate (P
N), transpiration rate (T
r), water use efficiency (WUE) and intercellular CO2 concentration (C
i) of Platycladus orientalis and Pinus tabulaeformis in the semi-arid region of the Loess Plateau, were studied. Results are as follows: within the photon range of 0–2,200 μmol/(m2·s), P
N, T
r and WUE were enhanced with an increase in SPR in both species. P
N and WUE of Platycladus orientalis and Pinus tabulaeformis, however, declined with continued increase in SPR. P
N, T
r, WUE and light saturation point (LSP) of Platycladus orientalis were higher than those of Pinus tabulaeformis, while light compensation point (LCP) of Platycladus orientalis was lower than that of Pinus tabulaeformis at the same soil moisture content. The efficiency of light energy utilization of Platycladus orientalis was higher than that of Pinus tabulaeformis; P
N, T
r and C
i of Platycladus orientalis and Pinus tabulaeformis were enhanced by increasing soil moisture content, whereas WUE declined. At soil moistures of 7.90%, 13.00% and 19.99%, LSP of Platycladus orientalis was 1,275, 1,450 and 1,675 μmol/(m2·s) respectively, and LCP was 42, 25 and 13 μmol/(m2·s) respectively, with corresponding maximal net CO2 photosynthetic rates (P
max) of 3.04, 4.06 and 5.53 μmol/(m2·s). At soil moistures of 7.83%, 13.04% and 20.15%, the LSP of Pinus tabulaeformis was 1,100, 1,325 and 1,500 μmol/(m2·s) respectively, and LCP was 60, 30 and 23 μmol/(m2·s), with P
max of 1.08, 3.35 and 4.36 μmol/(m2·s) respectively.
__________
Translated from Science of Soil and Water Conservation, 2006, 4(3): 108–113 [译自: 中国水土保持科学] 相似文献
20.
Stereochemistry and biosynthesis of guaiacylglycerol-8-O-4′-(sinapyl alcohol) ether (GGSE), an 8-O-4′ neolignan, which consists of coniferyl and sinapyl alcohol moieties, in Eucommia ulmoides were investigated. Four 8-O-4′ neolignans, GGSE, syringylglycerol-8-O-4′-(coniferyl alcohol) ether (SGCE), guaiacylglycerol-8-O-4′-(coniferyl alcohol) ether (GGCE), and syringylglycerol-8-O-4′-(sinapyl alcohol) ether (SGSE), were synthesized. Their erythro and threo diastereomers were separated through acetonide derivatives, intermediates of the synthesis, and identified by means of nuclear magnetic resonance (NMR) spectroscopy. All of the erythro-acetonide derivatives have larger coupling constants (ca 9 Hz) for the C7-H resonances than those of the threo ones (1.5–2 Hz). In the case of the four 8-O-4′ neolignans, the C7-H coupling constants of the threo-isomers are not smaller than those of the erythro ones. GGSE isolated previously from this plant was identified as the erythro isomer by comparison of the 13C-NMR data with synthetic erythro-GGSE and threo-GGSE and the other 8-O-4′ neolignans mentioned as above. Administration of a mixture of [8-14C]coniferyl alcohol and [8-14C]sinapyl alcohol to excised shoots of E. ulmoides was carried out and the incorporation of 14C into erythro-[14C]GGSE was found to be higher than that in threo-[14C]GGSE. The occurrence of diastereoselective formation of erythro-GGSE by cross coupling of coniferyl and sinapyl alcohols is suggested.Part of this paper was presented at the 47th Lignin Symposium, Fukuoka, October 2002 and the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, April 2003 相似文献