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1.
G. B. Douglas A. S. Walcroft S. E. Hurst J. F. Potter A. G. Foote L. E. Fung W. R. N. Edwards C. van den Dijssel 《Agroforestry Systems》2006,66(2):165-178
Silvopastoral systems involving poplars are widespread in rural landscapes in a number of regions of New Zealand. The effect
of widely spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the growth and botanical composition of understorey pasture mixes was determined over 3 years at a southern
North Island hill country site. Pasture mixes comprised existing pasture, and two introduced test swards comprising new grass
(Agrostis capillaris, Dactylis glomerata, Lolium perenne) and legume (Lotus uliginosus, Trifolium repens) cultivars. Pasture accumulation beneath trees (6.6 t DM ha−1 year−1) was 23% less than open (unshaded, no trees) pasture (8.6 t DM ha−1 year−1) and differences in accumulation occurred between tree aspects (North and South sides of trees) when trees were foliated.
In early spring, North plots produced 11–14% more herbage than South plots whereas in late summer, South plots produced up
to 44% more herbage than North plots. Yield of both test swards (6.4 and 8.0 t DM ha−1 year−1) was not significantly different from that of the existing sward (7.4 t DM ha−1 year−1) but productivity varied between swards in spring and summer. One test sward included Lotus uliginosus cv. Grasslands Maku, and the sward produced 30% more DM than the other swards in mid-summer. Dactylis glomerata cv. Grasslands Wana comprised 37% of the DM of swards in which it was sown and was the most successful cultivar, followed
by Grasslands Maku. Both cultivars are recommended for silvopastoral systems where pasture is lightly grazed. 相似文献
2.
Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L−1, 500 μL·L−1) and ambient CO2 concentrations (350 μL·L−1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate
carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the
three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L−1 CO2 concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L−1 CO2, out that ofF. mandshurica decreased under both concentrations 700 μL·L−1 and 500 μL·L−1 CO2. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO2 concentrations.
Foundation item: This paper was supported by the National Natural Science Foundation of China (No. 30070158). Knowledge Innovation Item of
Chinese Academy of Sciences (KZCX2-406) and “Hundred Scientists” Project of Chinese Academy of Sciences.
Biography: Zhou Yu-mei (1973-) Ph. Doctor, Assistant Research fellow Institute of Applied Ecology. Chinese Academy of Sciences. Shenyang
110016. P.R. China.
Responsible editor: Song Funan 相似文献
3.
S. J. Ouédraogo J. Bayala C. Dembélé A. Kaboré B. Kaya A. Niang A. N. Somé 《Agroforestry Systems》2006,68(1):69-80
In the Sahel zone, there is an increasing interest of farmers in conserving and enriching tree diversity on their farms as
a source of food and income. Ziziphus mauritiana Lam. is one of the tree species farmers maintain on their farms. Even though the local variety of Ziziphus mauritiana Lam. was ranked as one of the most preferred species, it produces small fruit whereas farmers are interested in varieties
producing bigger and tasty ones. A factorial experiment in a split split-plot design was carried out to assess the performance
of three introduced cultivars of Indian jujube in Burkina Faso. Investigated factors were irrigation (irrigated with 30 l plant−1 week−1, non-irrigated), rock phosphate containing 25% P2O5 (0 and 150 g P plant−1) and cultivar (Gola, Seb, Umran, and local variety as control). Eighteen months after planting, Umran responded positively
to irrigation and rock phosphate treatments by displaying the tallest height (313 cm) and the biggest collar diameter (6.4 cm).
Gola gave the largest crown diameter (316 cm) at 18 months and the highest fruit production at the first (15.3 kg tree−1) and second (71.6 kg tree−1) fruiting seasons in the irrigated and fertilized treatment. The local variety was less productive compared to the introduced
cultivars. In terms of income generation irrigated and fertilized Gola and irrigated Umran showed the highest potential after
two fruiting seasons with net revenues of F CFA 2,526,915 and F CFA 1,930,546 per hectare respectively. Therefore, Umran and
Gola may be recommended in intensive sub-Saharan peri-urban systems while Seb needs further investigation to improve its water
and nutrient use efficiency through either better timing of water and fertilizer application or symbiotic association with
arbuscular mycorrhizal fungi. 相似文献
4.
Patrick Chesney 《Agroforestry Systems》2008,72(2):149-159
The effect of pruning all branches (complete pruning) or retaining one branch (partial pruning) on the dynamics of nitrogen
cycling in aboveground biomass, nitrogen supplying power of an amended Eutric Cambisol, and fine root length, was studied
in an Erythrina poeppigiana (Walp.) O.F. Cook—tomato (Lycopersicon esculentum Mill.) alley cropping practice in Turrialba, Costa Rica during 1999–2000. Over the 1 year pruning cycle, in which trees were
completely or partially pruned four times, respective aboveground biomass production was 4.4 Mg or 7 Mg ha−1 (2-year-old trees) and 5.5 Mg or 9 Mg ha−1 (8-year-old trees); N cycled in aboveground biomass was 123 kg or 187 kg ha−1 (2-year-old trees) and 160 kg or 256 kg N ha−1 (8-year-old trees); mean fine root length was 489 or 821 m (2-year-old-trees), 184 or 364 m per tree (8-year-old-trees).
Pruning intensity did not significantly affect net N mineralisation and net nitrification rates during the tomato-cropping
season. For the tomato crop, pre-plant mean net N mineralisation rate of 2.5 mg N kg−1 soil day−1 was significantly lower than 16.7 or 11.6 mg N kg−1 soil day−1 at the end of vegetative development and flowering, respectively. Mean net nitrification rates of 3.5, and 4.3 mg N kg−1 soil day−1, at pre-plant and end of vegetative development, respectively, were significantly higher than 0.3 mg N kg−1 soil day−1 at end of flowering. In humid tropical low-input agroforestry practices that depend on organic inputs from trees for crop
nutrition, retention of a branch on the pruned tree stump appears to be a good alternative to removal of all branches for
reducing N losses through higher N cycling in aboveground biomass, and for conserving fine root length for higher N uptake,
although it might enhance competition for associated crops. 相似文献
5.
Changes in phosphorus (P) fractions in a P deficient allophanic soil under P. radiata seedlings grown with broom (Cytisus scoparius L.) and ryegrass (Lolium multiflorum) in pots were studied 14 months after the application of triple superphosphate at the rates of 0, 50, and 100 μg·g−1, to determine the fate of fertiliser-derived P in the rhizosphere soils. Application of P fertiliser increased NaOH-Pi, NaOH-Po, and H2SO4-Pi concentrations in the soil, but decreased the residual-P concentration. The resin-Pi concentration, which is extremely low in this soil (1 to 3 μg·g−1), remained the same. The majority of the added fertiliser P was however recovered in the NaOH-Pi fraction (40%–49%). This is due to the high P fixation in this soil (92%). The second highest P recovery was in NaOH-Po fraction (7%–19%). Under P deficient condition or addition at the rate of 0 μg·g−1, the NaOH-Pi concentration in the radiata rhizosphere soil was lower than that in the bulk soil and broom and grass rhizosphere soils.
This may be due to higher oxalate production by the roots and mycorrhiza under P deficient conditions which released some
of the P fixed to the soils in the rhizosphere, which needs to be tested in future studies.
Foundation project: This work was supported by Centre for Sustainable Forest Management at Forest Research Institute, New
Zealand. 相似文献
6.
Pathogenicity of 13 strains of entomopathogenic fungi belonging to genera Paecilomyces, Tolypocladium, Beauveria, Metarhizium, and Lecanicillium (=Verticillium) was evaluated on fourth instar larvae of Thaumetopoea pityocampa (Schiff.) (Lep.: Thaumatopoeidae). Larvae were treated individually by dipping into conidial suspension with the concentration
of 1.0 × 105 conidia ml−1. All the tested isolates resulted in various levels of mortality (16–100%), and eleven of them were able to grow and sporulate
on dead larvae. Mortality caused by three isolates of P. fumosoroseus, one isolate of Beauveria bassiana and one isolate of Metarhizium anisopliae were significantly higher than that of the other treatments. Three isolates of P. fumosoroseus, one isolate of P. farinosus, and one isolate of M. anisopliae showed mycelial growth and sporulation on significantly more cadavers compared to other treatments. Dose–mortality test was
conducted with P. fumosoroseus (isolate no: 2679), which appeared to be the most promising isolate among the tested fungi, by spraying five concentrations
of its conidia (1.0 × 106, 1.5 × 106, 7.5 × 106, 1.0 × 107 and 1.5 × 107 conidia ml−1). The estimation of the LC50 (95% confidence limits) was 3.4 × 106 (9.3 × 105 − 6.9 × 106) conidia ml−1. This study showed that P. fumosoroseus (isolate no: 2679) could be a good candidate as a microbial control agent against T. pityocampa in forest environment. 相似文献
7.
A participatory selection trial of five provenances from Burkina Faso (3), Mali (1) and Senegal (1) was established in Burkina
Faso in 1997 with the aim of addressing issues of the long juvenile phase and the large variability in annual fruit yields
of Vitellaria paradoxa C.F. Gaertn in West Africa. The objectives of the present study were to evaluate survival rate and the growth performance
of the five provenances, characterize the wetting profile under which the trees of these provenances are growing and quantify
the variation in their seasonal transpiration. The design was a randomized complete block design (RCBD) with single tree as
the experimental unit which was replicated 70 times. The results showed a mean survival rate of 50% for all provenances. Passoré
(Burkina Faso), Djonon-Karaba (Mali) and Botou-Fada (Burkina Faso) provenances showed the highest height and collar diameter
whereas the provenance of Gonsé (Burkina Faso) performed poorly. Djonon-Karaba provenance displayed the highest water use
(2.70 l day−1 tree−1 in 2004 and 2.85 l day−1 tree−1 in 2005). Soil water content under Passoré provenance was the lowest (9.38%) whereas its content under Gonsé provenance (11%)
was the highest with no clear pattern according to the distance from tree trunk. Samecouta and Djonon-Karaba provenances showed
the highest transpiration values per sapwood unit area in 2004 (0.079 l cm−2 day−1) and in 2005 (0.069 l m−2 day−1), respectively. Based on growth performance and water use, it can be recommended at this early stage the selection of Djonon-Karaba
and Passoré provenances as the most suitable for semi-arid regions of West Africa. However, there is a need for further data
to model the long term effects of these provenances on soil water balance and their fruit production before reliable recommendations
can be made to farmers. 相似文献
8.
在孟加拉诺阿卡利地区及相临裸地,对海岸植被(12年和17年生无瓣海桑Sonneratia apetala)进行探索性研究,以便了解海岸造林对土壤特性的影响.在三种不同地带(内陆、中部、海边),在12年生和17年生无瓣海桑林下,土壤深度分别为0-10,10-30和30-40cm,土壤湿度、土壤粒度、有机质、C含量、总N、pH、有效P、K、Na、Ca和Mg含量明显高(p≤0.05,p≤0.01,p≤0.001)于其相临裸地的数据,土壤含盐量明显(p≤0.01)低于其相临裸地的数据.在内陆CharAlim植被,土壤表面的土壤湿度,土壤粒度,有机质,C含量、总N、pH、土壤含盐量、有效P、K、Na、Ca和Mg含量分别为:31.09%、2.24 g·cm-3、2.41%、4.14%、0.58%、7.07、O.09 dS·cm-1、28.06 mg·L-1、O.50 mg·L-1、11.5 mg·L-1、3.30 mg·L-1和2.7 mmol·kg-1;而在相邻的Char Rehania贫瘠地区的相同土壤深度,其相关值分别为:16.69%、1.25g·cm-3、O.43%、0.74%、O.25%、6.57、0.13 dS·cm-1、13.07mg·L-1、O.30mg·L-1、1.4 mg·L-1、O.30 mmol·kG-1和0.50 nag·L-1.然而,在小内陆到海边的植被中,土壤湿度、土壤密度、有机质、C含量、总N、pH、有效P、K、Na和Ca含量逐渐降低,而土壤含盐量、Na和Mg含量却逐渐增加.虽然,在植被与相临裸地的不同土壤深度中土壤质地不同,植被地中砂土份额明显(p≤0.01)低于相临裸地,而粉砂土份额则明显(p≤0.001)高于裸地.在本研究中,所有参数的评价也在为其他地区相关研究得到应用. 相似文献
9.
CO2 fluxes of a Scots pine forest growing in the warm and dry southern upper Rhine plain, SW Germany
The effects of the warm and dry weather in the southern upper Rhine plain in the southwest of Germany on the carbon balance of the Scots pine forest at the permanent forest meteorological experimental site Hartheim were analysed over a 14-month period. The investigation of the net ecosystem exchange of carbon dioxide (F
NEE) of the Scots pine forest started in the extraordinary hot and dry August 2003. Carbon dioxide fluxes were measured continuously using an eddy covariance system and analysed by use of the EDDYSOFT software package. After determining the temperature dependence of the forest ecosystem respiration and the daytime light dependence of the CO2 exchange, monthly and annual carbon balances of the Scots pine forest were calculated. Mean peak daytime F
NEE rates observed in August and September 2003 (−6.5±3.6 μmol m−2 s−1) were drastically lower than in August and September 2004 (−11.8±5.2 μmol m−2 s−1), which did not show pronounced deviations from the mean long-term (1978–2002) climatic conditions. In August 2003, the Hartheim Scots pine forest was a distinct CO2 source (35 g C m−2). The estimates of the annual carbon sink strength of the Scots pine forest ranged between −132 g C m−2 (August 2003–July 2004) and −211 g C m−2 (October 2003–September 2004). The main uncertainty in the determination of the carbon balance of the Hartheim Scots pine forest was introduced by the frequently low turbulence levels, i.e. the friction velocity corrected night-time F
NEE fluxes. 相似文献
10.
Interest in planted fallow systems has focused on soil fertility improvement, neglecting other potential benefits of such
systems. It is important to quantify other processes responsible for crop yield increases under planted fallows, such as weed
control. The suppressive potential on weeds of Flemingia macrophylla [(Willd.) Merrill] and Pueraria phaseoloides (Roxb.) Benth, planted fallows was evaluated in field trials in three villages in southern Cameroon. In each village, experiments
were set up in 4–5 year-old bush fallow dominated by Chromolaena odorata (L.) R. M. King & H. Rob. and 20 year-old secondary forest. Total aboveground biomass production of P. phaseoloides was 7.45 Mg ha−1, 4.2 times higher than F. macrophylla (1.78 Mg ha−1 ; P < 0.05). The high biomass of P. phaseoloides resulted in a significantly greater reduction in total weed biomass compared to Flemingia macrophylla in both wet and dry seasons. In the wet season (11 and 18 MAP), there were significant fallow system × land use and fallow
system × village interactions for total weeds and broadleaf weeds. P. phaseoloides in bush (0.55 Mg ha−1), and P. phaseoloides at Ngoumou (0.09 Mg ha−1) had the lowest total weeds in the wet seasons. After the dry season, the lowest total weed mass was consistently recorded
in P. phaseoloides while the highest was in the natural regrowth. The population of grasses was always higher in the F. macrophylla system than in P. phaseoloides system throughout the wet and dry seasons. Grass biomass in the P. phaseoloides-forest LUS was the least (0.01 Mg ha−1), 58 times lower than in F. macrophylla-bush (0.58 Mg ha−1). Biomass production of P. phaseoloides was highly significantly correlated with total weed biomass (r = −0.64; P = 0.004) while no relationship was found between biomass production of F. macrophylla and total weed biomass (r = −0.08, P = 0.747). It was concluded that P. phaseoloides was a suitable leguminous species for weed control. But for F. macrophylla, its low biomass production coupled with a compact plant architecture compromised it as an appropriate species for weed control
in a planted fallow system. 相似文献
11.
Tree Performance and Root-Zone Salt Accumulation in Three Dryland Australian Plantations 总被引：3，自引：0，他引：3
Robert D. Archibald Richard J. Harper John E. D. Fox Richard P. Silberstein 《Agroforestry Systems》2006,66(3):191-204
Doubts exist about the effectiveness of establishing trees near saline discharge areas on farmland to manage dryland salinity.
These centre on low rates of water uptake from saline water tables, salt accumulation in tree root zones and the consequent
poor growth and survival of trees. Despite this, trees still survive in many plantations established adjacent to saline discharge
areas and land-holders often favour such locations, as they do not compete for arable land such as that occurs with plantings
in recharge areas. Tree performance and salt accumulation were assessed in three experimental plantations established adjacent
to saline discharge areas 20–25 years ago. These were all in the 400–600 mm rainfall zone of south-western Australia. Mean
soil salinity, within 1 m of the surface, ranged from 220 to 630 mS m−1, while permanent ground-waters occurred within 2–5 m of the surface and had electrical conductivities ranging from 175 to
4150 mS m−1. The study confirmed the low growth rates expected for trees established over shallow, saline water tables in a relatively
low rainfall environment, with estimated wood volumes in Eucalyptus cladocalyx, E. spathulata, E. sargentii, E. occidentalis and E. wandoo of between 0.5 and 1.5 m3 ha−1 yr−1. Values of up to 3 m3 ha−1 yr−1 were obtained on soils with low salinity (<200 mS m−1). The excellent survival (>70%) of several Eucalyptus species confirms that discharge plantations species can persist, despite increasing soil salinity. However, the long-term
sustainability of such plantings (50–100 years) without broader landscape treatment of the present hydrological imbalance
must be questioned. 相似文献
12.
Yoshihiro Hayashida 《Journal of Forest Research》2001,6(2):53-61
Multiple regression analyses were applied to the respiration data obtained by an excision method to distinguish between maintenance
and growth respiration in stems ofPinus densiflora. Among several types of regression models, a few models showed marked stability of coefficient of growth related respiration
that are independent of degrees of correlation between predictors and any combinations of predictors. These models predicted
growth respiration as 0.45 g CO2 g (dry weight)−1. At 15°C, sapwood maintenance respiration rate was estimated to 0.72 mg CO2 g−1 day−1. These estimates were not different from the results obtained with standing trees. 相似文献
13.
Tetsuji Itoh Yoshikazu Sato Tsutomu Mano Ryûtarô Iwata 《Journal of Forest Research》2009,14(2):117-122
We examined 24 microsatellite markers to
select those most suitable for individual identification
and parentage tests of brown bears
(Ursus arctos)
based on statistical parameters and experimental error
using liver samples (38 issues) from nuisance bears killed
in the Akan–Shiranuka Region, eastern Hokkaido, Japan from
1996 to 2006. We found seven microsatellite markers suitable
for identifying individuals (G1A, G10B, G10L, UarMU5, UarMU23,
UarMU50, and UarMU51; probability of identity
P
id = 3.17
× 10−7; probability of identity of
sibs P
id-sib
= 2.23 × 10−3), 12 microsatellite
markers suitable for parentage testing when one parent is
known [G1A, G1D, G10B, G10L, G10P, UarMU5, UarMU23, UarMU50, UarMU51,
UarMU59, UarMU61, and UarMU64; probability of excluding one parent
(PE I = 0.9991)], and 15 microsatellite markers for parentage
testing when neither parents are known [three markers added to
the above: G10M, G10X, and UarMU9;
probability of excluding both parents (PE II = 0.9869)]. 相似文献
14.
Arazá (Eugenia stipitata), a fruit shrub originating from Western Amazonia, was evaluated growing in association with timber shade trees (Acacia mangium or Cordia alliodora) or with plantain (Musa sp.) as a potential commercial species for the tropical moist lowlands of Talamanca, Costa Rica. Height and crown width of
the four-year-old shrubs varied between 2.7–2.8 m and 2.9–3.1 m, respectively. Flowering was positively correlated with initial
fruit formation 1 month later and initial fruit formation with fully developed fruits a subsequent month after that. Three
to four-year-old plants produced 20.0, 20.0, and 24.5 t ha−1 yr−1 (fresh fruits) in associations with A. mangium, C. alliodora and plantain, respectively, with higher production in rainy months. Fruit production in later years under C. alliodora (six to eight-year-old shrubs) was 26.5 t ha−1 yr−1. Where markets exist for E. stipitata fruit, the association can be recommended for tropical humid lowlands of Central America. 相似文献
15.
Junko Nagakura Akio Akama Takeo Mizoguchi Hiroaki Okabe Hidetoshi Shigenaga Takashi Yamanaka 《Journal of Forest Research》2006,11(5):299-304
To investigate the potential effects of nitrogen (N) deposition on Japanese forests, a chronic N-addition experiment that
included three treatments (HNO3, NH4NO3, and control) was carried out in a 20-year-old Japanese cedar (Cryptomeria japonica D. Don) stand in eastern Japan over 7 years. The amount of N applied was 168 kg N ha−1 year−1 on the HNO3 plots and 336 kg N ha−1 year−1 on the NH4NO3 plots. Tree growth, current needle N concentration, and soil solution chemistry were measured. Nitrogen application decreased
the pH and increased NO3
−, Ca2+, Mg2+, and Al concentrations in the soil solution. The needle N concentration increased in both of the N plots during the first
3 years. Nevertheless, the annual increments in height and in the diameter at breast height of the Japanese cedars were not
affected by N application, and no visible signs of stress were detected in the crowns. Our results suggest that young Japanese
cedar trees are not deleteriously affected by an excess N load. 相似文献
16.
Validation of a canopy photosynthesis model for cocksfoot pastures grown under different light regimes 总被引：3，自引：0，他引：3
Daily net canopy photosynthesis (P
n) was predicted for cocksfoot (Dactylis glomerata L.) canopies grown under different light regimes by integration of a leaf photosynthesis model developed for the light-saturated
photosynthetic rate (P
max), photosynthetic efficiency (α) and the degree of curvature (θ) of the leaf light–response curve. When shade was the only
limiting factor, the maximum P
n (P
nmax) was predicted to decrease approximately linearly from 33.4 g CO2 m−2 d−1 to zero as photosynthetic photon flux density (PPFD) fell from full sunlight (1800 μmol m−2 s−1 PPFD) to 10% of this in a fluctuating light regime. It was also predicted that at 50% transmissivity P
nmax was higher for a continuous light regime (10.4 g CO2 m−2 d−1) than for a fluctuating light regime with the same intensity (8.4 g CO2 m−2 d−1). The canopy photosynthesis model was then used to predict dry matter (DM) production for cocksfoot field grown pastures
under a diverse range of temperature, herbage nitrogen content and water status conditions in fluctuating light regimes. This
prediction required inclusion of leaf area index and leaf canopy angle from field measurements. The model explained about
85% of the variation in observed cocksfoot DM production for a range from 6 to 118 kg DM ha−1 d−1. The proposed model improves understanding of pasture growth prediction through integration of relationships between shade
limitations in fluctuating light regimes and other environmental factors that affect the canopy photosynthetic rate of cocksfoot
pastures in silvopastoral systems. 相似文献
17.
Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this
species was carried out in different light intensities (0.14–946.00 μmol·m−2·s−1). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation
point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and
leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m−2·s−1 to 569.00 μmol·m−2·s−1 (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency
was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of
569.000 μmol·m−2·s−1 or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m−2·s−1 (8–961 lx), or 10 μmol·m−2·s−1 for above 6 h.
Foundation item: This study was supported by the Research Foundation of Northeast Forestry University.
Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China.
Responsible editor: Zhu Hong 相似文献
18.
This paper summarizes several studies on N recycling in a tropical silvopastoral system for assessing the ability of the system
to increase soil fertility and insure sustainability. We analyzed the N2 fixation pattern of the woody legume component (Gliricidia sepium), estimated the recycling rate of the fixed N in the soil, and measured N outputs in tree pruning and cut grass (Dichanthium aristatum). With this information, we estimated the N balance of the silvopastoral system at the plot scale. The studies were conducted
in an 11-year-old silvopastoral plot established by planting G. sepium cuttings at 0.3 m × 2 m spacing in natural grassland. The plot was managed as a cut-and-carry system where all the tree pruning
residues (every 2-4 months) and cut grass (every 40-50 days) were removed and animals were excluded. No N fertilizer was applied.
Dinitrogen fixation, as estimated by the 15N natural abundance method, ranged from 60-90% of the total N in aboveground tree biomass depending on season. On average,
76% of the N exports from the plot in tree pruning (194 kg [N] ha–1 yr–1) originated from N2 fixation. Grass production averaged 13 Mg ha–1 yr–1 and N export in cut grass was 195 kg [N] ha–1 yr–1. The total N fixed by G. sepium, as estimated from the tree and grass N exports and the increase in soil N content, was about 555 kg [N] ha–1 yr–1. Carbon sequestration averaged 1.9 Mg [C] ha–1 yr–1 and soil organic N in the 0-0.2 m layer increased at a rate of 166 kg [N] ha–1 yr–1, corresponding to 30% of N2 fixation by the tree. Nitrogen released in nodule turnover (10 kg [N] ha–1 yr–1) and litter decomposition (40 kg [N] ha–1 yr–1) contributed slightly to this increase, and most of the recycled N came from the turnover or the activity of other below-ground
tree biomass than nodules.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
19.
AbbasAli Zamani AliAsghar Talebi Yaghoub Fathipour Valiollah Baniameri 《Journal of pest science》2006,79(4):183-188
The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2–64 third-instar nymphs of A.
gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A.
colemani increased linearly as the temperature increases from 10 to 30°C, but in A.
matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical dome-shaped pattern. The highest instantaneous attack rate for A.
colemani and A.
matricariae were calculated 0.940 ± 0.144 day−1 at 30°C and 0.687 ± 0.157 day−1 at 25°C, respectively. Handling time (T
h) for A.
colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A.
matricariae, (T
h) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A.
colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A.
colemani maybe more effective for biological control of the cotton aphid during warmer periods. 相似文献
20.
Despite growing attention to the role of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in forest nutrient
cycling, their monthly concentration dynamics in forest ecosystems, especially in subtropical forests only were little known.
The goal of this study is to measure the concentrations and monthly dynamics of DOC and DON in precipitation, throughfall
and stemflow for two plantations ofSchima superba (SS) and Chinese fir (Cunninghamia lanceolata, CF) in Jianou, Fujian, China. Samples of precipitation, throughfall and stemflow were collected on a rain event base from
January 2002 to December 2002. Upon collection, all water samples were analyzed for DOC, NO3
−−N, NH4
+−N and total dissolved N (TDN). DON was calculated by subtracting NO3
−−N and NH4
+−N from TDN. The results showed that the precipitation had a mean DOC concentration of 1.7 mg·L−1 and DON concentration of 0.13 mg·L−1. The mean DOC and DON concentrations in throughfall were 11.2 and 0.24 mg·L−1 in the SS and 10.3 and 0.19 mg·L−1 in the CF respectively. Stemflow DOC and DON concentrations in the CF (19.1 and 0.66 mg·L−1 respectively) were significantly higher than those in the SS (17.6 and 0.48 mg·L−1 respectively). No clear monthly variation in precipitation DOC concentration was found in our study, while DON concentration
in precipitation tended to be higher in summer or autumn. The monthly variations of DON concentrations were very similar in
throughfall and stemflow at both forests, showing an increase at the beginning of the rainy season in March. In contrast,
monthly changes of the DOC concentrations in throughfall of the SS and CF were different to those in stemflow. Throughfall
DOC concentrations were higher from February to April, while relatively higher DOC concentrations in stemflow were found during
September–November period.
Foundation item: This study was supported by the Teaching and Research Award program for MOE P.R.C. (TRAPOYT).
Biography: Guo Jian-fen (1977-), female, Ph. Doctor in College of Life Science, Xiamen University, Xiamen 361005, P.R. China.
Responsible editor: Zhu Hong 相似文献