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1.
Theosierx`,eevilxvasfirstfoundinHarbin,Chinainl953['].ltisascriouspestofpoplarandwillows.ltslarvaen1inetrtmksofhosttreesTheinLfestedtreeslosetheirvigorandwindfalloftenoccurs.Thelosscausedbythispestisverygreat.9o66.6hm2poplartreeshavebeeninfestedand5O22.2hIn2havebeendestroyedinHeilonaiiangPro1'incesincel97O.Inotherprovinces,suchasLiaoning,JilinandInnerMongolia,agreatnumberofpoplarhavebeendestroyedbythispest,too.Thispestbe-comesoneofthemostdesthectivepestsinChina.Thisstudvismai11lvtofindou… 相似文献
2.
Xiang Kai FuNortheast Forestry University 《林业研究》1993,4(1):1-5
Since the shelterbelt systems of 1,092,260 hm~2have been established for thirteenyears from 1978,have formed 526,541 networks and protected 13,619,400 hm~2 land in westernpart of Northeast region of China.According to the research work we did in the last five years,the results of research project showed that the shelterbelts had improved the environmentsignificantly.A parameter of comprehensive effects of temperature,moisture and wind in thenetworks(E_c=246.52-12.17E+0.58T+6.58U)which is an active method to estimate the effects ofshelterbelt on farmland,is around 21.1-30.9mm/month improving the moisture state in dryseason,helping the crop yield increasing on the average by 19.8%.The effective accumulatedtemperature(≥10℃)incrcases by 71℃;the cropland area which suffered from wind and frostdamage decreases by 80-90%,the grass coverage on the pastureland and grass production in-creases by 13% and by 49.4-72%,rough protein,rough fat and nitrogen-free extract of grassincrease by 3.34%,2.4% and 8.4%separat 相似文献
3.
Using thermal dissipation and the ICT-2000TE equipment made in Australia, the sap flow of Castanopsis jianfengensis and various environmental factors were measured simultaneously in a mixed tropical montane rainforest at Jianfengling Nature
Forest Reserve (18°369′N, 108°52′E, 860 m elevation) during the dry and rainy seasons of 2002. The results show that sap flow
velocity of C. jianfengensis exhibited a monopeak pattern on clear days and a multi-peak pattern on cloudy or rainy days. Sap flow velocity had significant
positive correlations with solar radiation, air temperature, vapor pressure deficit and wind speed and a negative correlation
with air relative humidity. In the dry season, sap flow velocity had a significant positive correlation with soil temperature
and poor correlation with soil moisture; it was the opposite in the rainy season, indicating that precipitation clearly affected
sap flow. Linear regression models between sap flow and environmental factors were established and were significant at the
0.005 level of probability. The mean transpiration rates of C. jianfengensis were 103.5 and 41.3 kg/d in our single tree and 1.94 and 0.77 mm/d in stand level in the dry and rainy season, respectively.
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Translated from the Chinese Journal of Applied Ecology, 2007, 18(4): 742–748 [译自:应用生态学报] 相似文献
4.
温度对杉木林土壤呼吸的影响(英文) 总被引：2，自引：0，他引：2
Soil samples collected from the surface soil (0(10 cm) in an 88-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at the temperatures of 15°C, 25°C and 35°C in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35°C, followed by those at 25°C, and 15°C. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25°C, but it decreased to 1.2 at 25- 35°C. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period (on the 90th day) was less than 10% of the initial C amounts prior to incubation. 相似文献
5.
《Forest Ecology and Management》1996,83(3):217-228
A gap-model was modified in order to utilise ground-true forest data to predict the effect of climate change on forests in Finland. The model's resonse to climate change was evaluated by using test scenarios of changing temperature and precipitation in Finland. Model computations indicated that in Southern Finland conifers, Norway spruce in particular, suffered from rapidly increasing temperature (0.5°C in a decade), but Scots pine derived a small benefit from a temperature increase of 0.1°C in a decade. Pendula birch profited by increasing temperature. In Northern Finland all tree species (Scots pine, Norway spruce, Pendula birch and Pubescent birch) used in simulations increased their stand volume and total production due to increased temperature. Precipitation changes had only little effect on stand volume and total production of trees on sites with coarse moraine as soil texture. The effect of soil texture on model performance was examined at a southern site under current climate using moraine, sand and silt as soil textures. Stand volume and total production of coniferous trees remained at a lower level on sand than on moraine soils or on silt. Response of birches to soil texture was similar to that of the conifers, but differences in total production between soil textures remained smaller. 相似文献
6.
JIN Zhao QI Yu-chun DONG Yun-she 《林业研究》2007,18(3):231-235
The diurnal and seasonal dynamics of soil respiration in the A. ordosica shrubland on Ordos Plateau were investigated in the growing season （May-October） of 2006 and their environmental driving factors were also analyzed, Results indicated that diurnal dynamics of soil respiration rate and its temperature dependence showed some discrepancy in two different growth stages （the vegetative growth stage and the reproductive growth stage）. During the vegetative growth stage, the diurnal variation of soil respiration was slight and not correlated with the daily temperature change, but during the reproductive growth stage, the daily respiration variation was relatively large and significantly correlated with the diurnal variation of air and soil temperature. In the growing season, the peak value of soil respiration occurred at July and August because of the better soil water-heat conditions and their optimal deployment in this period. In the shrubland ecosystem, precipitation was the switch of soil respiration pulses and can greatly increase soil respiration rates after soil rewetting. Moreover, the soil respiration rates in the growing season and the air temperature and soil surface water content were closely correlated （p〈0.05） each other. The stepwise regression model indicated that the variation of soil surface moisture accounted for 41.9% of the variation in soil respiration （p〈0.05）. 相似文献
7.
木麻黄防护林带对改善农田小气候效应的研究 总被引：2，自引：1，他引：1
通过对木麻黄防护林带庇护下的农田小气候进行定位观测,分析了木麻黄林带的防护功能,结果表明:木麻黄农田防护林带具有降低风速的作用,背风面20~100 m,风速比对照点降低27%~67%,且随着风速的增大,降低风速的效果越明显;林带对气温和地温具有调节作用,背风面各点白天增温,夜间降温;林带能够减小蒸发量,林带背风面20~100 m范围内日均蒸发量比对照点降低16.2%~24.2%。 相似文献
8.
Width is one of the key parameters of a shelterbelt. Traditional methods to acquire this width are mainly based on field measurement, which is impractical for monitoring shelterbelts at regional scale. There are many studies analyzing linear objects, but they are not directly applicable to width detection of such objects. In this paper, we analyzed relationships among vegetation fractions retrieved from SPOT5 remote sensing imagery with 10 m × 10 m spatial resolution, shelterbelt area, and shelterbelt width in one pixel. Based on this analysis, we developed a method for recognizing shelterbelt width from a remote sensing image of central western Jilin Province, China. The result was validated by field measurement data and measurement from an aerial image of 0.5 m × 0.5 m spatial resolution. Mean absolute error was 2.40 and 2.73 m respectively, suggesting that the proposed method is feasible and its accuracy is acceptable. The study provides a valuable method for monitoring shelterbelt width across large spatial scales and an accurate input parameter for the recognition of shelterbelt porosity from remote sensing data in future research. 相似文献
9.
The effect of climate conditions and strong thinning on the soil organic layer, surface soil, and nitrogen and water utilization
by plants was evaluated for hinoki cypress forests in Shikoku and Kinki districts in Japan. Thirty-five forests were selected
in Kochi, Ehime, Kagawa and Kyoto prefectures. The mean annual temperate of the studied forests ranged from 9.6 to 16.3°C,
and the mean annual precipitation ranged from 1,350 to 3,960 mm. Carbon and nitrogen content in the organic layer decreased
with increasing mean annual precipitation. In high precipitation areas, carbon and nitrogen content in the organic layer would
be lower due to rapid decomposition with low soil acidity and due to loss of litter because of heavy rainfall. Carbon and
nitrogen content in the surface soil at 0–5 cm depth decreased with increasing mean annual temperature, but was not related
to mean annual precipitation. The results indicate that loss of organic layer by raindrops in a high precipitation area causes
lower nitrogen availability for plants. Strong thinning significantly reduced carbon and nitrogen content in the organic layer
but did not affect nitrogen concentration and δ13C in leaves. These results suggest that climate conditions and strong thinning can affect carbon and nitrogen content in the
organic layer and subsequent nitrogen availability in soil, but strong thinning does not appreciably affect nitrogen and water
utilization by hinoki cypress. 相似文献
10.
Robinia pseudoacacia stands act as a typical ecological protection forest in hilly semi-arid area of China. Two fields of surface runoff were
separately set up inR. pseudoacacia stand and its clearcut area in the western Liaoning Province (18°50’–122°25’ E, 40°24’–42°34’ N) for measuring the characteristics
of runoff and sediment as well as soil moisture dynamics. Contractive analysis of the two land types showed that there existed
a significant difference in volumes of runoff and sediment between the sites ofR. pseudoacacia stand and its clearcut area. The runoff volume and sediment volume in clearcut are were much bigger than those inR. pseudoacacia stand, with an increase amount of 40%–177% for runoff and 180%–400% for sediment. Hydrograph of surface runoff of typical
rainfall showed that the peak value of runoff inR. pseudoacacia stand was decreased by 1.0–2.5×10−3m3·s−1 compared with that in its clearcut area, and the occurring time of peak value of runoff inR. pseudoacacia stand was 10–20 min later than that in its clearcut area. Harmonic analysis of soil moisture dynamics indicated that the
soil moisture inR. pseudoacacia stand was 2.3% higher than that in clearcut area, and the soil moisture both inR. pseudoacia stand and its clearcut area could be divided into dry season and humid season and varied periodically with annual raifall
precipitation. It was concluded thatR. pseudoacacia stand plays a very important role in storing water, increasing soil moisture, and reducing surface runoff and soil erosion.
Foundation item: This paper was supported by Chinese “863” Plan Water-Saving Agriculture (2002AA2Z4321), the Key Knowledge Innovation Project
(SCXZY0103), and The “Tenth-five” Plan of Liaoning Province (2001212001).
Biography: GAO Peng (1967-), male, Dr. candidate, associate professor of Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, P. R. China.
Responsible editor: Song Funan 相似文献
11.
We designed and tested a soil temperature control system for plant ecophysiological experiments in greenhouses and growth
chambers. The system consists of a plywood box, polyethylene liner, insulation, seedling containers, a water pump, and a flow-through
heater or chiller. One hundred and twelve seedling containers (11cm diameter, 13.5 cm high) are mounted in the plywood box.
There is a hole at the bottom center of each container to allow the free drainage of irrigation water and fertilizer solution.
The space between containers is filled with water that is circulated through the chiller/heater. The water is also circulated
within the plywood box by a water pump to increase the uniformity of temperature. The system was tested for three soil temperatures
(5, 20, and 30°C) over a period of four months. The containers were filled with a peat-moss vermiculite mixture and planted
with tree seedlings. The test showed that the soil temperature was almost equal to the water temperature for all three soil
temperatures (regression slop = 0.99, intercept = 0.12,r
2 = 1.00). The average soil temperatures were within (0.41°C of the set values. The soil temperature of the 112 containers
within the same box followed a normal distribution with a small standard deviation (0.34°C for the 30°C treatment). There
was a temperature gradient from the top to the bottom of the container (< 1°C). The direction of the temperature gradient
was determined by the direction of temperature difference between the soil and the ambient air. When the soil temperature
was lower than air temperature, the soil temperature decreased from the top to the bottom of the container, and vise versa.
The soil temperature was higher during the day than at night (difference < 1.5°C).
Funding for this research was provided by Lakehead University, CFI, ORDCF, and NSERC research grants to Dang, and an NSERC
PGS A to Cheng. 相似文献
12.
13.
Xiongwen Chen 《Journal of Sustainable Forestry》2013,32(4):261-279
ABSTRACTThe quantification of major biophysical features of forest and urban areas is important for assessing ecological service from land use change and is necessary for sustainable regional planning. This study compares biophysical indicators related to local climate, air quality, and hydrology using remote sensing and derived data at a representative forest area to a nearby urban area located in Huntsville, Alabama. Results indicate that (a) there was a higher albedo, a lower average air temperature, and 10% more annual precipitation in the forest area; the assumed air conditioner working time was about 7 days more per year in the urban area; (b) there was better air quality in the forest area based on lower levels of PM2.5, PM10, and SO2; and (c) there was a higher latent heat, more runoff per year (both aboveground and belowground runoff), and a greater soil water content at the forest area. Although Huntsville is a small city, there were some profound biophysical differences in this urban area compared to the nearby forest. These results are useful for analyzing sustainability, planning regional resources (e.g., energy, air, and water), and estimating ecological services from forests. 相似文献
14.
The advantages of associating shade trees in coffee agroforestry systems (AFS) are generally thought to be restricted mostly
to poor soil and sub-optimal ecological conditions for coffee cultivation whereas their role in optimal conditions remains
controversial. Thus, the objective of this study was to investigate, under the optimal coffee cultivation conditions of the
Central Valley of Costa Rica, the impact of Inga densiflora, a very common shade tree in Central America, on the microclimate, yield and vegetative development of shaded coffee in comparison
to coffee monoculture (MC). Maximum temperature of shaded coffee leaves was reduced by up to 5°C relative to coffee leaf temperature
in MC. The minimum air temperature at night was 0.5°C higher in AFS than air temperature in MC demonstrating the buffering
effects of shade trees. As judged by the lower relative extractable water (REW) in the deep soil layers during the dry season,
water use in AFS was higher than in MC. Nevertheless, competition for water between coffee and associated trees was assumed
to be limited as REW in the 0–150 cm soil layer was always higher than 0.3 in shaded coffee compared to 0.4 in monoculture.
Coffee production was quite similar in both systems during the establishment of shade trees, however a yield decrease of 30%
was observed in AFS compared to MC with a decrease in radiation transmittance to less than 40% during the latter years in
the absence of an adequate shade tree pruning. As a result of the high contribution (60%) of shade trees to overall biomass,
permanent aerial biomass accumulation in AFS amounted to two times the biomass accumulated in MC after 7 years. Thus provided
an adequate pruning, Inga-shaded plantations appeared more advantageous than MC in optimal conditions, especially considering the fact that coffee
AFS provides high quality coffee, farmers’ revenue diversification and environmental benefits. 相似文献
15.
Kazuki Miyamoto Shiro Okuda Yoshiyuki Inagaki Mahoko Noguchi Takeharu Itou 《Journal of Forest Research》2013,18(3):256-269
We investigated mean leaf retention time in order to elucidate the factors affecting regional and local variations in stand-level leaf longevity in hinoki cypress (Chamaecyparis obtusa) plantations. Our study sites consisted of six stands at a low elevation (320–370 m a.s.l.) and 12 stands at a high elevation (850–970 m a.s.l.) in southwestern Japan. We also used published data on leaf longevity in stands at various elevations to clarify the regional-scale variations in leaf longevity and their relationships to environmental factors. At the regional scale, leaf longevity increased with increasing elevation and with decreasing air temperature, growing season length, and Kira’s warmth index across sites. Similar relationships were obtained for the variation in leaf mass. At the local scale, leaf longevity did not show a clear relationship with topographic position, soil water content, or soil C/N ratio. Contrary to our expectation, leaf longevity was negatively correlated with the leaf C/N ratio at both study sites, although the significance level was marginal. This indicates greater leaf longevity with better leaf nutrient status. Our results suggest that responses of leaf longevity in hinoki cypress stands to environmental factors would be more prominent at the regional scale than at the local scale, although large variation was detected at the local scale. Air temperature and growing season length appear to be the main drivers of the variation in leaf longevity at the regional scale, whereas the causal factors are unclear at the local scale. 相似文献
16.
本文以生态经济型防护林为例 ,对“京九”铁路大兴段绿化模式的动力效应进行了研究。结果表明 :对比旷野农田 (对照点 ) ,防护农田的风速平均约降低 18.9% ,距林带树高 0 .5倍距离处 (0 .5H)风速的降低率可达 30 .0 %左右 ,距林带 4H处至农田中心的风速降低率为 1.8% 7.1% ,林带的有效防风距离至少可达 4H ;防护农田内理查逊数 (Ri)总体平均值比对照点约高 4 .6 % ,动力速度总体平均值比对照点约低 14 .7%。 相似文献
17.
To guide the development of thermal decomposition methods for disposal of CCA treated wood, reactions during the thermal
decomposition of CCA treated wood were modeled using thermogravimetric analysis (TGA), with special focus placed on arsenic
volatilization. Simple inorganic compounds, such as As2O5, CuO, and Cr2O3, were used to model the thermal behavior of the inorganics in CCA treated wood. In air and nitrogen, arsenic (V) oxide began
to volatilize at 600 °C during temperature ramps at 5 °C/min. During a 5 °C/min ramp in a hydrogen mix, arsenic (V) oxide
began decomposition at 425 °C. Arsenic volatile loss from CCA treated wood can depend strongly on the gases produced by wood
thermal decomposition. In the presence of As2O5, chromium (III) oxide and copper (II) oxide formed arsenates in air and nitrogen. Chromium arsenates began decomposition
as low as 790 °C. This suggested that chromium arsenates in CCA treated wood formed during original preservative fixation
may decompose as low as 790 °C. Copper arsenates were stable up to 900 °C in air, but showed only a limited range of stability
in nitrogen. Depending on process conditions, the formation of copper arsenates may limit arsenic loss during thermal decomposition
of CCA treated wood up to 900 °C. The thermal decomposition of inorganic oxides was influenced by interactions with wood and
wood decomposition products. In a dry YP sawdust/As2O5 mix, arsenic (V) oxide volatilized at 370 °C during inert pyrolysis at 5 °C/min and at 320 °C during smoldering combustion
at 5 °C/min. Thermal dwells of a dry YP/As2O5 mix showed no arsenic loss at 250 °C, but significant loss occurred during higher temperature dwells. During inert pyrolysis
at 5 °C/min, the formation of complexes and hydrates were shown to prevent arsenic loss up to 400 °C.
Received 14 July 1999 相似文献
18.
Populus simonii Carr trees are the most abundant species in Xinjiang farmland shelterbelt. They played an important role in protecting farmland ecosystem. Their stand transpiration rates and canopy conductances ranged from 0.14 to 1.02 cm d?1 and from 1.19*10?3 to 8.99*10?5 m s?1, respectively, during the 2014 growing season. Transpiration rate was showed quadratic polynomial regression with vapor pressure deficit (VPD) and air temperature (T), and exponential relationship with solar radiation (Rn). Furthermore, transpiration peaked at VPD, T, and Rn were 2.1 kPa, 23 °C, and 200 W m?2, respectively. Canopy conductance increased exponentially with the increasing Rn, whereas decreased logarithmically with the increasing VPD. Besides, transpiration increased with the increasing T and VPD ,and decreased sharply with the increasing soil water deficit. Finally, canopy conductance increased with the decreasing atmospheric water deficit. These results are not only providing the basis for more detailed analyses of water physiology and growth of Populus simonii Carr trees for the later application of a climate-driven process model, but also might have implications for farmland shelterbelt management. 相似文献
19.
By modeling the condition of light climate, we studied the negative effect of shadows in a shelterbelt forest. Based on the
calculation of the apparent trajectory of solar motion according to an ellipsoid crown projection model and a Monsi light
transmission model, radiation values of 36 experimental sites were measured using a light quantum meter. Estimates of daily
solar radiation distribution from measured values were obtained. We built a crown projection model and simulated the conditions
of a light climate in the forest. The trajectory of the shadow motion is shaped like a butterfly arc. The situation of the
outside is affected by tree height (H) and that of the inner arc by height below the branches. In an area of 1.0 × H (toward the east and west of the tree) and 0.6 × H (toward the north), transmittance was below 90%, which means that the effect of shadow hazards occurs in this area. As well,
the effect was strong at the bottom of the tree. The area of shadow hazards in the east and west of the tree was large and
small in the south. The projection area of the shelterbelt forest was largest along an east and west direction. A certain
distance between crops and the shelterbelt should be maintained when the shelterbelt is in a north-south direction. Therefore,
the effect of shadow hazard will decrease north of the tropic of cancer. Cutting out the lower branches from the trees of
the existing shelterbelt in a suitable and timely manner can reduce the area of the shadows.
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Translated from Journal of Northwest A&F University, 2008, 36(6): 113–118 [译自: 西北农林科技大学学报] 相似文献
20.
In order to understand the reason why glycerin pre-treatment can accelerate the deformation fixation of compressed wood, the
interaction between glycerin and wood at various temperatures was investigated in this study from stress relaxation approach.
The compression stress relaxation curves of poplar (Populus cathayana Rehd.) samples impregnated with glycerin were measured at temperatures ranging from 25 to 180°C, together with the curves
of oven-dry wood at temperatures between 100 and 180°C for comparison. The activation energy was calculated according to the
Eyring’s absolute rate reaction theory. The results showed that temperature had very obvious effect on stress relaxation for
both glycerin-treated wood (GTW) and oven-dry wood. The stress released very fast at higher temperatures. Glycerin showed
an accelerating effect on stress relaxation. At temperatures exceeding 120°C, a complete relaxation of the stress could be
expected. While for untreated wood, it cannot be reached until 160°C. By calculating the apparent activation energy (ΔE) of
GTW at different temperatures, it is clear that two mechanisms are responsible for different temperature ranges. From 40 to
100°C, ΔE is only 8.24 kJ/mol, which corresponds to the hydrogen bonds formed between wood and glycerin molecules; from 120
to 180°C, ΔE reached 81.38 kJ/mol, which corresponds to the degradation of hemicelluloses or lignin, and during this process,
new cross-linking would happen. 相似文献