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1.
Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations
similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing
nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH4+-N and NO3−-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman
Island of India. Concentration of NH4+-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the
tree species. On the contrary, concentration of NO3−-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were
the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the
highest under the nutmeg (561 mg kg−1 yr−1) and the lowest under the coconut trees (393 mg kg−1 yr−1). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April)
under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the
tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature. 相似文献
2.
Tree-crop interactions were monitored by measuring tree growth characters of Prosopis cineraria L. and Tecomella undulata L. and yields of Vigna radiata (L) in agroforestry systems in degraded lands of Indian Desert. Potential competition for resource between the trees and
associated crop was analyzed by measuring soil water contents, soil organic matters and NH4-N at different depths of soil layers i.e., 0–25 cm, 25–50 cm and 50–75 cm in the experimental plots. The plots size were
16 m × 18 m (D1), 20 m × 18 m (D2) and 32 m × 18 m (D3) with tree densities of 208, 138 and 104 trees·ha−1 after June 2002, respectively. Results showed that tree height increased by 3% to 7% during June 2002 to June 2004. Collar
diameter increased by 30% and 11% in D1, 23% and 19% in D2 and 18% and 36% in D3 plots, respectively, in P. cineraria and T. undulata in two years period. The increase in crown diameter was 9% to 18% in P. cineraria and 11% to 16% in T. undulata. Tree growth was relatively greater in 2002 than in 2003. Yield of V. radiata increased linearly from D1 to D3 plots. Lowest soil water content at 1 m distance from tree base indicated greater utilization of soil water within the tree
rooting zone. Concentrations of soil organic matters and NH4-N were the highest (p<0.05) in 0–25 cm soil layer. P. cineraria was more beneficial than T. undulata in improving soil conditions and increasing crop yield by 11.1% and thus more suitable for its integration in agricultural
land. The yield of agricultural crop increased when density of tree species was appropriate (i.e., optimum tree density),
though it varied with tree size and depended upon resource availability. The result indicated bio-economic benefits of optimum
density of P. cineraria and T. undulata over traditional practices of maintaining random trees in farming system in arid zones.
Biography: G. Singh (1961– ), male, Scientist E and Head, Division of Forest Ecology, Arid Forest Research Institute, New
Pali Road, Jodhpur-342005, India. 相似文献
3.
A study was conducted in the semi-arid regions of Haryana, in Northern India, to see the effect of Azadirachta indica, Prosopis cineraria, Dalbergia sissoo and Acacia nilotica on the yield of irrigated wheat crop. Data on crop yield for each tree species at different distances (1, 3, 5 and 7 m) and four directions (east, west, north and south) from the tree bases and control (no trees) were collected. Results indicate that A. indica and P. cineraria did not show any significant difference in the wheat yield while the other two species (D. sissoo and A. nilotica) showed a reduction in wheat yield. A. nilotica had the most significant and prominent effect, and a reduction of nearly 40 to 60% wheat yield was observed. The effect of this tree species was observed even beyond the spread of the crown. D. sissoo reduced yield by 4 to 30% but the reduction was only up to a distance of 3 m. In general, the impact of trees on wheat yield was observed up to 3 m distance and there is little, if any, impact up to 5 m distance and almost no impact at 7 m distance. In all the tree species, the wheat yield was reduced to a maximum on the north side of the trees and had almost no effect in the southern direction. Crop maturity was observed to be delayed by three weeks under A. nilotica, by 9–10 days under D. sissoo, and only by 6–7 days under P. cineraria and A. indica. 相似文献
4.
Studies on tree crop interaction under rainfed condition in Dehradun valley were conducted for 13 years during 1977 to 1990. Grewia optiva (Bhimal), Morus alba (Mulbery) and Eucalyptus hybrid were tried along with rice (CV: Akashi) — wheat (CV: RR-21) rotation. One-year-old tree seedlings of the above tree species were planted in line, 5 m apart in N-S direction, in July 1977, in the middle of the plot (size 20 m × 20 m). Eucalyptus was first harvested in 1987. Grewia optiva, Morus alba and coppice of Eucalyptus were harvested in 1990. All tree species had depressing effect on crop yields. Eucalyptus had maximum effect in depressing crop yield till the first harvest and had least effect thereafter. From 1987 onwards, Morus alba affected rice most, while wheat was mostly affected by Grewia optiva. The depressing effect on an average varied from 28 to 34% depending upon the species.Distance of tree line from the crop significantly affected the crop yield upto a distance of 5 m and there was 39% decrease in crop yield upto 1 m, 33% from 1–2 m, 25% from 2–3 m and 12% from 3–5 m distance. Annual removal of lops and tops from trees partly compensated the deficit. Grewia optiva could produce 1.08 t ha–1 yr–1 of branches and 0.26 t ha–1 yr–1 of leaves (air dry) and 1.28 t ha–1 yr–1 of branches and 0.28 t ha–1 yr–1 of leaves were obtained from Morus alba. Wood (ADT) produced by the trees was 33.6 t ha–1 from Eucalyptus, 9.5 t ha–1 from Grewia optiva and 11.6 t ha–1 from Morus alba. 相似文献
5.
M. J. Rozados-Lorenzo M. P. González-Hernández F. J. Silva-Pando 《Agroforestry Systems》2007,70(1):53-62
We studied the effect of six tree species planted at six different densities on pasture production seven years after establishment.
Annual and seasonal pasture production was studied every six months, over three years. Pasture production was lower under
conifer trees (Pseudotsuga menziesii (Mirb.) Franco, Pinus pinaster Aiton, Pinus radiata D. Don) than under broadleaved trees (Betula alba L., Quercus rubra L. and Castanea sativa Mill.). Annual pasture production under Pseudotsuga menziesii and Pinus pinaster decreased progressively starting from 952 trees ha−1, while decline in herbage production under Pinus radiata began to occur at 427 trees ha−1. Tree density effect on pasture production was detected at 2,000 trees ha−1 for all of the deciduous species studied. This effect on pasture production was more important in the first six months of
the year (June sampling), while from June to December herbage production was less affected by tree density. The tree effect
became more noticeable over time, with the last sampling showing the inverse relationship between tree density and herbage
production most clearly. Seven years after tree establishment, pasture production was quite consistent under tree densities
between 190 trees ha−1 and 556 trees ha−1 and declined remarkably from 556 trees ha−1 to 2,500 trees ha−1. The study also indicated that by the sixth growing season, annual pasture production under different tree species is inversely
correlated with tree leaf area index. 相似文献
6.
Trade-offs analysis for possible timber-based agroforestry scenarios using native trees in the Philippines 总被引：3，自引：2，他引：1
To assess possible new agroforestry scenarios the tree–soil–crop interaction model in agroforestry systems (WaNuLCAS 3.01)
was used based on-site specific data collected from Tabango (Central Philippines). Three native timber trees (Shorea contorta Vid., Pterocarpus indicus Juss., and Vitex parviflora Willd.) and one widely spread exotic specie (Swietenia macrophylla King.) were simulated under different intercrop scenarios with maize (Zea mays L.) and subsequently compared. Model simulation results quantified and explained trade-off between tree and crop. For example,
higher tree densities will lead to a loss of crop yield that is approximately proportional to the gain in wood volume. However,
beside this trade-off effect, there is considerable scope for tree intercropping advantage under a fertilization scenario,
with systems that yield about 50% of the maximum tree biomass still allowing 70% of monoculture maize yield. Maximum tree
yield can still be obtained at about 20% of the potential crop yield but intermediate tree population densities (400 trees ha−1) and the resulting larger stem diameters may be preferable over the larger total tree biomass obtained at higher tree densities.
Another advantage from intercropping systems is that trees directly benefit from the inputs (i.e., fertilizer) that are applied
to the crops. The three native trees species studied have different performance in relation to productivity but are similar
to (or even better than) S. macrophylla. 相似文献
7.
Fine-root dynamics (diameter < 2.0 mm) were studied on-farm in associations of Coffea arabica with Eucalyptus deglupta or Terminalia ivorensis and in a pseudo-chronosequence of C. arabica-E. deglupta associations (two, three, four and five years old). Coffee plants were submitted to two fertilisation types. Cores were taken
in the 0–40 cm soil profile two years after out-planting and subsequently in the following year in depth layers 0–10 and 10–20
cm, during and at the end of the rainy season, and during the dry season. Fine root density of coffee and timber shade trees
was greater in the coffee fertilisation strip as compared to unfertilised areas close to the plants or in the inter-rows.
Coffee fine roots were more evenly distributed in the topsoil (0–20 cm) whereas tree fine roots were mostly found in the first
10 cm. Although the two tree species had approximately the same fine root length density, lower coffee / tree fine root length
density ratios in T. ivorensis suggest that this shade tree is potentially a stronger competitor with coffee than E. deglupta. Coffee and tree fine root length density for 0–10 cm measured during the rainy season increased progressively from two to
five-year-aged associations and coffee fine root length density increased relatively more than E. deglupta fine root length density in the four and five-year-aged plantations suggesting that contrary to expectations, coffee fine
roots were displacing tree fine roots. 相似文献
8.
Planting trees in the cultivated fields of Pakistan is a controversial topic between foresters and agriculturists. Some farmers believe that trees significantly reduce their crop yields; therefore they avoid planting trees in their fields. On the other hand, many foresters claim trees are beneficial for crops. This study was conducted to determine the influence of boundary trees (Acacia nilotica) on the growth and yield of associated wheat crops under irrigated conditions in Punjab, Pakistan. Results indicate that close proximity to trees adversely affected tillers/m2, weight/1000 grain and the grain yield of wheat planted up to a distance of 8.5 m from the trees. Plant height and grains/spike were least affected. In general, the growth and yield of wheat improved as distance from the tree increased. Tree size did not affect wheat height, tillers/m2, grains/spike or weight/1000 grain. The grain yields were slightly lower near the largest trees (50–54.9 cm DBH trees). 相似文献
9.
To address tree–soil–crop interactions in the Sahel, we examined the growth-limiting factors (water, light and mineral nutrients)
of Sorghum bicolor growing under trees in agroforestry parklands of Burkina Faso. Growth and yields of sorghum were measured after (1) pruning
crowns of Vitellaria paradoxa and Parkia biglobosa trees, and (2) applying mineral fertilizers (nitrogen and/or phosphorus) and supplemental irrigation during normal wet cropping
seasons in 2007 and 2008. Irrigation treatments led to non-significant 29% and 23% gains in grain and dry matter yields (from
control values of 455 and 1,140 kg ha−1), respectively. The fertilizer showed variable but in general significant increases in grain and straw yields and more consistently
in the height of sorghum plants. The crown pruning increased the values of these variables much more strongly, by 520% and
348% (from control, no-pruning values of 282 and 612 kg ha−1), respectively. The growth and production of S. bicolor were also >56% higher under V. paradoxa than under P. biglobosa. The same trends were observed in both cropping seasons, although rainfall was much heavier in 2008 than in 2007, and the
mean sorghum grain yield was approximately twice as high in 2008. The results clearly indicate that competition for light
limits sorghum growth more than competition for other resources in the studied system, suggesting that parkland management
should aim at either increasing light availability (by reducing tree density or pruning) or growing shade-tolerant crops under
the trees. However, use of a poorly soluble phosphorus source during the first year, modest amount of water applied through
the supplemental irrigation (48 mm) and the wetness of the rainy season in 2008 (which led to abandonment of the irrigation
treatments and floods in the experimental plots) may have masked possible effects of the applied fertilizers and irrigation.
Therefore, more prolonged analyses of the effects of fertilizers and deficit irrigation are required before robust recommendations
can be made to farmers. 相似文献
10.
An on-farm trial was conducted to determine dry matter production of four fodder tree species and their effect on soil water
and maize production. The trees were planted in rows intercropped with maize. The four tree species selected were Acacia karroo Hayne (indigenous fodder tree), Leucaena leucocephala (Lam.) De Wit (nitrogen fixing), Morus alba L. (fodder and fruit), and Gleditsia triacanthos L. (fodder and fuel). Volumetric soil water was measured in the upper 0.3 m of soil in each row of the trial using the time
domain reflectometry technique. The neutron probe technique was used for monitoring the water content deeper in the soil.
Geostatistical methods were used to analyse treatment differences in the upper 0.3 m of soil. The soil water content did not
differ significantly between the maize and tree rows indicating that competition for water in the upper horizon was not the
reason for lower maize yields. However, at greater soil depths (75–125 cm) trees in the wide spacing used less water than
those in the narrow spacing. Light interception was an important factor in reducing maize yields in the row nearest to the
trees. High soil water values recorded during summer indicated that in the current cycle of good rainfall the plants in the
agroforestry trial were not stressed. Thus the trees do not compete with the crops for soil moisture in good rainfall seasons.
However, this study would need further evaluation for the competition for water for the low rainfall years. Since the trees
have access to water at greater depths, they are likely to be more productive into the dry season than shallow rooted crops. 相似文献
11.
In designing agroforestry systems, the combination of tree genotype (orspecies) and pasture species and the spatial arrangement
of trees are importantconsiderations. The spatial variation of fine root length density (FRLD) ofthree radiata pine (Pinus radiata D. Don) genotypes,referred to here as clone 3, clone 4 and seedlings, was studied in athree-year-old temperate silvopastoral
experiment. The genotypes were plantedwith three understorey types: ryegrass (Lolium perenne)mixed with clovers (Trifolium spp), lucerne(Medicago sativa), and control (bare ground). Also fineroot distribution of both tree and pasture species with soil depth and inrelation to
tree row (0.9 m north or south of and within the rippedtree row) was studied. Greater FRLD was found in clonal than in seedling
treesin the bare ground treatment but not in the two pasture treatments, and in the0–0.1 m but not in the 0.1–0.2 or 0.2–0.3m
soil layers. Clonal trees had a greater ability to develop a moreextensive root system, especially in the 0–0.1 m soil layer,but
that advantage disappeared when they were planted with pasture species sincecompetition from the pasture species was most
severe in the 0–10cm layer. The FRLD of lucerne was greater than that ofryegrass/clovers, consistent with the greater aboveground
biomass production oflucerne. Pasture species FRLD was greater on the south (wetter) than on thenorth side of the ripline
or in the ripline. The interception of prevailingsoutherly rain-bearing wind by tree crowns resulted in the south side beingwetter
than the north side. Results indicated that production and distributionof fine roots of both tree and pasture species responded
to changes in themicroclimate. We suggest that to optimize pasture/tree biomass productionplanting trees in the north-south
direction is better than in the east-westdirection at the studied site.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
LIU Zu-gen ZHU Jiao-jun HU Li-le WANG He-xin MAO Zhi-hong LI Xiu-fen ZHANG Li-jun 《林业研究》2005,16(3):193-199
In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-old Larix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003-2004 Five thinning treatments （0%, 10.2%, 19.8%, 29.7% and 40.3% thinned） were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density （PPFD）, soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase （p=0.30） after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly （p〈0.05）. In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of iudividual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness was Phellodendron amurense. This paper confirmed the following conclusions： after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing, the regeneration. 相似文献
13.
On-farm trials were conducted to assess the effects of four branch pruning levels on maize grain yield, tree growth and stem
shape. The experimental plots consisted of Gmelina (Gmelina arborea R.Br.) trees planted at 1 × 10 m with maize intercropped in the 10 m-wide alleys between lines of trees. Pruning levels consisted
of retaining a live crown ratio of 60–70% (T
1), 40–50% (T
2); 30–40% (T
3) and of 20–30% (T
4). At the end of the experiment, the total maize grain yield was highest under the high pruning intensity (T
4) (18.06 t ha−1) and lowest under T
1 (14.48 t ha−1). Maize grain yield under the pruning regime T
2 and T
3 were 16.08 and 17.21 t ha−1, respectively. Mean annual increment (MAI) in tree diameter was greater (5.0 cm year−1) under T
1 than those at T
4 (4.1 cm year−1). Pruning regimes T
2 and T
3 resulted in a MAI of 4.7 and 4.5 cm year−1, respectively. Financial analysis showed that maize-tree systems under T
4 were more profitable than under T
1 as long as the reduction of the average dbh at harvest were not greater than 1 cm. Pruning trees intensively also generated
greater returns from labour than moderate pruning, as the greater maize grain yields under T
4 compensated for the cost of pruning and the lower timber yield. In the context of resource-poor farmers, intensive branch
pruning was a practice that prolonged the period of profitable intercropping and was compatible with commercial timber production. 相似文献
14.
The most common trees on farm homesteads in Bangladesh were bamboo (several spp.), jackfruit (Artocarpus heterophyllus), mango (Mangifera indica), betelnut (Areca catechu), and jujube (Zizyphus jujube) in all agroecological zones studied. There were regional differences in the less common species. Species for new homestead
planting were chosen mainly by women and tended to include indigenous fruit trees and a few exotics of high timber value.
Choices were later influenced by new experience with exotic tree species and by perceptions from secondary information sources.
Farmer-managed action-research was used to test the survival and performance of new trees planted under the Village and Farm
Forestry Programme (VFFP). The main factors influencing tree survival were the role of women in selection of species and planting
site, the degree of personal attention paid aftercare by the owner, and the quality and size of the planting stock. Biophysical
factors and agroecological zones were unimportant. Main recorded causes of tree mortality were, in order of importance: damage
by livestock, pests or diseases, physical damage by people (mainly children playing), and drought. Cause of death could not
be attributed in about 35% of mortality, suggesting that the recorded causes should be treated with caution.
Previous articles 1 and 2 in the series appeared in Agroforestry Systems 25: 193–216 and 31: 39–57 with slightly different
main titles. 相似文献
15.
In northern Laos, shortened fallows in the slash-and-burn upland rice system are not sustainable either from a production
or economic standpoint. This paper evaluates the potential for using the indigenous fast-growing tree, Broussonetia papyrifera L. Vent. (paper mulberry) as an economic fallow crop. The objectives of this study are to assess the inner bark yield of
paper mulberry, and to evaluate rice productivity following paper mulberry cultivation. In addition, allometric models for
estimating the inner bark yield of paper mulberry are developed. Inner bark yield of paper mulberry stands ranging in age
from 9 to 48 months ranged from 10 to 208 g m−2, and increased with age. The models using diameter at breast height and stem height, or diameter at breast height only as
independent variables explained well the variation in inner bark yield. When paper mulberry was completely removed during
the rice growing season, rice yields in these areas were similar to those following weedy bush fallow. When paper mulberry
was allowed to grow, rice yields were negatively correlated to paper mulberry stem density. When paper mulberry lateral branches
were pruned back, rice yields could be maintained if the paper mulberry stem density was <0.22 stems m−2, suggesting that if paper mulberry is managed properly, rice yields can be maintained at current levels. The paper mulberry-upland
rice rotation system improves the productivity of a traditional slash-and-burn system through harvesting paper mulberry inner
bark; however the long-term sustainability of such a system remains unclear and warrants further investigation. 相似文献
16.
A study was conducted in South Kordofan, Sudan to determine the effect of tapping, tapping tools and date of tapping on the gum yield of Acacia polyacantha. A two-factor experiment was conducted for two seasons in 2008-2009. One location was used for two seasons and two locations for one season. The first factor (4 levels) was the tools of tapping: Makmak, Farrar, and Sonki, and the control which was not tapped. The second factor (2 levels) was the date of tapping that comprises mid October and mid November. These treatments were arranged in Randomaized Complete Block Design and replicated three times. Gum yield (g/tree and g/ picking) was recorded for five pickings. Economic analysis was done using the partial budget technique. The results showed highly significant (p < 0.01) differences on gum yield (g/picking and g/tree). The results indicated that the process of tapping increases gum production by 88.4% and 79.8% compared with un-tapped trees, respectively. The date of tapping has no significant effect on gum yield (g/tree and g/picking) of A. polyacantha. Tapping of the tree with Makmak in mid- November was found to be economically beneficial compared to using the other tools and the control. These results could identify a new source of income for the poor farmers in South Kordofan mainly because of the wild occurrence of Kakamut as a potential gum producing tree species grown naturally in the area. 相似文献
17.
Effect of trees on the yield of wheat crop 总被引：3，自引：0，他引：3
A study was conducted at the National Agricultural Research Center (NARC) of Pakistan Agricultural Research Council (PARC) by planting trees of four different species: Eucalyptus camaldulensis, Albizia procera, Morus alba and Leucaena leucocephala along the boundary of wheat fields in a randomized complete block design. Data on crop yield for each tree species and control (no trees) at different distances viz 2, 4, 6, 8, 10 and 12 meter (m) from the tree bases and control were collected and analyzed. The statistical analysis did not show any significant difference in the wheat yield among different tree species. However, the wheat yield was numerically lowest at 2 m distance in case of all the four tree species and control. In case of mulberry, it was lowest statistically also from other distances. Numerically higher wheat yield values were noted at later distances (8, 10 and 12 m) in case of all tree species including control except for siris where numerically highest value was found at 6 m distance. Therefore, it can be generalized that tree's impact on wheat yield can be experienced up to 2 m distance, there is little, if any, impact up to 6 m distance and almost no impact at 8, 10 and 12 m distances. 相似文献
18.
J. V. N. S. Prasad G. R. Korwar K. V. Rao K. Srinivas Ch. Srinivasarao B. Pedababu B. Venkateswarlu S. N. Rao H. D. Kulkarni 《New Forests》2011,42(1):51-61
On-farm experiments were conducted in Khammam district of Andhra Pradesh from 2001 to 2006 to evaluate the biomass productivity,
intercrop yields and profitability of Eucalyptus tereticornis clonal and Leucaena leucocephala variety K-636 based systems. Trees were planted at a spacing of 3 × 2 m and evaluated at three locations. Height growth was
significantly higher in leucaena during the 4 year where as difference in diameter growth was not significant. Biomass partitioning to the bole was high in case of leucaena, ranged from 83% in 2.5–5 cm diameter at breast height (DBH)
trees to 89% in 12.5–15 cm DBH trees and in eucalyptus clones the corresponding values were 71% in 2.5–5 cm DBH trees and
83% in 12.5–15 cm DBH trees. Marketable biomass productivity was higher with leucaena (95 Mg ha−1) in comparison to eucalyptus (87 Mg ha−1). Competition effects of trees on intercrops were observed from the 2 year (2002 post-rainy season). Intercrop yields were
45% of the sole crop in eucalyptus system and 36% in leucaena system during the 2 year. Sole eucalyptus and leucaena plantations
and intercropping systems recorded higher gross and net returns over arable cropping. Therefore, it can be concluded that
leucaena variety K636 and eucalyptus clonal based agroforestry systems are profitable alternatives to arable cropping under
rainfed conditions. 相似文献
19.
Water is the key factor in vegetation growth in a loess area. Researchers have been keen on the study of tree transpiration
for a long time. To provide a scientific basis and practical instruction for vegetation reconstruction and recovery in a loess
area, the paper measured and calculated the water consumption of potted Platycladus orientalis, Robinia pseudoacacia, Armeniaca vulgaris and Pyrus hopeiensis separately during the growing season (from Apr. to Nov.). The four were the main afforestation species in a loess area of
western Shanxi based on the principle of water balance. Using data on soil water dynamics and the range of available moisture
on potted mature trees, the relationship between water supply and consumption and soil moisture availability and deficit state
were analyzed. Several conclusions are listed as follows: 1) In the dry year (2002), during the growing season the precipitation
was 430.7 mm and the water consumption of potted trees was from 430 to 490 mm. More water consumption and less available water
supply occurred, showing a serious water deficiency. In the rainfall-rich year (2003), during the growing season the precipitation
was 870.2 mm and the water consumption of potted trees was from 480 to 515 mm. Due to the uneven distribution of rainfall,
the water budget balance was slightly affected in May and November. 2) The curves of soil water content of different species
had similar annual changes, although the trends were different in the same month, and those of the same tree species in different
test plots also had different trends in the same month. 3) Non-available soil water content of Platycladus orientalis, Robinia pseudoacacia, Armeniaca vulgaris and Pyrus hopeiensis was less than 8.0%, 8.4%, 9.2% and 9.7% respectively, which indicated that Pyrus orentalis used water more efficiently than the others. In the dry year (2002), for several months, soil water content of potted trees
was lower than its threshold value for non-available soil water content, which could influence the healthy growth of trees.
After supplements of precipitation of winter in the year and spring in the next year, soil water content was higher than the
lower limit of soil readily available moisture content, which implied that a balance between inter-annual water supply and
consumption could be maintained.
__________
Translated from Scientia Silvae Sinicae, 2006, 42(9): 18–23 [译自: 林业科学] 相似文献
20.
Field windbreaks can increase crop yield within a protected zone. However, they also take land out of crop production and
compete with adjacent crops. Although the beneficial aspects are generally recognized, the question arises whether the windbreak
will increase crop revenue enough to offset costs over time. Achieving additional yields to offset windbreak costs might be
a sufficient incentive for a producer to plant a windbreak. Additional maize (Zea mays) yields necessary to break even with costs are calculated for four typical Midwestern USA field windbreaks: poplar (Populus spp.), mixed tree/shrubs (Populus spp., Acer saccharinum L./Physocarpus spp., Viburnum spp., Cornus spp.), and two and four-row spruce (Picea spp.) windbreaks. Five lifespans, two management and two cost scenarios, and three protected zone widths to account for changing
sheltering effects are evaluated. Greatest additional yields are for a 4-row spruce windbreak with intensive management at
high cost and a 10-year lifespan: 15.38 Mg ha–1 yr–1 within 6H, 7.69 Mg ha–1 yr–1 within 12H and 6.15 Mg ha–1 yr–1 within 15H. If a 50-year lifespan is implemented, the additional yields are about 11% of those in 10-year lifespan. Smallest
additional yields are for a mixed tree/shrubs windbreak with extensive management at low cost and a 50-year lifespan: 0.56
Mg ha–1 yr–1, 0.28 Mg ha–1 yr–1 and 0.22 Mg ha–1 yr–1, respectively. The mixed windbreak is likely to have actual maize yield increases comparable to the added maize yields required
to break even as long as the lifespan is 30 years or longer with a minimum protected zone of 12H.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献