Good crop stand establishment and root system development are essential for optimum grain yield of dryland wheat （Triti-cum aestivumL.）. At present, little is known about the effect of tilage and straw mulch on the ...Good crop stand establishment and root system development are essential for optimum grain yield of dryland wheat （Triti-cum aestivumL.）. At present, little is known about the effect of tilage and straw mulch on the root system of wheat under dryland areas in southwestern China. The aim of this study was to evaluate the effect of three tilage treatments （no-til, NT; rotary til, RT; conventional til, CT） and two crop residue management practices （straw mulch, ML; non-straw mulch, NML） on stand establishment, root growth and grain yield of wheat. NT resulted in lower soil cover thickness for the wheat seed, higher number of uncovered seeds, lower percentage of seedling-less ridges and lower tiler density compared to RT and CT; ML resulted in higher tiler density compared to NML. Straw mulching resulted in more soil water content and root length density （RLD） at most of the growth stages and soil depths. The maximum RLD, root surface area density and root dry matter density were obtained under NT. In the topmost 10 cm soil layer, higher RLD values were found under NT than those under RT and CT. There were no signiifcant differences in the yield or yield components of wheat among the tilage treatments in 2011–2012, but NT resulted in a signiifcant higher yield compared to RT and CT in 2012–2013. Grain yield was signiifcantly higher in ML compared to in NML. A strong relationship was observed between the water-use efifciency and the grain yield. Both NT and ML proved beneifcial for wheat in term of maintaining higher tiler density, better soil water status and root growth, leading to a higher grain yield and enhanced water-use efifciency, especialy in a low rainfal year.展开更多
We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal are...We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.展开更多
The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equa...The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands.展开更多
Growth of stand average DBH is discussed bassed on relationship between standgrowth and stand density.Growth equation of stand average DBH is fitted with data of 65 plotsand 130 stem analyses of site index 18 meter of...Growth of stand average DBH is discussed bassed on relationship between standgrowth and stand density.Growth equation of stand average DBH is fitted with data of 65 plotsand 130 stem analyses of site index 18 meter of old-growth Larch(Larix gmeliniiRupr.)collectedin Great Xing’an Mountain m Inner Monglia.Variable-density yield tables of old—growth Larchare constructed based on growth equation of stand average DBH and relationship between standaverage DBH and the other stand attributes.展开更多
We present stationarity criteria for forest stands,and establish embodiments using a Norwegian empirical stand development model.The natural stationary states only slightly differ from the outcome of long-term simulat...We present stationarity criteria for forest stands,and establish embodiments using a Norwegian empirical stand development model.The natural stationary states only slightly differ from the outcome of long-term simulations previously implemented using the same empirical model.Human interference in terms of diameter-limit cutting is introduced.Consequently,stationary states differing from the natural one appear.Standing volume,growth and monetary value appear low but the financial return rate may be significant.Volume yield and financial return clearly contradict each other,the former arising from harvesting large trees,the latter from frequent removal of small trees.An exponential tree size distribution does not appear to comply with the stationarity criterion.展开更多
In this study, under conditions of enclosed soil, experiments were conducted on the dependence of the yield (weight of green mass) of alfalfa (Medicago) on plant density and diet. The experiments were carried out in f...In this study, under conditions of enclosed soil, experiments were conducted on the dependence of the yield (weight of green mass) of alfalfa (Medicago) on plant density and diet. The experiments were carried out in five variants, in different values of the integrated density of plants and lasted 89 days. As a feed, specially prepared bio fertilizer was used and added with the calculation of 1 kg per 1 m2 of area. In the corresponding control variants, bio fertilizer was not used. Analysis of the experimental results showed that the feeding regime made it possible to obtain a maximum yield at higher integral density. At the same time, the increase in the weight of green mass when using bio fertilizers was about 36%.展开更多
基金supported by the China Agriculture Research System(CARS-3)the Public Welfare Industry(Agriculture)Scientific Research of China(200903010-06)
文摘Good crop stand establishment and root system development are essential for optimum grain yield of dryland wheat （Triti-cum aestivumL.）. At present, little is known about the effect of tilage and straw mulch on the root system of wheat under dryland areas in southwestern China. The aim of this study was to evaluate the effect of three tilage treatments （no-til, NT; rotary til, RT; conventional til, CT） and two crop residue management practices （straw mulch, ML; non-straw mulch, NML） on stand establishment, root growth and grain yield of wheat. NT resulted in lower soil cover thickness for the wheat seed, higher number of uncovered seeds, lower percentage of seedling-less ridges and lower tiler density compared to RT and CT; ML resulted in higher tiler density compared to NML. Straw mulching resulted in more soil water content and root length density （RLD） at most of the growth stages and soil depths. The maximum RLD, root surface area density and root dry matter density were obtained under NT. In the topmost 10 cm soil layer, higher RLD values were found under NT than those under RT and CT. There were no signiifcant differences in the yield or yield components of wheat among the tilage treatments in 2011–2012, but NT resulted in a signiifcant higher yield compared to RT and CT in 2012–2013. Grain yield was signiifcantly higher in ML compared to in NML. A strong relationship was observed between the water-use efifciency and the grain yield. Both NT and ML proved beneifcial for wheat in term of maintaining higher tiler density, better soil water status and root growth, leading to a higher grain yield and enhanced water-use efifciency, especialy in a low rainfal year.
基金supported by the grant from Forest Research Branch of the Québec Ministry of Forests,Parks,and Wildlife(No.142332012)
文摘We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.
基金supported by the Forestry Technology Popularization Demonstration Project of the Central Government of China(No.[2015]GDTK-07)
文摘The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands.
文摘Growth of stand average DBH is discussed bassed on relationship between standgrowth and stand density.Growth equation of stand average DBH is fitted with data of 65 plotsand 130 stem analyses of site index 18 meter of old-growth Larch(Larix gmeliniiRupr.)collectedin Great Xing’an Mountain m Inner Monglia.Variable-density yield tables of old—growth Larchare constructed based on growth equation of stand average DBH and relationship between standaverage DBH and the other stand attributes.
基金funding provided by University of Eastern Finland(UEF) including Kuopio University Hospital
文摘We present stationarity criteria for forest stands,and establish embodiments using a Norwegian empirical stand development model.The natural stationary states only slightly differ from the outcome of long-term simulations previously implemented using the same empirical model.Human interference in terms of diameter-limit cutting is introduced.Consequently,stationary states differing from the natural one appear.Standing volume,growth and monetary value appear low but the financial return rate may be significant.Volume yield and financial return clearly contradict each other,the former arising from harvesting large trees,the latter from frequent removal of small trees.An exponential tree size distribution does not appear to comply with the stationarity criterion.
文摘In this study, under conditions of enclosed soil, experiments were conducted on the dependence of the yield (weight of green mass) of alfalfa (Medicago) on plant density and diet. The experiments were carried out in five variants, in different values of the integrated density of plants and lasted 89 days. As a feed, specially prepared bio fertilizer was used and added with the calculation of 1 kg per 1 m2 of area. In the corresponding control variants, bio fertilizer was not used. Analysis of the experimental results showed that the feeding regime made it possible to obtain a maximum yield at higher integral density. At the same time, the increase in the weight of green mass when using bio fertilizers was about 36%.
