scholarly journals Growth, Biomass Production and Root Development of Chinese fir in Relation to Initial Planting Density

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 236 ◽  
Author(s):  
Taimoor Farooq ◽  
Wenjing Wu ◽  
Mulualem Tigabu ◽  
Xiangqing Ma ◽  
Zongming He ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Biomass Production ◽  
Stand Density ◽  
Tree Height ◽  
Root Systems ◽  
Chinese Fir ◽  
High Density ◽  
Planting Density ◽  
Low Density ◽  
Intermediate Density

Chinese fir (Cunninghamia lanceolata (Lamb) Hook) is a commercially valuable timber species that is widely planted in southern China and accounts for 6.1% of the global plantation forests. However, appropriate planting density that ensures high plantation productivity is largely unexplored in this species. The aim of the study was to examine tree growth, biomass production, and its allocation among different organs in relation to initial planting density, and to examine whether planting density has an impact on root development. Mortality, diameter at breast height and tree-height of all trees were determined and measured in wider (2.36 × 2.36 m), intermediate (1.83 × 1.83 m) and narrow (1.44 × 1.44 m) spacing with stand density of 1450 trees ha−1, 2460 trees ha−1 and 3950 trees ha−1, respectively. In each stand, three plots of 20 × 20 m at a distance of 500 m were delineated as the sampling unit. Biomass was determined by destructive sampling of trees in each stand and developing allometric equations. Root morphological traits and their spatial distribution were also determined by carefully excavating the root systems. The results showed an increase in diameter of trees with decreasing stand density while tree height was independent of stand density. Biomass production of individual trees was significantly (p < 0.05) less in high-density stand (32.35 ± 2.98 kg tree−1) compared to low-density stand (44.72 ± 4.96 kg tree−1) and intermediate-density stand (61.35 ± 4.78 kg tree−1) while stand biomass production differed significantly in the order of intermediate (67.63 ± 5.14 t ha−1) > high (57.08 ± 3.13 t ha−1) > low (27.39 ± 3.42 t ha−1) stand density. Both average root length and root volume were significantly (p < 0.05) lower in the high-density stand than stands with low and intermediate density. Analysis of spatial distribution of root systems revealed no overlap between roots of neighboring trees in the competition zone in low-density stand, a subtle overlap in the intermediate density stand and larger overlap in the high-density stand. It can be concluded that better growth and biomass production in intermediate density stand could be explained by better root structural development coupled with minimal competition with understory vegetation and between trees; thus intermediate stand density can be optimal for sustaining long-term productivity and may reduce the management cost in the early phase of the plantation.

scholarly journals Transport of Apolipoprotein B-Containing Lipoproteins through Endothelial Cells Is Associated with Apolipoprotein E-Carrying HDL-Like Particle Formation

2018 ◽  
Vol 19 (11) ◽  
pp. 3593 ◽  
Author(s):  
Hong Yang ◽  
Ningya Zhang ◽  
Emmanuel Okoro ◽  
Zhongmao Guo
Keyword(s):  
Endothelial Cells ◽  
Apolipoprotein B ◽  
Density Lipoprotein ◽  
High Density ◽  
Low Density ◽  
Endothelial Monolayer ◽  
Aortic Endothelial Cells ◽  
Pass Through ◽  
Intermediate Density ◽  
Current Report

Passage of apolipoprotein B-containing lipoproteins (apoB-LPs), i.e., triglyceride-rich lipoproteins (TRLs), intermediate-density lipoproteins (IDLs), and low-density lipoproteins (LDLs), through the endothelial monolayer occurs in normal and atherosclerotic arteries. Among these lipoproteins, TRLs and IDLs are apoE-rich apoB-LPs (E/B-LPs). Recycling of TRL-associated apoE has been shown to form apoE-carrying high-density lipoprotein (HDL)-like (HDLE) particles in many types of cells. The current report studied the formation of HDLE particles by transcytosis of apoB-LPs through mouse aortic endothelial cells (MAECs). Our data indicated that passage of radiolabeled apoB-LPs, rich or poor in apoE, through the MAEC monolayer is inhibited by filipin and unlabeled competitor lipoproteins, suggesting that MAECs transport apoB-LPs via a caveolae-mediated pathway. The cholesterol and apoE in the cell-untreated E/B-LPs, TRLs, IDLs, and LDLs distributed primarily in the low-density (LD) fractions (d ≤ 1.063). A substantial portion of the cholesterol and apoE that passed through the MAEC monolayer was allotted into the high-density (HD) (d > 1.063) fractions. In contrast, apoB was detectable only in the LD fractions before or after apoB-LPs were incubated with the MAEC monolayer, suggesting that apoB-LPs pass through the MAEC monolayer in the forms of apoB-containing LD particles and apoE-containing HD particles.

Exploring agronomic strategies to improve oat productivity and control weeds: leaf type, row spacing, and planting density

2018 ◽  
Vol 98 (5) ◽  
pp. 1084-1093 ◽  
Author(s):  
Pufang Li ◽  
Fei Mo ◽  
Defeng Li ◽  
Bao-Luo Ma ◽  
Weikai Yan ◽  
...  
Keyword(s):  
Crop Production ◽  
Competitive Ability ◽  
High Density ◽  
Weed Suppression ◽  
Planting Density ◽  
Row Spacing ◽  
Environment Interaction ◽  
Weed Biomass ◽  
Intermediate Density ◽  
Erect Leaf

The trade-off between crop production and weed control is a fundamental scientific issue, as it is frequently influenced by individual crop competitive ability, population density, and planting pattern. A 2 yr field study was conducted to examine the relationship between planting density and row spacing, using two contrasting oat varieties. On average, high planting density (480 plants m−2) reduced weed biomass at oat maturity by 59% in 2012 and by 56% in 2013, when compared with a low density (120 plants m−2). The droopy-leaf variety suppressed weed biomass by up to 69% and weed density up to 72%, compared with the erect-leaf variety. In a drier year, the greatest grain yield was achieved with the droopy-leaf variety under the intermediate density, while in 2013, the erect-leaf variety under the high density had similar yield to the droopy-leaf variety at the intermediate density. A general trend was that increasing plant density suppressed weed infestation, and promoted crop biomass and yield. The droopy-leaf variety exhibited a strong competitive ability under the intermediate planting density, while the erect-leaf variety had a strong competitive ability under the high density. Taken together, there was a complex variety-by-environment interaction to achieve the balance between crop production and weed suppression, which was mediated by growing-season conditions.

THE EFFECT OF PLANTING DENSITY ON THE NUTRITIVE VALUE OF CORN SILAGE FOR LACTATING COWS

1982 ◽  
Vol 62 (4) ◽  
pp. 1143-1148 ◽  
Author(s):  
L. J. FISHER ◽  
N. A. FAIREY
Keyword(s):  
Milk Fat ◽  
Dry Matter ◽  
Nutritive Value ◽  
Fat Content ◽  
High Density ◽  
Corn Silage ◽  
Planting Density ◽  
Low Density ◽  
Lactating Cows ◽  
Density Treatment

A late-maturing corn hybrid, Funk brand G4444, was planted in 2-ha plots at 60 000 plants per hectare (low density) and at 100 000 plants per hectare (high density). At harvest, the dry matter and ear contents were 24.2 and 34%, respectively, for the low-density treatment and 22.8 and 28%, respectively, for the high-density treatment. Two groups of 10 lactating cows were used to compare the nutritive value of the ensiled forages over a 10-wk feeding period. Silage dry matter intake, milk yield and milk fat content were 10.33 kg/day, 27.11 kg/day and 3.52% for the cows fed high-density silage compared to 11.79 kg/day, 31.88 kg/day and 2.91% for those fed the low-density silage. Feeding the low-density silage resulted in a decreased level of acetic acid in the rumen and an increased level of propionic acid. Blood hematocrit and plasma calcium levels were lower for cows fed the silage from the low-density planting. Dry matter digestibility of the complete ration was 72.5 and 71.8% for the high- and low-density plantings, respectively. It was concluded that an increased ear content of approximately 10 percentage units resulted in a corn silage which was consumed more readily, altered rumen fermentation and caused a decrease in milk fat content. Key words: Corn silage, lactating dairy cows, planting density

scholarly journals Life at the margin: the mating system of Mediterranean conifers

Web Ecology ◽  
2008 ◽  
Vol 8 (1) ◽  
pp. 94-102 ◽  
Author(s):  
G. Restoux ◽  
D. E. Silva ◽  
F. Sagnard ◽  
F. Torre ◽  
E. Klein ◽  
...  
Keyword(s):  
Mating System ◽  
Stand Density ◽  
High Density ◽  
Published Data ◽  
Mixed Mating ◽  
Low Density ◽  
Selfing Rate ◽  
Water Regimes ◽  
Single Tree ◽  
Mature Stand

Abstract. Mixed mating, where a single tree progeny results from a mixture of selfing and outcrossing, is widespread in conifers and could be an evolutionary advantage at ecological margins when mating partners become scarce. This study analyzes how the mating system responds to bioclimate and density variations. We surveyed published data on the mating system of Abies, Picea and Pinus species when information on bioclimate and stand density was available. Our survey revealed that Mediterranean species demonstrate a lower selfing rate than other species and that the proportion of selfed versus outcrossed progeny is not fixed within species. The highest variability in mating types within populations was found when stand density was the most variable. To show how density affects the proportion of selfed versus outcrossed progeny, we used isozymes to genotype single tree seeds from a marginal Abies alba forest in Mediterranean France (Mont Ventoux) where low-to high-density stands are found. We then tested the adaptive potential of the different high and low density progenies by sowing them under controlled nursery conditions and measuring germination rate and seedling survival after 4 yr under 3 different water regimes. Although the mean value of outcrossing rate was typical for mixed mating conifers (tm = 0.85), individual outcrossing rates varied from 0.05 to 0.99 and were strongly correlated with stand type and density (tm from 0.87 in high-density to 0.43 in low-density marginal stands). Significantly fewer seeds from the low density marginal stand germinated (32% vs. 53% in the high density mature stand), although seedlings from the marginal stand had a better 4-yr survival (81%) than seedlings from the high-density mature stand (63%) when the three water regimes (from least to most stressful) were averaged. Trees from low density stands may be at a selective disadvantage because they produce more selfed progeny than trees from high-density stands. However, selfed seeds may be purged early on (at the embryo stage) and the remaining seeds tend to produce seedlings with better fitness. Variability of the selfing rate might thus be an adaptive strategy for species in highly contrasted environments where selection of both reproductive assurance and avoidance of inbreeding depression may be density dependent.

scholarly journals Effect of Stand Density and Soil Layer on Soil Nutrients of a 37-year-old Cunninghamia lanceolata Plantation in Naxi, Sichuan Province, China

2019 ◽  
Vol 11 (19) ◽  
pp. 5410 ◽  
Author(s):  
Jie Lei ◽  
Hailun Du ◽  
Aiguo Duan ◽  
Jianguo Zhang
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Nutrient ◽  
Stand Density ◽  
Chinese Fir ◽  
Understory Vegetation ◽  
Cunninghamia Lanceolata ◽  
Available P ◽  
Low Density ◽  
Soil Layers

In order to study the characteristics of soil nutrient elements and the changes in biomass under different densities and soil layers of forest stand, this paper considers Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) density test forests with five densities (A: 1667 trees·ha−1; B: 3333 trees·ha−1; C: 5000 trees·ha−1; D: 6667 trees·ha−1; E: 10,000 trees·ha−1) as the research objects, located in Naxi District, Sichuan Province, China. Eleven soil physical and chemical property indicators, understory vegetation, and litter biomass were measured. The results were as follows: (1) The stand density had a significant effect on the soil nutrient content, understory vegetation, and litter biomass. A low density is conducive to the accumulation of soil organic matter, hydrolytic N, available P, available K, and total Ca. (2) With the increase in soil depth, the contents of soil organic matter, total N, hydrolytic N, and total P decreased gradually; pH and total Ca decreased gradually; and available P showed a trend of decrease-up-decrease. The soil layers had no significant effect on the total K, total Fe, and total Mg concentrations. (3) Low density (density A or B) was found to be beneficial to the growth of undergrowth vegetation and forest trees, the return of nutrients, long-term soil maintenance, and the stable high yield of Chinese fir plantations.

Effects of stand density on outcrossing rate in two Norway spruce (Picea abies) populations

1991 ◽  
Vol 69 (12) ◽  
pp. 2704-2708 ◽  
Author(s):  
M. Morgante ◽  
G. G. Vendramin ◽  
P. Rossi
Keyword(s):  
Picea Abies ◽  
Mating System ◽  
Norway Spruce ◽  
Stand Density ◽  
Major Effect ◽  
Outcrossing Rate ◽  
High Density ◽  
Low Density ◽  
The Mean ◽  
Key Words Mating System

The mating system was investigated in two neighbouring Norway spruce (Picea abies (L.) Karst.) populations with markedly different stand densities. The amount of outcrossing was estimated using open-pollinated array data at four enzyme loci. Multilocus estimates of the proportion of viable progeny owing to outcrossing were 0.956 and 0.955 for the low- and high-density stand, respectively, indicating that the large reduction in stand density had no impact on outcrossing rates. The multilocus estimate was higher than the mean single-locus estimate only for the low-density stand. The lowering of the mean estimate in the low-density stand is probably a consequence of the clustering of related individuals. The regression of pollen allele frequencies on ovule genotype, which is a direct measure of the effective selfing caused by consanguineous matings, had a significant coefficient for the low-density stand and a nonsignificant one for the high-density stand. This obvservation confirms that the major effect of low-stand density in Norway spruce is the occurrence of consanguineous matings. Key words: mating system, outcrossing rate, inbreeding, Norway spruce, stand density.

Palmer Amaranth (Amaranthus palmeri) Demographic and Biological Characteristics in Wide-Row Soybean

Weed Science ◽  
2017 ◽  
Vol 65 (4) ◽  
pp. 491-503 ◽  
Author(s):  
Nicholas E. Korres ◽  
Jason K. Norsworthy
Keyword(s):  
Mortality Rate ◽  
Population Density ◽  
Seed Production ◽  
Biomass Production ◽  
High Density ◽  
Palmer Amaranth ◽  
Low Density ◽  
Seedling Mortality ◽  
Trade Off ◽  
Flowering Initiation

Knowledge of Palmer amaranth demographics and biology is essential for the development and implementation of weed management strategies. A field experiment was conducted to investigate the effects of Palmer amaranth density on seedling mortality, flowering initiation, and flowering progress throughout the growing season and biomass production and fecundity in wide-row soybean. The experimental design was a randomized complete block design with three levels of Palmer amaranth density-clusters: high, medium, and low. Palmer amaranth mortality rate was greater at high Palmer amaranth population density-cluster, reaching a peak within 30 to 40 d after Palmer amaranth emergence (DAE) (0.55 and 0.80 for 2014 and 2015, respectively), in comparison with mortality rate at medium and lower density-clusters. Likewise, as Palmer amaranth density increased, biomass and seed production per unit area of the weed also increased. Biomass production at the high density-cluster in 2014 was 664.7 g m−2compared with 542.9 and 422.1 g m−2at medium and low density-clusters, respectively. Similarly, biomass production at high density-cluster in 2015 was 100.6 g m−2compared with 37.3 and 34.2 at medium and low density-clusters, respectively. In addition, seeds produced at high density-cluster were 1.5 million and 245,400 seeds m−2for 2014 and 2015, respectively. Seed production was reduced by 29% and 54% in 2014 and by 65% and 75% in 2015 at medium and low density-clusters, respectively. Earlier flowering initiation (i.e., between 30 to 40 DAE) occurred in higher Palmer amaranth density-clusters, indicating a trade-off between reproduction and survival at high densities and more stressed environments for species survival. Palmer amaranth male-to-female sex ratio was greater at high densities, 1.3 and 1.9, compared with lower densities of 0.6 to 0.7 and 0.7 to 0.8 in 2014 and 2015, respectively. The plasticity of Palmer amaranth population and population-structure regulation, vegetative growth, and flowering shifts at various levels of intraspecific competition (i.e., high vs. low population density-clusters) and the trade-off between these biological transitions merits further investigation.

Population density influences assessment and application of site index

2000 ◽  
Vol 30 (9) ◽  
pp. 1472-1475 ◽  
Author(s):  
David W MacFarlane ◽  
Edwin J Green ◽  
Harold E Burkhart
Keyword(s):  
Loblolly Pine ◽  
Geographic Location ◽  
Stand Density ◽  
Tree Height ◽  
Significant Negative Correlation ◽  
Site Index ◽  
Height Growth ◽  
Planting Density ◽  
Site Quality ◽  
Pinus Taeda L

The height growth of dominant trees in plantations is often assumed to be independent of initial planting density. This assumption allows for the use of dominant tree height as an index of site quality. We found that this assumption was false for the seven tallest trees in 184 even-aged loblolly pine (Pinus taeda L.) stands, planted at nine initial planting densities, at four different geographic locations. A strong, highly significant negative correlation was found between dominant height and initial planting density for stands 14 and 16 years of age. This leads to large differences in predicted site index for stands with different initial planting densities planted at the same geographic location. Use of these site indices to predict yield produced large differences in predicted yield (m3/ha) at age 25. These results provide strong evidence for density-dependent height growth, even for dominant trees in the stand, and suggest that site index, used as a measurement of site quality, is confounded with stand density.

A physiological analysis of the effect of sowing density on the growth rate of subterranean clover

1982 ◽  
Vol 33 (2) ◽  
pp. 213 ◽  
Author(s):  
J-L Prioul ◽  
JH Silsbury
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Growth Curves ◽  
Subterranean Clover ◽  
Crop Growth ◽  
High Density ◽  
Planting Density ◽  
Low Density ◽  
Response Curves ◽  
Crop Growth Rate

The initial planting density of subterranean clover swards is known to affect the subsequent crop growth rate in such a way that a low density crop reaches the same final yield as does one sown at high density. To explain this phenomenon, daily carbon influxes and effluxes were measured during the growth of 'low' and 'high' density swards in a constant environment. The growth characteristics of individual plants in the sward and the photosynthetic responses of individual leaves to light were measured during ontogeny. Good agreement was found between the growth curves reconstructed from daily carbon increment and growth curves previously derived from dry matter sampling. The crop growth rate of a low density sward was found to be higher than that of a high density sward, and this is shown to be due to a lower respiratory loss. The high respiration rate of a high density crop can be attributed to plant mortality when dry matter density is higher than 400 g m-2. The photosynthetic light response curves of individual leaves at the top of the canopy were not found to be affected by the initial planting density, which suggests that subterranean clover plants are extremely well adapted to growth under sward conditions.

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