Shoot Basal Diameter Research Articles

Environmental extremes affect productivity and habitus of common reed in intermittent wetland

This article describes the effect of extreme water level events and extreme temperatures on the primary productivity and habitus of the common reed (Phragmites australis) growing in lake and riparian habitats at intermittent Lake Cerknica between 2007 and 2021. At each sampling site, the above-ground biomass, leaf biomass and shoot density per m2, the number of internodes and leaves per plant, average shoot height, shoot basal diameter and the ratio of flowering plants per total plant number were determined. Stand and plant properties varied significantly between the locations, with exception of the basal diameter, that varied less. Biomass per area and per plant showed the trend of decrease across years, but the reed density remained at the same level. Redundancy analysis of the relationships between environmental parameters and productivity and habitus parameters revealed the importance for the lake stand of high-water level parameters in the 4th quarter of the previous year, while the 1st quarter of the current year was important for the riparian stand. High water level variables explained 60% of variance of productivity parameters of the lake stand and 21% of those of the riparian stand. For low water level parameters, the explained variance was 51 and 24%, respectively. In the case of habitus parameters, variances explained by high water level parameters were 66% for lake stand and 34% for riparian stand and of low water level parameters, the corresponding variances were 45% for lake stand and 59% for riparian stand. Temperature extremes can explain the lower variance. The interrelation between wetland hydrological extremes and reed stand/plant properties that was obtained suggests that an ecohydrological approach may provide a basis for successful management of reed-colonised wetlands.

Effects of Shoot Size and Genotype on Energy Properties of Poplar Biomass in Short Rotation Crops

Eight poplar genotypes grown in a short rotation forest plantation established in an acid soil in South Europe were sampled at the age of 7 years to determine the energy properties regarding thermochemical conversion. The goal was to address the effect of selection of genotypes or shoot size at harvest on the energy quality of biomass. Between 34 and 50 biomass samples were obtained for each genotype: three disks were systematically sampled along the stem and were pooled together with a subsample of leafless branches representative of the biomass share of this component. Several energy properties were determined: higher calorific value, net calorific value, fresh moisture content, basic density, ash, volatile matter, fixed carbon content and elemental composition. Genotype had a significant effect on most of these properties, and the balsam genotypes displayed superior quality parameters and also higher biomass yield than the Euramerican genotypes. As a covariate, shoot basal diameter had a significant effect on the moisture content, basic density, ash content and on the concentrations of the elements N, K, Ca, Mg, S, Na and C. It was concluded that genotypes with low nutrient requirements planted at low density (<8000 cuttings ha−1) and harvested at a long enough rotation (7 years) produce good yields and high chip quality. Poplar short rotation crops can be grown to produce chips of A2 quality for non-industrial heating use (according to UNE-EN ISO 17225-4), able to be combusted in domestic thermal facilities of <1 MWth power.

Above- and below-ground carbon accumulation and biomass allocation in poplar short rotation plantations under Mediterranean conditions

Beside the production of biomass, short rotation coppice (SRC) poplar plantations can also contribute to carbon sequestration in the soil through their below-ground biomass. The present study evaluated the allocation of above and below-ground biomass at the end of the first rotation of four SRC plantations under Mediterranean conditions. The genotypes evaluated are commonly used for biomass plantations, i.e. genotypes ‘AF2’ and ‘I-214’ (Populus × canadensis Mönch), and ‘Monviso’ (P. × generosa Henry × P. nigra L.). No significant differences among genotypes were found with regard to below-ground biomass yield. The root:shoot ratio decreased in line with the growth in shoot basal diameter, with values ranging from 0.15 to 0.26. The accumulation of carbon in the below-ground fraction of the biomass ranged from 0.86 to 0.91 Mg C ha−1 yr−1, whereas the above-ground carbon accumulation ranged from 3.89 to 6.48 Mg C ha−1 yr−1. A general as well as a genotype-specific allometric model allowed to accurately predict the below-ground biomass yield using shoot basal diameter as the predictor variable. Both models provide an important tool to quantify the carbon accumulated in the below-ground fraction of the biomass.

Ectomycorrhizal inoculation with Pisolithus tinctorius reduces stress induced by drought in cork oak.

We investigated whether the performance of cork oak under drought could be improved by colonization with the ectomycorrhizal fungus Pisolithus tinctorius. Results show that inoculation alone had a positive effect on plant height, shoot biomass, shoot basal diameter, and root growth. Under drought, root growth of mycorrhizal plants was significantly increased showing that inoculation was effective in increasing tolerance to drought. In accordance, mycorrhizal plants subjected to drought showed less symptoms of stress when compared to non-mycorrhizal plants, such as lower concentration of soluble sugars and starch, increased ability to maintain fatty acid content and composition, and increased unsaturation level of membrane lipids. After testing some of the mechanisms suggested to contribute to the enhanced tolerance of mycorrhizal plants to drought, we could not find any by which Pisolithus tinctorius could benefit cork oak, at least under the drought conditions imposed in our experiment. Inoculation did not increase photosynthesis under drought, suggesting no effect in sustaining stomatal opening at low soil water content. Similarly, plant water status was not affected by inoculation suggesting that P. tinctorius does not contribute to an increased plant water uptake during drought. Inoculation did increase nitrogen concentration in plants but it was independent of the water status. Furthermore, no significant mycorrhizal effect on drought-induced ROS production or osmotic adjustment was detected, suggesting that these factors are not important for the improved drought tolerance triggered by P. tinctorius.

Population characteristics of giant reed (Arundo donax L.) in cultivated and naturalized habitats

In the present study, we analyzed the variability among naturalized and cultivated giant reed (Arundo donax L.) populations in terms of density, morphology and primary production along the prevailing environmental gradient in Nile Delta, Egypt. For this purpose, a sampling was carried out in homogeneous and monospecific A. donax stands in Nile Delta. The samples were collected to represent the cultivated populations (planted habitat) and the naturalized populations in four habitats (canal banks, waste lands, road and railway sides). Each habitat was represented by 3 stands; and in each stand, density, morphology and biomass were recorded using five randomly distributed quadrats (each of 0.5×0.5m). The results had indicated a significant variation in density, morphological and biomass parameters between naturalized and cultivated populations. Generally, naturalized populations along the railway and road sides (the less moist habitats) had the minimum values for most measured population parameters, while the cultivated populations (the moistest habitat) had the maximum. The dependence of shoot height, number of branches and panicle length on shoot density indicated the density-size effects. Density, morphology and biomass of A. donax were correlated significantly with some soil properties such as salinity, pH, organic matter and nitrogen. The regression technique was applied to develop equations for predicting the biomass of A. donax shoots from more easily determined shoot height and shoot basal diameter. These methods were time-saving, so the equations might be useful in evaluating management techniques which were used for monitoring A. donax.

Leaf-trait responses to irrigation of the endemic fog-oasis tree Myrcianthes ferreyrae: can a fog specialist benefit from regular watering?

Myrcianthes ferreyrae is an endemic, endangered species, with a small number of individuals located only in hyperarid, fog-oases known as lomas along the Peruvian desert in southern Peru, where fog is the main source of water. Following centuries of severe deforestation, reforestation with this native species was conducted in the Atiquipa lomas, Arequipa-Perú. On five slopes, five 2-year-old seedlings were irrigated monthly with water trapped by raschel-mesh fog collectors, supplementing natural rainfall with 0, 20, 40, 60 and 80 mm month(-1) from February to August 2008. We measured plant growth, increment in basal diameter, height and five leaf traits: leaf mass area (LMA), leaf carbon isotope composition (δ(13)C), nitrogen per leaf area, total leaf carbon and stomatal density; which are indicative of the physiological changes resulting from increased water supply. Plant growth rates, estimated from the variation of either shoot basal diameter or maximum height, were highly correlated with total biomass. Only LMA and δ(13)C were higher in irrigated than in control plants, but we found no further differences among irrigation treatments. This threshold response suggests an on-off strategy fitted to exploit pulses of fog water, which are always limited in magnitude in comparison with natural rain. The absence of a differential response to increased water supply is in agreement with the low phenotypic plasticity expected in plants from very stressful environments. Our results have practical implications for reforestation projects, since irrigating with 20 mm per month is sufficient to achieve the full growth capacity of this species.

Yield prediction of young black locust (Robinia pseudoacacia L.) plantations for woody biomass production using allometric relations.

Black locust ( Robinia pseudoacacia L.) is an increasingly popular tree species for the production of woody biomass for bioenergy generation with short rotation coppices. Due to its potential to produce large amounts of biomass yields even under unfavourable growth conditions, this tree species is especially suitable for marginal sites, such as can be found in the post mining area of NE-Germany. Current research aims to reliably predict the yield potential of black locust short rotation coppices, but suffers from a lack of sufficient exact allometric functions until recently. This is especially true for the early growth years, which are of special importance for short rotation coppices. The objective of this study was to develop allometric equations based on tree height and shoot basal diameter (SBD) for estimating yields of young black locust plantations. Therefore, dendrometric data were collected in a two, three, four and fourteen years old black locust short rotation forest located in the reclamation area of an opencast-lignite mining area in the Lower Lusatian region (Germany) and used for equation developing. Until measurement, none of the plantations had been harvested. Closed correlations between SBD and tree height were observed, as well as between these parameters and single tree mass. The scattering of single tree masses could be explained slightly better by the SBD than by the tree height. In the year before a harvest an even better prediction probability of woody biomass was obtainable when both parameters were simultaneously interrelated with the single tree mass. The results illustrate that the woody above ground biomass of young black locust plantations can be estimated sufficiently precisely based on the easy determinable parameters tree height and particularly SBD.

GRAFTING AND PERFORMANCE IN THE FIRST YEAR OF 'MARSOL' GRAFTED ONTO DIFFERENT ROOTSTOCKS

The seedlings of four (Castanea sativa x Castanea crenata) hybrids 'Marsol', 'Precoce Migoule', 'Maraval' and 'Bouche de Betizac', as well as three Slovene domestic Castanea sativa genotypes, i.e., 'Domaci', 'Martin' and 'Kozjak' were evaluated as rootstocks for 'Marsol'. At the beginning of September 2007, 50 two year-old seedlings per rootstock were grafted in an open field using the chip-budding method. Quantitative assessment of graft unions was then done in the following Spring. In the combination 'Marsol'/'Marsol', 100% of successful grafts were observed. The rootstock 'Kozjak' had only 65% of successful grafts, and in other cases, between 80 and 90% of the grafts were good. In October 2008, the grafted plants were qualitatively assessed. In all stock/scion combinations, strong central shoot of the 1 st order together with syleptic lateral shoots of the 2 nd order were developed. Central shoots of the grafted plants were the highest (between 220 and 228 cm), when 'Marsol' was grafted onto 'Bouche de Betizac', 'Marsol' and 'Precoce Migoule'. The last one also provoked vigorous growth of the central shoot's basal diameter. When 'Marsol' was grafted onto domestic genotypes, the central shoots of the grafts only measured between 175 and 191 cm in height. A statistically significant impact of the rootstock on the lateral branching was observed. 8,3 syleptic lateral shoots were sprouting on the central axis on the `Marsol'/`Marsol' grafts, compared to 'Marsol'/'Kozjak', and 'Marsol'/'Domaci', where only 2,9 and 3 lateral shoots were developed, respectively. In addition, all the hybrids used, strongly influenced primary (in length), and secondary (in diameter) growth of the lateral shoots, as well as the number of leaves/shoot.

Rapid and Nondestructive Estimation of Leaf Area on Field-Grown Concord (Vitis labruscana) Grapevines

Three potential variables, shoot basal diameter, leaf count per shoot, and shoot length, were examined as potential rapid, nondestructive methods for estimating leaf area per shoot, a frequent component of estimates of leaf area per vine. The metrics were recorded in large field-grown vines over five years. Shoot basal diameter, the most rapid method, was not a good predictor of leaf area per shoot. After transformation, shoot length and leaf count per shoot had relatively tight linear relationships with the square root of leaf area per shoot (R² = 0.90 and R² = 0.85, respectively). Some of the variation in the relationships due to between-year and within-season variability can be reduced by expressing the relationships as a function of thermal time. Furthermore, nonlinear models can be fit to the ratio of leaf area per shoot to the rapidly obtained metrics. Using this ratio approach accounts for the dynamics of canopy development and should increase the accuracy of leaf area estimates during early-season rapid shoot growth. Early in the season the length and count measurements can be made at ~0.5 min per shoot, but as the canopy develops and shoots intertwine, the sampling rate progressively slows to ~2.5 min per shoot.

Management Effects on Biomass and Foliar Nutritive Value of Robinia pseudoacacia and Gleditsia triacanthos f. inermis in Arkansas, USA

The browse potential of black locust (Robinia pseudoacacia L.) and thornless honey locust [Gleditsia triacanthos f. inermis (L.) Zabel] has not been adequately tested. Our objective was to determine effects of fertilization and pollarding on biomass and foliar nutritive value in separate studies of black locust and thornless honey locust in Arkansas, USA. Shoots were sampled monthly for two consecutive growing seasons in 2002 and 2003 to determine foliar, shoot, and total aboveground biomass, shoot basal diameter, and foliar nutritive value (crude protein and in vitro digestibility). Black locust yielded more foliar biomass when pollarded at 50 or 100 cm and fertilized with 600 kg P ha 1 , than at 5 cm with or without P, averaging 3.5 Mg dry matter ha 1 . Black locust foliar crude protein and in vitro dry matter digestibility ( £170 and 534 g kg 1 , respectively) decreased as leaves aged, but still met maintenance needs for beef cattle (Bos taurus L.). Thornless honey locust had little agronomic potential because of slow establishment, low foliar yield (330 kg ha 1 ), and a 2% reversion to undesirable thorny phenotype. Black locust should be

Within-tree distribution of attack by Hypsipyla robusta Moore (Lepidoptera: Pyralidae) in Australian Red Cedar ( Toona australis (F. Muell.) Harmes)

Field and laboratory evaluations were made of the within-tree distribution of attack of Hypsipyla robusta in Australian Red Cedar ( Toona australis). Proportions of shoots attacked by the insect increased with shoot height, relative shoot height, shoot length, shoot basal diameter and shoot slenderness (shoot length/shoot basal diameter). The most significant factor influencing the log-odds of attack of shoots was their relative height. Shoots positioned at above 90% of tree height were attacked twice as often as the lower-positioned shoots. This suggests that terminal shoots would be among the first to be attacked once a tree is attacked. There was a gradual shift of feeding loci with respect to host tissues as the larva aged. Feeding by larvae of the first two instars was found most often in terminal foliage or previously damaged tissues of shoots or tree stems. Pith-feeding (tunnelling) started at the later 2nd instar. On average, a larva initiated feeding in a mean of 5.4 different locations during its life time, with a minimum of three and a maximum of 11. Switching of feeding loci was most frequent during early 1st instar and much of the 3rd and early 4th instars.

Influence of Feeding by Zeiraphera canadensis (Lepidoptera: Tortricidae) on Growth of White Spruce: Larval Density-Damage and Damage-Shoot Production Relationships

Field studies were conducted in New Brunswick, Canada to evaluate the relationship between larval density of the spruce bud moth, Zeiraphera canadensis Mut. & Free. (Lepidoptera: Tortricidae), and damage to current year's shoots of white spruce, Picea glauca (Moench) Voss, and the response of white spruce, in terms of shoot production, in the year following damage. The length of undamaged shoots was closely related to the length of buds, the length of the previous internode, and shoot basal diameter. Basal diameter explained 78-94% of the variability in shoot length in the absence of herbivory and was chosen to estimate potential growth of damaged shoots. The number of larvae per shoot, shoot size, whether shoots were broken at a feeding scar, the amount of previous herbivory, and the position of damage along shoots explained 24-87% of the variation in six damage indices (i.e. area and percentage of shoots defoliated, area and percentage of cortical tissue consumed, percentage shoot length reduction and incidence of shoot breakage) examined over 2 years and at two sites (...)