114 research outputs found
Fine-root morphological and growth traits in a Turkey-oak stand in relation to seasonal changes in soil moisture in the Southern Apennines, Italy
We investigated the effects of seasonal changes
in soil moisture on the morphological and growth traits
of fine roots (<2 mm in diameter) in a mature Turkeyoak
stand (Quercus cerris L.) in the Southern Apennines
of Italy. Root samples (diameter: <0.5, 0.5\u20131.0, 1.0\u20131.5,
and 1.5\u20132.0 mm) were collected with the Auger method.
Mean annual fine-root mass and length on site was
443 g m!2 (oak fine roots 321 g m!2; other species
122 g m!2) and 3.18 km m!2 (oak fine roots 1.14 km
m!2; other species 2.04 km m!2), respectively. Mean
specific root length was 8.3 m g!1. All fine-root traits
displayed a complex pattern that was significantly related
to season. In the four diameter classes, both fineroot
biomass and length peaked in summer when soil
water content was the lowest and air temperature the
highest of the season. Moreover, both fine-root biomass
and length were inversely related with soil moisture
(p < 0.001). The finest roots (<0.5 mm in diameter)
constituted an important fraction of total fine-root
length (79 %), but only 21 % of biomass. Only in this
root class, consequent to change in mean diameter,
specific root length peaked when soil water content was
lowest showing an inverse relationship (p < 0.001).
Furthermore, fine-root production and turnover decreased
with increasing root diameter. These results
suggest that changes in root length per unit mass, and
pulses in root growth to exploit transient periods of low
soil water content may enable trees to increase nutrient
and water uptake under seasonal drought conditions
Early pine root anatomy and primary and lateral root formation are affected by container size: implications in dry-summer climates
Although the presence of root anatomical structures of young Pinus ponderosa seedlings grown in containers of contrasting volume (164 vs. 7000 cm3) was similar, seedlings reared 60 days in the large container had more vascular cambium although the xylem thickness was similar. In addition, seedlings in large containers had nearly twice as many resin ducts within the vascular cambium as their cohorts in small containers. Taproot length closely matched container depth. Though lateral root emission rates were similar between container sizes, large container seedlings had more than 2X the number of lateral roots as those from small containers. These differences in morphophysiological characteristics may be important to seedling establishment on sites that experience dry summer conditions, or for seedlings destined to drier, harsher sites. Further work to elucidate the ramifications of these morphophysiological differences on seedling establishment is warranted
Light spectra of biophilic LED-sourced system modify essential oils composition and plant morphology of Mentha piperita L. and Ocimum basilicum L
Investigating morphological and molecular mechanisms that plants adopt in response to artificial biophilic lighting is crucial for implementing biophilic approaches in indoor environments. Also, studying the essential oils (EOs) composition in aromatic plants can help unveil the light influence on plant metabolism and open new investigative routes devoted to producing valuable molecules for human health and commercial applications. We assessed the growth performance and the EOs composition of Mentha x piperita and Ocimum basilicum grown under an innovative artificial biophilic lighting system (CoeLux®), that enables the simulation of natural sunlight with a realistic sun
perception, and compared it to high-pressure sodium lamps (control) We found that plants grown under the CoeLux® light type experienced a general suppression of both above and belowground biomass, a high leaf area, and a lower leaf thickness, which might be related to the shade avoidance syndrome. The secondary metabolites composition in the plants’ essential oils was scarcely affected by both light intensity and spectral composition of the CoeLux® light type, as similarities above 80% were observed with respect to the control light treatments and within both plant species. The major differences were detected with respect to the EOs extracted from plants grown under natural sunlight (52% similarity in M. piperita and 75% in O. basilicum). Overall, it can be speculated that the growth of these two aromatic plants under the CoeLux® lighting systems is a feasible strategy to improve biophilic approaches in closed environments that include both plants and artificial sunlight. Among the two plant species analyzed, O. basilicum showed an overall better performance in terms of both
morphological traits and essential oil composition. To increase biomass production and enhance the EOs quality (e.g., higher menthol concentrations), further studies should focus on technical solutions to raise the light intensity irradiating plants during their growth under the CoeLux® lighting systems
Ongoing modifications to root system architecture of Pinus ponderosa growing on a sloped site revealed by tree-ring analysis
Abstract Our knowledge of the root system architecture of trees is still incomplete, especially concerning how biomass partitioning is regulated to achieve an optimal, but often unequal, distribution of resources. In addition, our comprehension of root system architecture development as a result of the adaptation process is limited because most studies lack a temporal approach. To add to our understanding, we excavated 32-year-old Pinus ponderosa trees from a steep, forested site in northern Idaho USA. The root systems were discretized by a low magnetic field digitizer and along with AMAPmod software we examined their root traits (i.e. order category, topology, growth direction length, and volume) in four quadrants: downslope, upslope, windward, and leeward. On one tree, we analyzed tree rings to compare the ages of lateral roots relative to their parental root, and to assess the occurrence of compression wood. We found that, from their onset, first-order lateral roots have similar patterns of ring eccentricity suggesting an innate ability to respond to different mechanical forces; more root system was allocated downslope and to the windward quadrant. In addition, we noted that shallow roots, which all presented compression wood, appear to be the most important component of anchorage. Finally, we observed that lateral roots can change growth direction in response to mechanical forces, as well as produce new lateral roots at any development stage and wherever along their axis. These findings suggest that trees adjust their root spatial deployment in response to environmental conditions, these roots form compression wood to dissipate mechanical forces, and new lateral roots can arise anywhere and at any time on the existing system in apparent response to mechanical forces
Estimating forest aboveground biomass by low density lidar data in mixed broad-leaved forests in the Italian Pre-Alps
Background: Estimation of forest biomass on the regional and global scale is of great importance. Many studies
have demonstrated that lidar is an accurate tool for estimating forest aboveground biomass. However, results vary
with forest types, terrain conditions and the quality of the lidar data.
Methods: In this study, we investigated the utility of low density lidar data (<2 points∙m−2) for estimating forest
aboveground biomass in the mountainous forests of northern Italy. As a study site we selected a 4 km2 area in the
Valsassina mountains in Lombardy Region. The site is characterized by mixed and broad-leaved forests with variable
stand densities and tree species compositions, being representative for the entire Pre-Alps region in terms of type
of forest and geomorphology. We measured and determined tree height, DBH and tree species for 27 randomly
located circular plots (radius =10 m) in May 2008. We used allometric equations to calculate total aboveground
tree biomass and subsequently plot-level aboveground biomass (mg∙ha−1). Lidar data were collected in June 2004.
Results: Our results indicate that low density lidar data can be used to estimate forest aboveground biomass with
acceptable accuracies. The best height results show a R2 = 0.87 from final model and the root mean square error
(RMSE) 1.02 m (8.3% of the mean). The best biomass model explained 59% of the variance in the field biomass.
Leave-one-out cross validation yielded an RMSE of 30.6 mg∙ha−1 (20.9% of the mean).
Conclusions: Low-density lidar data can be used to develop a forest aboveground biomass model from plot-level
lidar height measurements with acceptable accuracies. In order to monitoring the National Forest Inventory, and
respond to Kyoto protocol requirements, this analysis might be applied to a larger area.
Keywords: LiDAR; Allometric equations; Plant height; Mixed fores
Reaction Wood Anatomical Traits and Hormonal Profiles in Poplar Bent Stem and Root
Reaction wood (RW) formation is an innate physiological response of woody plants to counteract mechanical constraints in nature, reinforce structure and redirect growth toward the vertical direction. Differences and/or similarities between stem and root response to mechanical constraints remain almost unknown especially in relation to phytohormones distribution and RW characteristics. Thus, Populus nigra stem and root subjected to static non-destructive mid-term bending treatment were analyzed. The distribution of tension and compression forces was firstly modeled along the main bent stem and root axis; then, anatomical features, chemical composition, and a complete auxin and cytokinin metabolite profiles of the stretched convex and compressed concave side of three different bent stem and root sectors were analyzed. The results showed that in bent stems RW was produced on the upper stretched convex side whereas in bent roots it was produced on the lower compressed concave side. Anatomical features and chemical analysis showed that bent stem RW was characterized by a low number of vessel, poor lignification, and high carbohydrate, and thus gelatinous layer in fiber cell wall. Conversely, in bent root, RW was characterized by high vessel number and area, without any significant variation in carbohydrate and lignin content. An antagonistic interaction of auxins and different cytokinin forms/conjugates seems to regulate critical aspects of RW formation/development in stem and root to facilitate upward/downward organ bending. The observed differences between the response stem and root to bending highlight how hormonal signaling is highly organ-dependent
Mulching in lowland hay meadows drives an adaptive convergence of above- and below-ground traits reducing plasticity and improving biomass: A possible tool for enhancing phytoremediation
We aimed to understand the effect of mulching (i.e., cutting and leaving the crushed biomass to decompose in situ) on above- and below-ground plant functional traits and whether this practice may be a potential tool for enhancing the phytoremediation of lowland hay meadows. To this aim, we evaluated at the community level seven years of mulching application in a PCBs and HMs soil-polluted Site of National Interest (SIN Brescia-Caffaro) through the analysis of the floristic composition and the above- and below-ground plant traits. We found that the abandonment of agricultural activities led to a marked increase in the soil organic carbon and pH, and the over-imposed mulching additionally induced a slight increase in soil nutrients. Mulching favored the establishment of a productive plant community characterized by a more conservative-resource strategy, a higher biomass development, and lower plasticity through an adaptative convergence between above- and below-ground organs. In particular, the analysis of the root depth distribution highlighted the key role of roots living in the upper soil layer (10 cm). Mulching did not show a significant effect on plant species known to be effective in terms of PCB phytoremediation. However, the mulching application appears to be a promising tool for enhancing the root web that functions as the backbone for the proliferation of microbes devoted to organic contaminants' degradation and selects a two-fold number of plant species known to be metal-tolerant. However, besides these potential positive effects of the mulching application, favoring species with a higher biomass development, in the long term, may lead to a biodiversity reduction and thus to potential consequences also on the diversity of native species important for the phytoremediation
HONO emissions from snow surfaces
Photochemical production of NO_x and HONO from surface snow can significantly impact the NO_x, OH, and O_3 budgets in the overlying atmosphere. NO_x production is driven by the solar photolysis of NO_3^− within or at the surface of snowpacks. HONO, however, is a secondary species that involves H-atom transfer between natural donors and photogenerated NO_2. Here we investigate the mechanism of HONO generation in snowpacks by exploring how its emissions respond to on-and-off illumination and temperature cycles, and to the addition of various snow dopants. The presence of humic substances within or at the surface of the snowpack significantly enhances, and may be an essential requisite for HONO production.
Emission fluxes of NO, NO_2, and HONO from snow surfaces were measured under controlled temperature, ozone mixing ratio and actinic flux conditions. We used natural mid-latitude surface snow as the snow substrate. Their combined peak emission fluxes reached up to ~3 × 10^(10) molecules cm^(−2) s^(−1), ~10^3 times larger than typical emissions from polar snowpacks. Less than 1% of available N was released in these experiments. We report significant post-irradiation HONO emissions from the snow. Present results indicate a strong, direct correlation between HONO emissions and the HULIS (humic-like substances) content of the snow surface
Anti-proliferative effects of GW441756, a novel inhibitor of NGFreceptor tyrosine kinase a (TRKA), in human sarcoma
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