Una Iscrizione Commeaiorativa Già Esistente All'Orto Botanico di Padova

Abstract

The use of the mini-plug system for the production of container seedlings is relatively new, so there is little information on the potential impact of method on the quality of planting stock. The objective in this study was to evaluate the impact of mini-plug growing method on quality of Pinus brutia seedlings, and compare the performance of this stock type with that of standard container nursery stock. Seedling survival, growth and physiological status (root growth potential, shoot electrolyte leakage) were measured after pre-cultivation in mini-plugs, at the end of the first growing season in standard containers and after field transplanting. Our results showed that mini-plug transplants of P. brutia seedlings performed as well as the standard planting stock currently used in nursery operation in Greece. For the pre-cultivation of P. brutia seedlings in mini-plugs, the use of peat and a density of 2000 mini-plugs m^?2 are recommended.     

Carbon stock and allocation of five restoration ecosystems in subalpine coniferous forest zone in Western Sichuan Province, Southwest China

As the largest carbon pool of the terrestrial ecosystem, forest plays a key role in sequestrating and reserving greenhouse gases. With the method of replacing space with time, the typical restoration ecosystems of herb (dominated by Deyeuxia scabrescens, P1), shrub (dominated by Salix paraqplesia, P2), broadleaf (dominated by Betula platyphylla, P3), mixed forest (dominated by Betula spp. and Abies faxoniana, P4), and climax (dominated by Abies faxoniana, P5) were selected to quantify the carbon stock and allocation in the subalpine coniferous forest in Western Sichuan (SCFS). The results indicated that the soil organism carbon (SOC) stock decreased with the depth of soil layer, and the SOC per layer and the total SOC increased largely with the vegetation restoration. The contribution of SOC to the carbon stock of ecosystems decreased with the vegetation restoration from 89.45% to 27.06%, while the quantity was from 94.00 to 223.00 t C hm^?2. The carbon stock in ground cover increased with the vegetation restoration, and its contribution to the carbon stock of ecosystems was similar (3–4% of the total). Following the vegetation restoration, the plant carbon stock multiplied and reached to 430.86 ± 49.49 t C hm^?2 at the climax phase. During the restoration, the carbon stock of different layers increased, and the contribution of belowground to the carbon stock of ecosystems decreased sharply. The carbon stock on ecosystem scale of the climax phase was 5.89 times that of the herb phase. Our results highlighted that the vegetation restoration in SCFS was a large carbon sink.     

Disentangling the effects of facilitation on restoration of the Atlantic Forest

Facilitation is an important ecological mechanism with potential applications to forest restoration. We hypothesized that different facilitation treatments, distance from the forest edge and time since initiation of the experiment would affect forest restoration on abandoned pastures. Seed and seedling abundance, species richness and composition were recorded monthly during two years under isolated trees, bird perches and in open pasture. Seed arrival and seedling establishment were measured at 10 m and 300 m from the forest edge. We sampled a total of 131,826 seeds from 115 species and 487 seedlings from 46 species. Isolated trees and bird perches increased re-establishment of forest species; however, species richness was higher under isolated trees. Overall, abundance and richness of seeds and seedlings differed between sampling years, but was unaffected by distance from the forest edge. On the other hand, species composition of seeds and seedlings differed among facilitation treatments, distance from the forest edge and between years. Seedling establishment success rate was larger in large-seeded species than medium- and small-seeded species. Our results suggest that isolated trees enhance forest re-establishment, while bird perches provide a complementary effort to restore tree abundance in abandoned pastures. However, the importance of seed arrival facilitation shifts toward establishment facilitation over time. Arriving species may vary depending on the distance from the forest edge and disperser attractors. Efforts to restore tropical forests on abandoned pastures should take into account a combination of both restoration strategies, effects of time and proximity to forest edge to maximize regeneration.     

Assessment of the restoration of a degraded semi-humid evergreen broadleaf forest ecosystem by combined single-indicator and comprehensive model method

We conducted a long-term restoration experiment in the degraded ecosystems of a semi-humid evergreen broadleaf forest in Muding County, Yunan Province, China. We used single-indicator assessment and our newly established comprehensive assessment model to compare the effects of four types of management (different historical disturbances + restoration measures) on forest restoration based on a vegetation survey. (1) Species richness in each of the four restoring communities was still lower than that of the zonal forest. There was a compensatory effect of species richness among different layers within communities. Restoration management by natural succession was clearly efficient at restoring species richness and composition, but the effect of disturbance history was minor. Human-assisted restoration had a great effect on biomass accumulation and model tree growth. Plant density was also affected by the different management types, which progressively led to differences in model tree growth and biomass accumulation. (2) The comprehensive assessment model, a simple method based on the restoration mechanism, can precisely quantify the overall restoration of ecosystems, historical disturbance and actual disturbance, using only one set of data. Restoration index (R_d), turning-point restoration index (R₀), restoration-effect index (R_a), turning-point disturbance index (D₀), actual disturbance index (D_r) and overcoming disturbance index (D_a) presented gradual changes in the four restoring communities. The combined single-indicator and comprehensive model method fully assessed the restoration of degraded ecosystems in a semi-humid evergreen broadleaf forest.     

Macrobenthos functional groups as indicators of ecological restoration in the northern part of China’s Yellow River Delta Wetlands

Freshwater releases to restore degraded wetlands are a globally recognized way to maintain the biodiversity and enhance the health of wetland ecosystems. To better understand the efficacy of freshwater releases in the northern part of China’s Yellow River Delta Wetlands, we used macrobenthos functional groups in spring (before freshwater releases), summer (during), and autumn (after) as indicators of the ecological responses. We also created abundance–biomass comparison curves and analyzed secondary production of each trophic level to evaluate the magnitude of the disturbance of the macrobenthos community. Abundance, biomass, and biodiversity of macrobenthos functional groups generally improved after the freshwater releases. In contrast with an intertidal (reference) area, the macrobenthos community in the ecological restoration area tended to be freshwater species. In the ecological restoration area, strong and moderate ecological disturbance of the macrobenthos community was evident during and after freshwater releases because the abundance curve remained above the biomass curve. Secondary production was in the order trophic level III > II ≅ IV in the summer, which indicates fragility of the macrobenthos community. The ecological restoration area had the highest sediment total organic carbon and moisture contents, but the lowest salinity and median particle size, and these differences were statistically significant. Our results suggest that adaptive freshwater releases, including a long-term freshwater release plan that more closely emulates natural flows and increasing the efficiency of freshwater utilization, will be necessary to achieve sustainable management of the wetland’s ecosystem and reduce the disturbance caused by the freshwater releases.     

Morphological and physiological response of sour orange (Citrus aurantium L.) seedlings to the inoculation of taxonomically characterized bacterial endophytes

Entophytic bacteria (EBs) are very diverse and found in virtually all plant species studied. These natural EBs live insides the host plant and can be used to maximize crop and fruit yield by exploiting their potential. In this paper, EBs characterization from various citrus genotypes and their influence on the morphological and physiological functioning of sour orange (Citrus aurantium) seedlings are described. To assess the influence of 10 distinct EBs, three different techniques (injection, soil mix, and spray) were applied for single and mixed inoculation on sour orange (C. aurantium) seedlings. The selected strains were identified as firmicutes (Enterococcus faecalis, Bacillus safensis, Bacillus cereus, Bacillus megaterium, Brevibacillus borstelensis & Staphylococcus haemolyticus), and gamma Proteobacteria (Enterobacter hormachaei, Proteus mirabilis, Pseudomonas aeruginosa, & Pseudomonas sp.) by 16S rRNA gene sequencing. To investigate the influence of these EBs on host plant morphology, different parameters (morphometric) were recorded after five WOI (weeks of inoculation), including shoot/root length, shoot/root fresh and dry biomass, and biophysical analyses i.e., relative water content (RLWC). Physiological markers such as chlorophyll & carotenoid content, protein content, proline content, phenolics, and flavonoids were also analyzed to determine the influence of endophytes on sour orange seedlings. Five strains such as SM-34, SM-20, SM-36, SM-68, and SM-56 significantly improved the development and physiology of sour orange seedlings. Bacillus cereus and Pseudomonas aeruginosa produced the best outcomes in terms of plant growth. The relative quantification of bacterial inoculums was determined using real-time PCR. A rise in the number of bacterial cells in inoculated treatment suggests that bacterial strains survived and colonized successfully, and also shown their competitiveness with native bacterial community structure. As per the results of inoculation methods, soil mixing, and injection methods were determined to be effective for bacterial inoculation to plants but a variable trend was found for different parameters with test bacterial strains. After testing their impact on field conditions, these strains can be applied as fertilizers as an alternative to conventional chemical fertilizer, although in the context of mixed inoculation of bacterial strains, 5 M and 6 M performed best and enhanced plant growth-promoting activity.     

Changes in soil microbial functional diversity under different vegetation restoration patterns for Hulunbeier Sandy Land

Grassland desertification seriously threatens economic and social sustainable development. How to control grassland desertification, and even to restore and reconstruct grassland has been paid much attention. Vegetation restoration is considered to be a very effective solution. Soil contains an immense diversity of microbes, and the characteristics of soil microbial communities are sensitive indicators of soil. It is important to understand the relationship between vegetation and soil microbial diversity during the restoration process. Based on Biolog-Eco technology, a case study was carried out to investigate the effects of five different vegetation restoration patterns on soil microbial functional diversity after four years in sandy land in Hulunbeier, China. The five vegetation restoration patterns included mono-cultivar planting of Agropyron cristatum (UA), mono-cultivar planting of Hedysarum fruticosum (UH), mono-cultivar planting of Caragana korshinskii (UC), and mixed-cultivar planting of A. cristatum and H. fruticosum (AC), mixed-cultivar planting of A. cristatum, H. fruticosum, C. korshinskii and Elymus nutans (ACHE). Completely degraded sandy land was used as control.The results indicated that the vegetation restoration significantly increased soil microbial activity. The Average Well Color Development (AWCD), which represents soil microbial metabolic activity, followed the order of UC > UH > UA > ACHE > AC > control. AWCD of five vegetation restoration patterns were all higher than that of control, and the highest soil microbial metabolic activity in mono-cultivar planting of C. korshinskii treatment was found. Five vegetation restoration patterns resulted in significant increase in Shannon index (H), evenness (E) and Simpson’s Dominance (D) of soil microbial community. Greater Shannon index and Simpson’s Dominance was observed in UC treatment than in other four vegetation restoration treatments and control. ACHE treatment had the highest evenness index (E) of soil microbial community. The principal component analysis (PCA) indicated a similar mode in carbon utilization for soil microbial community of UA, AC, ACHE and CK. However, UH and UC treatments had special carbon utilization mode. Treatments of UA, AC, ACHE and CK concentrated in the negative direction of the first principal component. Conversely, treatments of UH and UC concentrated in the positive direction of the first and second principal component respectively. The carbon sources mostly used by soil microbes were carbohydrates, amino acids, metabolic mediates and secondary metabolites. Therefore, vegetation restoration enhanced the metabolic activity and functional diversity of microbial community in sandy soil.     

Fine-tuning of sewage sludge application to promote the establishment of Pinus halepensis seedlings

Planting woody vegetation is frequently a first step towards the restoration of degraded drylands. Seedling establishment on unfertile soils may be favoured by applying organic amendments such as biosolids. But the outcome of such a practice is strongly dependent on the type of amendment and the application rate used. High application rates may have deleterious effects on plant performance and compromise plantation success. Thus amendment type and dose should be carefully selected to optimise benefits and minimize risks. In this study, we evaluated the effect of two organic amendments (composted and air-dried sewage sludge) applied at 5 doses (0, 15, 30, 45 and 60 Mg ha^?1) on soil properties and on the performance of 1-year-old Pinus halepensis seedlings planted in a dry Mediterranean degraded area. Soil organic matter, electrical conductivity and nutrient availability increased with the application rate, but the magnitude of this increase depended on the type of amendment and the time. Organic amendments improved N and P status and promoted seedling growth. Nevertheless, at the higher application rates they showed a negative impact on seedling survival 1 and 3 years after application. Drought effects intensified by root competition with extant vegetation and reduced water availability within the planting hole were the main causes attributed to the higher mortality. Low to moderate doses showed the best combination of seedling survival and growth and can thus be recommended to promote the establishment of P. halepensis in dry Mediterranean areas.     

Survival of black alder (Alnus glutinosa L.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) seedlings in a reclaimed oil shale mining area

Early survival and growth of black alder, silver birch and Scots pine were investigated on reclaimed extremely stony and heterogeneous calcareous (pH 8) opencast oil shale mining areas (OOSMAs). Biomass allocation, production, leaf and root adaptations, and mineral nutrition in relation to tree species and soil heterogeneity were analysed. The adaptive strategies of tree species in first-year plantations on OOSMA were different. Scots pine allocated 1.5–2 times more biomass into leaves and fine roots than deciduous trees. The lower leaf/fine root biomass ratio was in proportion to the better survival (%) of seedlings, decreasing in the following order: black alder (93%) ≥ Scots pine (83%) > silver birch (64%). Deciduous trees improved mineral nutrition more by fine-root morphological adaptations than Scots pine; e.g. the mean specific root length (SRL, m g^?1) of short roots increased in the following order: Scots pine (62) < black alder (172) < silver birch (314). The effect of soil heterogeneity on growth and adaptations was minor. All studied species suffered from P and N, and deciduous species also from K deficiency. In the first year after planting, black alder was best adapted to the harsh conditions of the post-mining substrate. The approaches of this study can be used for other regions where wastelands require reclamation.     

Expanding ecological appropriation approach: Solar space method and a case study in Yangzhou city,East China

In this paper, the authors made an attempt to measure appropriation of ecosystems more reasonably and effectively based on examining the advantages and disadvantages of emergy analysis and ecological footprint. By combining emergy analysis with ecological footprint (EF) in terms of spatial equivalent of energy productivity, a new method of solar space (SS) and its calculating framework was proposed, and some necessary parameters for this method of analysis were calculated. A case study was followed under this calculating framework for Yangzhou city, Jiangsu province, Eastern China, using the data of the year 2000. The main results are as follows: (1) The ecological space in Yangzhou city includes earth surface space and solar space, and their demands were bigger than their supply. In the year of 2000, the earth surface space had an absolute deficit of 2.3063E?02 Ga-ha per capita (global hectares), and the solar space had an absolute deficit of 1.4944E?04 Sa-ha per capita (solar hectares). (2) There was a relative ecological deficit of 3.68% in earth surface space, and that of 154.86% in solar space. (3) Only freshwater areas and built-up areas were in a state of surplus, and there was a relative ecological surplus of 82.66% for freshwater areas, being greater than that for built-up areas. (4) The ranking of absolute ecological deficit in a descending order was as follows: solar space > arable land > pasture > forest > marine area > garden land, while the relative ecological deficit was the following: solar space > pasture land > forest land > arable land > garden land, except marine areas.A qualitative comparison of methodology was made between solar space method and ecological footprint according to their capability to describe the temporal-spatial characteristics of ecosystems appropriation. Moreover, a quantitative comparison was also conducted to show their differences in applicability to the assessment of ecosystems appropriation. It was shown that the calculating results from solar space method were bigger than that from ecological footprint because the former supplemented additional items of appropriation omitted by the later and included some new items of indirect appropriation that were excluded by the later. It is found that the new measure of solar space operates well as an indicator of the city's appropriation to ecosystems.     

Preparation,characterization of silver phyto nanoparticles and their impact on growth potential of Lupinus termis L. seedlings

The current study reports rapid and easy method for synthesis of eco-friendly silver nanoparticles (AgNPs) using Coriandrum sativum leaves extract as a reducing and covering agent. The bio-reductive synthesis of AgNPs was monitored using a scanning double beam UV-vis spectrophotometer. Transmission electron microscopy (TEM) was used to characterize the morphology of AgNPs obtained from plant extracts. X-ray diffraction (XRD) patterns of AgNPs indicate that the structure of AgNPs is the face centered cubic structure of metallic silver. The surface morphology and topography of the AgNPs were examined by scanning electron microscopy and the energy dispersive spectrum revealed the presence of elemental silver in the sample. The silver phyto nanoparticles were collected from plant extract and tested growth potential and metabolic pattern in (Lupinus termis L.) seedlings upon exposure to different concentrations of AgNPs. The seedlings were exposed to various concentrations of (0, 0.1, 0.3 and 0.5 mg L^?1) AgNPs for ten days. Significant reduction in shoot and root elongation, shoot and root fresh weights, total chlorophyll and total protein contents were observed under the higher concentrations of AgNPs. Exposure to 0.5 mg L^?1 of AgNPs decreased sugar contents and caused significant foliar proline accumulation which considered as an indicator of the stressful effect of AgNPs on seedlings. AgNPs exposure resulted in a dose dependent decrease in different growth parameters and also caused metabolic disorders as evidenced by decreased carbohydrates and protein contents. Further studies needed to find out the efficacy, longevity and toxicity of AgNPs toward photosynthetic system and antioxidant parameters to improve the current investigation.     

Ecological effects of desertification control and desertified land reclamation in an oasis–desert ecotone in an arid region: A case study in Hexi Corridor,northwest China

Desertification around oases is the major obstacle for sustainable development of oases in arid regions of northwest China. An effective way of maintaining the stability of oases is to recover the relatively stable ecological zone between an oasis and desert from the destroyed ecological rift zone. This paper presents a typical case of successful efforts in ecological restoration and desertified land reclamation of oasis–desert ecotone. On the basis of stabilization of mobile dunes and agricultural use of reclaimed land, some successful techniques including established straw checkerboards and planting drought-tolerant indigenous shrubs, leveling sand dunes and drawing water for irrigation, closing dunes for grass reservation were carried out in 1975. In the restoration area, a stable artificial protective forest system had been developed. Pedological analyses indicate that the fine particle fraction (silt and clay content) in 0–10 cm soil surface layer has been increased from 2.6% on the untreated mobile sandy land to 9.3–37.3% in the restoration areas, and correspondingly, soil organic C has been increased from 0.63 to 1.88–9.70 g kg⁻¹ during the 28 years of restoration period. In these 28 years, a 10 cm depth of minero-organic topsoil in the irrigated Picea sylvestris forestland has been developed. It is also observed that sand transportation rate during sandstorm events has been significantly reduced. The increase of vegetation cover indicates a remarkable environmental improvement. Overall, the ecological restoration approach in this study is of practical significance for the rebuilding of rift zone ecosystem and maintenance of the stability of oasis in the arid regions of northwest China.     

Herbivory,foliar survival and shoot growth in fragmented populations of Aristotelia chilensis

Habitat fragmentation may modify ecological interactions such as herbivory, and these changes can impinge upon plant fitness. Through a natural experiment, we evaluated if herbivory, foliar survival and shoot growth of the evergreen tree Aristotelia chilensis differ between a continuous forest (600 ha) and small fragments (∼3 ha) of the Maulino forest. From September 2002, we monthly recorded leaf emergence, area lost to herbivores and survival in four cohorts of leaves. Although herbivory of A. chilensis was low overall (foliar area loss <12%), herbivory was higher in the continuous forest than in small fragments. Nevertheless, differences in herbivory hold only for the first cohort of leaves, which were the largest ones. At the end of the growing season, herbivory rates in the continuous forest and fragments converge for all cohorts. Except for the first cohort of leaves, whose survival was higher in the fragments than in the continuous forest, foliar survival and shoot growth was similar in the continuous forest and fragments, and there was no correlation between herbivory and foliar survival or shoot growth. Although Maulino forest fragmentation negatively affects the intensity of herbivory, this effect is only transient, affecting only leaves that emerge early in the season, and might not affect the vegetative fitness of A. chilensis adults. The consequences of changes in ecological interactions triggered by forest fragmentation ought to be assessed rather than inferred from variations in patterns of resource use.     

Influence of cattle grazing on the density of oak seedlings and saplings in a Tabor oak forest in Israel

The effects of cattle grazing on the density of seedlings and saplings in a Tabor oak forest (Quercus ithaburensis subsp. ithaburensis) are investigated. The Tabor oak forest studied is located in a Nature Reserve in the Mediterranean region of Israel. Cattle graze at a stocking density of 0.71 head/ha for 6 months a year. The cattle grazing in the Nature Reserve is a beneficial management measure because it enhances plant species richness and reduces shrub encroachment.The impact of grazing on the densities of seedlings and young saplings was quantified in 46 large sampling plots (333 m² each) distributed over two experimental sites; the first being used as a rangeland for decades while the second is a forest patch totally free from grazing. The density and the height of Tabor oak individuals in each sampling plot were recorded. Four height categories were distinguished with a special focus on young seedlings (<0.15 m), established seedlings and young saplings (0.15 m–1 m).The density of seedlings and young sapling in the grazed Tabor oak forest were, respectively, 61% to 67% lower than in the ungrazed treatment. Implications on the continuity of the entire Tabor oak forest ecosystem are discussed. Three management measures that enable to prevent a decrease in young oak densities are proposed – reduction of stocking rate, deferment of the commencement of grazing, and fencing young seedlings.     

Experimental complexities in evaluating the comparative phytotoxicity of chemicals with different modes of action

Careful attention should be paid to bioassay experiments to examine the comparative phytotoxicity of chemicals with different modes of actions. Experimental complexities in examining comparative phytotoxicity of chemicals with differing modes of action are determined and discussed to appreciate the importance of relevant secondary effects that can be quickly measured. The chemicals selected were: benzoic acid, isoxaflutole and rimsulfuron. Data on shoot and root length of 7-day-old mustard (Brassica napus L.) seedlings, shoot height of 4-week-old mustard plants and total leaf chlorophyll concentrations were determined when plants were grown in soil treated with different concentrations of the three chemicals. Scanning electron microscope (SEM) studies were conducted to determine any damage to mustard root hairs after treatment. Root growth of 7-day-old mustard seedlings was reduced when treated with different concentrations of benzoic acid or rimsulfuron. Root growth of mustard seedlings, however, largely remained unaffected when plants were grown in soil treated with isoxaflutole. While no significant reduction in either chlorophyll concentration or shoot height of 4-week-old mustard plants was observed when treated with soil-applied benzoic acid, both parameters were inhibited when mustard plants were treated with isoxaflutole or rimsulfuron. SEM studies revealed significant damage to root hairs in a 7-day-old mustard seedlings when plants were grown in soil treated with 500, 1000 and 2000 mg/L benzoic acid, and 0.5 mg/L rimsulfuron. No such damage was observed when mustard was grown in soil treated with isoxaflutole.     

A novel optical interference technique to measure minute root elongations of Japanese red pine (Pinus densiflora Seibold & Zucc.) seedlings infected with ectomycorrhizal fungi

This study presents a new technique to measure root elongation of Japanese red pine (Pinus densiflora Seibold & Zucc.) seedlings with very high sensitivity in the order of sub-nanometer by using a novel optical interference method called statistical interferometry. The principle of the statistical interferometry is based on the statistics of a speckle field, which is generated when a rough surface is illuminated by a laser light. The technique facilitates to obtain minute root elongation measurements in the order of sub-seconds. The root elongation behavior of Pinus densiflora seedlings infected with ectomycorrhizal fungi, Pisolithus sp. (Ps) and Cenococcum geophilum Fr. (Cg), was investigated in comparison with that of an uninfected control. In the experiments, two points on a root with the separation of 3 mm were illuminated by laser beams and the elongation was measured continuously by analyzing speckle patterns successively taken by a CCD camera. The root elongation rate (RER), measured as the length of root elongation per second per millimeter (mean ± S.D.) for Ps-infected, Cg-infected and uninfected seedlings were 10.85 ± 2.41, 5.54 ± 1.43, and 2.41 ± 1.01 nm s⁻¹ mm⁻¹, respectively. We found that the RERs of seedlings infected with ectomycorrhizal fungi were significantly higher than that of the uninfected seedlings, and the seedlings infected with Ps fungi showed the highest RER. We conducted another experiment to observe two-dimensional root growth, in which the growth measurements were obtained for 4 months. From this experiment, we observed that root growth of ectomycorrhizal fungi infected seedlings were higher than that of the uninfected seedlings. The evaluation of results from these two techniques proves that the proposed statistical interferometry is much faster and very sensitive technique, where the time required for growth monitoring is 10⁷ times less than the other. We can conclude that, at the scale of either very short time or relatively long time, the symbiotic relationship between root and ectomycorrhiza has a positive effect steadily on the root elongation.     

A novel optical interference technique to measure minute root elongations of Japanese red pine (Pinus densiflora Seibold & Zucc.) seedlings infected with ectomycorrhizal fungi

This study presents a new technique to measure root elongation of Japanese red pine (Pinus densiflora Seibold & Zucc.) seedlings with very high sensitivity in the order of sub-nanometer by using a novel optical interference method called statistical interferometry. The principle of the statistical interferometry is based on the statistics of a speckle field, which is generated when a rough surface is illuminated by a laser light. The technique facilitates to obtain minute root elongation measurements in the order of sub-seconds. The root elongation behavior of Pinus densiflora seedlings infected with ectomycorrhizal fungi, Pisolithus sp. (Ps) and Cenococcum geophilum Fr. (Cg), was investigated in comparison with that of an uninfected control. In the experiments, two points on a root with the separation of 3 mm were illuminated by laser beams and the elongation was measured continuously by analyzing speckle patterns successively taken by a CCD camera. The root elongation rate (RER), measured as the length of root elongation per second per millimeter (mean ± S.D.) for Ps-infected, Cg-infected and uninfected seedlings were 10.85 ± 2.41, 5.54 ± 1.43, and 2.41 ± 1.01 nm s^?1 mm^?1, respectively. We found that the RERs of seedlings infected with ectomycorrhizal fungi were significantly higher than that of the uninfected seedlings, and the seedlings infected with Ps fungi showed the highest RER. We conducted another experiment to observe two-dimensional root growth, in which the growth measurements were obtained for 4 months. From this experiment, we observed that root growth of ectomycorrhizal fungi infected seedlings were higher than that of the uninfected seedlings. The evaluation of results from these two techniques proves that the proposed statistical interferometry is much faster and very sensitive technique, where the time required for growth monitoring is 10⁷ times less than the other. We can conclude that, at the scale of either very short time or relatively long time, the symbiotic relationship between root and ectomycorrhiza has a positive effect steadily on the root elongation.     

The potential of paleoecology for functional forest restoration planning: lessons from Late Holocene Italian pollen records

We describe forest landscape transformations during the last two millennia in the Italian peninsula by analyzing local (Rieti basin – Lago Lungo) and regional (RF93-30 Adriatic Sea) sediment cores. We identify a dynamic forest ecosystem through paleoecologic reconstruction and consider potential interventions for effective restoration of the most ancient, least disturbed forest ecosystem. The most degraded ecosystems in consequence of human activities were hygrophilous (wet) and mesic forests. In the Rieti Basin, degraded forest ecosystems on mountain slopes are undergoing some degree of forest succession and have less need of restoration. However, management plans for biodiversity, ecosystem services and resources conservation are needed to achieve more sustainable development. In Rieti, the paleoecological investigation revealed a dramatic decrease of deciduous wet and mesic tree taxa through time due to human landscape transformation. The starting point for restoration of a Mediterranean forest ecosystem that preserves natural biodiversity and associated ecosystem services requires recreating some portion of the floodplain wetland ecological niche. Once floodplain forest ecological niche has been recreated, the original ecosystem composed of Alnus, Fraxinus excelsior, Tilia spp., Carpinus betulus and Acer spp., all species which today are rare, should be planted on the basis of microsite characteristics and tree autoecology.     

Effect of arsenic on visible symptom and arsenic concentration in hydroponic Japanese mustard spinach

Responses of Japanese mustard spinach (JM-spinach; Brassica rapa L. var. pervirdis) were investigated at elevated levels of arsenic (As). Plants were grown hydroponically in the greenhouse under 0, 6.7, 33.5 and 67 μM As (equal to 0, 0.5, 2.5 and 5 mg L^?1 As, respectively) for 14 days. Arsenic was used as sodium meta-arsenite (NaAsO₂). Toxicity symptom was solely shown as shoot growth repression at 33.5 and 67 μM As exposures. Dry weight (DW) enhanced by 19.4% in shoot and 38.9% in root in the 6.7 μM As level as compared to control but decreased by 48.1% and 72.1% DW in shoot and 24.1% and 61.1% DW in root in the 33.5 and 67 μM As levels, respectively. This result indicated that As at lower concentration might have slight stimulating effect on JM-spinach growth, but toxicity increased with increasing As. Based on the regression lines between growth and As concentration in the plant tissues, the critical toxicity level (CTL) of As in JM-spinach shoot was 7.85 μg g^?1 DW considering 10% DW reduction. The CTL for the root was almost 2110 μg As g^?1 DW, indicating that shoot of JM-spinach was more sensitive to As-toxicity than that of root. Arsenic concentrations increased in plant parts with increasing As in the medium. Arsenic concentrations were also compared in DW and fresh weight (FW) basis. The JM-spinach concentrated unaccepted level of As in shoots for human consumption in the higher As levels without showing visible toxicity symptom. In spite of decreasing iron (Fe) concentration in shoot in the highest As level, chlorophyll index did not decrease accordingly. Phosphorus (P) concentration also decreased. Phosphorus concentration decreased much more than Fe concentration. Low P might help to mobilize Fe in shoots, resulting in higher chlorophyll index at 67 μM As level. Phosphorus might compete with Fe in shoot tissues of As-stressed JM-spinach.     

Response in root morphology and nutrient contents of Myriophyllum spicatum to sediment type

Sediment may play an important role during the submerged macrophyte decline in the eutrophication progress. In order to investigate the response in root morphology and nutrient contents of submerged macrophytes Myriophyllum spicatum to sediment, five sediment types were treated and used (five types of sediment were used in the experiment: treatment 1 was nature sediment + sand, a 50:50 (v/v) mixture, treatment 2 was the studied sediment only, treatment 3 was sediment + nitrogen (N, NH₄Cl 400 mg kg^?1), treatment 4 was sediment + phosphorus (P, NaH₂PO₄ 300 mg kg^?1); treatment 5 was sediment + phosphorus (P, NaH₂PO₄ 600 mg kg^?1)). The results show that the root N content was only significantly affected by adding N in sediments and P was elevated by adding N and P. The root mass and its percentage increased at first, the peak values were reached at 35 d, and then decreased. The root growth was restrained by adding sand and N in sediments, root senescence process was delayed at the later experimental time by adding P in sediments. The increase of root volume showed a similar trend to that of root growth, except for plant with P addition where root volume remained high after 35 d. The root volume decreased while the main root number increased significantly by adding sand in sediments. The mean root length and main root diameter were reduced by adding P in sediments. The compatible sediment nutrient condition is necessary to restore submerged macrophytes in a degraded shallow lake ecosystem, and the effect of sediment on the root morphology and nutrient content is one of the important aspects restricting the restoration of submerged macrophytes.