Effect of water stress conditioning on morphology,physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiologicalattributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded forfour growing seasons after planting. The mostsignificant effect of irrigation was onmorphology. Increased irrigation lead toseedlings with significantly higher height,root collar diameter and shoot and rootbiomass. Starch and soluble carbohydrateconcentrations were also affected byirrigation. However, parameters derived frompressure-volume curves were not significantlydifferent among treatments, nor were N, P, andK concentrations. There were no differencesamong treatments for survival in the field,which was highly related to summer rainfall. Incomparison, absolute and relative heightgrowth showed some significant but minordifferences among treatments.     

Restoration of oak forest: Effects of former arable land use on soil chemistry and herb layer vegetation

Abstract

Stands of pedunculate oak (Quercus robur) planted 50–80 years ago on two types of land (previously forested land and former arable fields) were compared regarding vegetation and soil. Former arable soils were characterized by a higher pH, higher nitrate concentration and higher soil density, but had lower organic matter content and lower ammonium concentration in the topsoil (0–5 cm). These differences, however, decreased with soil depth. Phosphorus concentration was consistently higher in former fields throughout the soil profile (0–45 cm). Nitrogen mineralization, determined by in situ incubation, showed a strong seasonal pattern with peak values in spring. Non-metric multidimensional scaling ordination revealed marked compositional differences in the vegetation between the two land-use categories, and also compositional turnover along gradients in soil pH and nitrogen availability. Differences in soil pH between land-use categories occurred in a range critical for the establishment of many typical forest herb layer species. Plant indicator species were identified for the two land-use categories. The results showed that acid-sensitive forest herbs may benefit from the higher pH soils in new woodlands, in contrast to ancient forest soils with little buffer capacity towards natural and anthropogenic acidification. In conclusion, former arable use has long-lasting effects on soil properties and vegetation composition in broadleaved forests. New woodlands on former fields can thus offer relatively persistent new habitats for acid-sensitive species that have suffered from reduction in habitat area during historic periods of deforestation and cultivation.     

苗龄对华木莲苗木质量及其造林成效的影响

为更好提高华木莲造林质量,以1年生(S1-0)、2年生(S2-0)、3年生(S3-0)实生苗进行造林试验,分析了不同苗龄苗木的质量及其造林效果的差异.结果表明:1)华木莲苗期生长指标与苗龄显著正相关,苗木在第2年的各生长指标的相对生长率显著高于第3年;2)采用S2-0、S3-0苗营造的人工林第1年的成活率分别为93％、90％,显著高于S1-0林分的成活率;S2-0林分第2、3年保存率分别为89％、84％,显著高于S3-0、S1-0林分;3)生长指标来看,S1-0、S2-0、S3-0"同年造林"时,造林后第2年、第3年,S2-0林分的树高生长量、地径生长量均显著高于S1-0、S3-0林分;苗木"逐年造林"时,在树龄为6 a时,S1-0、S2-0、S3-03种苗型所造林分的树高无显著差异,S2-0、S1-0所造林分的地径均显著高于S3-0林分.4)叶绿素含量来看,S1-0与S2-0所造人工林在第3年时SPAD值分别为60.05、47.12,高于S3-0所造3 a人工林的SPAD;5)相关性分析表明,仅有苗龄与1 a林分的树高、地径、保存率等指标相关系数在0.75以上,为显著正相关.综合保存率、生长量、叶绿素含量等指标,S2-0苗适应性强,所造林分质量稳定,效果更佳.在同等条件下,华木莲苗龄显著地影响造林效果,造林时选用合格的S2-0苗能提高华木莲造林成效.     

Effects of Douglas-fir 2+0 seedling morphology on field performance

The relationships between field performance of Douglas-fir (Pseudotsuga menziesii) 2+0 seedlings and their initial diameter and root mass were evaluated on five sites in Oregon in the early 1980s to identify opportunities for improving seedling grading prior to planting. Survival and height 3–5 years after planting were positively related to seedling size at the time of planting. On all sites, survival nearly doubled from the smallest to largest diameter classes. Root mass had a similar relationship to survival on sites with environmental stress. Increasing root size class increased survival more for the small diameter classes than for the larger diameter clases. On the other hand, increasing root size class increased total height more for the large diameter class than the smaller ones. Although height was not as strongly affected as survival on several sites, height differences among initial seedling diameter classes were still significant and increasing after five years. Root class effects on height were less important than diameter class effects.     

Field performance of <Emphasis Type="Italic">Pinus halepensis</Emphasis> planted in Mediterranean arid conditions: relative influence of seedling morphology and mineral nutrition

In Mediterranean arid regions, relatively small planting stock has traditionally been used in an attempt to reduce drought susceptibility, though few studies have examined influences of initial seedling morphology and nutrition on long-term plantation establishment. We fertilized Pinus halepensis Mill. seedlings in the nursery with controlled release fertilizer (CRF) varying in formulations and rates; 9-13-18 and 17-10-10 (N-P-K) formulations at 3, 5 and 7 g l⁻¹ substrate plus an unfertilized control and we evaluated growth and survival 7 years after planting in arid conditions in Almería province, southeast Spain. Interactions between initial height and fertilizer treatments occurred during the first 3 years; initial size advantages of specific fertilizer treatments (7 g l⁻¹ of 9-13-18 and 17-10-10 at 3 g l⁻¹) persisted after 7 years. The largest and most nutrient-rich seedlings from 9-13-18 at 7 g l⁻¹ (41.0 cm tall, 4.4 mg of P per g of root tissue at time of planting) exhibited the highest survival after 7 years (79%), while survival declined to 42% for non-fertilized plants (12.9 cm tall and 0.6 mg of P per g of root tissue). Initial seedling morphological parameters were most consistently correlated with field performance. Root P concentration was the nutrient variable most closely related to survival. Our data emphasizes importance of longer-term experiments to accurately assess influences of nursery treatments on field responses, particularly in arid areas. We suggest that larger seedlings with greater nutrient reserves than are currently being used should be incorporated into Mediterranean plantations.     

Effects of pre-commercial thinning on growth and reproduction in post-fire regeneration of Pinus halepensis Mill

Context

Excessive recruitment in post-fire regeneration of Pinus halepensis can require pre-commercial thinning. The 1994 Moratalla fire (Spain) and the thinning applied there since 2004 provided good conditions for testing pre-commercial thinning effectiveness.

Aims

To analyse pre-commercial thinning effects on tree size, reproductive potential, stem biomass and annual growth in 15-year-old saplings.

Methods

Twenty nine circular plots (5 m radius) were established based on (1) years since thinning and (2) aspect. Non-thinned plots were included as controls. Sapling variables were measured and pine cones were counted and classified according to maturity. Three saplings per plot were felled, five sample disks were extracted from each and tree rings were analysed with Windendro® software.

Results

Sapling size, annual growth and stem biomass were higher in thinned plots than in control plots 2–4 years after thinning. Annual growth declined five years after thinning. Cone counts were higher 2–5 years after thinning, depending on the cone type. Aspect influenced some variables.

Conclusion

Thinning accelerated stand maturity but positive effects were indiscernible until 2–5 years later. Serotinous cones, which are fundamental to regeneration after fire, increased in number after 5 years. The effects of aspect were inconclusive due to interactions with years since thinning.     

Effects of light/darkness, thermal shocks and inhibitory components on germination of Pinus canariensis, Pinus halepensis and Pinus pinea

Knowledge of the germination characteristics of Pinus species can help in the understanding, prediction and management of the regeneration of pine forests. In the Canary Islands, several exotic pines (Pinus halepensis L. and Pinus pinea L.) were planted with Pinus canariensis Chr. Sm. Ex DC, the only native pine species, and there is now an interest in controlling these exotic species to restore the original forest. The main objective of the present study is to determine the germination response of P. canariensis, P. halepensis and P. pinea to different light regimes (darkness and light/darkness), thermal shocks and the presence of inhibitory substances from the leaves and litter of P. canariensis. P. halepensis seeds showed the highest viability and germination rate. Darkness accelerated P. halepensis germination, while exudates accelerated P. canariensis germination. Only treatments of 200 °C for 5 min and 300 °C for 5 min significantly decreased the germination of all three pine species. In the absence of strong differences in germination among species after treatments, the key for fire management or prescribed burning in this case may be the sprouting ability of P. canariensis. A possible management strategy to control the two obligate seeder exotic species could be to use one intense prescribed fire followed by a low-intensity prescribed fire after seed bank germination in the field, so in this way, only P. canariensis could resprout after fire and it would eliminate only the exotic pines in a mixed stand.     

Container characteristics influence Pinus pinea seedling development in the nursery and field

The growth and development of Pinus pinea seedlings grown in different containers was followed through one growing season in the nursery and 3 years following outplanting in the field. The variables studied in the nursery were height, diameter, biomass of shoots and roots, nutrient uptake and root density. The measured field variables, height and diameter increment and survival, were correlated with the nursery variables. Container volume had the greatest influence on plant morphology. Containers with larger rooting volume had seedlings with larger height and diameter, greater nutrient content, and better field performance. Growing density was correlated with seedling morphology and nutrient concentration in the nursery. Among the variables that influenced container volume, the diameter of the container was the most important, while the depth of the container had a minor influence on seedling morphology.The best indicator of seedling development in the nursery was the ratio of container depth to container diameter, and the optimum ratio was 4. All containers produced seedlings with some root spiralling, including those containers with ribs. There was no relationship between either the number of spiralling roots or the angle of spiralling and container characteristics. Furthermore, root spiralling did not influence seedling performance following outplanting. Root density (root biomass/cm³) was inversely correlated with container volume but there was no correlation with either depth or growing density. The largest plants were produced with container volumes of 300–400 cm³, depth/diameter ratios of 4, and growing densities of 200–300 seedlings/m². These growing conditions will result in larger Pinus pinea seedlings coming out of the nursery, which will increase growth following outplanting.     

Long-term response of weed control intensity on Scots pine survival, growth and nutrition on former arable land

The effects of post-planting weed control intensity on the cover and composition of ground vegetation, and on growth, survival and foliar nutrient concentrations of 4-year old bare-rooted Scots pine (Pinus sylvestris L.) seedlings were studied over a 15-year period with experimentation on former arable land. Weed control treatments with terbuthylazine and glyphosate were carried out 1?C3 times during successive years, either as overall or as spot applications. The vegetation cover and the shading effect of vegetation decreased with increasing weed control intensity. The more intensive the weed control was, the better was the afforestation result in terms of tree seedling growth and survival. Overall application repeated three times increased seedling survival by 79 percentage points, and their final height, breast height, diameter, and stand volume after 15 years were increased by 183, 19, 15, and 822%, respectively. Weed control did not affect the foliage nutrient concentrations, except for magnesium. However, increase in weed control intensity was reflected in larger needle size 5 years after planting.     

Soil water content and water relations in planted and naturally regenerated Pinus halepensis Mill. seedlings during the first year in semiarid conditions

The capacity of Aleppo pine (Pinus halpensis Mill.) seedlings to overcome the planting shock in dry conditions was assessed by firstly studying the survival and water status during the first year after planting in relation to soil water content. In spite of receiving only 177 mm rainfall during the year studied, survival of planted Aleppo pine was very high (88.5%). Soil water during summer months (after receiving 67 mm rainfall in winter and spring) was only available at 30–60 cm depth, with tension values of –1.1 and –1.3 MPa in July and August respectively; in these conditions, July predawn xylem water potential measured was –2.5 MPa, and midday potential was –3.6 MPa. According to different authors, these values don't jeopardize the survival of Aleppo pine. In addition, acclimation of outplanted seedlings to environmental conditions was followed by comparing their water relations with those of naturally regenerated seedlings on the site. Predawn and midday xylem water potential showed differences in favour of outplanted seedlings since June, indicating an adjustment to this dry site. Compared to naturally regenerated trees, nursery grown stock of the same age before field planting had much more biomass and higher N and P concentrations and contents; although shoot:root balance and Dickson quality index were not significantly different. Finally, planted seedlings acclimation level during first year was also evaluated by Transplant Stress Index, which value (–0.1278) indicated a slight planting impact.     

Influence of cavity size, seedling growing density and fungicide applications on Keithia blight of western redcedar seedling growth and field performance

To determine the influence of cavity size, seedling density and fungicide application on severity of Keithia blight caused by the fungus Didymascella thujina (Durand) Maire, western redcedar (Thuja plicata Donn) seedlings were grown in styroblocks of 3 cavity sizes, thinned to 3 growing densities and sprayed several times monthly with mancozeb fungicide. After two growing seasons cavity size, seedling growing density and number of fungicide applications all significantly (p0.05) affected blight severity. Blight severity was inversely related to the number of mancozeb fungicide applications. The only significant two-way interaction was for cavity size and seedling growing density.Eighteen seedlings from each of the nine cavity sizes and seedling densities combinations were assessed for shoot height, root collar diameter and blight severity, prior to planting at both Holt Creek and Salmon Creek on Vancouver Island, British Columbia in March 1994. Growth was reassessed during October 1994. Seedling height and root collar diameter increased significantly (p0.05) with certain cavity size and seedling density combinations. Blight severity increased significantly (p0.05) for all nine treatments at both sites, however, between sites blight severity increased significantly (p0.05) only at the wetter, Salmon Creek site.     

Effects of aspect and slope position on growth and nutritional status of planted Aleppo pine (<Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill.) in a degraded land semi-arid areas of Jordan

Plantation of open grazing lands with Pinus halepensis are the most widely used practices in afforestation and reforestation in Jordan and other semi-arid areas around the Mediterranean Basin. The effect of aspect North (N), South (S), East (E) and West (W) and slope position (upper, middle, lower and valley bottom) on growth of planted Aleppo pine, nutritional status, plantation on restoring, needle, forest floor, nutrients concentration and soil properties were studied in Jubilee forest in Rakeen area, south of Jordan. Tree height was significantly higher in W than N, S and E aspects which mainly due to better moisture and nutritional conditions. All growth parameters were obtained on valley bottom were significantly higher than all aspect slope position combinations due to accumulation of run off and depositions from upper towards middle, and finally in lower slopes. In general, pH and EC were significantly reduced and soil organic matter was significantly improved by Allepo pine plantations compared to unplanted areas. West and N aspects as well as valley bottoms showed better soil physical and chemical properties.     

Effects of nursery shading on seedling quality and post-planting performance in two Mediterranean species with contrasting shade tolerance

In Mediterranean climates, seedlings are frequently shaded in the nursery to avoid heat damage and save water. However, the impact of this shading on the seedling quality and transplanting performance of Mediterranean species is not well known. We studied the effect of nursery shading on pre-planting features and post-planting performance of two Mediterranean tree species: the shade-intolerant pioneer Pinus halepensis and the shade-tolerant late-successional Quercus ilex. We grew one-year-old seedlings of both species under 100, 40 and 5% full sunlight. Shade had a low impact on the morphology and physiology of Q. ilex seedlings. In pines, only the deep shade treatment produced low quality seedlings with poor root development. In both species, transference to high light at planting in autumn did not impose any additional stress than that caused by frosts, but initial root growth was impaired in the two shaded treatments in pine. Post-planting growth and survival of oak seedlings showed no difference between treatments. Pine seedlings grown in deep shade showed higher mortality and lower growth after planting than those grown in full sun and intermediate light treatments, while intermediate light only reduced growth. For the nursery culture of Q. ilex seedlings, we advise using low light levels during summer to save water without impairing field performance. In P. halepensis, seedlings should be cultured under full sunlight conditions to maximize post-planting growth, but they can be cultured under intermediate light without impairing survival.     

Concentrations and fluxes of dissolved organic carbon and nitrogen in a Picea abies chronosequence on former arable land in Sweden

Shifting land use from agriculture to forestry induces major changes in the carbon (C) and nitrogen (N) cycles, including fluxes of dissolved organic carbon (DOC) and nitrogen (DON). This study investigated the long-term effects of afforestation on ecosystem DOC and DON dynamics using a chronosequence approach comprising four arable fields and nine differently aged (10–92 years) Norway spruce stands growing on similar former arable soils in the same area. Along the chronosequence, concentrations and fluxes of DOC and DON were determined in bulk precipitation, throughfall, O horizon leachate and mineral soil solution during a 2–3-year period. Soil water fluxes were calculated using a soil hydrological model (SWAP). Results showed that DOC concentrations and fluxes with throughfall were strongly positively correlated with tree height (r² = 0.95; P < 0.05 for both conc. and flux) and stand age, while DON showed no such trends, suggesting different origins of DOC and DON in throughfall. The highest concentrations and fluxes of DOC and DON occurred in soil leachate from the O horizon. Here, DOC flux was 250–310 kg C ha⁻¹ yr⁻¹ and DON flux 8–9 kg N ha⁻¹ yr⁻¹ in stands afforested between 65 and 92 years ago. Concentrations and fluxes of DOC and DON in the mineral subsoil were consistently low. Flux calculations suggest that there was a net loss of >90% (230–280 kg ha⁻¹ yr⁻¹) of DOC leached from the O horizon within 0–60 cm of the mineral soil. There was no significant effect of land use or forest age on DOC concentrations in solution from the lower part of the A horizon. The effect of time since afforestation was masked by soil properties that influence DOM retention in the mineral soil. Our data indicate that DOC concentrations in the A horizon of the sites studied were primarily related to the oxalate-extractable Al and Fe amounts in the same horizon. Afforestation of arable land induced a gradual qualitative change in soil organic matter (SOM) and dissolved organic matter (DOM), with significantly increasing C:N ratios in soil and soil solution over time. The development of an O horizon and the subsequent leaching of DOC and DON to the underlying mineral soil are important drivers of a changing soil C and N turnover following afforestation.     

The current situation and future perspectives of Quercus ilex and Pinus halepensis afforestation on agricultural land in Spain under climate change scenarios

New Forests - Between 1994 and 2017, 137,455&nbsp;ha of agricultural land were afforested in Andalusia (Spain), using a great diversity of tree species, under the Common Agricultural Policy...     

Effects of seed size on seedling attributes in Sitka spruce

No statistically-significant effects of size (small and large) of wind-pollinated seeds from 18 seed-orchard clones could be found in the attributes of 8-month-old seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.). Clonal variations in seedling attributes was highly significant (P < 0.01), but these variations were within regional specifications for operationally-produced nursery stock.     

两株外生菌根真菌对盐渍土壤中黑松幼苗生长的影响

为了研究外生菌根真菌对宿主植物黑松幼苗耐盐性的影响,采用盆栽实验,将成功侵染菌种土生空团菌(Cg)、紫晶蜡蘑(La)的黑松幼苗移栽于盐渍土壤中,培育3个月后,测定相关生理指标。结果表明:1)与非菌根化幼苗相比,接种菌根真菌Cg和La显著提高了针叶叶绿素a(由0.78 mg/g FW增加到1.27 mg/g FW和1.47 mg/g FW)和叶绿素b(由0.28 mg/g FW增加到0.40 mg/g FW和0.43 mg/g FW)的含量,增加了宿主体内脯氨酸含量(地上部:La> Cg> NM;地下部:La> Cg> NM),增强了K^+的吸收、转运,有效地维持(Cg菌种)或是降低(La菌种)了宿主地上部分Na^+/K^+的比值;显著(P <0.05)降低了宿主幼苗地下部的Na^+/K^+比值(由0.70降低到0.47和0.64)。2)外生菌根真菌有利于松树幼苗的生长,提高了其耐盐性,但因菌种而异(La> Cg)。深入研究不同菌种对不同宿主植物耐盐性的影响,将会成为后续菌根技术研究的一个重要方向,为沿海滩涂盐碱地的植被恢复提供理论依据及技术支持。     

Effects of different site preparation methods on the root development of planted Quercus petraea and Pinus nigra

New Forests - Mechanical site preparation (MSP) is often performed prior to planting to improve the growth and survival of planted seedlings. In this study, we compared root development of...     

Modelling the diameter distribution of Pinus sylvestris, Pinus nigra and Pinus halepensis forest stands in Catalonia using the truncated Weibull function

Parameter prediction models for the diameter distribution ofPinus sylvestris L., Pinus nigra Arn. and Pinus halepensis Mill.in Catalonia were developed using the truncated Weibull functionas the theoretical distribution. The parameter models allowone to use individual-tree models in the simulation of standdevelopment when only stand-level data are collected in forestinventories. Parameter models for the diameter distributionof stand basal area were developed. The data consisted of permanentsample plots from the Spanish National Forest Inventory in Catalonia.A total of 1780 empirical distributions of P. sylvestris, 1204distributions of P. nigra and 1535 distributions of P. halepensiswere used as modelling data. The empirical data represent left-truncateddistributions, as the smallest diameter measured in the fieldwas 7.5 cm. Two different approaches, namely, regression (two-stepmethod) and optimization approach (one-step method), were usedto find the coefficients of the parameter models. In the two-stepmodelling method, the Weibull parameters were first estimatedseparately for every empirical distribution by maximizing thelog-likelihood function of the Weibull density function. Inthe second-step, regression analysis was used to find the relationshipbetween Weibull parameters and stand basal area, number of treesper hectare and elevation of the site. The one-step method usedoptimization to find such coefficients for the parameter models,which minimized the mean of the squared differences betweenempirical and predicted cumulative tree frequencies in the wholemodelling data. The one-step optimization method performed betterthan the two-step regression method for all tree species. Theparameter prediction models developed in this study enable theprediction of the diameter distribution of P. sylvestris, P.nigra and P. halepensis in Catalonia from limited stand information.