Development Of Tree Seedlings Research Articles

Northern hardwoods seedlings respond to a complex of environmental factors when deer herbivory is limited

Deer herbivory has a reputation for suppressing tree seedling development in Northern hardwood forests. We examined survival and growth of sugar maple (Acer saccharum) and ash (Fraxinus spp.) seedlings in a controlled factorial experiment with differing light conditions and levels of deer access in a Northern hardwoods forest in Wisconsin, USA. Measurements were made in ∼380 m3 harvest gaps, in transition zones adjacent to gaps, and under closed canopy conditions, both inside and outside of deer exclosures. Browse incidence was initially greater in unfenced treatments, but a general decline through time eliminated this difference. Seven-year survival of both species groups was correlated positively with initial root collar diameter (RCD) and was greater in transition zones. Ash seedling survival was greater in plots with greater overall seedling aggregate height. Soils were primarily differentiated by available nitrogen, which positively influenced height growth of sugar maple in transition zones but did not influence ash growth. Although sugar maple height growth was correlated positively with initial RCD, greater initial height reduced growth rates, both as a simple effect (sugar maple) and in combination with initial RCD (ash). Ash growth correlated negatively with seedling aggregate height in gaps but was unaffected in transition or canopy zones. Allometric coefficients of RCD:height indicated some influence of deer herbivory which was not detected in other analyses. Coefficient values trended downward from year 2 to year 9, but wide confidence intervals limit the value of this metric as an indicator of seedling community resilience with regard to deer.

Constraints on tree seedling establishment after fires: passing the germination bottlenecks.

Persistence and colonization by tree species in an environment following a fire depends on the effects on seed germination and seedling development. We used seeds of Kielmeyera coriacea and Qualea parviflora as a model to test the effects of high temperatures on germination and initial development of tree seedlings. We exposed the seeds to heat flow (70, 100, 130, 150 or 170 °C) for 2 or 5 min and compared the germination with that of unheated seeds (control). Seedlings were then harvested after 3, 7 or 15 days to evaluate aerial and root mass, root:shoot ratio, presence of cotyledon opening, true leaves, and secondary roots. We found no effect on germination for seeds exposed to temperatures ≥150 °C. However, germination was significantly reduced for seeds exposed to 100 °C for both 2 and 5 min. The mass of 15-day-old K. coriacea seedlings was smaller when seeds were heated at 70 °C for 5 min or at temperatures higher or equal to 100 °C. Qualea parviflora seedlings did not show any difference in mass, but there were marginal differences in the presence of roots and the opening of cotyledons. Kielmeyera coriacea seedlings allocated biomass faster than Q. parviflora. High temperatures affect both quantity and quality of germinable seeds, as well as biomass allocation during initial seedling development. These factors may explain the decrease in seedlings observed after fire, suggesting a bottleneck effect that influences population dynamics and species persistence in systems with frequent fires.

Biochemical attributes and establishment of tree seedlings in soil after urochloa decumbens cultivation in soil with deposition of iron mining residues

background: the recovery of areas impacted by mining activities is a major challenge and requires knowledge of how the biological and biochemical processes of the soil as well as the establishment of plant species are affected by mining residue. in this work, the influence of deposition of iron mining mud and tailings on soil biochemical attributes and the initial development of tree seedlings was studied in a simulated event in the greenhouse. pots (n = 27) with natural soil (2.0 kg) received deposition (280 ml) of iron mining mud or tailings and by three-month was cultivated with urochloa decumbens. at the end of this period, part of the pots was sampled and the soil biochemical activities were evaluated. then tree seedlings (schinus terebinthifolius and eremanthus incanus) were planted and cultivated for a year, when then shoot (sdw) and roots (rdw) dry weight were evaluated. results: deposition of iron mining mud and tailings did not affect microbial biomass carbon or basal soil respiration, however both conditions reduced (p < 0.05) β-glucosidase activities by up to 30%, and the easy extractable glomalin by about 19%. in addition, the mud deposition reduced (p < 0.05) the sdw and rdw of s. terebinthifolius by about 21% and 24%, respectively. nevertheless, uruchloa decumbens and eremanthus incanus had no variation in dry weight production between treatments, so they have good ability to grow settle in soil affected by mining residue. conclusion: this study shows that the sequential planting of u. decumbens and e. incanus can be an alternative for use in environments with deposition of iron mining tailings.

Biosynthesis of zinc oxide nanoparticles using leaf extract of Calotropis gigantea: characterization and its evaluation on tree seedling growth in nursery stage

Green synthesis of zinc oxide nanoparticles was carried out using Calotropis leaf extract with zinc acetate salt in the presence of 2 M NaOH. The combination of 200 mM zinc acetate salt and 15 ml of leaf extract was ideal for the synthesis of less than 20 nm size of highly monodisperse crystalline nanoparticles. Synthesized nanoparticles were characterized through UV–Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), EDX (energy dispersive X-ray), and AFM (atomic force microscopy). Effects of biogenic zinc oxide (ZnO) nanoparticles on growth and development of tree seedlings in nursery stage were studied in open-air trenches. The UV–Vis absorption maxima showed peak near 350 nm, which is characteristic of ZnO nanoparticles. DLS data showed that single peak is at 11 nm (100%) and Polydispersity Index is 0.245. XRD analysis showed that these are highly crystalline ZnO nanoparticles having an average size of 10 nm. FTIR spectra were recorded to identify the biomolecules involved in the synthesis process, which showed absorption bands at 4307, 3390, 2825, 871, 439, and 420 cm−1. SEM images showed that the particles were spherical in nature. The presence of zinc and oxygen was confirmed by EDX and the atomic % of zinc and oxygen were 33.31 and 68.69, respectively. 2D and 3D images of ZnO nanoparticles were obtained by AFM studies, which indicated that these are monodisperse having size ranges between 1.5 and 8.5 nm. Significant enhancement of growth was observed in Neem (Azadirachta indica), Karanj (Pongamia pinnata), and Milkwood-pine (Alstonia scholaris) seedlings in foliar spraying ZnO nanoparticles to nursery stage of tree seedlings. Out of the three treated saplings, Alstonia scholaris showed maximum height development.

Occurrence of brambles (Rubus L.) in young forest plantations on the Kolbuszowa Plateau

Abstract In forests of the Kolbuszowa Plateau, bramble thickets are common mainly in young forest plantations and clear-cut areas. 11 bramble species were found in 20 plantations visited during the field study. The most frequent bramble species in young forest plantations include: Rubus plicatus, R. nessensis, R. hirtus, R. idaeus, while less frequent are: R. gracilis, R. ambrosius and R. apricus. The largest patches of brambles were found in plantations established on sites of mixed pine-oak forest, subcontinental lime-oak-hornbeam forest and dried alder carrs. Rubus thickets in young forest plantations occur together with numerous species characteristic of communities classified into the following classes: Vaccinio-Piceetea, Querco-Fagetea, Epilobietea angustifolii, Molinio-Arrhenatheretea and Nardo-Callunetea. Brambles growing in young forest plantations can be roughly divided into three groups: I - species with thin, prostrate and rooting stems (R. hirtus, R. apricus, R. pedemontanus), which may significantly affect the growth of tree seedlings if bramble specimens or diaspores are present at the time of tree planting; II - species with strong, poorly branched and arcuate stems (R. plicatus, R. gracilis, R. ambrosius, R. glivicensis), whose negative effect on tree seedlings depends on the potential of a tree species to produce quickly a high and dense thicket thereby overshadowing the lower vegetation; III - species with erect and relatively sparsely growing stems (R. idaeus), which do not pose any threat to young forest plantations. Species with intermediate biological traits (e.g. R. nessensis) may have a negative impact on young plantations, as they generate large and dense bush, however, in most cases, their populations grow rather sparsely and do not hinder the development of tree seedlings.

The Effect of Restoration Treatment Soils and Parent Tree on Tropical Forest Tree Seedling Growth

Restoration treatments can impact the growth and development of tree seedlings; however, it is often difficult to discern whether responses are driven by changes in microclimate, biotic interactions, or soil properties. To isolate for the latter, we quantified the growth response of four species [Ocotea puberula (Lauraceae); Otoba novogranatensis (Myristicaceae); Pseudolmedia mollis (Moraceae); Senna papillosa (Fabaceae)] grown under similar shade-house conditions in soils collected from 6 - 7 year old active (four species plantation) and passive restoration plots (natural recovery), and nearby reference forest sites in Costa Rica. We also evaluated the role of parent tree by collecting individuals from five mother trees. We measured height, above- and below-ground biomass, and determined root: shoot ratios (RSR). Species differed markedly in their responses. Ocotea, and to a lesser extent Pseudolmedia, were largely driven by parent tree. In contrast, Senna showed a strong soil response for all variables with more growth in active than passive restoration soils; reference forest seedlings were typically intermediate. An interaction suggested that some genotypes are more responsive to different soil properties than others. Otoba had higher soil-driven RSR in both restoration treatments. Surprisingly most soil nutrients, including %N, were similar or significantly lower in active restoration soils, suggesting that seedlings are responding to differences in soil microbial communities or more labile nutrients (e.g., NH4+ and NO3-). Active restoration appears to facilitate the growth of other species by improving certain soil properties. Additionally, genotypes are an important driver of seedling vigor and some species may be more responsive to subtle differences in soil properties than others.

Does crotalaria (Crotalaria breviflora) or pumpkin (Cucurbita moschata) inter-row cultivation in restoration plantings control invasive grasses?

Alternative methods to control invasive fodder grasses are necessary to reduce the use of herbicides in forest restoration, which has been carried out primarily in riparian zones. We sought to investigate if inter-row cultivation of crotalaria (Crotalaria breviflora DC) or pumpkin (Cucurbita moschata Duschene ex. Poir) with native tree species is an efficient strategy to control invasive fodder grasses in restoration plantings. We tested five treatments in a randomized block design, namely (1) control of brachiaria grass (Urochloa decumbens (Stapf.) Webster) with glyphosate in the implementation and post-planting grass control of the reforestation, (2 and 3) glyphosate use in the implementation and inter-row sowing of crotalaria (2) or pumpkin (3), and control of brachiaria by mowing in the post-planting phase, (4 and 5) mowing in the implementation and inter-row sowing of crotalaria (4) or pumpkin (5), and control of brachiaria by mowing in the post-planting phase. Post-planting grass control was carried out four and nine months after tree seedling planting. Throughout 13 months, we evaluated the percentage of ground cover by brachiaria grass, pumpkin production, and native tree seedling mortality, height and crown cover. The exclusive use of glyphosate, without inter-row sowing of pumpkin or crotalaria showed the most favorable results for controlling brachiaria grass and, consequently, for tree seedling development. Hence, inter-row cultivation of green manure or short-lived crop species is not enough to control invasive grasses in restoration plantings, and complementary weeding is necessary to reduce the highly competitive potential of C4 grasses for supporting native species seedlings growth.

Competition theory — science and application in mixed forest stands: review of experimental and modelling methods and suggestions for future research

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.

Interference to Hardwood Regeneration in Northeastern North America: Assessing and Countering Ferns in Northern Hardwood Forests

Abstract The extremely dense shade cast by spreading ferns, particularly hayscented, New York, and bracken ferns, interferes with the survival and development of tree seedlings in northern hardwood forests. Excessive bracken frond litter and hayscented fern root mats can also prevent adequate germination and seedling development. In addition, the herbaceous cover may harbor detrimental small herbivores, while large ones often preferentially browse seedlings that grow through this layer. Increased understory light levels after an overstory disturbance, abundant soil moisture, fire, and herbivory promote ferns, whereas excessive and repeated cold or drought deter fern development and propagation. The most promising control methods repress ferns until seedlings cast adequate shade to inhibit further development of the fern layer. When ferns cover more than 30% of the understory, well-timed applications of either glyphosate or sulfometuron methyl have successfully controlled hayscented, New York, and bracken ferns. Two carefully timed mowings annually for at least 2 years have also provided long-lasting control on level, accessible sites. Deer populations must be reduced where browsing prevents development of desirable plants.

Irradiance and Spectral Quality Affect Asian Tropical Rain Forest Tree Seedling Development

Plant developmental responses to shade are the combination of reductions in photosynthetic photon flux density (PPFD) and changes in spectral quality (reductions in the quantum ratio of red to far—red band widths, R:FR). We studied the seedling development of six Asian tropical rain forest trees, Dryobalanops aromatica, Endospermum malaccense, Hopea wightiana, Parkia javanica, Shorea singkawang, and Sindora echinocalyx under varying PPFD and R:FR. Seedlings were grown in replicated shadehouse treatments: (1) 40% solar PPFD and 1.25 R:FR; (2) 11% PPFD and 1.25 R:FR; (3) 11% PPFD and 0.24 R:FR; (4) 3% PPFD and 1.25 R:FR; and (5) 3% PPFD and 0.23 R:FR. Species differed in the influence of light variables on seedling (1) total height; (2) internode distance; (3) branch to trunk internodes; (4) stem length/mass; (5) leaf area/stem length; (6) percent allocation to leaf, stem and root mass; (7) specific leaf mass; (8) mean leaf area; (9) leaf thickness; (10) petiole length; and (11) stomatal density. The simple factorial design of treatments 2–5 allowed a two—way ANOVA and the calculation of coefficients of determination of the treatment effects. The characters in most taxa were primarily influenced by light intensity, but spectral quality also influenced characters in many cases. The taxa that responded most strongly to the light treatments were the most shade—intolerant: E. malaccense and P. javanica; the former species responded strongly to R:FR, particularly in stem mass allocation and leaf area/stem length. The four taxa with moderate—to—extreme shade tolerance varied considerably in responses of individual characters to R:FR and PPFD. The patterns of morphological responses to reduced PPFD and R:FR help explain how the shade tolerances of the seedlings of rain forest trees vary in a continuous manner. Recommendations concerning seedling shade tolerance for sylviculture or nursery practice may need revision if they were based on shade trials using spectrally neutral shade fabrics or slat houses. Future research on the effects of shading on tree seedling development and ecology must consider the potential influence of changes in spectral quality under canopy shade.

Adequacy of Advance Tree-Seedling Regeneration in Pennsylvania's Forests

Abstract Measurement of tree seedlings and herbaceous vegetation from 499 sample locations across Pennsylvania revealed that advance tree-seedling regeneration is inadequate for new stand establishment across most of the State. The samples were located in stands from 40% to 75% stocked to focus on stands with ample light and growing space for establishment of abundant advance regeneration. A range of regeneration adequacy criteria was applied to the measurements. Using the least stringent criterion, a low density of stems of any tree species, resulted in 40% of the sample locations being adequately stocked. Applying the most stringent criterion, a high density of stems of desirable species, resulted in only 4% of the sample locations being adequately stocked. With the exception of forest-type group, no significant relationship was found between the adequacy of regeneration and other variables tested at the broad level of geographic scale of this study. Levels of fern and grass sufficient to hamper tree-seedling development were found at 54% of the sample locations. Fern species that propagate primarily by spreading rhizomes accounted for 70% of the total fern sample. North. J. Appl. For. 12(4):187-191.

Tree seedling development in tropical dry abandoned pasture and secondary forest in Costa Rica

AbstractDevelopment of planted seedlings of four canopy tree species in recently abandoned pastures (mown and unmown) and in ca. 40‐yr old secondary dry forest in Guana‐caste National Park, Costa Rica, was studied from July 1989–June 1992. The species were the light‐demanding Cedrela odorata and Swietenia macrophylla, and the shade‐tolerant Hymenaea courbaril and Manilkara chicle. Seedling mortality was high and primarily correlated with dry season drought. After the first dry season, M. chicle and C. odorata showed &lt; 5 % survival in the pasture and 20 % in the forest, but after 3 yr survival had decreased to 3% in all plots. Survival of S. macrophylla was highest in the mown pasture (45 % after 3 yr) and lowest in the forest (10 %). For H. courbaril, survival was 40–55 % under all three conditions.Growth rates were low, with a height increment of &lt; 15 cm/yr, possibly due to low precipitation in 1990 and 1991. All species grew taller in the pasture than in the forest.Differences in soil depth, texture and drainage appeared to contribute to variation in the results both within and between plots. Herbivory contributed to the lower survival of C. odorata and S. macrophylla in the forest.

Effect of dolomite lime and wood ash on peat substrate and development of tree seedlings.

Effect of dolomite lime and wood ash on peat substrate and development of tree seedlings.

Emergence and initial development of tree seedlings on burnt-over forest land

Emergence and initial development of tree seedlings on burnt-over forest land