Seedlings Of Woody Species Research Articles

Facilitation in Brazilian semiarid zone: remnant trees show a positive effect on caatinga regeneration

Arid and semiarid ecosystems display several environmental filters naturally restricting plant community composition. Such filters become more severe after some disturbance and may thus hamper the survival of young plants. The role of remnant trees in succession needs to be better understood to identify patterns and functional traits that might facilitate natural regeneration in drylands. This study evaluated the role of remnant trees in the succession process in the caatinga vegetation (Brazilian seasonally dry tropical forest), testing the effect of a typical tree, the juazeiro (Ziziphus joazeiro Mart.) in richness and abundance of seedlings in areas of abandoned pasture, in Northeastern Brazil. A perimeter was outlined around each plant (n = 20) with a diameter equivalent to each tree crown; all seedlings of woody species up to 0.5 m in height, within that perimeter, were collected and identified. Control areas with the same dimensions were delimited in adjacent locations (n = 20) without the influence of remnant trees, followed by the same data surveys. Mean species richness was of 7.8 ± 4.8 under the juazeiro canopies, compared to 2.3 ± 1.9 in the control areas. Species abundance was also greater under the presence of Z. joazeiro, with an average of 16.9 ± 4.8, against 4.1 ± 4.2 individuals in the controls. Among the abiotic factors evaluated, it is suggested that soil and air temperatures may show a greater influence on the recruitment of seedlings, benefiting natural regeneration under Z. joazeiro. Z. joazeiro ramnant trees appear to facilitate the natural regeneration of tropical drylands. We suggest considering the use of these plants as catalysts for the nucleation process in the restoration of the caatinga.

Влияние препарата «Биостим» на рост и развитие семян и сеянцев древесных видов в засушливой зоне

The aim of the study was to study the effect of the biostimulator of growth «Biostim» on the germination and development of seeds and seedlings of woody species in order to develop a resource-saving technology of cultivation for nursery breeding in the Volgograd region. The objects of research were the woody species Quercusrobur L., Robiniapseudoacacia L., PopulusbolleanaLouche., Populusnigra var. italica Münchh., Catalpa bignonioides, Pinusnigra subsp. pallasiana (Lamb.), Platycladusorientalis (L.) Franco., Piceapungens Engelm. ofdifferentgeographicalorigin. As a result of the conducted studies, the best result was shown by poplars and catalpa with a concentration of «Biostim» at a dose of 2.5 l/ha (20 ml) for cuttings and 20 ml/l for seeds. The concentration of the preparation at a dose of 10 ml / kg (the consumption of the working solution is 1.5-2 l/kg) with soaking of seeds before sowing for 10-20 minutes, followed by drying, was suitable for Robiniapseudoacacia. The concentration of the preparation in a dose of 10 ml / l with soaking of the seeds before sowing for 10-20 minutes followed by drying was suitable for robiniapseudoactation. The worst result in the test of laboratory germination of seeds was shown by oak petiolate, due to the lack of reaction of seeds to processing and their mold formation. In coniferous species, the best result was shown by Crimean pine with a concentration of the preparation«Biostim» of 10 ml / l and 2.5 l / ha. The germination of spruce and thuja seeds was weak. According to the results of the test of the preparation «Biostim» on seedlings and seeds in a nursery on dark chestnut soils, the best result was shown by seedlings of poplar and catalpa species with a concentration of «Biostim» at a dose of 2.5 l/ha and 20 ml/l for seeds. Additional top dressing with poplar preparation proved to be effective, after which good growth, development and leafing of plants were observed. Seedlings and seeds of eastern thuja and blue spruce after additional processing grew and developed satisfactorily, subsequently their drying and loss was observed, which makes the topic of testing biostimulators of growth on conifers is promising for further research.

Survival of young, dense Betula ermanii stands after wildfire at top soil removal sites

Abstract A forest fire in a cool-temperate broadleaved forest in northern Japan, from 26 May to 19 June 2019, provided an opportunity to examine the post-fire dynamics of young, dense birch (Betula ermanii Cham.) stands that had previously undergone top soil removal through soil scarification. To characterize the post-fire responses (survival and resprouting) of birch trees, we set up two plots, 6 months after the fire. We investigated the trunk diameter at breast height and burn marks on the trunks (scorch height and bole charring percentage) of all B. ermanii trees in both plots. Survival and resprouting of each tree were monitored over a 10-month period (6 and 16 months after the fire). To quantify post-fire vegetation recovery of the forest floor, we manually mapped the dominant understory plant, dwarf bamboo (i.e. Sasa kurilensis (Rupr.) Makino et Shibata), from orthomosaic images obtained using an unmanned aircraft vehicle, and estimated the recovery rate in the second year after the fire. Additionally, the seedlings of woody species were counted in both plots. A logistic generalized linear model revealed that the size-dependent survival rates of the plants in each plots were similar in the first year after fire. All B. ermanii trees died without resprouting in the second year after the fire, indicating the lethal effects of fire on young birch trees in top soil removal sites. Moreover, a high recovery rate of dwarf bamboo over 2 years in both plots and limited woody seedling establishment of woody plants suggest that the fire resulted in the regeneration failure of young stands in the top soil removal sites. Based on these findings, we suggest that the vulnerability of young trees can lead to the rapid change in vegetation from young forest to dense dwarf bamboo cover after a fire.

Pre-damage biomass allocation and not invasiveness predicts tolerance to damage in seedlings of woody species in Hawaii.

Plant-herbivore interactions have been predicted to play a fundamental role in plant invasions, although support for this assertion from previous research is mixed. While plants may escape from specialist herbivores in their introduced ranges, herbivory from generalists is common. Tolerance traits may allow non-native plants to mitigate the negative consequences of generalist herbivory that they cannot avoid in their introduced range. Here we address whether tolerance to herbivory, quantified as survival and compensatory growth, is associated with plant invasion success in Hawaii and investigate traits that may enhance tolerance in seedlings, the life stage most susceptible to herbivory. In a greenhouse experiment, we measured seedling tolerance to simulated herbivory through mechanical damage (50% leaf removal) of 16 non-native woody plant species differing in invasion status (invasive vs. non-invasive). Seedlings were grown for 2 weeks following damage and analyzed for biomass to determine whether damaged plants could fully compensate for the lost leaf tissue. Over 99% of all seedlings survived defoliation. Although species varied significantly in their levels of compensation, there was no consistent difference between invasive and non-invasive species. Seedlings of 11 species undercompensated and remained substantially smaller than control seedlings 2 weeks after damage; four species were close to compensating, while one species overcompensated. Across species, compensation was positively associated with an increased investment in potential storage reserves, specifically cotyledons and roots, suggesting that these organs provide resources that help seedlings re-grow following damage. Our results add to a growing consensus that pre-damage growth patterns determine tolerance to damage, even in young seedlings which have relatively low biomass. The lack of higher tolerance in highly invasive species may suggest that invaders overcome herbivory barriers to invasion in other ways, such as resistance traits, or that herbivory does not play an important role in the seedling invasion dynamics of these woody species in Hawaii.

Divergent scaling of respiration rates to nitrogen and phosphorus across four woody seedlings between different growing seasons.

Empirical studies indicate that the exponents governing the scaling of plant respiration rates (R) with respect to biomass (M) numerically vary between three‐fourth for adult plants and 1.0 for seedlings and saplings and are affected by nitrogen (N) and phosphorus (P) content. However, whether the scaling of R with respect to M (or N and P) varies among different phylogenetic groups (e.g., gymnosperms vs. angiosperms) or during the growing and dormant seasons remains unclear. We measured the whole‐plant R and M, and N and P content of the seedlings of four woody species during the growing season (early October) and the dormant season (January). The data show that (i) the scaling exponents of R versus M, R versus N, and R versus P differed significantly among the four species, but (ii), not between the growing and dormant seasons for each of the four species, although (iii) the normalization constants governing the scaling relationships were numerically greater for the growing season compared to the dormant season. In addition, (iv) the scaling exponents of R versus M, R versus N, and R versus P were numerically larger for the two angiosperm species compared to those of the two gymnosperm species, (v) the interspecific scaling exponents for the four species were greater during the growing season than in the dormant season, and (vi), interspecifically, P scaled nearly isometric with N content. Those findings indicate that the metabolic scaling relationships among R, M, N, and P manifest seasonal variation and differ between angiosperm and gymnosperm species, that is, there is no single, canonical scaling exponent for the seedlings of woody species.

Fire regime (recency, interval and season) changes the composition of spinifex (Triodia spp.)-dominated desert dunes

Between 2000 and 2002, central Australia experienced the largest fire season in three decades when ~500 000 km2 burned. The effects of these and preceding wildfires in the 1980s on spinifex (Triodia spp.) sand-ridge plant communities were examined at 38 sites in central Australia. We used both multivariate and univariate techniques to assess floristic differences among sites of contrasting time-since-fire, fire season and fire interval. Time-since-fire had a consistent floristic influence across the landscape, with increased abundances of ephemeral grasses and forbs and Triodia seedlings, and species richness soon after fire but decreasing long after fire. Fire season had little effect on most functional groups of plants, although seedlings of woody species were significantly more abundant following summer than winter fires. Likewise, recent short fire intervals appeared to have little impact on the population dynamics of most functional groups, although some transient effects were observed on abundances of ephemeral forbs, Triodia seedlings and herbaceous clonal species. Long-term woody species abundances appeared to be affected by short fire intervals in the 1980s when repeated fires seemed to stimulate recruitment of some resprouting species. The present study highlighted the relative stability of spinifex vegetation types in the face of landscape-scale pyric perturbation, but emphasised that localised shifts in the composition and structure of the plant community may occur under certain fire regimes.

Restoration of Araucaria Forest: The Role of Perches, Pioneer Vegetation, and Soil Fertility

Abstract The Araucaria forest is Brazil's highly threatened subtropical forest ecosystem that has been disappearing in recent decades. Restoration programs involving this forest type are scarce, and there is a lack of scientific information on how ecological processes such as competition, facilitation, and seed dispersal influence natural forest restoration. This work aims to investigate how use of perches to attract seed dispersers and the influence of pioneer vegetation and soil fertilization could affect the colonization of woody species in a degraded area. An experiment was conducted in an abandoned field where the natural establishment of seeds and seedlings of woody species was monitored under factorial combinations of the following treatments: (1) pioneer vegetation (presence and absence); (2) soil fertility (addition of NPK and control); and (3) perches (presence and absence). Seed and seedling abundance, seed and seedling species richness, and seedling mortality were recorded monthly during 12 months. Seed abundance and species richness were significantly greater in places with perches than in control plots. These results were consistent over the year and more pronounced when the surrounding forest produced a higher amount of fruit. Species richness and abundance of seedlings were significantly greater in places with perches than in control plots, and in places with vegetation than without. Soil fertility did not influence seedling establishment. Facilitation and seed dispersal are important factors affecting the colonization of woody species in this subtropical area. Nutrient availability neither regulates the facilitation process nor influences species replacement during the early stages of Araucaria forest succession.

Root/Shoot Allocation and Root Architecture in Seedlings: Variation among Forest Sites, Microhabitats, and Ecological Groups1

ABSTRACTI analyzed patterns of variation in root mass allocation and root morphology among seedlings of woody species in relation to environmental factors in four Neotropical forests. Among forests, I explored the response of root traits to sites varying in water or nutrient availability. Within each forest, I explored the plastic response of species to different microhabitats: gaps and understory. Additionally, I explored evidence for life history correlation of root and shoot traits by comparing species differing in their successional group (light‐demanding [22 spp.] or shade tolerant [27 spp.]) and germination type (species with photosynthetic cotyledons or species with reserve cotyledons). At each forest site, young seedlings from 10 to 20 species were excavated. A total of 55 species was collected in understory conditions and 31 of them were also collected in gaps. From each seedling, six morphological ratios were determined. Allocation to roots was higher in forest sites with the lowest soil resources. Roots were finer and longer in the most infertile site, while roots were deeper in the site with the longest dry season. Seedling traits did not differ between germination types. Shade tolerant species allocated more to roots and developed thicker roots than light‐demanding species. Light‐demanding species showed stronger plastic responses to habitat than shade tolerant species, and species with photo‐synthetic cotyledons showed lower plasticity than species with reserve cotyledons. Overall, these results suggest that among Neotropical species, root allocation and root morphology of seedlings reflect plant adjustments to water or nutrient availability at geographic and microhabitat scales. In addition, life history specialization to light environments is suggested by differences among groups of species in their allocation to roots and in their root morphology.

Seedling establishment under native tamaulipan thornscrub and Leucaena leucocephala plantation

In order to investigate the influence that plantations and clearing of native vegetation might have on plant regeneration in northeastern Mexico, seedling survival and germination (i.e., seedling emergence from the soil surface) were measured monthly in native fragments and an exotic plantation over a one-year period. Seedlings were measured in 1-m 2 plots, using 10 replicates under each of three different treatments: (i) dense thornscrub, (ii) semi-cleared thornscrub, and (iii) a dense L. leucocephala plantation. Seedling number peaked during summer and early autumn, lowest number of seedlings occurred during early spring. Excluding grasses, 36 species were present during the study, and only 14 were present in L. leucocephala plantation. Thornscrub and open thornscrub had similar number of grass seedlings, whereas more forb seedlings were present in open thornscrub. Seedlings of woody species were similar for all treatments. Under L. leucocephala germination was low for most species other than itself, most seedlings, however, died during the winter months.

Effect of simulated acid rain of growth, biomass increment, and ethylene production in seedlings of woody species

Effect of simulated acid rain of growth, biomass increment, and ethylene production in seedlings of woody species

Stratification in a New Zealand rain forest

An undisturbed podocarp-broadleaved rain forest was sampled in eight strata (synusiae): canopy, small tree, shrub, low shrub, herb, ground, epiphyte and liane. Independent classifications of the quadrats were performed using the eight strata, and the classifications were correlated. Relations between strata were significant, but weak. Using records of plants of all ages, the relations largely reflected the presence of seedlings of woody species in the ground and herb strata. Using only records of species present as adults, the relations were quite different, and at least some seemed to reflect sociological interactions. Relations between a tree and a herb stratum was lower than in McCune & Antos' (1981) investigation, probably because of the narrow ecological range of the present study area.