Diameter At Ground Level Research Articles

Cluster planting facilitates survival but not growth in early development of restored tropical forest

Interspecific interactions are considered to be important structuring forces in early successional vegetation. Whereas competition seems to prevail in less severe environments, facilitation tends to increase in importance in harsh environments. Hence, facilitation is expected to play an important role in degraded tropical areas with high irradiance, heat loads, and evapotranspiration, where conditions are far from optimum for most forest species. We planned a restoration project on the southeastern Brazilian coastal plain to compare growth and survival of tree seedlings planted at two densities (isolated or aggregated) in a factorial experiment with nutrient addition. We monitored survival, height, ground level diameter, and crown projection of 4132 saplings from 19 species that ranged along a successional gradient, over an 18-month period. We used mixed-effect models to analyze the relationship between species performance and treatments, and Akaike's information criterion (AIC) to select the models. The best model showed higher survival in aggregated plantations (indicating facilitation) for non-pioneer (slower growing) species. In contrast, we found lower diameter growth in aggregated plantation (indicating competition). Fertilizer addition did not affect survival in clusters, but, surprisingly, it had a negative effect on isolated plants of both pioneer and non-pioneer species. Fertilizer addition had a positive effect on diameter and crown projection growth in aggregated plantations (reducing competition), especially for pioneer species. Thus, whether facilitation or competition was the predominant interaction depended on the effect analyzed. As establishment of non-pioneer species in disturbed sites can be challenging, restoration designs could take advantage of higher survival rates in clusters and use resource addition to ameliorate growth and decrease competition for limited resources.

An improved technique for non-destructive measurement of the stem volume of standing wood

An improved technique, cheaper and less time-consuming, to measure standing wood volume by using an electronic theodolite was tested, by which greater information from the forest could be acquired accurately and non-destructively. This was achieved by recording the diameter at breast height and ground-level diameter of a tree as well as the included angle between the electronic theodolite and the left and right tangents of the stem at any point. The standing wood volume then was computed precisely by section. In addition, the factors that influence the precision of the method (observable distance and number of segments) were also analysed. In the study, 175 Larix gmelinii (Rupr.) Kuzen. trees and 190 Populus tomentosa Carrière trees chosen randomly for sampling were measured with the electronic theodolite, and then were cut down for measurement of the average cross-section volume. Based on the data acquired from 100 sample trees, a standard volume table was compiled, and then the data for the remaining random 10 sample trees in each group were selected for a comparison test. The results indicated that the optimal distance for indirect observation should be as high as the sample tree, and the optimal visual distinguished section was about 2 m. The correlation coefficient between the value measured non-destructively and the value of the felled trees of L. gmelinii was 0.97, with an average relative error of 1.62%. With regard to P. tomentosa, the correlation coefficient between the two values obtained by the two methods was 0.905 with an average relative error of 8.40%. It was concluded that the standard volume model based on the non-destructive measurement technique meets the requirements for precision in forest surveys. The precision of the standard volume model for L. gmelinii (a coniferous tree) was superior to that of the model for P. tomentosa (a broad-leaved tree). The electronic theodolite method provides an alternative technique for measuring trees without destructive sampling and is widely applicable for forest surveys.

Assessing the effects of natural and anthropogenic drivers on the demography of Himatanthus drasticus (Apocynaceae): Implications for sustainable management

The extent of the impacts of non-timber forest product harvesting on plant population dynamics is influenced by both natural and anthropogenic drivers. However, the environmental impacts on population vital rates and the simultaneous effects of anthropogenic disturbances on exploited populations have been poorly studied. We assessed harvesting impacts on the population dynamics of Himatanthus drasticus (Mart.) Plumel, a Brazilian savanna tree that has been exploited for its medicinal latex. We studied populations in the cerrado (open savanna) and in the cerradão (woodland), for three years (2008–2010). In each habitat, we surveyed populations subjected to different harvesting intensities (high-harvest and low-harvest). The diameter at ground level (DGL), height and reproductive status were recorded for each tagged plant. We used matrix population models and a factorial life-table response experiment (LTRE) to distinguish between the effects of harvesting intensity and habitat type on H. drasticus population dynamics. The different factor combinations revealed population stability in most cases. We observed a population reduction under only one condition (cerradão×high-harvest) in one of the two demographic intervals. The LTRE values for the interaction cerradão×high-harvesting were higher than the values of each treatment isolated, suggesting an interactive effect of harvesting and habitat on the population growth rates. In sum, our data showed that H. drasticus harvesting is potentially sustainable; however, cerradão populations were vulnerable when high levels of exploitation were considered, indicating that management criteria specific to each studied habitat are needed to achieve sustainable harvesting goals. We recommend the traditional management system, characterized by the removal of small amounts of bark from each tree and by longer intervals between harvestings, as the management option for these areas.

Development of Northern White-Cedar Regeneration Following Partial Cutting, with and without Deer Browsing

Northern white-cedar (Thuja occidentalis L.) is an important commercial species with a high wildlife value, both as a food source and habitat for many bird and mammal species. Concerns have been expressed about its decreasing abundance across its range, and especially in mixedwood stands, where it has to compete with several other species and can suffer from heavy browsing. In this study, we quantified the development of natural northern white-cedar seedlings and saplings under various partial cutting regimes, with and without white-tailed deer (Odocoileus virgianus Zimmerman) browsing, in three selected sites in Quebec (Canada) and in Maine (USA). Our data show that northern white-cedar regeneration was present in all studied stands, but that only a few stems were taller than 30 cm on the two sites with high densities of deer. In the absence of heavy browsing, stems reached a height of 30 cm in 11 years, and 130 cm in 28 years. Height growth of northern white-cedar regeneration increased with canopy light transmittance, while ground-level diameter increment increased after partial cutting. This suggests that partial cutting can be used in mixedwood stands to release natural northern white-cedar regeneration, but also that the recruitment of northern white-cedar seedlings to larger size classes constitutes a major challenge in stands subject to heavy deer browsing.

Genetic parameters and clone by environment interactions for growth and foliar nutrient concentrations in radiata pine on 14 widely diverse New Zealand sites

Genetic variations and genotype by environment (G × E) interactions in growth and foliar traits were studied with 40 clones of radiata pine in a trial series on 14 sites across a range of environments in New Zealand. Total height was assessed at ages 1, 3, 5, 6 and 8 years from planting. Stem diameter was assessed as ground-level diameter at ages 1 and 3 years and diameter at breast height (DBH) at ages 5, 6 and 8 years. Fascicle weight, foliar nutrient concentrations, foliar carbon isotope composition and nitrogen isotope composition were assessed at age 5 years at seven sites. Significant genetic variation in these traits existed at most of the sites but with variable and incomplete consistency from site to site, indicating G × E interactions. Individual-tree clonal repeatability (cf. broad-sense heritability) of total height and stem diameter tended to increase with age. Furthermore, across-sites estimates of clonal repeatability of total height and stem diameter were lower than single-site estimates. Marked G × E interactions were observed in growth and foliar traits. The interaction levels for growth traits were significantly associated with site differences in soil nutrient levels of nitrogen and total phosphorus and annual mean temperature. The G × E interaction levels for two foliar traits calcium content and fascicle weight were significantly associated with the site difference of soil nutrient levels of magnesium and potassium, respectively. Foliar carbon isotope composition and carbon/nitrogen ratio showed moderate clonal repeatability and high genetic correlations with growth, suggesting that they could be used as selection traits for improving radiata pine growth rate.

How weed control and fertilisation influence tree physiological processes and growth at early establishment in an exotic F1 hybrid pine plantation of subtropical Australia

This study investigated how nitrogen (N) nutrition and key physiological processes varied under changed water and nitrogen competition resulting from different weed control and fertilisation treatments in a 2-year-old F1 hybrid (Pinus elliottii Engelm var. elliottii × P. caribaea var. hondurensis Barr. ex Golf.) plantation on a grey podzolic soil type, in Southeast Queensland. The study integrated a range of measures including growth variables (diameter at ground level (DGL), diameter at breast height (DBH) and height (H)), foliar variables (including foliar N concentration, foliar δ13C and δ15N) and physiological variables (including photosynthesis (An), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi) (A/gs) and xylem pressure potential (ΨXPP)) to better understand the mechanisms influencing growth under different weed control and fertilisation treatments. Five levels of weed control were applied: standard (routine), luxury, intermediate, mechanical and nil weed control, all with routine fertilisation plus an additional treatment, routine weed control and luxury fertilisation. Relative weed cover was assessed at 0.8, 1.1 and 1.6 years after plantation establishment to monitor the effectiveness of weed control treatments. Soil investigation included soil ammonium (NH4 +-N), nitrate (NO3 −-N), potentially mineralizable N (PMN), gravimetric soil moisture content (MC), hot water extractable organic carbon (HWETC), hot water extractable total N (HWETN), total C, total N, stable C isotope composition (δ13C), stable N isotope composition (δ15N), total P and extractable K. There were significant relationships between foliar N concentrations and relative weed cover and between tree growth and foliar N concentration or foliar δ15N, but initial site preparation practices also increased soil N transformations in the planting rows reducing the observable effects of weed control on foliar δ15N. A positive relationship between foliar N concentration and foliar δ13C or photosynthesis indicated that increased N availability to trees positively influenced non-stomatal limitations to photosynthesis. However, trees with increased foliar N concentrations and photosynthesis were negatively related to xylem pressure potential in the afternoons which enhanced stomatal limitations to photosynthesis and WUEi. Luxury and intermediate weed control and luxury fertilisation positively influenced growth at early establishment by reducing the competition for water and N resources. This influenced fundamental key physiological processes such as the relationships between foliar N concentration, A n, E, gs and ΨXPP. Results also confirmed that time from cultivation is an important factor influencing the effectiveness of using foliar δ15N as an indicator of soil N transformations.

White spruce(Picea glauca)restoration in temperate mixedwood stands using patch cuts and enrichment planting

The use of gap-based silviculture and enrichment planting was tested in temperate mixedwood forests in eastern Canada. Four different sizes of canopy opening or patch cuts were applied to six stands in the maple–birch domain of Quebec. We evaluated the influence of opening size, cardinal quadrant within the opening, and distance from the forest edge of openings on white spruce height and ground-level diameter (GLD) five years after enrichment planting. At ≥5 m from the edge, initial canopy transmittance was generally >60% in all four canopy treatments. White spruce seedling height and GLD were lower within 10 m from the edge, and generally increased where understory light levels were higher. Seedling survival, height, and GLD in the smallest opening (0.05 ha) were comparable or higher than those found in relatively larger openings. The 0.05-ha opening that more closely emulates natural canopy gaps of temperate mixedwood forests provided satisfactory seedling development, and is therefore compatible with a gap-based stand dynamics approach to management of mixedwood stands in Quebec.

Structure and Floristics of Home Gardens in an Altitudinal Marsh in Northeastern Brazil

Home gardens are a traditional land use practice, which is very common in the tropics. The main goal of the home garden is to produce food for subsistence purposes. Therefore, they have been considered very important from an economic, cultural and ecological point of view. Despite their importance, there has been a lack in research of these environments in Northeastern Brazil. This research was carried out in a rural community belonging to Areia City (Paraiba, Brazil), and aimed to study the floristic diversity of home gardens and their contribution in the conservation of the local diversity. Semi-structured interviews were conducted, also using the technique of guided tours with the home garden maintainer. At the same time, the yards were measured, as well as all shrubby arboreal individuals present with DGL (diameter at ground level) ≥ 3 cm. A total of 19 yards were analyzed. 177 species were recorded, of which 155 were identified, representing 63 families and 131 genera. Fabaceae (16 spp.), Euphorbiaceae (10 spp.) and Myrtaceae (7 spp.) were the most represented plant families. 94 of the identified species are considered exotic and 83 are native, considering the origin at regional level. Structurally, the home gardens from Vaca Brava community have shown themselves as complex and rich in diversity, as a result of the association of crops and fruit, as well as the presence of native woody plants for which no uses were reported.

Enrichment planting of Picea glauca in boreal mixedwoods: can localized site preparation enhance early seedling survival and growth?

Conserving forest biodiversity has become a significant global concern. A change in forest composition, compared to pre-industrial values, is an important biodiversity issue. In this regard, there is a significant decrease in Picea glauca densities at the landscape level in boreal mixedwoods of northeastern Canada, compared to pre-industrial abundance. Enrichment planting is considered a promising silvicultural approach for improving P. glauca stocking and re-establishing its natural co-dominance with Abies balsamea. However, optimal enrichment scenarios must be identified, notably regarding site preparation treatments that can enhance planted seedling survival and growth while protecting Abies advance regeneration. We established a field trial in Quebec (Canada), laid out as a complete block split-plot design. Picea glauca and P. mariana seedlings (main plot) were planted according to 3 “microsite” treatments (subplot): (1) planting in the humus layer; (2) planting in the mineral soil, with minimal humus disturbance; and (3) planting in a microsite mechanically-prepared using modified brushsaws. After 3 growing seasons, P. mariana seedlings were taller than P. glauca seedlings, but had smaller ground-level diameters. Seedlings planted in the mineral soil had overcome the initial height difference they had with seedlings planted in the humus and mechanically-prepared microsites, with no interaction with species. Ground-level diameter was similar for seedlings planted in the humus and mechanically-prepared microsites, but smaller for seedlings planted in the mineral soil. Water potentials, available light, and foliar nutrient concentrations were not influenced by treatments or species; survival was >90 %. Our results indicate that P. glauca can be established through enrichment planting in boreal mixedwoods. Localized site preparation is not required to limit initial plantation stress in this ecosystem.

造纸废水灌溉对毛白杨苗木生长及养分状况的影响

The pulp and paper industry is a very large consumer of fresh water,and almost all the input reappears as effluent requiring treatment and disposal.As poplar can recycle organic residues from wastewater due to its high water and nutrient use,paper mill effluent(PME) could serve as a source of water and nutrients for poplar plantations.Consequently,irrigating poplar plantations with PME will reduce the need for other inputs of irrigation and fertilization.However,some elements(e.g.Na) which commonly occur in PME also represent a potential risk to poplar growth,since they have only moderate tolerance to salinity.Improper irrigation can result in toxicities and nutrient imbalance in plants.We hypothesized that diluting PME with pure water to a suitable concentration could avoid negative effects and would have better irrigation and fertilization value.In this study,a pot experiment was conducted from June to September in 2009 to investigate the effect of irrigation with different dilutions of PME on(1) the growth and nutrient status of one-year-old triploid Populus tomentosa seedlings and(2) soil chemical properties.The experiment included five PME irrigation treatments which diluted the concentration of PME to 12.5%(1F7Q),16.7%(1F5Q),25%(1F3Q),33.3%(1F2Q) and 50%(1F1Q),respectively.A control pure water irrigation treatment(CK) was also included.At the end of the experiment,height,ground-level diameter,and biomass of the seedlings in all treatments were measured as indicators of plant growth,total N and P of stems,leaves,and roots were analyzed to indicate plant nutrient status,and soil chemical properties(pH,organic matter,total N,available N and P) were also measured.PME irrigation had no significant effect on the pH and available P content of the soil(P0.05),but percentages of organic matter,total N,and available N increased significantly with increasing concentration of PME(P0.05).With appropriate dilution,PME irrigation significantly increased the N content in roots and leaves and the P content in stems(P0.05),but had no significant influence on the P content in leaves and roots and the N content in stems(P0.05).The growth of P.tomentosa seedlings increased markedly when the concentration of PME increased from 12.5%(1F7Q) to 16.7%(1F5Q),but when the concentration continued to increase(1F3Q,1F2Q,1F1Q),increments in ground-level diameter and height decreased gradually.Relative to the CK treatment,the increment of ground-level diameter and height of P.tomentosa seedlings following only the 1F5Q treatment were significantly higher(102% and 47% respectively,P0.05).Biomass of P.tomentosa seedlings in the 1F5Q and 1F3Q treatments reached 247 and 230 g,respectively,which were significantly higher than the CK treatment(19.3% and 11.1%,P0.05).However,no significant difference was detected between the other PME treatments and CK(P0.05).In conclusion,PME irrigation promoted the growth of P.tomentosa seedlings,and increased plant nutrient status and soil fertility.When the dilution concentration of PME was appropriate,the growth of P.tomentosa seedlings was significantly improved by PME irrigation.Consequently,our findings suggest that PME can be used to irrigate P.tomentosa seedlings,but it should be diluted to an appropriate concentration.From our results,it is recommended that the dilution concentration of PME should be 16%—25%,and trials are needed to validate these conclusions under field conditions.

Efeito de Brachiaria decumbens na herbivoria e no desenvolvimento de duas leguminosas nativas de cerrado

Este estudo avaliou o impacto da presença da gramínea exótica (Brachiaria decumbens) na herbivoria e no desenvolvimento de plântulas de espécies nativas (Hymenaea stigonocarpa e Dipteryx alata) de Cerrado. Para avaliar o impacto da presença da gramínea, 10 blocos em pastagem (antiga área de Cerrado) na Embrapa Gado de Corte (Campo Grande-MS) foram demarcados em janeiro de 2009. As gramíneas foram mantidas intactas em metade dos blocos e, na outra metade, foram removidas. Em cada tratamento, foram avaliados a herbivoria, a altura e o diâmetro na altura do solo (DAS) de 25 plântulas de cada espécie ao longo do ano. O conteúdo de carbono, nitrogênio e água das folhas também foi quantificado. Plântulas de Hymenaea stigonocarpa nos tratamentos com gramínea tiveram maior taxa de crescimento em diâmetro que as plântulas no tratamento sem gramíneas. As plântulas de Dipteryx alata que estavam no tratamento sem gramíneas tiveram maiores taxas de crescimento em altura que as do tratamento com gramíneas. Houve diferença na taxa de herbivoria de D.alata entre os tratamentos. As plântulas das duas espécies que estavam no tratamento com gramínea mostraram maiores concentrações de carbono e menores de água. O conteúdo de nitrogênio foliar foi maior no tratamento com gramíneas que no sem gramíneas em D.alata; já o nitrogênio em H. stigonocarpa não variou entre os tratamentos. Esses resultados mostram que cada espécie nativa possui distintas respostas fisiológicas e suscetibilidade à herbivoria em ambientes sob competição de recursos com a gramínea exótica, B. decumbens.

Plant Stem Bark Extractivism in the Northeast Semiarid Region of Brazil: A New Aport to Utilitarian Redundancy Model

We use the model of utilitarian redundancy as a basis for research. This model provides predictions that have not been tested by other research. In this sense, we sought to investigate the stem bark extraction between preferred and less-preferred species by a rural community in Caatinga environment. In addition, we sought to explain local preferences to observe if preferred plants have a higher content of tannins than less-preferred species. For this, we selected seven preferred species and seven less-preferred species from information obtained from semistructured interviews applied to 49 informants. Three areas of vegetation around the community were also selected, in which individuals were tagged, and were measured the diameter at ground level (DGL) diameter at breast height (DBH), and measurements of available and extracted bark areas. Samples of bark of the species were also collected for the evaluation of tannin content, obtained by the method of radial diffusion. From the results, the preferred species showed a greater area of bark removed. However, the tannin content showed no significant differences between preferred and less-preferred plants. These results show there is a relationship between preference and use, but this preference is not related to the total tannins content.

Genetic effects on stand-level uniformity and above- and belowground dry mass production in juvenile loblolly pine

Genetic differences in stand-level above- and belowground dry mass production in loblolly pine ( Pinus taeda L.) may influence southern pine plantation productivity, sustainability and carbon (C) sequestration. Furthermore, deployment of more or less genetically homogeneous individuals could impact stand uniformity and ecosystem processes. In this study, we aimed to compare stand uniformity and above- and belowground dry mass production among loblolly pine genotypes of contrasting inherent genetic homogeneity. We hypothesized that stand-level uniformity would increase as within-genotype inherent genetic variation decreased (open-pollinated (half-sib) > full-sib > clone). To examine genetic effects on stand uniformity and productivity, we grew ten different genotypes (three open-pollinated families, three full-sib families, three clones, and one seed orchard mix variety) in a plantation setting for 4 years, at two different planting densities (∼539 and 1077 trees ha −1), and used allometric relationships to estimate standing dry mass and annual dry mass production. In the low planting density treatment, age 3 total standing dry mass of the most productive genotype (5824 kg ha −1) was 82% higher than that of the least productive genotype (3207 kg ha −1). In the high planting density treatment, age 3 total standing dry mass of the most productive genotype (11,393 kg ha −1) was 110% higher than that of the least productive genotype (5427 kg ha −1). Genetic differences in annual dry mass production were of a similar magnitude with peak rates during the third year as high as 4221 and 8198 kg ha −1 yr −1 in the low and high planting density treatments, respectively. More genetically homogeneous genotypes did not show greater stand-level uniformity under operational management conditions. Over time, genotypes showed no consistent differences in the coefficient of variation (CV) for ground-level diameter; however, two full-sib and two half-sib families showed significantly lower CV’s for total tree height than all three clones. Moreover, genotypes with lower CV’s for height growth displayed greater stand-level dry mass production which supports the premise that greater stand uniformity will lead to enhanced productivity. Since uniformity and stand-level productivity of loblolly pine clones will be principally governed by environmental heterogeneity, our results highlight the need for silvicultural prescriptions that maximize site uniformity. In addition, our results demonstrate how the deployment of highly productive loblolly pine genotypes may provide a means of enhancing southern pine ecosystem sustainability by sequestering C in both harvestable aboveground biomass and woody belowground biomass.

Silviculture and planted species interact to influence reforestation success on a Kalmia-dominated site – a 15-year study

Successful regeneration following harvesting or natural disturbance is a fundamental prerequisite for sustainable forest management. However, some regenerating stands have poor juvenile growth rates, which compromise sustainable management objectives. In particular, the presence of some ericaceous species that proliferate after forest disturbance, such as Kalmia angustifolia, can slow succession of boreal stands to the point that ecosystem retrogression is induced. We used data from a silvicultural field trial established in central Newfoundland to evaluate how various combinations of silvicultural treatments (trench scarification, herbicide application, fertilization at planting) influenced growth of three conifer species planted on a Kalmia-dominated cutover. Ground-level diameter (GLD), height, diameter at breast height (DBH), and percent Kalmia cover were assessed at the end of 15 growing seasons after planting. We detected several interactions between silvicultural treatments and planted conifer species. Globally, height and estimates of foliar biomass of all conifer species responded positively to scarification. Fifteen-year height in both scarified and unscarified treatments was in the order Picea mariana < Pinus banksiana < Larix laricina. Black spruce and jack pine height increased when Kalmia was controlled with herbicide, but height of tamarack was not. The use of herbicide significantly increased 15-year GLD and volume index of all three conifer species, but only black spruce responded positively to fertilization at planting. Our results confirm that species-specific responses to silvicultural treatments are to be expected when managing Kalmia-dominated sites. Although chemical vegetation management has great silvicultural potential, our results suggest that mechanical site preparation can also be effective in promoting early conifer seedling growth that leads to rapid canopy closure. It is anticipated that canopy closure will lead to exclusion of Kalmia later in the rotation through natural successional pathways. Key words: Kalmia angustifolia, vegetation management, scarification, herbicide, fertilizer, black spruce, jack pine, tamarack

Crescimento inicial de Eucalyptus tereticornis em plantios puro e consorciado com Mimosa caesalpiniifolia E Mimosa pilulifera, em Campos dos Goytacazes-RJ

Este trabalho objetivou avaliar o crescimento inicial de Eucalyptus tereticornis, em plantios puro e consorciado com Mimosa caesalpiniifolia e Mimosa pilulifera, e seus efeitos sobre as características químicas do solo, em Campos dos Goytacazes, RJ. Foram avaliadas, ao longo de 30 meses, a sobrevivência, a altura, o diâmetro da base e o DAP. A caracterização do solo, nas profundidades de 0-5 e 5-10 cm, foi realizada aos seis e 30 meses. O delineamento experimental foi em blocos casualizados com quatro repetições e 14 plantas úteis por parcela. O plantio de E. tereticornis consorciado com M. caesalpiniifolia apresentou, aos 30 meses, sobrevivência superior (87%) e melhor desempenho em crescimento dendrométrico. Nos plantios consorciados, o teor de C do solo mostrou menores valores, na profundidade de 5-10 cm. Os teores de P e Ca e saturação de bases (%) do solo decresceram, enquanto os valores de pH, N, Na, Al e H+Al aumentaram em todos os sistemas de plantio. No plantio puro e no consórcio com M. caesalpiniifolia, os teores de K foram menores na profundidade de 0-5 cm. O consórcio entre E. tereticornis e M. caesalpiniifolia causou redução da CTC efetiva, da soma de bases e do teor de Mg

Respostas da Parkinsonia aculeata L. ao corte e queima em área invadida no agreste paraibano

Biological invasion cause many impacts on the ecosystem invaded, that is why human interference is often necessary in order to eradicate or control the alien species. Among the main practices for controlling invasive tree species are lumberjacking, followed by burning, as well as easier and less costly than other types of management. The objective of this study was to evaluate the effectiveness of management adopted for the control of Parkinsonia aculeata L. in an invaded area in the agreste on the Paraíba state, Brazil. The population of P. aculeata was deforested and burned. Three months after application of the control, all dead and living steams were sampled, and measured by means of the diameter at ground level (DGL). The shoots of the survived specimens had measures its diameter at the base (DBB) and height. From these parameters, the statistical analysis was performed and evaluated the responses of species to control. The management employee was inefficient because it eliminated only part of the individuals. It was also observed that the species has high capacity for re-growth of both regenerates and adults, which further difficult the control of the species as well as the choice of a right moment to improve the control.

Outplanting performace of eucalyptus clonal cuttings produced in different containers and substrates

The objective of this work was to evaluate the outplanting growth of Eucalyptus grandis e E. saligna clones, produced by cuttings in tubes (50cm³) and in pressed blocks (40x60x07cm) - 175 cm³/ seedlings, with different substrates (BT - sugarcane bagasse+sugarcane filter cake; AR - carbonized rice hull + eucalyptus bark; TF - peat). The experiment was arranged in a randomized block design, in a 2x7 factorial (2 clones and 7 treatments), with four replicates with 25 plants. Survival was evaluated two months later. Plant growth was monitored through height and ground level diameter at 20, 40, 60, 120 and 180 days after outplanting. To evaluate the effect of the containers on stem and root biomass in both clones, 180 days after outplanting, the cuttings grown in BT substrate with fertilizer were selected. One plant per plot of each clone, grown in tubes and in pressed blocks was selected. The E. grandis and E. saligna cuttings grown in pressed blocks with sugarcane bagasse+sugarcane filter cake presented greater height and diameter after out planting. Both clones presented larger root, bark, log and branch biomass production in plants produced in the block system. Cuttings of E. saligna grown in pressed blocks showed 80% most wood biomass 180 days after outplanting, compared to that grown in tubes. In E. grandis, the differences in diameter and height, in function of the cutting production system, decreased along time, while in E. saligna these differences increased along the evaluation period.

Genetic analysis of plant height and diameter at ground level of silver birch (Betula platyphylla) seedlings

AbstractSix silver birch (Betula platyphylla) parents of diverse provenances were crossed according to Griffing 4 diallel design, and the plant height and diameter at ground level (DGL) of their F1 progeny were observed. The analysis of general combining ability (GCA) and specific combining ability (SCA) showed that two phenotypes were simultaneously controlled by additive and non-additive effects. The GCA between two phenotypes in a parent, and GCA of the same phenotype among different parents displayed significant differences: Q2 from Qingyuan was the best of the parents, followed by M2 from Maoer-mountain. On the other hand, the SCA of two phenotypes in a cross and the SCA of a phenotype among different crosses also varied considerably: the cross between E8 from Finland and Q1 from Qingyuan showed the highest SCA of plant height and DGL. The heritability of plant height and diameter at ground level was strong (over 60%), suggesting that these phenotypes can be used for early selection.

Desempenho de quatro de Eucalyptus spp em plantios puros e consorciados com sabiá (Mimosa caesalpiniaefolia Benth) em cava de extração de argila

Para a recuperação ambiental de áreas mineradas, uma das alternativas é o florestamento ou reflorestamento, havendo a necessidade de selecionar espécies e práticas silviculturais que favoreçam o estabelecimento dos povoamentos. O objetivo deste trabalho foi avaliar o desempenho de Eucalyptus camaldulensis Dehnh, E. pellita F. Muel, E. tereticornis Sm. e E. robusta Sm., em plantios puros e consorciados com a leguminosa arbórea Mimosa caesalpiniaefolia Benth, em áreas degradadas pela extração de argila. Este estudo foi realizado em uma cava de 1,5 ha, com solo salino, localizada em Campos dos Goytacazes, RJ, de onde foi removido argila até a profundidade média de 1,5 m. O delineamento experimental foi em blocos ao acaso com quatro repetições, em esquema fatorial 4 x 2, com quatro espécies de eucalipto, em plantios puros, e cada uma delas em consórcio com M. caesalpiniaefolia . O desempenho das plantas foi avaliado quanto à sobrevivência, altura, diâmetro ao nível do solo (DAS), diâmetro a 1,30 m de altura (DAP), área de copa, razão altura/DAP, área superficial e comprimento de raízes finas (? 2 mm). Até 24 meses, observou-se que E. pellita não é indicado para plantios em cavas de extração de argila, enquanto E. camaldulensis, E. tereticornis e E. robusta apresentam melhor desempenho. Não foi detectado, até o momento, efeito do sistema de plantio sobre o crescimento das quatro espécies de eucalipto. No entanto, foi verificado que o consórcio com sabiá resultou em efeito negativo sobre a sobrevivência do E. robusta. O consórcio entre essas duas espécies não é indicado para as condições deste experimento.

Ten year responses of Engelmann spruce and a high-elevation Ericaceous shrub community to manual cutting treatments in southern interior British Columbia

Vegetation management treatments are often applied to high-elevation, Ericaceous shrub-dominated sites in southern interior British Columbia to facilitate reforestation. We studied the effects of manual cutting on an established vegetation community and newly planted to 2-year-old Engelmann spruce ( Picea engelmannii Parry ex Engelm.) over a 10-year period. Spruce survival was significantly higher in the treatment than the control 3 years after brushing ( p = 0.020). Although differences in survival continued to be large after 10 years (79% versus 61%), they were no longer significant due to increased between-site variability. Relative height estimates indicated that brushed spruce were taller relative to the vegetation canopy than control spruce throughout the 10 years assessment period, but growth responses were small even where significant. The cutting treatment significantly increased ground-level diameter after 3 and 5 years, but not after 10 years. The loss of statistical significance is attributed to ongoing mortality of small diameter suppressed stems in the control. After 10 years, shrub cover was still lower in the cutting treatment than the control, but height had recovered within 3 years. Manual cutting increased Shannon diversity in the first year post-treatment ( p = 0.039), after which it returned to control levels. There were no differences in species richness. A competition index based on the first year relationship between spruce and vegetation cover and height (CRH TS1) explained 33% of the variation in spruce diameter 10 years after treatment, and first year total shrub cover (COV TS1) explained 28% of the variation. R 2 values increased slightly over time, suggesting that vegetation competition was still affecting at least some surviving seedlings when they were 10–12 years old. Thresholds for spruce diameter of 139 and 64% were identified for CRH TS1 and COV TS1, respectively.