Morphology and rooting of shoots developing in response to decapitation and pruning of Caribbean pine

The effects of decapitation at various levels, combined with heavy pruning of remaining branches, were examined for Caribbean pine. This treatment stimulated the development of shoots with long primary needles at all levels in the crown of trees aged one, four and eight years. Although a significant positive relationship between primary needle length and rooting was demonstrated, the very juvenile appearance of these shoots was not a reliable guide to rooting. There was an over-riding effect on rooting of the ortet age × level in crown × decapitation height treatment. Decapitated trees provided shoots of higher rooting capacity than intact trees for the one and four, but not the eight year old trees. Shoots developing in the lower crown in response to decapitation and heavy pruning of four year old trees displayed a high level of rooting-equivalent to that of shoots from the decapitated and pruned one year old trees.     

Biomass and biomass change in lodgepole pine stands in Alberta

We describe methods and results for broad-scale estimation and mapping of forest biomass for the Canadian province of Alberta. Differences over successive decades provided an estimate of biomass change. Over 1500 permanent sample plots (PSP) were analyzed from across the range of lodgepole pine (Pinus contorta var. latifolia Engelm.), the major forest tree species of Alberta. The PSP network is densest in stands aged between 70 and 100 years and is well-represented by stands of all ages to 150 years of age. Stand biomass (Mg ha(-1)) was estimated for each PSP plot as the sum of the respective biomass components for each tree (live and standing dead). The biomass components for live trees were stem, bark, branches, foliage and roots. The components for standing dead trees excluded foliage. Equations from previous biomass studies were used for biomass component estimation. Biomass estimates of additional non-tree components were attempted, but without much success. Biomass of the soil organic layer was estimated once on 452 PSPs and a mean estimate of total dead fuels on the ground (28.4 Mg ha(-1)) was available only for the entire distribution of lodgepole pine. However, values of these two components were essentially constant over time and therefore did not alter the analysis or conclusions obtained by analyzing total tree biomass alone. We then used this spatial network of 1549 plots as the basis for mapping biomass across Alberta. Mapping methods were based on Australian National University SPLINe (ANUSPLIN) software, Hutchinson's thin-plate smoothing spline in four dimensions (latitude, longitude, elevation and biomass). Total tree biomass (mean = 172 Mg ha(-1)) was dominated by stem biomass (mean = 106 Mg ha(-1)), which was an order of magnitude greater than the mean estimates for the bark (11 Mg ha(-1)), branch (12 Mg ha(-1)) and foliage (12 Mg ha(-1)) components. A close relationship was found between total tree biomass and stand stem volume (R(2) = 0.992 with n = 3585; note that volume and biomass were calculated independently). We compared total tree biomass for two decades, the 1980s and the 1990s. After correcting for changes in harvest removals over time, the mean change in total biomass was positive (0.99 Mg ha(-1) year(-1)) and differed significantly from zero (n = 421; P < 0.001). Estimates ranged from -13.9 to 8.0 Mg ha(-1) year(-1). The heart of the lodgepole pine distribution (primarily the Foothills subregions) showed an increase in biomass, whereas isolated pockets of lodgepole pine in the boreal northern subregion indicated a decline in biomass.     

Genetic variation in rooting ability of loblolly pine cuttings: effects of auxin and family on rooting by hypocotyl cuttings

After about 20 days, hypocotyl cuttings from 20-day-old loblolly pine (Pinus taeda L.) seedlings rooted easily in the presence of the auxin indole-3-butyric acid (IBA), with roots forming directly from xylem parenchyma. In contrast, woody cuttings from 1-2-year-old hedged seedlings formed roots indirectly from callus tissue in 60-90 days, but IBA had little effect on rooting. Variation in rooting among hypocotyls from both half- and full-sib families was highly significant in response to IBA, and rooting did not occur within 20 days unless IBA was applied. Hypocotyls from poor rooting families tended to produce fewer roots per cutting than hypocotyls from good rooting families. Rooting by woody cuttings and hypocotyl cuttings from the same nine full-sib families was weakly correlated, raising the possibility that at least some common genetically controlled processes were affecting rooting by both types of cutting. The phytotropin N-1-naphthylphthalamic acid (NPA), supplied at 1 micro M with 10 micro M IBA, significantly inhibited rooting by hypocotyl cuttings from both good and poor rooting families, but there was no significant family x treatment interaction. Family variation in rooting ability may be a function of the frequency of occurrence of auxin-responsive cells in the hypocotyls.     

皖南丘岗地区火炬松人工林伴生树种的选择与配置

简要介绍了试验林地的概况,选择了25个树种进行试验,并按各树种林分平均胸径、平均树高、平均单株材积和平均单位面积蓄积的年平均生长量进行排序。对主要伴生树种的生长发育过程作了说明,指出伴生树种选择应遵循的原则以及混交形式,同时提出把建立林道和营造生态防火林带相结合。为皖南丘岗地区火炬松人工林提出可供选择的主要伴生树种。     

Biomass allocation in five semi-arid afforestation species is driven mainly by ontogeny rather than resource availability

Key message

The changes in the relative biomass allocation to roots in juvenile stands of fast-growing ( Leucaena leucocephala Lam., Moringa oleifera Lam., and Jatropha curcas L.) and slow-growing ( Anacardium occidentale L. and Parkia biglobosa Jacq.) afforestation species are driven mainly by ontogeny rather than resource availability. However, silvicultural management aiming at increasing availability of water and particularly nutrients enhances biomass production in all species.

Context

Understanding the patterns of biomass allocation among tree species in response to ontogeny and to variation in resource availability is key to the successful restoration of degraded land using forest plantations.

Aims

This study assessed the effects of resource availability and ontogeny on biomass accumulation and partitioning in five semi-arid afforestation species.

Methods

The aboveground and belowground biomass production of fast-growing Leucaena leucocephala Lam., Moringa oleifera Lam., and Jatropha curcas L. and slow-growing Anacardium occidentale L. and Parkia biglobosa Jacq. was monitored following the application of manure (1 kg plant^?1) and/or supplemental irrigation (0.5 L per sapling daily) during the first two rainy seasons and the intervening dry season on degraded cropland in Northern Benin.

Results

Biomass accumulation in the fast-growing species was positively impacted by fertilization and irrigation during both rainy seasons. The slow-growing species responded positively to the silvicultural treatments during the dry and second rainy season. The application of fertilizer alone increased the biomass of P. biglobosa by up to 335% during the dry season. Fifteen months after planting, manure-treated L. leucocephala accumulated the most biomass (2.9 kg tree^?1). The root fraction decreased with increasing tree size in all species. The comparison of root versus shoot allocation in trees of equal size indicated that the treatment-induced shifts in biomass partitioning were controlled by ontogeny, which explained 86–95% of the variation in root-shoot biomass relationships.

Conclusion

While ontogeny was the main driver of biomass partitioning, increased resource availability induced a larger production of biomass, overall leading to greater aboveground production in all species.

     

Morphology, gas exchange, and chlorophyll content of longleaf pine seedlings in response to rooting volume, copper root pruning, and nitrogen supply in a container nursery

Few pine species develop a seedling grass stage; this growth phase, characterized by strong, carrot-like taproots and a stem-less nature, poses unique challenges during nursery production. Fertilization levels beyond optimum could result in excessive diameter growth that reduces seedling quality as measured by the root bound index (RBI). We grew longleaf pine (Pinus palustris), a grass stage species, in containers of four different volumes (60–336 ml) either coated with copper oxychloride or left untreated and fertilized at low, medium, or high levels of nitrogen (N). In general, N concentration of tissues rose as N rate increased, with larger changes in concentration occurring between low and medium levels than between medium and high levels. N rate influenced root tissue N concentration less than it did stems and needles. Subtle needle color differences caused by N rate were significant, suggesting its potential utility during nursery production. As expected, seedlings grew larger as container volume increased and as N rate increased. Copper treatment, which we posited could influence the RBI, tended to increase root-collar diameter and tap root biomass and decrease total root volume. Chlorophyll abundance was affected more by N rate than by container volume or copper treatment, but photosynthesis was affected more by copper treatment than N rate or container size. Although RBI was 25 % greater for seedlings grown in small containers with high N rates than those grown in large containers with low N rates, RBI ranged only from 11 to 15 %, well below the critical 27 % threshold.     

Relationship of water to adventitious rooting in stem cuttings of Populus species

Populus species, characterized by fast growth and easy vegetative propagation, are widely used in agroforestry practices. The substantial water requirement of poplars make them interesting subjects for water balance studies. No information exists on soil moisture requirements for initial root and shoot growth of Populus cuttings. This study on leafless hardwood cuttings of Populus x euramericana (Dode) Guinier cv. Robusta examined the dynamics of water use during propagation, as influenced by two initial soil water potentials (–0.006 and –0.06 MPa). Differences in the initial water potential of the cuttings was achieved by three pretreatments i.e., fresh, soaked and dried. Initial _shoot was –1.45, –0.10 and –2.10 MPa in fresh, soaked and dried cuttings, respectively. Soil moisture had a major effect on rooting. Water-stressed cuttings took a longer time to root and had fewer roots. Pre-soaking of cuttings stimulated rooting, particularly under the drier soil moisture conditions. Initially the water potential of cuttings decreased with time and with the formation of roots it stabilized in all the pretreatments. The reduction in water potential of cuttings after planting was related to an increase in resistance to water flow in the xylem.This revised version was published online in November 2005 with corrections to the Cover Date.     

Biomass allocation strategies and productivity of tropical trees related to successional status

The productivity and biomass allocation strategies of two early successional (ES) and two late successional (LS) tropical tree species were compared and related to their successional status. Apart from distinct differences in clean bole length, crown depth, maximum crown width and leaf area index (LAI), the ES species showed higher allocation to the shoot, particularly to the bole, whereas the LS species had higher allocation to the root. The ES species with shallow root system had more root biomass within the upper 20 cm of the soil profile while the LS species with deeper roots had a higher proportion of root biomass distributed below the 20 cm depth. The productivity of the shoot of ES species was significantly higher than that of LS species. However, root productivity for ES species was higher only up to 4 years of age; the differences were not significant between 5 and 7 years. The implication of these results for agroforestry and mixed plantation forestry is emphasized.     

Within crown variation in the relationship between foliage biomass and sapwood area in jack pine

The relationship between sapwood area and foliage biomass is the basis for a lot of research on eco-phyisology. In this paper, foliage biomass change between two consecutive whorls is studied, using different variations in the pipe model theory. Linear and non-linear mixed-effect models relating foliage differences to sapwood area increments were tested to take into account whorl location, with the best fit statistics supporting the non-linear formulation. The estimated value of the exponent is 0.5130, which is significantly different from 1, the expected value given by the pipe model theory. When applied to crown stem sapwood taper, the model indicates that foliage biomass distribution influences the foliage biomass to sapwood area at crown base ratio. This result is interpreted as being the consequence of differences in the turnover rates of sapwood and foliage. More importantly, the model explains previously reported trends in jack pine sapwood area at crown base to tree foliage biomass ratio.     

A merchantable volume system for major pine species in El Salto,Durango (Mexico)

A compatible volume system for the major pine species in El Salto, Durango (Mexico) was developed from data corresponding to 1930 destructively sampled trees. Several well-known taper functions were evaluated and compared against the model selected in a previous study of these pine species in the same area. Appropriate statistical procedures were used in model fitting to account for the problems of autocorrelation and multicollinearity that are associated with the construction of taper functions. A compatible segmented model best described the experimental data and was found to be better than the previously selected model. It is therefore recommended for estimating diameter at a specific height, height to a specific diameter, merchantable volume, and total volume for the five species analyzed. The non-linear extra sum of squares method indicated differences in species-specific taper functions. A different taper function should therefore be used for each pine species.     

Shade acclimation in the forage grass Festuca Pallescens: biomass allocation and foliage orientation

Plants can acclimate to shade through different processes. In particular, they can modify their biomass allocation and the architecture in order to increase light interception. The objective of this study was to evaluate the shade acclimation capacity of Festuca pallescens (St. Ives) Parodi, as part of research concerning the use of this species in silvopastoral systems in Patagonia, Argentina. Biomass allocation was estimated from the leaf and root dry weights of plants growing in an open pasture and forested plots. Crown architecture of plants growing in the open and in two shade treatments was studied dividing each plant in three concentric cylinders, within which leaf angles and leaf area were measured. Light interception of plants in each treatment was estimated from the projected leaf areas and the relative amount of radiation reaching each location. Biomass allocation changed significantly in plants growing under shade conditions, increasing the proportion of leaves relative to the roots (Leaf Mass Fraction = 0.29 (SD: 0.12) and 0.40 (SD: 0.09) in plants in the open and under shade, respectively). Also, mean leaf inclination angles changed in plants growing under shade conditions, allowing an increase in light interception of approximately 35% compared to plants with the crown architecture typical of the open treatment. Previous studies have shown that F. pallescens does not change its photosynthetic response to light under shade conditions. Therefore, we conclude that the reported changes in biomass allocation and crown architecture, in addition to the increment in specific leaf area explain the relatively high shade tolerance of this species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biomass allocation and nitrogen limitation in a Cryptomeria japonica plantation chronosequence

We investigated soil net nitrogen mineralization rate, above- and belowground biomass allocation, and nitrogen use in a Cryptomeria japonica plantation chronosequence. Total biomass accumulation showed an asymptotic accretion pattern, and the peak total biomass accumulation rate occurred approximately 30 years after afforestation. Soil net nitrogen mineralization rate was lowest 30 years after afforestation. Between years 30 and 88, net nitrogen mineralization increased again. These results indicate that an imbalance in soil nitrogen supply and plant nitrogen demand occurred approximately 30 years after afforestation. Furthermore, leaf nitrogen concentration, which was used as an index of plant nitrogen status, was lower in mature forest than in young forest, suggesting that mature stands did not take up nitrogen as successfully. If soil resources such as nitrogen limit plant growth, plants may increase biomass allocation to fine root structure; however, fine root biomass was not higher in 30- and 88-year-old stands than in younger stands, suggesting that changes in biomass allocation may not be effective against nitrogen deficiency in a C. japonica plantation chronosequence.     

Estimation of culm volume reduction factors in five bamboo species(Phyllostachys spp.)

The hollow cylindrical culm is one of the most remarkable morphological characters of most bamboo species. In relation to its hollow structure, there are two different attributes of the culm volume in bamboo: the apparent culm volume(v_a: the total culm volume including the hollow portion) and the woody culm volume(v_w: the volume of the woody walls of the culm). The ratio of v_w to v_a is defined as the reduction factor for culm volume(f_v).The quantity f_v is useful to quantify the biomass resources of bamboo culms as well as to evaluate the carbon stock of bamboo forests. However, the direct measurement of f_v requires destructive sampling, which consumes time and labor. Hence, an alternative method for obtaining f_v is desired. In this study, we examined f_v in five species of the genus Phyllostachys and proposed alternative methods to estimate f_v. Our data showed that f_v varied by species, some of which exhibited a dependency of f_v on culm sizes. These findings indicate that the intraspecific and interspecific variation in f_v should be considered carefully when converting v_a into v_w by f_v. Based on our results, we propose here six approaches for predicting f_v and we discuss their advantages and disadvantages. Our results are intended to facilitate evaluation of the carbon sequestration capacity of bamboo forests and the commercial utilization of bamboo culms.     

Biomass allocation and assimilation efficiency of naturalTilia amurensis samplings in response to different light regimes

Biomass allocation and assimilation efficiency of natural Amour linden (Tilia amurensis) samplings in different light regimes were analyzed in the paper. The results showed that shoot increment of samplings in gap was the highest and that of samplings under canopy was the least. Samplings in gap expressed apical dominance strongly but samplings in full sun and under canopy behaved intensive branching. Lateral competition or moderate shading was favored to bole construction. The patters of biomass allocation of samplings in different light environment were rather similar. The biomass translocated to stem was more than that to other organs, and about one half of photosynthate was used to support leaf turn over. On the contrary, photosynthates of samplings in full sun were mostly consumed in leaves bearing and energy balancing. The carbon assimilation for leaves of samplings in gap was the most efficient, and more carbons were fixed and translocated to non-photosynthetic organs, especially to stemwood. Responsible editor: Zhu Hong     

Growth and yield of nine pine species in Angola

A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict (1975-2002) and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis (Martinez) Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3·ha-1, followed by P. kesiya with 1,200 m3·ha-1. The widely planted P. patula had a growing stock volume of 892 m3·ha-1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m2·ha-1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment (MAI) showed that rotation lengths of 20-30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m3·ha-1. Other productive species were P. kesiya, P. oocarpa and P. chiapensis. P. patula had a maximum MAI of 20 m3·ha-1. P. greggii had the lowest mean annual volume production, only about 13 m3·ha-1.     

Biomass allocation and assimilation efficiency of natural Tilia amurensis samplings in response to different light regimes

IntroductionAmourIinden(THisamurensiS),animportantcom-ponentofnaturaIIymixedbroad-Ieaved--KoreanpinecommunityineasternmountainareaofNortheastregionofChina,isoneofmainspeciesusedashighqualjtyveneerandcabinetworkingtimber.ButtheamountofnaturallindenresourceswithhighquafitywassharplydecreasedwithIonghistoricaIexpIoita-tionwithoutpIantingsothatlittleIindentimberhavebeenslJppliedintimbermarket.BeIongingtoassociatingspeciesinclimaxcom-munityintheregion,thespecieshasabigfacuIty.Butthegerminat…     

Belowground carbon allocation in unfertilized and fertilized red pine plantations in northern Wisconsin

We estimated carbon allocation to belowground processes in unfertilized and fertilized red pine (Pinus resinosa Ait.) plantations in northern Wisconsin to determine how soil fertility affects belowground allocation patterns. We used soil CO(2) efflux and litterfall measurements to estimate total belowground carbon allocation (root production and root respiration) by the carbon balance method, established root-free trenched plots to examine treatment effects on microbial respiration, estimated fine root production by sequential coring, and developed allometric equations to estimate coarse root production. Fine root production ranged from 150 to 284 g m(-2) year(-1) and was significantly lower for fertilized plots than for unfertilized plots. Coarse root production ranged from 60 to 90 g m(-2) year(-1) and was significantly lower for fertilized plots than for unfertilized plots. Annual soil CO(2) fluxes ranged from 331 to 541 g C m(-2) year(-1) and were significantly lower for fertilized plots than for unfertilized plots. Annual foliage litterfall ranged from 110 to 187 g C m(-2) year(-1) and was significantly greater for fertilized plots than for unfertilized plots. Total belowground carbon allocation ranged from 188 to 395 g C m(-2) year(-1) and was significantly lower for fertilized than for unfertilized plots. Annual soil CO(2) flux was lower for trenched plots than for untrenched plots but did not differ between fertilized and unfertilized trenched plots. Collectively, these independent estimates suggest that fertilization decreased the relative allocation of carbon belowground.     

Sensitivity of ring growth and carbon allocation to climatic variation vary within ponderosa pine trees

Most dendrochronological studies focus on cores sampled from standard positions (main stem, breast height), yet vertical gradients in hydraulic constraints and priorities for carbon allocation may contribute to different growth sensitivities with position. Using cores taken from five positions (coarse roots, breast height, base of live crown, mid-crown branch and treetop), we investigated how radial growth sensitivity to climate over the period of 1895-2008 varies by position within 36 large ponderosa pines (Pinus ponderosa Dougl.) in northern Arizona. The climate parameters investigated were Palmer Drought Severity Index, water year and monsoon precipitation, maximum annual temperature, minimum annual temperature and average annual temperature. For each study tree, we generated Pearson correlation coefficients between ring width indices from each position and six climate parameters. We also investigated whether the number of missing rings differed among positions and bole heights. We found that tree density did not significantly influence climatic sensitivity to any of the climate parameters investigated at any of the sample positions. Results from three types of analyses suggest that climatic sensitivity of tree growth varied with position height: (i) correlations of radial growth and climate variables consistently increased with height; (ii) model strength based on Akaike's information criterion increased with height, where treetop growth consistently had the highest sensitivity and coarse roots the lowest sensitivity to each climatic parameter; and (iii) the correlation between bole ring width indices decreased with distance between positions. We speculate that increased sensitivity to climate at higher positions is related to hydraulic limitation because higher positions experience greater xylem tensions due to gravitational effects that render these positions more sensitive to climatic stresses. The low sensitivity of root growth to all climatic variables measured suggests that tree carbon allocation to coarse roots is independent of annual climate variability. The greater number of missing rings in branches highlights the fact that canopy development is a low priority for carbon allocation during poor growing conditions.     

Use of stump diameter to estimate diameter at breast height and tree volume for major pine species in El Salto, Durango (Mexico)

Foresters may require to estimate the diameter at breast height(d.b.h.) and the volume of trees that have been cut, and mayonly have available the stumps as an indicator of the size ofthe trees. In the present study, equations for predicting bothd.b.h. and volume from stump diameter inside bark were developedfor major pine species in the forest region of El Salto, Durango(Mexico). The d.b.h. was estimated with relatively high accuracywith a simple linear model. The tree volume was also estimatedwith high precision by use of an allometric equation. Weightedlinear and non-linear least squares methods were used to takeinto account the problem of heteroscedasticity observed in thevolume–stump diameter relationships. The results of thenon-linear extra sum of squares method and of the F tests indicatedthat species-based equations for estimating both d.b.h. andvolume from stump diameter are required.     

Response to the interaction of thinning and pruning of pine species in Mediterranean mountains

Pruning allows knot-free timber to be obtained, thereby increasing the value of the highest-value wood products. However, the effect of pruning on growth is under discussion, and knowledge about the tree response to the simultaneous development of thinning and pruning is scarce. The objective of this study was to analyze the effect of the interaction of thinning and pruning on tree and stand level and the annual radial growth of two pine species native to Mediterranean mountains. We used long-term data of three trials installed in pine stands where several combinations of pruning and thinning were developed. Five inventories were carried out for each trial, and the mean dasometric features of the different treatments were compared using linear mixed models including a competition index. In addition, we collected cores from ten trees per plot in order to evaluate the annual response of trees to the thinning and pruning. We analyzed the annual radial growth using a semiparametric approach through a smooth penalized spline including rainfall and temperature covariates. Pruning did not show any effect on growth. However, larger diameter and increased annual radial growth were found in thinned plots, both with and without pruning, as compared to unthinned plots. Also, we found significant effects of climate on annual radial growth. We recommend the application of thinning and pruning in stands of Mediterranean mountains in order to get knot-free timber since growth reduction was not found in thinned stands.