Avian community response to pine flatwoods management

Across the southeastern United States, changing disturbance regimes threaten the integrity of pine flatwoods, reducing their suitability as habitat for a variety of avian species, many of which are considered of conservation priority. Prescribed burning and roller chopping are management practices widely used in pine flatwoods to control shrubs and increase the growth of herbaceous vegetation. However, the impacts these treatments have on this system and its associated avian communities are largely unknown. We examined the effects of prescribed burning and roller chopping on pine flatwoods avian communities using a paired sample approach. Avian communities were compared between treated (e.g., burned) and untreated areas. We considered abundance and richness of all birds, but also groups of conservation concern, and those likely impacted by seasonal management practices (e.g., breeding and non-breeding categories, and woodland, successional-scrub, and grassland guilds). Dormant season burning resulted in decreases in avian species richness and abundance within the non-breeding, overwintering community. In situations where the maintenance or enhancement of this avian group is desired, growing season burning appears beneficial and should be used in preference to dormant season burning. Growing season burning benefited breeding avian communities, resulting in increases in species richness and abundance within this group. Dormant season roller chopping had no effect on species richness or abundance of any avian category or guild. Increases in abundance within breeding avian communities were observed following growing season roller chopping and a roller chopping/burning combination. Grazing, did not mediate the effects of prescribed burning or roller chopping on avian species richness or abundance. The use of dormant season burning is likely inappropriate in situations where conservation and management of non-breeding, overwintering species is a priority. The use of growing season roller chopping appears to provide a potential treatment alternative in situations where positive effects on breeding species are desired. Overall, maintenance of avian abundance and richness may be best achieved through the diverse application of prescribed burning and roller chopping based on season, frequency, and space.     

Effects of burning season and frequency on saw palmetto (Serenoa repens) flowering and fruiting

Medicinal use of saw palmetto (Serenoa repens) fruits in treating benign prostatic hypertrophy has driven a recent sharp increase in fruit harvesting. At the same time, saw palmetto often is considered a keystone species, serving as habitat or a food source for several hundred mammal, bird, reptile, amphibian and insect species. Due to harvesting pressure on this ecologically important, non-cultivated species, land management practices that produce environmentally sustainable harvests are needed. As part of research focusing on use of controlled burning as a management tool, we investigated effects of burning season and frequency on saw palmetto flowering and fruiting in 32 pine flatwoods sites in central and southwest Florida from 1997 to 1999. The study was conducted as two repeated measures experiments, each involving 16 sites. Each experiment included two among-subjects factors – burning season and past burning frequency – and one within-subjects factor – year – with four replications of each treatment combination. For both experiments, growing season (i.e., April–July) burns had high flowering levels the first year after burning (mean proportion of saw palmettos flowering = 0.49, n = 16 sites), but decreased the second year after burning (mean proportion flowering = 0.15, n = 16 sites), while winter (i.e., November–February) burns had intermediate levels of flowering during both the first and second years after burning (mean proportions flowering = 0.21 and 0.28 for first and second years after burning, n = 16 sites). Although most flowering occurred during April and May, flowering occurred 2–5 months after winter burns, but did not occur until 9–12 months after growing season burns. During the 1997–1998 experiment, fruit infection by the fungus Colletotrichum gloeosporioides caused a fruiting failure in all sites. During the 1998–1999 experiment, fruit yields were higher in growing season burns only in infrequently burned (i.e., burned less often than every 5 years) sites, and only in 1998 (mean fruit yields = 325 kg/ha and 0.25 kg/ha for growing season, infrequently burned sites and winter, infrequently burned sites; n = 4 sites in each group). Frequently burned (i.e., burned every 2–3 years) sites generally had low fruit yields (mean fruit yields = 163 kg/ha and 242 kg/ha for frequently burned sites in 1998 and 1999; n = 8 sites). Although controlled burning can be an effective management tool in producing economically sustainable saw palmetto fruit harvests, land managers also must consider ecological needs of other plant and animal species when planning environmentally sustainable burning regimes.     

Scleroderris canker of Todo-fir in Hokkaido,Northern Japan

The first symptom of canker on Todo-fir appears in spring, although infection of current year shoots by spores must be established early in the growing season of the previous year. Isolation experiments demonstrated the presence of dormant infection of the causal fungus in the shoots and invasion of new bark tissues under snow cover during the winter.     

Storage of biomass and net primary productivity in desert shrubland of Artemisia ordosica on Ordos Plateau of Inner Mongolia, China

Biomass and net primary productivity （NPP） are two important parameters in determining ecosystem carbon pool and carbon sequestration. The biomass storage and NPP in desert shrubland of Artemisia ordosica on Ordos Plateau were investigated with method of harvesting standard size shrub in the growing season （June-October） of 2006. Results indicated that above- and belowground biomass of the same size shrubs showed no significant variation in the growing season （p〉0.1）, but annual biomass varied significantly （p〈 0.01）. In the A. ordosica community, shrub biomass storage was 699.76-1246.40 g.m^-2 and annual aboveground NPP was 224.09 g-m^-2·a^-1. Moreover, shrub biomass and NPP were closely related with shrub dimensions （cover and height） and could be well predicted by shrub volume using power regression.     

Gradient analysis of an eastern sand savanna's woody vegetation,and its long-term responses to restored fire processes

Little information is available comparing historic and modern sand savannas, and how remnants respond to restored fire. We compared short- and long-term effects of restored fire on the Tefft Savanna, a 197 ha eastern sand savanna in northwest Indiana that had undergone three decades of fire protection. U.S. Public Land Survey data from Tefft in 1833 indicate black and white oak barrens, and pin oak savanna, with trees averaging 50 stems/ha and 4 m²/ha basal area. We used ordination and a digital elevation model to assess topographic distribution of tree species in 1986. In 1986, we also compared initial effects of high- and low-intensity dormant season fire on woody vegetation among nine blocks containing black oak, white oak, and pin oak stands. Twenty years later, we compared the same blocks, all of which had been burned three times per decade with low-intensity fires. In 1986, black oak, white oak and pin oak occurred across a gradient of decreasing elevation and slope. At that time, unburned black oak and white oak stands averaged >400 stems/ha and about 10 m²/ha basal area, and their smaller size classes contained non-oak woody vegetation that apparently had invaded with fire exclusion. After initial burns, black oak and white oak stands receiving high-intensity fire averaged <200 stems/ha and had significantly lower oak canopy cover and basal area than unburned stands. Stands receiving low-intensity fire had intermediate oak canopy cover, with basal area similar to unburned stands. Pin oak stands were more fire-resistant, apparently because spring flooding often reduced fire effects. Density, cover and basal area of non-oak tree species were much lower than oaks, and were not reduced by initial burning. Repeated low-intensity burning over 20 years tended to maintain structure caused by initial fires. However, it reduced lower size class stem densities, promoted post-fire sprouting into the shrub layer, and allowed oak basal area to increase in larger size classes. Time since fire regulated shrub layer structure on a 4-year cycle. Density and cover of trees and shrubs returned to pre-burn conditions by the second and fourth growing seasons after fire, respectively, with non-oak tree species exceeding pre-burn cover and density by the fourth season. These results suggest that high-intensity fire is more important than repeated low-intensity burning in structuring and restoring eastern sand savanna, and that non-oak tree species, once established, may be resistant to low-intensity fire.     

Vegetation response to intensity of herbaceous weed control in a newly planted loblolly pine plantation

Growth of loblolly pine (Pinus taeda L.) seedlings through three growing seasons after planting increased with intensity of herbaceous weed control using herbicides. Weed control had no effect on pine survival. Two years of complete herbaceous weed control (CHC, control throughout the first two growing seasons after planting) and operational herbaceous weed control (OHC, sulfometuron at 0.42 kg ai/ha at the beginning of the first growing season), resulted in lower biomass of weeds plus trees than with no herbaceous weed control (NHC) during the first growing season. Differences in total biomass during the first year were due to differences in biomass of herbaceous weeds. Total biomass on CHC and OHC plots was at least as great as NHC the second year, and greater by the third year, as pines assumed dominance as a result of increased growth from reduction of herbaceous weeds. The operational herbicide treatment had no significant impact on overall herbaceous weed biomass and cover, and little effect on species composition compared to no herbaceous weed control two and three growing seasons after treatment. The CHC treatment significantly reduced herbaceous weed biomass, cover and composition through three growing seasons.     

Effects of nurse shrubs and tree shelters on the survival and growth of two Austrocedrus chilensis seedling types in a forest restoration trial in semiarid Patagonia, Argentina

? Context

Harsh environmental conditions in xeric sites of Andean Patagonia, affect the emergence, survival, and growth of either naturally grown or planted Austrocedrus seedlings.

? Aims

We evaluated the effects of nurse shrubs and tree shelters on the survival and growth of Austrocedrus seedlings as compared to unprotected (control) areas and how differently produced seedling types perform under these treatments.

? Methods

In 2006, two Austrocedrus seedling types (1?+?2?=?S1 and Plug 2?+?1?=?S2) were planted under shrub cover (C1), tree shelter (C2), and control (C3). Soil surface temperature and moisture were measured for each treatment during the first growing season, while seedling survival and height were recorded during 5 years.

? Results

Survival was not affected by cover type the first year, but it was affected by seedling type (S1?>?S2). After an extremely dry second growing season, seedling survival significantly decreased in relation to either cover or seedling type. Five years after plantation, survival was significantly higher for C1 and C2 (40?C60 %) as compared to C3-S2 (18 %). Seedling height was significantly affected by cover, but not by seedling type.

? Conclusions

The use of nurse shrubs and/or tree shelters is useful in Austrocedrus seedling restoration trials. Seedling morphology appears as relevant for survival in semiarid environments.     

Spatial patterns of shrub cover after different fire disturbances in the Pyrenees

? Woody encroachment into grasslands is a worldwide phenomenon. In the Pyrenees, fire has been used as a management tool to transform part of the encroached land to grassland.

? This study aims to compare the spatial patterns of shrub cover 4 y after 4 different fire disturbances (prescribed burning, repeated prescribed burning, wildfire in 20 year-old shrubs and wildfire in 5 year-old shrubs); and also to compare shrub cover after different fire disturbances, accounting for spatial autocorrelation. The study focuses on the shrub Cytisus balansae. Two-dimensional transects (20 × 0.5 m) were established to monitor shrub cover for 4 y after each disturbance type. Autoregressive models and Markov models were used with a Monte Carlo procedure to account for the presence of spatial autocorrelation.

? Shrub cover was greater after prescribed burning than after repeated prescribed burning, and it increased with shrub age before disturbance. Differences in spatial patterns were detected in shrub patch size, with repeated prescribed fires and wildfires reducing shrub patch size by half in comparison with prescribed burning.

? From the management point of view, the effects of repeated prescribed burning were similar to those of a wildfire on reducing shrub cover and shrub patch size.

     

Forage production and small ruminant grazing responses in Mediterranean shrublands as influenced by the reduction of shrub cover

Reduction of shrub cover in Mediterranean shrublands is considered as a method of optimising forage and animal production. In this study, forage production in grazed and protected plots and grazing responses of small ruminants in cleared (25% shrub cover), slashed (34% shrub cover) and not treated (control, 55% shrub cover) kermes oak (Quercus coccifera L.) shrublands were compared during the spring seasons of 1992, 1993 and 1994. The alterations in shrub density were done in October 1991 and pastures remained ungrazed until spring of 1992. Clearing and slashing of shrub vegetation resulted in higher amounts of available herbaceous forage and useable browse. At the end of the growing season, averaged across years, herbaceous biomass was generally two to three times higher in the treated shrublands than in the control; also, browse biomass was slightly less (1,078 vs 1,533 kg/ha) but easily accessible because of the open structure and the lower height of the sprouting shrubs. There were generally no grazing response differences between the cleared and slashed pastures. However, grazing animals (sheep and goats) had a higher bite rate (bites/min; P 0.05) in the treated pastures than in the control. Levels of crude protein in the forage selected by animals were higher (P 0.05) in the treated pastures than in the control. Animals in the improved pastures maintained diets that were significantly more digestible (53.5%) than those in the control pasture (48.5%). Neutral detergent fibre and lignin contents of animal diets were similar in the improved pastures but lower (P 0.05) than those of the control. It is concluded that removing of woody vegetation in Mediterranean shrublands results in increased forage production (available herbage and useable browse) and improved forage quality and availability for small ruminants.     

Diversification of Pinus halepensis forests by sowing Quercus ilex and Quercus pubescens acorns: testing the effects of different vegetation and soil treatments

The goal of this study was to develop management strategies favouring establishment and survival of holm oak (Quercus ilex L.) and downy oak (Quercus pubescens Willd.)??two species co-occurring in Southern France??in mature Allepo pine forests (Pinus halepensis Mill subsp. halepensis). An experimental design was assessed in a partially cut mature stand of Aleppo pine in which five soil and vegetation treatments??chopping, chopping followed by scarification in one or two directions, prescribed burning, control??and two slash treatments (presence/absence) were applied. A total of 1,600 sowing points, each composed of 3 Q. ilex or Q. pubescens acorns, were installed in the different treatments in November of two consecutive years at 6 and 18 months, after the end of treatments. Survival was monitored 3 and 2 years after sowing, soil surface at the sowing points was characterized at different dates, and predawn leaf water potentials were measured during the dry season. High mortality occurred after the first summer, but survival after 1 year was 2.3?C5.2 higher in Q. ilex than in Q. pubescens, confirming that Q. ilex was better adapted to the drier parts of the Mediterranean area. Survival was significantly influenced by the treatments, but there was a variable response between the two sowing years under most of the treatments. Only intense fire proved the most beneficial treatment for seedling survival in both years. The micro-local soil cover conditions induced by the treatments played a major role in explaining oak survival. In particular, grass cover (mainly Brachypodium retusum) proved to be largely unfavourable to seedling survival and growth, and this detrimental effect was also confirmed by lower predawn leaf water potential values with increasing grass cover. Acorn introduction designed to diversify mature Aleppo pine forest after soil and vegetation treatments therefore has to be considered for treatments that most efficiently impair the pre-existing competing grass cover such as prescribed high-intensity fire treatment.     

Mechanical cleaning and prescribed burning for recruiting commercial tree regeneration in a Bolivian dry forest

A critical component of sustainable forest management is the regeneration of commercially valuable tree species. Mechanical cleaning with machetes and chainsaws, prescribed burning, and a combination of both treatments were applied to recently-created logging gaps in a Bolivian dry forest to evaluate their impact on the natural regeneration of commercial tree species and on control of competing vegetation. The three treatments and an untreated control were applied to logging gaps during the dry season of 1998 and replicated ten times. Eight months following burning, the density of commercial tree regeneration in gaps did not differ statistically among treatments. Relative height growth of total commercial regeneration also did not differ among treatments, although it did vary by species. Reduction in competing vegetation following the application of site preparation treatments was significantly higher, but competing plant cover was beginning to converge among treatments after eight months. Despite better control of competing vegetation, early recruitment and growth responses to burning and cleaning of vegetation in logging gaps do not appear to justify application of these treatments in this forest, especially considering their high costs.     

Growth and physiological response of eastern white pine seedlings to partial cutting and site preparation

We examined how white pine (Pinus strobus L.) seedlings planted under a mature cover of white and red (Pinus resinosa Ait.) pine in eastern Ontario (Canada) responded to treatments aimed at improving light and soil conditions for seedling growth. The treatments were: (a) three levels of partial cutting (no cut or CS0, cut to one-crown spacing between residual trees or CS1, cut to two-crown spacing or CS2); (b) two levels of vegetation control (without herbicide or H0, with herbicide or H1); and (c) two levels of soil scarification (S0 and S1). On the third growing season after planting, total growth of seedlings was lowest in CS0 treatment and similar in CS1 and CS2 treatments. The CS2 created better growing light conditions than the CS1, with and average of 50% of full light at seedling height, which corresponded to the maximum height and diameter growth rates of seedlings. However, CS2 also stimulated the growth of competing woody vegetation (both understory trees and shrubs), and resulted in greater microsite heterogeneity of light availability. Scarification warmed the soil (approximately 1–3 °C in the middle of the growing season), decreased the density of competing trees, but increased the shrub density, with no impact on white pine seedling growth. The treatments had no effect on light-saturated photosynthetic rate (A) of current-year foliage of seedlings, nor on their midday shoot water potential. Leaf N was higher in partial cuts and with vegetation control, but the relationship between N and A was weak to non-existent for the different foliage classes. Measures of the proportion of aboveground biomass allocated to foliage (leaf-mass ratio) suggest an acclimation response of young white pine that improves growth under moderate light availability and compensates for the lack of leaf-level photosynthetic plasticity. We suggest a combination of soil scarification under a one-crown spacing partial cut (corresponding to 14 m² ha⁻¹ of residual basal area, or an average of 32% of available light at seedling height) as an establishment cut. This should provide optimum growth conditions for planted understory white pine, while also favoring natural regeneration and providing some protection against damage from insects and disease.     

Relationship between shrub cover and available forage in Mediterranean shrublands

Shrublands with kermes oak (Quercus coccifera L.) as a dominant species play an important role in the nutrition of grazing animals in the Mediterranean region during all seasons of the year. Their proper management, however, is inhibited by the lack of easy and inexpensive methods for measuring available forage. In this paper, the spatial distribution of available forage as well as its relationship with shrub cover measured on the ground and in aerial photographs were investigated. The research was conducted in kermes oak shrublands of central Macedonia, Greece. Two-phase sampling was applied by using 1:15,000 aerial photographs to select 47 plots, 0.1 ha each, on an area of 545 ha where shrub cover and available forage (herbage, current year's and total browse) were measured. These measurements were carried out on four shrub cover classes: open (0 to 15%), moderate (16 to 40%), dense (41 to 70%) and very dense (71 to 100%); and three height classes: low (0 to 0.5 m), middle (0.6 to 1.0 m) and tall (1.1 to 1.5 m). High resolution aerial photographs (1:6,000) taken during the year of ground sampling were used to estimate shrub cover and correlate to ground measurement. Estimated cover had a high correlation (r 0.96) with ground measurements in open, moderate and dense shrub stands. The open to dense cover classes had significantly more available forage than the very dense cover class; and the low height class significantly higher than the other two classes. The regression of available forage with shrub cover measured on the ground and on aerial photographs produced non-linear equations with high coefficients of determination (R² > 0.70) only when shrub height up to 0.5 m irrespective of the cover class was considered. It is concluded that shrub cover measured on aerial photographs can be used to predict shrub cover on the ground as well as available forage in kermes oak shrublands provided that the shrubs are not too tall (up to 0.50 m).This revised version was published online in November 2005 with corrections to the Cover Date.     

炼山对杉木人工林群落学特征影响的研究

The effects of human disturbance on community features of Cunninghamia lanceolata mixed forests were stud-ied, the results showed that 1 ) the proportion of phanerophyes in the not burning forests were larger than in the control burn-ing forests; 2)the species richness in the control burning forests were larger than that in not burning forests, but the speciesdiversity and Simpson evenness in the control burning forests were lower than that in the not burning forests;3)the effect ofcontrol burning on the dominant species in tree and shrub layers of Cunninghamia lanceolata mixed forests were little, buton the herb layer was very large,which dominated by positive plant species; 4)the community structure was more complexwhich would increase the crown density of stand.     

Plant community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Intensively managed loblolly pine (Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations (n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (?4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives.     

Root carbohydrates and aspen regeneration in relation to season of harvest and machine traffic

Season of harvest has often been suggested as a driver for the erratic success of aspen (Populus tremuloides) sucker regeneration, partially due to root carbohydrate reserves and soil conditions at the time of harvest. A field experiment in western Manitoba, Canada, assessed root suckering and root carbohydrates of aspen in response to season of harvest and machine traffic. Six sites (120 m × 120 m) were selected within two large mature aspen stands slated for summer harvest. Plots (50 m × 50 m) were hand-felled (without machine traffic) in mid-summer, late summer, winter, and one plot was left uncut as a control. Season of cut with no traffic had no effect on sucker density, height or leaf dry mass per sucker. During the dormant season, root starch reserves were highest in the winter cut plots, however, just prior to suckering, this difference in carbohydrate reserves among the three seasons of harvest disappeared and by the end of the first growing season root reserves in all three seasons of cut had recovered to near control levels. Adjacent plots that were conventionally harvested in the summer and impacted by logging traffic had similar sucker densities but had 19% less height growth of suckers and 29% less leaf dry mass per sucker compared to suckers in plots harvested at the same time without traffic. After one growing season, root carbohydrate levels were similar whether or not machine traffic was used; however, the reduction in leaf dry mass in plots with machine traffic could have negative implications for carbohydrate accumulation and growth. The study suggests that the phenological state of the mature aspen plays a very small role in aspen regeneration and that harvesting practices and site conditions are likely the main drivers of aspen regeneration success.     

Conservation of Mediterranean oak woodlands: understorey dynamics under different shrub management

The effect of experimental disturbances on the dynamics of a shrub community was studied on a ‘Montado’ ecosystem, in southern Portugal. The evolution of the community physiognomy, composition and diversity were monitored after shrub clearing followed by biomass removal, deposition on soil surface and incorporation with the soil, over a 9-year period. Maximum shrub density was recorded in the first year after the disturbances, excepting in mulched plots which showed the greatest number of individuals 1 year later. The increment of shrub leaf biomass was very fast in the first 3 years, whereas wood production was slower but occurred along the whole study period. At the end of the study, leaf and wood biomass was still significantly lower than in the pre-disturbance situation. The variation pattern of leaf area index was similar to that of leaf biomass. The evolution of total plant cover and diversity was similar across treatments. The highest species richness and diversity were recorded 2 years after cutting, decreasing afterwards with the increasing dominance of shrubs. Thus it seems likely that, although a 9 year period is too short for these communities to reach steady equilibrium, they are very resistant and resilient to disturbances, as regeneration was fast and vegetation dynamics was not influenced by differences among treatments. We can conclude that shrub clearing promotes biodiversity and the time of permanence of shrub patches depends on the particular goal we want to achieve.     

Field performance of Quercus petraea seedlings grown under competitive conditions: influence of prior undercutting in the seedbed

Quercus petraea was undercut according to the following procedure: undercutting first year once (July, September, November), twice (July and November), or undercutting in two consecutive years (September of year 1 and either July, September or November of year 2). Undercutting decreased height and dry weight of the seedlings compared to uncut control seedlings. Undercutting in September and July in two consecutive years increased the number of first-order lateral roots. Field performance was evaluated by transplanting under two conditions, (a) competition with a mixture of grasses with no irrigation or fertilisation and (b) standard conditions with fertilisation and irrigation first year and no competition with grass. After two growing seasons under competitive conditions, seedlings undercut in September of year 1 had a significantly higher dry weight compared with that of uncut control seedlings. Numbers of lateral roots and field performance under competitive conditions was related when numbers of lateral roots were small, but not when high. Competitive conditions had limited effect on root growth after one growing season, whereas shoot growth was reduced. After two growing seasons both shoot and root growth were reduced in all treatments compared with standard conditions.     

马占相思育苗容器与基质的选择试验

马占相思采用３种容器和９种配方基质育苗试验，结果表明：３种容器育苗对苗高，地径，根鲜重和根瘤数存在显著影响，其中以塑料薄膜育苗袋育生长最快，舒根型软育苗器次之，舒根型硬质塑料育苗筒最短，但根素发达，结根瘤最多；９种配方基质中以７０％黄芯土＋２８％火烧土＋２％过磷酸钙的苗木生长最好，结瘤量也多，根瘤数略次于含４０％锯木糠＋５８％黄芯土＋２％过磷酸钙基质的，苗木生长量总趋势是含火烧土基质〉含泥炭土基质