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1.
In the southeast of South Australia and the adjacent south west of Victoria (called the Green Triangle Region), planting of Pinus radiata D. Don (radiata pine) plantations began about 130 years ago and these now occupy 175,000 ha. They are growing on sites with generally podsolised sandy soils, low in soil fertility and where evaporation typically exceeds precipitation for five to six months of the year. Regional softwood industries producing a range of value added products are completely dependant on the versatile radiata pine wood from these plantations.  相似文献   

2.
Jack pine (Pinus banksiana) forests in parts of northern Lower Michigan have been managed with 30 years of extensive clearcut harvesting followed by planted stand establishment in order to maintain habitat for the endangered Kirtland's warbler (Dendroica kirtlandii). We used two, parallel chronosequences to study how this management has affected the structural development of jack pine stands relative to the historically dominant disturbance regime of stand-replacing wildfire. Each chronosequence consisted of three young stands (age range 3–6 years), three intermediate-aged stands (age range of 12–17 years) and three mature stands (age range of 39–69 years). Average stem density in young plantations (2300 stems/ha) was lower than the average for young, fire-origin stands (11,000) and varied over a much narrower range among stands (1403–2667 for plantations and 1552–24,192 in fire stands). In addition, within-stand patchiness of stem density was also much higher in the wildfire sites for young and intermediate ages. Plantation sites possessed very little dead wood at young ages (averaging 3 snags/ha and 12 m3/ha CWD) compared to young fire-origin stands (averaging 252 snags/ha and 49 m3/ha CWD). In contrast, mature plantations had similar levels of dead wood (averaging 269 snags/ha and 22 m3/ha CWD) as mature fire-origin stands (averaging 557 snags/ha and 12 m3/ha CWD). Differences between the plantation and fire-origin chronosequences were driven mainly by young- and intermediate-aged stands, whereas mature stands were typically quite similar in all structural features. Our results show clearly that forest management aimed at preserving and enhancing the population of a single endangered species results in greatly simplified habitat structure at the stand level, and suggest that this simplification is perpetuated across the landscape as well. Of particular concern are the effects of extensive harvesting and planting on the availability of snags and CWD.  相似文献   

3.
Pine plantations in Argentinian Patagonia cover ca. 95,000 ha in Chubut, Río Negro and Neuquén provinces. Exotic bark beetles (Orthotomicus laricis, Hylastes ater and Hylurgus ligniperda) commonly occur in freshly cut logs, stumps and slash. These beetles are vectors of “ophiostomatoid” fungi which include primary tree pathogens as well as important agents of blue stain. The aim of this study was to identify these beetle‐associated fungi. Sawing mills and pine plantations were surveyed three consecutive years. Fungal isolates from stained logs, processed wood and insect galleries were identified based on morphological and DNA sequence comparisons of ITS and β‐tubulin gene regions. Two Grosmannia, one Graphilbum and three Ophiostoma species were identified. Ophiostoma piliferum and O. peregrinum sp. nov. were the most frequently isolated taxa. O. peregrinum occurred in all provinces, colonizing different conifer species and, interestingly, also the native broadleaved species Nothofagus dombeyi. Pine plantation forestry in southern South America includes Argentina, Brazil, Chile, Paraguay and Uruguay. Emerging data from Argentina, Chile and Uruguay revealed some coincidences between these countries, but also several differences, probably, as a result of multiple introduction events.  相似文献   

4.
The main silvopastoral systems carried out in arid and semiarid zones of northern Chile are presented. Plantations with queñoa (Polylepis besseri) in the Precordillera (3,000–4,000 meters above sea level) and with ‘queñoa de altura’ (Polylepis tarapacana) in the High Plateau (over 4,000 m.a.s.l.) are described. For extremely arid zones (2 mm/yr), tamarugo (Prosopis tamarugo) and algarrobo (Prosopis chilensis) plantations in Pampa del Tamarugal are reviewed. In this zone 20,483 ha have been planted, 88% with P. tamarugo. These plantations feed a variable herd of 7,000–9,000 sheep and goats per yr. The forage produced per tree varies from 20 to 70 kg/yr for 14 to 22 yr old trees, planted in densities of 100/ha. For the semiarid zone, plantations with forage shrubs of the genus Atriplex are described. Between 1975 and 1989, about 37,000 ha were planted in the coastal zone of Coquimbo region, 60% of them with A. nummularia and the rest with A. repanda. Productivity varies widely in both species. It depends on management techniques and environmental variables. Afforestation with such species offers green forage during periods of scarcity of natural grasses, especially during long droughts. The rate of afforestation is declining because the government has stopped planting, and the private sector is planting less than expected. This is because often yields have been low, due to either natural causes or deficient management.  相似文献   

5.
Black stain root disease (BSRD) caused by Leptographium wageneri var. ponderosum (Verticicladiella wageneri) is a destructive disease in many Jeffrey pine (Pinus jeffreyi) and ponderosa pine (Pponderosa) forests of the western United States. Overcrowding is a pervasive problem in these forests, unless alleviated by thinning. In an overcrowded BSRD‐infested second‐growth Jeffrey/ponderosa pine forest in northern California, a large study (16.2 hr; 40 acres) was designed to determine the impact of thinning to four levels—6.9 m2/ha (30 ft2/acre), 13.8 m2/ha (60 ft2/acre), and 20.7 m2/ha (90 ft2/acre) of basal area and a control with no thinning—on the incidence of BSRD‐caused mortality. Ten years after this experiment was initiated, results indicate that thinning to any of these levels lowered the incidence of BSRD‐caused mortality as compared with BSRD‐caused mortality in unthinned control plots.  相似文献   

6.
This study addresses concerns that harvesting marketable pine straw from forests may decrease timber productivity by allowing water to evaporate more quickly from the soil surface. Three harvesting schedules and a control treatment (no straw harvest) were replicated six times on 24 plots (0.18 ha each), and compared to determine harvesting effects on water content of the soil vadose zone in an established (16 yr) loblolly (Pinus taeda L.) plantation (3.0?×?1.5 m2 tree spacing). Pine straw harvesting tended to decrease volumetric soil water content (%) at depths below 20 cm, but the effect was significant (p < .05) only at the 50-cm depth in Weeks 3 and 4 (late June) of the study, when water content at this depth averaged 20.9% for soils where straw was harvested annually, and 30.2% for soils where the straw was never harvested (control). In soils where pine straw had been allowed to accumulate for at least a year after the previous harvest, average water content was not significantly different than in the control plots. Therefore, pine straw harvesting can potentially lengthen drought-stress periods for loblolly pine on some soils during the 1st yr after pine straw has been removed.  相似文献   

7.
Restoring longleaf pine (Pinus palustris Mill.) over much of its original range requires artificial regeneration. In central Louisiana, USA, two fertilization levels—No (NF) or Yes (F-36 kg/ha N and 40 kg/ha P) in combination with three vegetation treatments—Check, four prescribed fires (PF), or multi-year vegetation control by herbicidal and mechanical means (IVM) were applied to container-grown longleaf pine plantings in a grass savanna. After 10 years, P concentration in longleaf pine foliage was less on NF plots than F plots, but fertilization did not significantly affect tree stature. Survival was greater on NF plots than F plots, and so, NF plots were more productive (NF—63 m3/ha and F—45 m3/ha). Pine trees on IVM plots (37 dm3/tree) were significantly larger than on Check and PF plots, which averaged 17 dm3/tree. Survival was better on IVM plots (88%) than PF plots (78%), which was better than Checks (58%). Consequently, IVM plots were most productive (99 m3/ha), followed by PF plots (44 m3/ha), and lastly Checks (28 m3/ha). PF plots had greater grass cover (38%) than Check and IVM plots, which averaged 5%, whereas PF and IVM plots had less understory arborescent cover (an average of 25%) than Checks (91%). A wildfire in March 2007 reduced pine survival by 22, 14, and 1 percentage points on IVM, Check, and PF plots, respectively. Seven months later, longleaf pine production had decreased to 92 m3/ha on IVM plots while increasing to 55 m3/ha on PF plots and 30 m3/ha on Checks. Overall, the wildfire rejuvenated the herbaceous plant community. Grass cover on Check and IVM plots averaged 20% while grass cover on PF plots was 36%. Forb cover increased on all treatments from 2% before the wildfire to 13% seven months after the wildfire. Understory arborescent cover decreased on Checks to 62% but increased slightly on PF and IVM plots and averaged 30%.  相似文献   

8.
An analysis is made of the animal stocking rate used in commercial Pinus caribaea plantations 2.5–8.5 yr old. Pines were planted at 2.5 × 2.5 m and programmed for clear-cut harvest at 10 yr rotations (pulpwood). Cattle grazing was introduced to reduce weeding costs.Stocking rate in 1983–1985 was 0.67 AU/ha/yr (AU = animal units 350 kg live weight). A quadratic model calculated using 1984 data (S = 0.0108 + 0.385A–0.0418A2) describes the relationship between animal stocking rate (S) and stand age (A 9.5 in yr).The model predicts a maximum of 0.89 AU/ha/yr at plantation age 4.5 yr. Grazing started at plantation ages 2.5 yr; no plantations older than 9.5 yr are grazed.  相似文献   

9.
A critical mass of farm forestry and private forestry is now developing in Ireland with over 211,000 ha planted since 1980, with 190,000 ha of this planted since 1990. Currently, 90,000 ha of private forests are over 10 years of age, with 41,000 ha over 15 years of age. This paper examines the potential of the farm forest resource in Ireland and highlights some issues that need to be addressed in order that the full potential of farm forestry is realised. It is estimated that 876,000 m3 of timber is currently available from forests through removals from thinning operations from plantations that are at or have passed first thinning age. Cumulative volume output from thinning could be as high as 1.9 M m3 by 2010 increasing to 5.9 M m3 by 2015. Farm forestry has the potential to be a financially important farm enterprise with 15% of farmers (16,460) currently engaged in forestry in Ireland. The development of volume production forecasts will provide crucial supply information for gearing up of the wood-processing sector for additional volume from farms. However many enterprises face high harvesting and extraction costs. Solutions to overcoming economies of scale due to the small size of plantations (averaging 9.2 ha) are proposed using methods to group forestry operations together. The network of small sawmills throughout the country is favourable for private growers as analysis indicates that 82% of private forests are within 32 km of a sawmill and efforts to stimulate local processing are being encouraged. Financial analysis indicates that farmers can increase forestry returns by thinning their plantations. The risk of windthrow to plantations is one of the major factors that can lead to financial losses in farm forestry in Ireland and can be reduced by adequate management planning. A series of forestry extension programs will provide farmers with adequate information to help aid decision-making in managing their plantations.
Niall FarrellyEmail:
  相似文献   

10.
《Southern Forests》2013,75(3):195-202
Pine plantations are thought to negatively impact species diversity and to irreversibly modify arid zones. However, some studies have suggested that through the application of appropriate management practices, the negative impacts of plantations may be reduced. Our aim was to study the effects of early pruning and thinning on the ground-dwelling insects found in pine tree plantations in Patagonia. We compared the abundance, species richness and composition of the beetle and ant assemblages within 16-year-old pine stands (n = 10) subjected to early pruning and thinning (i.e. before canopy closure) against a steppe habitat exposed to sheep grazing (‘control’, n = 10). To sample ground-dwelling insects, we deployed nine pitfall traps per plot (100 m2) for a 10-day period. Vegetation cover and plant species richness were significantly lower in the plantations than in the steppe. We found that beetle species richness was reduced in the managed plantations in comparison to the steppe but abundance was higher. In turn, species composition in the plantations was different from that of the controls. Ant species richness was similar among habitats but abundance was lower in the plantations. We conclude that, contrary to our expectations, management practices that lead to sparse plantations at early stages in the production cycle, do not offer a significant advantage in terms of reducing the impact of pines on ground-dwelling insects of Patagonia.  相似文献   

11.
  • ? In forests, the substitution of broadleaf species by conifers can reduce biodiversity because coniferous forests generally provide less diverse vascular understories than broadleaf forests. However, in some cases, former pine plantations might be useful for restoring native forests. We compared plant species composition on the plot scale in natural beech and mixed oak forests with that in plantations of Pinus radiata. Links between plant diversity and landscape parameters (patch size, fractal dimension and distance to the nearest patch of the same type) were investigated.
  • ? The objective of this study was to evaluate the use of pine plantations for restoring native diversity in a zone where native forests are very fragmented.
  • ? Similar to oak forests, plant diversity in pine plantations was high, mainly due to the presence of generalist species. Some species characteristic of oak forests also appeared in pine plantations, suggesting the onset of natural forest regeneration.
  • ? These results suggest that pine plantations could be used to promote natural regeneration of original oak forests. Moreover, residual native stands should be conserved as important sources of native species and their seeds.
  •   相似文献   

    12.
    新西兰造林事业始于1898年,历史上曾出现两次造林高潮。新西兰现有人工林总面积为1 133 022公顷,其中90%为辐射松。新西兰人工林的主要特点是:(1)几乎全部由外来树种组成;(2)人工林的生产周期较长,25-35年,经营强度高;(3)政府大量投资营建人工林;(4)政府采取各种方针和政策刺激和鼓励私营公司和个体农场主营建人工林;(5)人工林已经发展成为独立的产业,与其它产业部门一样,具有商业性的竞争能力。  相似文献   

    13.
    In commercial forestry, regular terrestrial enumerations of the growing stock are required for the valuation, sustain-able management and planning of current and future timber supplies. In this study we examined whether the combination of synthetic aperture radar (ALOS PALSAR) and optical satellite (SPOT 4) image data can accurately predict the timber volume of even-aged Eucalyptus plantations located in South Africa. Results from this study show that the combination of ALOS PALSAR and SPOT 4 produces a R 2 value of 0.68 for the planted model, whereas the coppiced model produced a R 2 value of 0.55. However, by including stand age as an independent variable in the stepwise model, there was a 15% improvement for the planted model, whereas the coppiced model produced a 27% improvement. The final model developed in this study produced a R 2 value of 0.83 and a RMSE of 31.71?m3 ha?1 for planted stands, whereas the model for coppiced stands produced a R 2 value of 0.82 and a RMSE of 27.70?m3 ha?1. As it is not practical or financially feasible for commercial forestry companies to carry out terrestrial enumerations for all plantations on an annual basis, the model developed in this study presents an alternative and accurate method to calculate timber volume for even-aged Eucalyptus plantations.  相似文献   

    14.
    Further study is needed on loblolly pine (Pinus taeda L.) growth in a systematic array of plantation designs or stocking rates commonly used in temperate forestry and agroforestry practices. Our objective was to determine loblolly pine growth responses and agroforestry implications of 13 plantation designs (i.e., stocking rates in trees ha−1 [TPH]) at mid-rotation (14 years old). Survival, diameter at 1.3 m above soil surface (dbh), height, basal area (BA), and volume (V) were measured in unthinned plantations ranging from 490 to 2,300 TPH. Stocking rate was positively correlated with BA (r ≥ 0.67) and V (r ≥ 0.55) and negatively correlated with survival (r ≤ −0.83) and dbh (r ≤ −0.83). Plantations with ≥2,000 TPH had closed canopies and excessively high BA and V at mid-rotation. The 4- and 5-row plantations (≥12 m alley spacing) had small dbh (≤17.5 cm). Single-row plantations with ≥3.6 m within row spacing and ≤700 TPH, and the 3-row multiple-row plantations (1,200 TPH), had acceptable BA (29.4–33.2 mha−1) and V (127–136 mha−1). Basal area was ≥30 mha−1 in most plantations indicating thinning is needed to optimize individual tree growth. Besides timber, an array of design-dependent agroforestry and forestry products should drive the selection of any one of these plantation designs: pine straw or biomass production at ≥1,800 TPH, and alley cropping or silvopasture in single-row (≤1,000 TPH) and multiple-row plantations (<1,400 TPH).  相似文献   

    15.
    Agroecosystems are not only recognized by their high capacity of carbon storage and sequestration, they could also offer an opportunity of financial benefits in the event of payment for environmental services. The present study aimed to evaluate the carbon storage and describe the structure of cashew nut plantation. Three types of cashew stand were selected according to the age of plantations; we also used savannah as a treatment witness. Carbon stocks varied according to the age of plantations; 14.51 ± 0.306 t C/ha for plantations aged 0–10 yr; 34.78 ± 0.331 t C/ha for plantations aged 10–20 yr, and 40.02 ± 0.381 t C/ha for plantations aged over 20 yr. In the witness, we found 13.05 ± 0.177 t C/ha. These values were significantly different between the studied sites (p < 0.05). The mean values of the service of carbon sequestration also varied with the age of stands; $53.5/ha/yr (0–10 yr); $63.35/ha/yr (10–20 yr); $73.95/ha/yr (over 20 yr). In regard to carbon storage, $3279 are stored in these stands. These agroecosystems are also true carbon sinks. A development plan of such agroecosystems should be considered for the conservation of the species already endangered by anthropogenic activities on natural ecosystems.  相似文献   

    16.
    Forest managers are increasingly required to enhance the productivity and profitability of plantation management while simultaneously reducing the negative ecological effects associated with forest operations. NuBalM (from Nutrient Balance Model) is presented here as a decision support tool that has the potential to assist forest managers in meeting these requirements in Pinus radiata D. Don (radiata pine) plantations. NuBalM incorporates nutrient dynamics and allocation into projections of growth, allowing management techniques to be optimised for productivity and nutrient pool retention over single or multiple rotations.NuBalM was developed using data from biomass, nutrient allocation and soil nutrient dynamics studies conducted in New Zealand radiata pine plantations. The capability of NuBalM to predict stem wood mass based on nitrogen supply and demand was tested against data from multiple trial sites established to examine the effects of variations in stocking, thinning and fertilization regimes. NuBalM satisfactorily predicted stem wood masses across a range of stand ages, with the exception of a trial examining ultra-high applications of nitrogen fertilizer. With the exclusion of the data from this trial, the predicted stem wood masses underestimated the observed figures by a mean value of 1.1 ± 1.0 t ha−1 (95% CI, n = 92).The utility of NuBalM as a tool to predict biomass allocation in radiata pine and nitrogen pools in the forest floor and soil was assessed using comprehensive biomass, nutritional and site data collected from two radiata pine trial sites subjected to differences in organic matter removal at site establishment. NuBalM performed acceptably, generating accurate estimates of stem mass (mean overestimate of 5.5 ± 7.4 t ha−1, 95% CI, n = 6) and total above ground biomass (mean overestimate of 3.1 ± 9.6 t ha−1, 95% CI, n = 6). The effects of organic matter removal and fertilization on total nitrogen pools were also predicted with a reasonable degree of accuracy (mean overestimate of 52 ± 53 kg N ha−1, 95% CI, n = 9).From these results we conclude that NuBalM can be utilised to provide projections of productivity and nitrogen pools in radiata pine plantations, and enables the effects of various management practices to be predicted with a reasonable degree of confidence.  相似文献   

    17.
    Abstract

    Quantitatively and qualitatively good Scots pine (Pinus sylvestris L.) seed years are rare in northern areas because of the short growing seasons. The seed crop size was studied in four natural pine forests in northern Finland during 1960–2004. Data on seed crop quality were collected during 1986–2004 and quality was determined by X-ray radiography. The long-term average annual seed crop of pine was 77 seeds m?2, varying from 5 to 225 seeds m?2. The expected average annual germination percentage of the seed crop was 61%, varying from 7 to 81%. General linear models were used to analyse the size and quality of the seed crop. Independent variables explained 52% of the variation in annual seed crop quality, and no proper model was found for determining the size of the seed crop; the coefficient of determination was only 5%. A combination of more than 100 seeds m?2 and an expected germination percentage of over 50% was observed once during the years 1986–2004. In most years, natural regeneration in northern Finland is difficult and often limited by the seed crop's quality as well as quantity. These results confirm the importance of seed tree cutting in abundant seed crop years to enable the natural regeneration of pine.  相似文献   

    18.
    If some suitable treatments are used plantations can be grown and established on thesoil of soda-saline-alkali with the soil condition of PH 8.5—9.6,salinity 0.1—0.3% and normalityratio of saline base Na~+/(Ca~(++)+Mg~(++))≥4.From the results of plot Inventery and tree stem ana-lysis,the increment of Poplus simonigra is highest. For 9 years,the volume can reach 100 m~3/ha,the biomass(above ground)can reach 28.7 ton/ha.Poplus simonigra grows very well on the allkinds of soda-saline-alkali soils except for the alkali spot with the worst Soil condition.So Poplussimonigra is a good tree species for planting on the Soil of soda-saline-alkali.  相似文献   

    19.
    In the north Saxon lowlands (near Torgau), effects of conversion of pure pine stands (Pinus sylvestris L.) into mixed stands by planting deciduous trees [Fagus sylvatica L. and Quercus petraea (Matt.) Liebl] were investigated on parasitoid wasps as pest antagonists. The effects of planting deciduous trees in pine stands were investigated using the strategy of space-for-time substitution including advanced plantations of beech and oak of different age classes. Wasps were captured at 4-week intervals by ground photoeclectors (GPE, n=6, 1 m2) and flight-interception traps (FIT, n=8), placed in the tree crown layer during the vegetation period (April–October) of 2000. A total of 32,479 parasitoid wasps belonging to 30 families were caught in the traps. Fifty-nine percent of individuals were representatives of families relevant as antagonists of forest insect pests: Ichneumonidae, Braconidae, Pteromalidae, Eulophidae, Mymaridae, Trichogrammatidae, and Scelionidae. Compared to the pure pine stand, individual numbers of most families of parasitoid wasps were statistically significantly higher in mixed stands with deciduous trees. The clearest promoting effects of deciduous trees on parasitoid wasps were manifested in the oldest age classes of advanced beech and oak plantations. Oak exerted stronger effects than beech. This applied especially to the tree crown layer, the stratum with the highest spatial correlation between important phytophagous pine pests and relevant parasitoids. The increased structural diversity of the stands and the broader spectrum of potential hosts are regarded as key factors for the promoting effects of advanced plantings of deciduous trees in pine stands on the community of parasitoid wasps.  相似文献   

    20.
    Historical land use and management practices in the southeastern United States have resulted in the dominance of loblolly pine (Pinus taeda L.) on many upland sites that historically were occupied by longleaf pine (Pinus palustris Mill.). There is currently much interest in restoring high quality longleaf pine habitats to such areas, but managers may also desire the retention of some existing canopy trees to meet current conservation objectives. However, fast-growing natural loblolly pine regeneration may threaten the success of artificially regenerated longleaf pine seedlings. We evaluated the establishment and growth of natural loblolly pine regeneration following different levels of timber harvest using single-tree selection (Control (uncut, residual basal area ∼16 m2/ha), MedBA (residual basal area of ∼9 m2/ha), LowBA (residual basal area of ∼6 m2/ha), and Clearcut (complete canopy removal)) and to different positions within canopy gaps (approximately 2800 m2) created by patch cutting at two ecologically distinct sites within the longleaf pine range: Fort Benning, GA in the Middle Coastal Plain and Camp Lejeune, NC in the Lower Coastal Plain. The density of loblolly pine seedlings was much higher at Camp Lejeune than at Fort Benning at the end of the first growing season after harvesting. Following two growing seasons, there were no significant effects of canopy density or gap position on the density of loblolly pine seedlings at either site, but loblolly pine seedlings were taller on treatments with greater canopy removal. Prescribed fires applied following the second growing season killed 70.6% of loblolly pine seedlings at Fort Benning and 64.3% of seedlings at Camp Lejeune. Loblolly pine seedlings were generally less than 2 m tall, and completeness of the prescribed burns appeared more important for determining seedling survival than seedling size. Silvicultural treatments that include canopy removal, such as patch cutting or clearcuts, will increase loblolly pine seedling growth and shorten the window of opportunity for control with prescribed fire. Therefore, application of prescribed fire every 2-3 years will be critical for control of loblolly pine regeneration during restoration of longleaf pine in existing loblolly pine stands.  相似文献   

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