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1.
When combining pines and cattle on tame pasture, grazing is often delayed for several years until trees are large enough to resist injury. As an alternative approach to delayed or deferred grazing during the early years, this study in central Louisiana, USA, examined the effects of cattle grazing in subterranean clover (Trifolium subterraneum L.) pastures on slash (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) seeding survival and growth during the first 3 years of tree establishment. Pines were planted at about 1200 trees/ha in 3 rows on 0.4-ha subclover units with 1.3 m spacing within rows. Three grazing treatments included: (1) ungrazed pines, (2) limited grazing with a single-wire electric fence above the planted pines, and (3) grazed pines. Thirty Brahman crossbred cows with calves and a bull grazed the tame pasture on a controlled grazing, rotational basis from December through May each year, during the subterranean clover growing season. Pine trampling injury during the year was 8% on the grazed seedlings while essentially none occured under limited grazing. During the first 2 growing seasons, survival and height of the pines were significantly less on the grazed seedlings than on either the limited grazing or ungrazed seedlings. Pine heights from the limited grazing and ungrazed treatments were not different during the 3-year study; loblolly pine heights from the limited grazing treatment continued to be taller than the grazed treatment through the third year while the slash pine heights were similar for all treatments by the third year. Seedling mortality became more acute as severity of grazing injury increased; the greatest mortality occured when the terminal bud and needles were both browsed off.  相似文献   

2.
The total area ofPinus densiflora andP. thunbergii forests in Ibaraki Prefecture in 1978 was 65,200 ha, which decreased to 30,300 ha by 1985 mainly due to pine wilt mortality caused byBursaphelenchus xylophilus. This damage has also continued thereafter. To estimate the survivability of pine trees in Ibaraki Prefecture, pine tree mortality has been studied in eight experimental forests for over 20 years, and ground surveys throughout the Prefecture were also conducted in 1995. Survival in the experimental forests corresponded well to the results of ground surveys. Pine forests remained as pure stands if control measures were undertaken or if they were located in cool areas. In warm areas where no control was undertaken, most of the pine forests disappeared and only a few pine trees remained in mixed forests, while on dry soils no mature or old pine trees survived. Since surviving pine forests are often cut for wood utilization,P. densiflora andP. thunbergii may decrease in area to become rare species in the future unless controls are applied and/or reforestation with resistant pines is carried out. A part of this paper was orally presented at the 108th Annual Meeting of the Japanese Forestry Society (1997).  相似文献   

3.
Annual ryegrass (Lolium multiflorum Lam.) and cereal rye (Secale cereale L.) pastures can extend the grazing season in the lower Midwest. There is little data from this region on the productivity of these forages in a silvopasture system. Our objective was to determine the forage and livestock production from annual ryegrass/cereal rye in a silvopasture versus an open (non-forested) system. This study was conducted near New Franklin, MO, USA. The treatments were (1) annual ryegrass/cereal rye planted into a 6- to 7-year-old stand of pitch pine (Pinus rigida Mill.) × loblolly pine (Pinus taeda L.) hybrids and black walnut (Juglans nigra L.) (TREE treatment) and (2) the same forages planted into pastures without trees (OPEN treatment). Marshall annual ryegrass and cereal rye were no-till seeded at 22 and 67 kg ha-1 of pure live seed, respectively, on 18 September 2000 and 30 August 2001. Treatments were replicated three times in a randomized complete block. In March 2001 and 2002, three beef heifers were assigned to each pasture and rotationally grazed until early June. Cumulative forage production and quality were measured for each treatment. Cumulative forage production in the TREE treatment was reduced by approximately 20% compared to the OPEN treatment. However, beef heifer average daily gain and gain ha-1 were equal for both treatments. Beef producers using a annual ryegrass/cereal rye in a silvopasture system likely would not sacrifice livestock production when hybrid pine and black walnut trees are 6- to 7-year-old when compared to an open pasture. Contribution of the Missouri Agricultural Experiment Station and the University of Missouri Center for Agroforestry. This work was funded through the University of Missouri Center for Agroforestry under cooperative agreements AG-02100251 with the ARS and CR 826704-01-0 with the US EPA. The results presented are the sole responsibility of the authors and/or the University of Missouri and may not represent the policies or positions of the ARS or EPA.  相似文献   

4.
Silvopastoral systems offer an alternative to the conventional cow-calf segment of the beef industry in the Midwestern region of the United States. Little information exists for transitioning from a conventional pasture-based beef operation to a silvopastoral system utilizing multiple deciduous tree species. Nine pastures approximately 1 ha in size were established with a mixture of cool-season grasses and legumes to investigate tree protection methods and cattle performance. Four tree species (Juglans nigra, Gleditsia triacanthos, Quercus rubra, & Carya illinoensis) were planted within six of these pastures. Three methods of protection were tested, and included a no protection control (Con), foliar application of 0.20% denatonium benzoate (TreeGuard™), or a single strand of electrified poly-wire (EF) in each of the two grazing years. Cattle damage to young trees was prominent during the two years for Con and TreeGuard™. EF offered acceptable protection. Red oak trees suffered the highest degree of damage from livestock. Establishing trees within grazed pastures did not hinder performance of beef cattle. Transitioning from conventional pastures to silvopastures can be accelerated utilizing an electrified fencing system to prevent cattle damage. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

5.
Agroforestry research in central Louisiana, USA, examined the effects of agronomic cultural treatments (disk, chemical, hay, and hay-graze) on subterranean clover (Trifolium subterraneum L.) yields and slash pine (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) survival and growth. Cultural treatments appear necessary for successful production of subterranean clover in tame pastures, especially for early fall forage growth. Subterranean clover yields in volunteer swards during spring were highest on the disk and chemical treatments. Generally, pine survival and growth during the first 5 years following tree establishment were not affected by cultural treatments.  相似文献   

6.
Planting slash pine in a dense pasture sod   总被引：1，自引：1，他引：0  
Recommendations for planting pines usually include providing a competition-free site to assure establishment and good early growth. When combining pines and pasture in agroforestry systems, the possibility of planting pines directly into a pasture sod without site treatment would be economically desirable. In south Georgia, USA, slash pine (Pinus elliottii) was planted into a pasture sod and on well-disked sites; both with and without annual fertilization. Partial weed control was maintained in subsequent years on the cultivated treatments and the pasture sod was mowed periodically.Slash pine establishment and growth rate through 5 years generally was not different among treatments. Survival was 96% intially and 86% after 5 years. The pines grew rapidly with no measurable advantage from cultivation or fertilization.This alternative to providing a competition-free environment needs to be tested under differing climates, soils, tree species, and pasture species. It could be a suitable technique in various situations and of special interest to small, nonindustrial landowners.Cooperative study between the Coastal Plain Experiment Station, University of Georgia, and USDA Forest Service, Tifton, GA 31794, USA.  相似文献   

7.
There is interest in producing alfalfa as an alley crop because alfalfa (Medicago sativa L.) is the most profitable hay crop in the USA. Field experiments were conducted near Stockton, MO in 2003 and 2004. Treatments consisted of alfalfa grown in open plots and in plots that were alley cropped between 20-year-old black walnut trees (Juglans nigra L.) planted in rows 24.4- and 12.2-m apart. Alfalfa was sampled for three harvest cycles each year. In the alley-cropping plots, samples were taken beneath the canopy (2.5 m from the tree row) and in the center of the alleys. Data were taken on dry-matter yield, maturity, and forage quality. At all harvest dates over both years, yields from beneath the canopy of both alleys and the narrow alley centers were less than yields from the wide alley centers and open plots. Yield from the wide alley centers was similar to that in open plots in every harvest but the final harvest of 2004. Transects across the plots indicated that yields increased linearly from the tree row to the center of both alleys. Alfalfa tended to mature faster in the open and wide alley centers compared to beneath the canopy of both alleys and the narrow alley centers. Forage quality differences were inconsistent across treatments. Alfalfa yield was significantly reduced and maturity was delayed by the narrow 12.2 m tree spacing, but yield was not reduced in the centers of the wider 24.4 m alleyways.  相似文献   

8.
In Fennoscandia, young stands of Scots pine (Pinus sylvestris L.) are intensively used by moose (Alces alces L.) during winter. We studied whether forage amounts on high-cut pines in high-stump commercial thinning influenced browsing intensity and damage incidence on retained (i.e. uncut) pine stems. High-cut pines were browsed, but to a lesser extent than retained pines. At a scale corresponding to individual feeding sites (≈40 m2), browsing intensity on retained pines was not influenced by the amount of forage on high-cut pines but was positively related to moose pellet group counts. The incidence of lower-height damage (stem breakage and bark stripping) was positively related to the amount of forage on high-cut pines, whereas higher damage (leader shoot browsing) was not. Overall browsing damage incidence on retained pines was positively related to the density of deciduous trees and negatively related to the amount of forage on retained pines. Our results suggest that although high-stump thinning supplies additional food resources for moose, larger amounts of forage on high-cut pines may increase the risk for bark stripping and stem breakage on retained trees. Further research is needed at larger spatial scales to assess the feasibility of high-stump thinning as a damage mitigation measure.  相似文献   

9.
The role of herbivores in controlling plant population abundance and distribution is unclear. We experimentally determine the effect of damage by wild boars (Sus scrofa) in recruitment rate and spatial pattern of a Mediterranean tree, the holm oak (Quercus ilex). We monitored oak establishment in the Sierra Nevada of southeastern Spain during 4 years (1999–2002) in four plots, two fenced and two unfenced that were used as controls. In addition, we planted 1-year-old seedlings in all microhabitats, both in fenced and control plots, to experimentally determine the effect of wild boar on their microhabitat-dependent survival. Despite seedling abundance being similar inside and outside the fences, sapling abundance diminished up to 50% in unfenced plots compared to fenced plots. Wild boars also seemed to modify the spatial distribution of seedlings and saplings. Whereas seedlings were most abundant under pines both in fenced and control plots, sapling abundance was highest under pine trees in fenced plots, but similarly abundant under pines or shrubs in control plots. This change in spatial pattern was due to the effect of wild boars killing seedlings when looking for food under pines. The effects of the different mortality factors were not additive. Where ungulates are absent, recruitment is high and occurs under oaks and especially under pines. Where wild boars are present, recruitment diminishes and occurs mostly under shrubs and pines. Wild boars arrest population growth and modify the spatial pattern of recruitment.  相似文献   

10.
Small Appalachian hill farms may benefit economically by expanding grazing lands into some of their under-utilized forested acreages. Our objective was to study the forage production potential of forest to silvopasture conversion. We thinned a white oak dominated mature second growth forested area establishing two orchardgrass-perennial ryegrass-white clover silvopasture replications for comparison with two nearby open pasture replications. After thinning trees, silvopastures were limed, fertilized and seeded. Sheep were fed hay and corn scattered across the area to facilitate removal of residual understory vegetation, disruption of litter layer and incorporation of applied materials into surface soil. Each area was divided into multiple paddocks and rotationally grazed by sheep. Two 1 m2 herbage mass samples were taken from each paddock prior to animal grazing. There was no significant difference in soil moisture between silvopastures and open pastures however, there was adequate rainfall to prevent drought all 3 years. The two silvopastures received 42 and 51% of total daily incident PAR compared to the open field. Total dry forage mass yield from open pasture over the 3 years averaged 11,200 kg ha−1 y−1 and from silvopasture 6,640 kg ha−1 y−1. Silvopastures, however, had a higher PAR use efficiency (PARUE) than open pasture. Hill farms could increase grazing acreages without sacrificing all benefits from trees on the landscape by converting some areas to silvopasture.  相似文献   

11.
On two silt loam flatwoods in Louisiana, use of mounds as planting sites for slash pine (Pinus elliottii Engelm. var. elliottii) was shown to be more effective than planting without mounds (untreated control) after six growing seasons in the field. Mounds formed were of two sizes: low mounds made of 550 dm3 of soil and high mounds made of 1,000 dm3 of soil. One site was in central Louisiana and had two drainage classes: a somewhat poorly drained Caddo-Messer complex and a poorly drained Caddo soil. On both drainage classes, pine survival was not affected by treatment, but the incidence of fusiform rust galls on the main stem (caused by Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme Burdsall and Snow) was greater on trees planted on mounds. The second site was a poorly drained Caddo soil in southwestern Louisiana. At this site, there were fewer surviving pines on controls than on mounds, but the incidence of rust galls was not affected by treatment. At both sites, pines were taller and had a greater mean diameter at breast height on mounds than on controls. Mound size did not influence tree size at either site.  相似文献   

12.
Forage and wood yield of Acacia cyanophylla, also known as Acacia saligna, was studied in a 300–400 mm precipitation zone in Tunisia. Yields were measured during and after drought. This short (2–8 m) evergreen leguminous tree is used as a forage drought reserve in frost free regions where mean annual precipitation exceeds 250 mm. The standing crop of leafy forage builds up year after year for at least four years or until the tree is cut. It rapidly regrows after cutting from coppice shoots. The leaves provide high protein forage for sheep and goats during the long dry summer season typical of the Mediterranean climate as well as emergency forage during drought. The tree is used to stabilize moving sand dunes, and as a windbreak to protect cropland. It also provides fuelwood and increasaes soil nitrogen by fixation. The need for supplemental irrigation during establishment is a major constraint. Research in the 350 mm precipitation zone of Tunisia found 3.2 year old trees to yield over 1400 kg of forage standing crop per hectare after a severe drought. Trees harvested at 2.5 years of age in May, during the worst drought in over 30 years, yielded a standing forage crop of 724 kg per hectare. Forage regrowth 8 months after cutting and 4 months after rains returned was 700 kg/ha. The forage standing crop for trees harvested only once during the 3.2 year period was double the amount of forage regrowth from trees harvested the previous year, but mean annual forage yield similar. This demonstrates that it is possible for forage to be conserved as a living forage reserve for later use during drought. Total wood yield was only 1621 kg/ha for trees cut twice compared to 3683 kg/ha for trees cut only once. Annual cutting will substantially reduce the amount of forage available during drought and reduce the production of fuelwood. It may also reduce the vigor, productivity and life of the tree. Acacia cyanophylla alley cropped on cereal farmland can protect the soil from erosion, protect the associated crop from wind damage, fix nitrogen, provide fuelwood and provide a reserve of high quality forage for use during drought. This work was supported by the Government of Tunisia and the U.S.A.I.D. Tunisia Range Development and Management Project (664-0312.8).  相似文献   

13.
Pathophysiological changes during the symptom development of pine wilt disease are reconsidered from recent investigations. The symptom development is divided into two stages: the early and the advanced stages. In the early stage, small number of nematodes migrate in cortex, then in xylem of the stem, and induce denaturation and necrosis of parenchyma cells. These changes in parenchyma are regarded as defense reactions of pines which result in terpene synthesis in xylem cells and embolism in tracheids. Such changes in the early stage can be induced in both susceptible and resistant pine species by either virulent or avirulent isolates of pinewood nematode (Bursaphelenchus xylophilus), or byB. mucronatus. No change occur in physiological status of leaves, and nematode reproduction is suppressed during this stage. Pine trees can survive if symptom does not progress from this stage. The symptoms of the advanced stage usually occur only in susceptible pines infected by virulent nematode isolates. At the beginning of the advanced stage, enhanced ethylene production by stem which coincides with cambial destruction occurs, and results in embolism of the outermost xylem in the portion. The embolism causes decrease in leaf water potential and cessation of photosynthesis. After cessation of photosynthesis, symptoms develop drastically with a burst of nematode population. There seems to be some unknown mechanism which suppress nematode reproduction and invasion to the cambial zone. This mechanism is thought to be photosynthesis-dependent, so that in photosynthesis-decrased conditions, even avirulent nematodes can multiply and invade cambium to induce tree death. Water stress in hot and dry summer should accelerates symptom development from the early to the advanced stage through such decrease of photosynthesis-dependent “cambial resistance”.  相似文献   

14.
Honey locust (Gleditsia triacanthos), black locust (Robinia pseudoacacia), and honey mesquite (Prosopis glandulosa) are warm season forage trees with potential to efficiently share site resources with cool season pasture plants in Pacific Northwest silvopastures. Establishment of hardwood trees can be difficult, however, because of feeding damage from wildlife and livestock. This study compared establishment and growth of trees planted in 88 cm tall solid plastic shelter tubes to 88 cm tall plastic mesh tubes, used to protect trees from animal damage. Three replications were established in May 1995 for each of the three tree species on a hill pasture near Corvallis, Oregon. Initial tree survival during the first summer and winter following planting was higher in shelter tubes than in mesh tubes. At the end of the third growing season, 58% of black locust and 94% of honey locust trees in shelter tubes were still alive compared to only 14% of black locust and 47% of honey locust in mesh tubes. Few honey mesquite trees survived regardless of tube type used. Average three-year total height growth for black locust was increased by 650% and basal diameter growth by 380% within shelter tubes, while honey locust height growth was increased by 300% and diameter growth was increased by 150% compared to trees in mesh tubes. However, shelter tube trees tended to be taller relative to their diameter and had difficulty standing upright if tubes were removed. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

15.
Trees and shrubs as sources of fodder in Australia   总被引：2，自引：0，他引：2  
Experience with browse plants in Australia is briefly reviewed in terms of their forage value to animals, their economic value to the landholder and their ecological contribution to landscape stability. Of the cultivated species only two have achieved any degree of commercial acceptance (Leucaena leucocephala and Chamaecytisus palmensis). Both of these are of sufficiently high forage value to be used as the sole source of feed during seasonal periods of nutritional shortage. Both are also leguminous shrubs that establish readily from seed. It is suggested that a limitation in their present use is the reliance on stands of single species which leaves these grazing systems vulnerable to disease and insects. Grazing systems so far developed for high production and persistence of cultivated species involve short periods of intense grazing followed by long periods of recovery. Similar management may be necessary in the arid and semi-arid rangelands where palatable browse species are in decline.  相似文献   

16.
Soil drainage characteristics in winter and the heights and diameters of 10-year-old loblolly and slash pines (Pinus taeda L. and P. elliottii Engelm. var. elliottii) were measured on three poorly-drained silt loam sites that had been bedded, furrowed, or disked before planting. Quadratic response functions were used to determine the relationship between depth to water table or volume of drained soil in winter and mean tree height or diameter. These quadratic response functions (species × height or diameter: drainage characteristics) showed that diameter and height were significantly related to soil drainage in winter on these silt loams soils. Slash pines grew better than loblolly pines under more poorly drained conditions while loblolly pines grew better under the better drained conditions. On unbedded silt loams, the soil drainage in winter needed to maximize tree height was 42 cm for loblolly and 49 cm for slash pine. Pines planted on beds did not generally grow better than those on flat-disked plots because where bedding would be most benefical the practice did not form enough additional drainage to significantly influence pine development.  相似文献   

17.
Abstract

The effect of different cleaning treatments on moose (Alces alces L.) damage to Scots pines (Pinus sylvestris L.) was examined using a generalized linear mixed model (GLMM) with a binomial response (logit-link function). The treatments were the following: no cleaning, point-cleaning of broadleaves (mainly birch, Betula pendula Roth and B. pubescens Ehrh.) within a radius of 1 m from the pine, point-cleaning delayed 2 years, topping of competing broadleaves (main stem cut at a height of 1.3 m) and total cleaning of broadleaves. A randomized complete block design with three replicates was established in three planted pine stands (mean height of pines 1.5 m). Measurements taken four growing seasons later (mean height of pines 3.5 m) showed that all cleaning treatments reduced moose damage, although the difference was not significant (p=0.078) in the case of topping. The proportion of damaged pines was predicted as a function of the characteristics of pines and broadleaves in two untreated, planted pine stands with a height of 3 m. Within these untreated stands the number of damaged pines increased in plots with a higher number of broadleaves and taller broadleaves. In conclusion, the results show that on relatively fertile growing sites of pine cleaning treatments reduced moose damage on pine. It is recommended that cleaning is performed before broadleaved trees occur as overgrowth above pines.  相似文献   

18.
Haywood  James D. 《New Forests》2000,19(3):279-290
Herbaceous plant control with mulchor hexazinone herbicide influenced planted longleafpine (Pinus palustris Mill.) seedling totalheight on a silt loam site in central Louisiana. Thesite had been sheared and windrowed in 1991 and rotarymowed before three treatments were established in arandomized complete block design: (1) Untreatedcheck: no herbaceous plant control after planting;(2) Five mulches: on each plot, five randomlyassigned mulches were placed around seedlings; themulches were either a mat of cotton, hemlock andpolyester, pine straw, woven polypropylene, orperforated polyethylene; and (3) Hexazinone: theherbicide hexazinone at 1.12 kg active ingredient/hawas annually sprayed in the first two growing seasonsover the rows of unshielded seedlings. The longleafseedlings were planted in February 1993.After three growing seasons, seedlings on the mulchand hexazinone treatments were taller than those onthe check plots. About 59% of the mulched andhexazinone treated seedlings had grown out of thegrass stage (at least 12 cm tall) compared to 17% ofthe check seedlings. After five growing seasons, thepercentage of longleaf pine seedlings out of the grassstage was similar on all treatments and averaged 87%. However, these better growing pines were taller on themulch and hexazinone treatments (a 142-cm average)than on the checks (78 cm). Pine straw was anineffective mulch probably because the straw smotheredthe seedlings. The longleaf saplings were tallestwhen the perforated polyethylene mat was used.  相似文献   

19.
Extensive cattle production currently occupies more than 27% of the rural landscapes in Latin America, and continues to expand. This activity, deeply rooted in the culture and rural economy of the region, requires an urgent transformation if it is to become both more efficient and environmentally friendly. Silvopastoral systems that incorporate native trees and shrubs are instrumental for the productive rehabilitation of cattle production and for biodiversity conservation in agricultural landscapes. We discuss research progress and adoption of intensive silvopastoral systems in Colombia and Mexico. Intensive silvopastoral systems (ISS) are a sustainable form of agroforestry for livestock production that combines fodder shrubs planted at high densities (more than 10,000 plants ha−1), trees and palms, and improved pastures. High stocking and the natural production of milk and meat in these systems are achieved through rotational grazing with electric fencing and a permanent supply of water for the cattle. While milk and meat production and cattle reproduction are enhanced, production costs decline as external inputs are replaced by natural processes related to fertility and biological control. We also discuss the importance of the ISS with native trees for climate change adaptation and mitigation, the barriers for their adoption, and how these have been successfully addressed using payment for environmental services, special credits and technical assistance. Finally, we highlight the need for enhancing landscape connectivity by integrating SPS to conservation corridors with native species to promote biodiversity conservation and other environmental services demanded by society.  相似文献   

20.
The objective of this study was to compare the survival and volume of conifer stands at 26 years of age with their status at planting. Survival, growth and damage were studied in eight clear felled stands regenerated in 1972. Five of the areas were planted with Norway spruce (Picea abies (L.) Karst.) and three with Scots pine (Pinus sylvestris L.). The plantings were examined in 1972 and 1974. In 1974, the number of living undamaged planted seedlings was low (10–15%). However, the number of undamaged seedlings was supplemented by naturally regenerated conifer and birch seedlings. The total number of undamaged seedling in 1974 was equivalent to 20–30% of the number of seedlings planted. In 1998, the main species in three stands had changed from Norway spruce to Scots pine, and in one stand from Norway spruce to birches. Actual volume in 1998 for the stands was compared to stand volume generate according to five scenarios based on recommended and actual seedling number in 1972 and 1974. The actual volume was 64% of that expected if the recommended number of trees had been planted. Naturally regenerated Scots pine and Norway spruce increased stand density in 1998. The actual volume was 37% higher than the average volume in the surrounding county. On average, 36% of the trees were damaged. More than 50% of the total damage was caused by moose (Alces alces L.). For Scots pine, moose or other browsing animals damaged 30% of the trees. The results of this study indicate that the 1998 volume was higher than expected, considering the low number of undamaged seedlings in 1974. This was mainly due to the large amount of naturally regenerated plants. In addition, the results indicate that the volume could have been higher if the initial conditions had been better. Despite the low number of undamaged seedlings in 1974, seven of the eight studied stands produced a higher volume than the average stand for the region. In practise, high numbers of seedlings should be planted on scarified areas. In most cases there will be a supply of naturally regenerated seedlings.  相似文献   

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