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1.
The cultivation of ornamentals to produce woody floral products—the fresh or dried stems that are used for decorative purposes—may
be an attractive option for southeastern landowners looking to generate income from small landholdings. Since many shrubs
native to the understory of the longleaf pine (Pinus palustris Mill.) ecosystem have market potential, one possibility is the intercropping of select species in the between-row spacing
of young longleaf pine plantations. The objective of this study was to evaluate how interspecific competition affects the
fate of 15N fertilizer when American beautyberry (Callicarpa americana L.), wax myrtle (Morella cerifera (L.) Small) and inkberry (Ilex glabra (L.) A.Gray) are intercropped with longleaf pine. Nitrogen derived from fertilizer (NDF), utilization of fertilizer N (UFN)
and recovery of fertilizer N (RFNsoil) were compared between agroforestry and monoculture (treeless) treatments to assess the effects of competition. Results varied
by species, with NDF being higher for C. americana foliage and lower for all M. cerifera tissues in the agroforestry treatment. No effect was observed for I. glabra. UFN was lower for all species in the agroforestry treatment. RFNsoil was higher in the agroforestry treatment for I. glabra, but no treatment effects were observed for C. americana or M. cerifera. Overall, while it is clear that interspecific competition was present in the agroforestry treatment, the inefficiency of
fertilizer use suggests that nitrogen was not the most limiting resource. Management interventions, particularly those that
address competition for water, will likely be critical to the success of this system. 相似文献
2.
Economics of intercropping loblolly pine and switchgrass for bioenergy markets in the southeastern United States 总被引：1，自引：1，他引：0
Andres Susaeta Pankaj Lal Janaki Alavalapati Evan Mercer Douglas Carter 《Agroforestry Systems》2012,86(2):287-298
The main objective of this study was to assess the economics of alley cropping of loblolly pine (Pinus taeda L.) and switchgrass (Panicum virgatum) in the southern United States. Assuming a price range of switchgrass between $15 and $50?Mg?1 and yield of 12?Mg?ha?1 year?1, we investigated the effect of switchgrass production on the optimal forest management for loblolly pine stands under different stumpage prices. We considered the following potential scenarios: no competition between species for resources; reduced loblolly pine productivity due to competition with switchgrass; and reduced productivity of both species due to competition for nutrients, water and light. Findings also suggested that the optimal system would depend on the competitive interactions between switchgrass and loblolly pine crops, and the expected prices for each crop. Loblolly pine monoculture would be the most profitable option for landowners compared to intercropping systems with switchgrass below $30?Mg?1. However, when switchgrass prices are ??$30?Mg?1, landowners would be financially better off adopting intercropping if competitive interaction between crops were minimal. In order to realize higher economic returns for intercropping system, forest landowners must make some efforts in order to diminish the decline of productivity. 相似文献
3.
A study was conducted in northwest Florida, USA, to investigate root development and morphology of cotton (Gossypium hirsutum L.) under pecan (Carya illinoensis K. Koch) trees in an alleycropping experiment. Root:shoot ratio, root biomass, total root length and root length density
were examined under three treatments: (1) barrier (separating belowground interspecific competition by trenching to a depth
of 120 cm and installing polyethylene barrier), (2) non-barrier (root systems were free to interact), and (3) monoculture
of cotton (without above and belowground interspecific competition with trees). Results indicated that plants in the barrier
and non-barrier treatments had lower root:shoot ratios compared to the monoculture treatment. Belowground competition for
resources between pecan and cotton in the non-barrier treatment resulted in 25 and 33% reduction of total root length (359 cm)
when compared to that of the barrier (477 cm) and monoculture (539 cm) treatments, respectively. The non-barrier plants also
exhibited the lowest root length density. Specific root length was highest for the monoculture (179 cm g−1) and lowest for the non-barrier treatment (146 cm g−1) with the barrier treatment being intermediate (165 cm g−1). Interspecific competition with pecan significantly altered root development and morphology of cotton plants. Research in
agroforestry should take into account the developmental differences in root systems of the associated crop species so that
better models incorporating nutrient and water uptake can be developed. 相似文献
4.
Jānis Liepiņš Andis Lazdiņš Kaspars Liepiņš 《Scandinavian Journal of Forest Research》2018,33(1):58-70
This study aims to derive allometric functions to estimate the above- and belowground biomass components of the most important tree species in Latvia. The study material included a total of 81 Norway spruce (Picea abies [L.] Karst), 102 Scots pine (Pinus sylvestris L.), 105 birch spp. (mainly silver birch (Betula pendula Roth)) and 84 European aspen (Populus tremula L.) trees sampled in 124 forest stands. The suitability of three mathematical models for the prediction of total aboveground biomass, stem biomass, total live and dead branch biomass, belowground biomass and small root biomass was evaluated. Our analysis revealed that the use of the Intergovernmental Panel on Climate Change mean default values for the root-to-shoot ratio recommended for temperate and boreal ecological zones leads to the overestimation of root biomass of young trees, especially Scots pine and Norway spruce. Our findings indicate that biomass functions recommended for other Baltic Sea countries are not appropriate for the assessment of the biomass stock in Latvia’s forests because these lead to biased estimates. The biomass functions derived in our study are recommended for reporting the biomass stock in Latvia. 相似文献
5.
We evaluated effects of belowground competition on morphology of naturally established coast Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) saplings in 60- to 80-year-old thinned Douglas-fir stands in southwestern Washington. We separately quantified
belowground competition from overstory and understory sources using trenching and understory removal. In this light-limited
environment of 26 ± 16% (std. dev.) full sunlight, 2-year exclusion of tree root competition by trenching increased sapling
stem biomass by 18%, total aboveground biomass by 21%, number of interwhorl buds by 68%, total foliar biomass by 33%, and
foliar biomass on branch components over 4 years old by 143%. Belowground competition did not influence shoot:root ratio or
foliar efficiency (i.e., stem growth per unit foliage biomass). Sapling needle size, specific leaf area, and internodal distance
also were not affected by belowground competition; these variables were apparently a function of the low-light environment.
The principal source of belowground competition was roots of overstory trees; effects of belowground competition from understory
vegetation were minor. Thus, under a partial overstory, morphology of Douglas-fir regeneration was influenced by both belowground
and aboveground competition from overstory trees. In this environment, understory vegetation control would not likely influence
belowground competition to an extent that would affect sapling morphology. 相似文献
6.
Trade-offs analysis for possible timber-based agroforestry scenarios using native trees in the Philippines 总被引：3，自引：2，他引：1
To assess possible new agroforestry scenarios the tree–soil–crop interaction model in agroforestry systems (WaNuLCAS 3.01)
was used based on-site specific data collected from Tabango (Central Philippines). Three native timber trees (Shorea contorta Vid., Pterocarpus indicus Juss., and Vitex parviflora Willd.) and one widely spread exotic specie (Swietenia macrophylla King.) were simulated under different intercrop scenarios with maize (Zea mays L.) and subsequently compared. Model simulation results quantified and explained trade-off between tree and crop. For example,
higher tree densities will lead to a loss of crop yield that is approximately proportional to the gain in wood volume. However,
beside this trade-off effect, there is considerable scope for tree intercropping advantage under a fertilization scenario,
with systems that yield about 50% of the maximum tree biomass still allowing 70% of monoculture maize yield. Maximum tree
yield can still be obtained at about 20% of the potential crop yield but intermediate tree population densities (400 trees ha−1) and the resulting larger stem diameters may be preferable over the larger total tree biomass obtained at higher tree densities.
Another advantage from intercropping systems is that trees directly benefit from the inputs (i.e., fertilizer) that are applied
to the crops. The three native trees species studied have different performance in relation to productivity but are similar
to (or even better than) S. macrophylla. 相似文献
7.
In Minas Gerais, Brazil, Eucalyptus plantation agroforestry techniques for small farms appear to be an adequate alternative to small-scale plantations, and by integrating timber and food production, they can meet local demands for aliment and wood. Intercropping of Eucalyptus camaldulensis with rice and beans was studied to compare yields of intercropping and monocultures over 2 years. In the first year, no differences were found in the productivity between the intercropped and monoculture systems of E. camaldulensis, rice and beans in both seasons. In the second year, E. camaldulensis in monoculture showed the lowest productivity. If compared with E. camaldulensis intercropped with agricultural crops, during the rainy season, beans intercropped with E. camaldulensis showed similar productivity when compared to monoculture. In the dry season, the productivity of beans in monoculture was higher than intercropping. In the second year, rice productivity was very low for both systems due to the lack of precipitation during the fructification phase. The equivalence area index (EAI) confirmed the advantages of the intercropping system over the monoculture system for E. camaldulensis and beans and rice, at least in the first 2 years. 相似文献
8.
The survival of bare-root and container-grown loblolly pine (Pinus taeda L.) seedlings exceeded 90% when outplanted in March at two sites in Lee County, Alabama. At both sites, soil moisture and seedling survival were greater in March than in May. A March herbicide application reduced weed biomass by 75–80% at both sites. At the moist site, herbicide application did not affect survival. However, at the drier site, a reduction in weed biomass increased both the percent soil moisture and the survival of May-planted bare-root seedlings. When soil moisture at planting time was less than 13% on a dry weight basis container-grown seedlings survived better than bare-root seedlings. At both sites, reduced weed competition resulted in greater seedling heights and diameters.Alabama Experiment Station Journal Series No. 9-85802. 相似文献
9.
S. M. Gathumbi 《Agroforestry Systems》2004,60(3):233-237
Accurate quantitative assessment of roots is key to understanding the belowground plant productivity as well as providing
an insight of the plant-soil interactions. In this study, root recoveries by sieves of different mesh sizes (2.0, 1.0, 0.5
and 0.25 mm) were measured for five tropical tree and shrub species grown in monoculture stands: crotalaria (Crotalaria grahamiana Wight and Arn.), pigeonpea [Cajanus cajan (L.) Millsp.], sesbania [Sesbania sesban (L.) Merr.], tephrosia (Tephrosia vogelii Hook F.), siratro [Macroptilium atropurpureum (DC.) Urb.] and tithonia [Tithonia diversifolia (Hemsl.) Gray]. Root samples were take from 0-15 cm soil depth. Recovery of coarser roots (>1.0 mm) ranged from 70 to 93%
and 90 to 98% of the cumulative root length and biomass respectively. The proportion of root length of the finer roots (<1.0
mm) was greater for pigeonpea (30%), tithonia (22%) and siratro (18%) compared with other species, but contributed negligibly
to the cumulative total root biomass for all species. The use of 0.5 mm sieve improved the recovery of root length for most
species but had little effect on root biomass. The 0.25 mm sieve was most effective in capturing finer roots (<0.5 mm) of
pigeonpea which represented 16% of cumulative root length and 4% of root biomass recorded for this species. Recovery of roots
of different diameter classes depended on species, suggesting that for an improved estimation of root parameters especially
when sieves of large mesh sizes (>0.25 mm) are used, a correction factor could be useful for root length measurements but
not root biomass measurements for a particular species in each site and for a specific study.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Belowground competition in a broad-leaved temperate mixed forest: pattern analysis and experiments in a four-species stand 总被引：1，自引：0，他引：1
We investigated fine root biomass and distribution patterns in a species-rich temperate Carpinus–Quercus–Fagus–Tilia forest and searched for experimental evidence of symmetry or asymmetry in belowground competition. We conducted extensive
root coring and applied the recently introduced in situ-root growth chamber technique for quantifying fine root growth under
experimentally altered intra- and interspecific root neighbourhoods in the intact stand. In 75% of all soil cores, fine roots
of more than two tree species were present indicating a broad overlap of the root systems of neighbouring trees. Quercus trees had more than ten times less fine root biomass in relation to aboveground biomass or productivity (stem growth) and
a much higher leaf area index/root area index ratio than Carpinus, Fagus and Tilia trees. The root growth chamber experiments indicated a high belowground competitive ability of Fagus in interspecific interactions, but a low one of Quercus. We conclude that (1) interspecific root competition is ubiquitous in this mixed stand, (2) root competition between trees
can be clearly asymmetric, and (3) tree species may be ranked according to their belowground competitive ability. Fagus was found to be the most successful species in belowground competition which matches with its superiority in aboveground
competition in this forest community. 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(2):138-146
New silvicultural regimes with high within-stand competition require new functions for estimation of standing stock and growth of biomass components, since the allometry of trees is changed by light competition. This paper presents functions for estimation of the aboveground biomass dry weights for stem wood, stem bark, branches and leaves of young (diameter at breast height <10 cm) Scots pine (Pinus sylvestris L.), Norway spruce [Picea abies (L.) Karst.] and birch (Betula pendula Roth. and Betula pubescens Ehrh.) trees growing in dense mixed stands. The functions were derived from a sample consisting of 84 Scots pine, 43 Norway spruce and 66 birch trees from six stands in northern Sweden with high stand densities (>10000 st ha-1). The logarithmically transformed power function displayed a good ability to stabilize the variance of dry weights and showed a good fit to the material (0.37< R 2 <0.99). A comparison with the most commonly used biomass functions in Sweden today showed that they overestimated the weight of stem wood and branches, while the weight of foliage was underestimated. The nature of these discrepancies suggested that the precision of biomass estimations might also be improved for young trees at wider spacing. 相似文献
12.
采用分层挖掘法,对株行距为3 m×8 m的核桃-决明子复合模式中的根生物量、总根长密度、吸收根的根长密度和根系直径等进行了调查。结果表明：核桃单作的总根长密度比核桃间作的高7%左右,且在各个土层中吸收根的根长密度都高于核桃间作,而二者的总根生物量和根系直径则差异较小。决明子单作的根系直径比间作决明子的大27.73%,但二者的根长密度和根生物量则差异不大。在核桃-决明子复合模式中,核桃总根生物量和吸收根长均占复合模式总根量的一半以上,其中,在水平方向上,决明子在树行南侧2.5、4.0 m位置根系分布最多,而树行南北1.5 m范围内则较少;核桃根系则主要分布在树行两侧1.5 m范围内。垂直方向上,核桃在30~80 cm土层中的根生物量和吸收根长分别占其总量的64.79%和61.17%,而59.54%的决明子根系分布在0~20 cm土壤中。 相似文献
13.
《Scandinavian Journal of Forest Research》2012,27(1-4):429-436
Silvicultural cleaning is commonly carried out in young stands to control competition between conifers and deciduous tree species. However, it has been questioned whether this practice affects moose (Alces alces L.) browsing on Scots pine (Pinus sylvestris L.) with respect to damage at the stand level. In this study, moose winter browsing was examined in relation to food availability in 19 Scots pine stands divided into silviculturally cleaned and non‐cleaned blocks. Cleaning had a negative effect on moose foraging in terms of reduced density, biomass availability, and height of the deciduous tree species. The total biomass consumed by moose was significantly lower on the cleaned blocks than on the non‐cleaned ones. There were no differences between the treatments in the amounts of pine consumed and in moose damage to pines. The density or biomass available of different deciduous tree species did not explain the variation in moose browsing on pine. In conclusion, timing of silvicultural cleaning with reference to moose browsing should be taken into account. If pines are not overtopped by deciduous trees, as in the present study, silvicultural cleaning is not necessary to prevent moose damage. 相似文献
14.
Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil. 相似文献
15.
Michael E. L. Perry Walter H. Schacht Gregory A. Ruark James R. Brandle 《Agroforestry Systems》2009,77(1):23-35
A study to determine the feasibility of producing forage for grazing livestock under trees was conducted as a step toward
evaluating the potential for silvopasture systems in the northern and central Great Plains. The effects of overstory leaf
area index (LAI), percentage understory light transmittance (LT), and soil moisture (SM) on yield and crude protein (CP) of
big bluestem [Andropogon gerardii Vitman; (BB)], smooth bromegrass [Bromus inermis Leyss.; (SB)], and mixtures with birdsfoot trefoil [Lotus corniculatus L.; (BFT)] were examined. The study was conducted in both Scotch pine (Pinus sylvestris L.) and green ash (Fraxinus pennsylvancia Marsh.) tree plantations, at the University of Nebraska Agriculture Research and Development Center near Mead, Nebraska.
Thirty-six plots representing a wide range of canopy cover were selected at each location and seeded in April 2000 to BB,
SB, or mixtures with BFT. Measurements of LAI, LT, and SM were taken throughout the 2001-growing season and plots were harvested
in June and September 2001. Soil moisture generally did not explain much of the variability in yield or CP for BB, SB, or
BFT. Cumulative LAI or LT averaged over the growing season was the best predictor of yield or CP, particularly under the pine.
Yields of BB and SB increased as LAI decreased or LT increased. Conversely, the CP of BB and SB increased as LT decreased
for both the June and September harvests. Both BB and SB maintain relatively high productivity under partial shading; however,
BFT yields were low at LT levels below 75%.
At the time of the research, the senior author was research assistant, Department of Agronomy and Horticulture, University
of Nebraska-Lincoln, Lincoln, NE 68853-0915. 相似文献
16.
Edward H. Fletcher III Mack Thetford Jyotsna Sharma Shibu Jose 《Agroforestry Systems》2012,86(1):49-60
Suitability for production of woody floral stems in a pecan [Carya illinoinensis (Wangenh.) C. Koch] alley cropping was determined for nine shrub species in northwest Florida. Treatments included partial shade without root competition, partial shade with root competition, and full sun. Only three species had high rates of survival for all treatments throughout both years of the study: Callicarpa americana L. (American beautyberry), C. americana var. Lactea (white American beautyberry), and Crataegus marshallii Eggl. (parsley haw). For C. americana, plant growth index increased through time and was similar among the three treatments, indicating that this species grew equally well in sun or shade irrespective of root competition from the tree crop. C. americana var. Lactea had similarly high rates of survival and grew largest in partial shade without root competition (81.7?cm) compared to partial shade with root competition (67.2?cm) and full sun (57.0?cm). C. marshallii had 100 % survival in partial shade without root competition, with one mortality in partial shade with root competition (91.7 % survival) and one in full sun (91.7 % survival). Growth index did not increase over time and was similar among all three treatments. Other species tested had low rates of survival in all treatments throughout both years of the study and included: Ilex glabra L. (inkberry), Ilex myrtifolia Walt. (myrtle-leaf holly), Hydrangea paniculata Seibold var. ??Tardiva?? (panicle hydrangea), Hydrangea quercifolia Bart. (oakleaf hydrangea), Lyonia lucida (Lam.) K. Koch, and Salix matsudana Koidz. F. tortuosa Rehd. (corkscrew willow). No species produced sufficient flowers, fruits or ornamental stems during this establishment period to allow a florist evaluation of the stems for use as woody floral stems. 相似文献
17.
The influence of woody and herbaceous plant competition, either alone or in combination, on microclimate and growth of planted eastern white pine (Pinus strobus L.) seedlings was examined over four consecutive growing seasons in a central Ontario clearcut. Treatments that manipulated the comparative abundance of these two plant functional groups significantly affected light availability, soil moisture, and air and soil temperature regimes. These microclimate alterations, coupled with the relative competitiveness of herbaceous and woody vegetation, corresponded to temporal changes in vegetation cover and dominance. The more rapid colonization and growth of the herbaceous plant community, dominated by bracken fern (Pteridium aquilinum) and ericaceous shrubs (Kalmia sp., Vaccinium sp.), resulted in this form of vegetation being a comparatively important early competitor for soil moisture. As the woody plant community, dominated by naturally regenerated trembling aspen (Populus tremuloides Michx.), grew in height and leaf area, it became a comparatively strong competitor for both light and soil moisture. For all vegetation treatments combined, white pine seedling growth responses were strongly correlated with total cover of competing vegetation and its relative influence on above- and belowground microclimatic variables. Higher total cover of competing vegetation was generally associated with lower light and soil moisture availability and cooler soil temperatures. Multiple regression analyses indicated that pine seedling relative height growth increased with soil moisture content and growing season soil heat sum, while seedling relative diameter and relative volume growth increased with light availability. 相似文献
18.
Intercropping Ginkgo and crop species in southern China is receiving increasing attention because it offers potential advantages
for resource utilization, higher economic income to farmers and increased sustainability in crop production, We carried out
a 2-year field intercropping system composed of Ginkgo with wheat, broad bean, and rapeseed, respectively, to determine the
competitive interactions between the different species, and productivity and the economic yield of each intercropping system.
The density of Ginkgo and crop species was varied systematically in a two-way density matrix composed of three monoculture
densities and nine intercropping of all possible pairwise combinations of monoculture densities. Intercropping systems were
assessed on the basis of several intercropping indices such as land equivalent ratio, relative crowding coefficient, relative
competition intensity and vector competition analysis. The results showed that the combined biomass production of the component
crop species was significantly greater in the Ginkgo/crop mixtures than in monocultures crops (Ginkgo, broad bean, wheat,
and rapeseed). Ginkgo: rapeseed ratio 24:12, Ginkgo: bread bean ratio 24:5, and Ginkgo: wheat ratio 24:200 had the best total
biomass production. Ginkgo: rapeseed (and broad bean) ratio 24:5 and Ginkgo: wheat ratio 24:200 in respective Ginkgo/crop
mixtures had the maximum economic yield. Vector competition analysis showed that Ginkgo/rapeseed mixture exhibited an antagonistic
interaction type and therefore is not suitable for intercropping. Ginkgo/broad bean mixture demonstrated the most beneficial
effects among the three intercropping systems. 相似文献
19.
灌木状白蜡--农作物间作系统的生物量及养分分配的初步研究 总被引：4，自引：1，他引：3
灌木状白蜡 (Ｆｒａｘｉｎｕｓｃｈｉｎｅｎｓｉｓ,又称白蜡条 )—农作物间作系统是豫东沙区重要的农林复合经营形式 ,有数百年的经营历史 ,仅宁陵县就有 1 50 0ｈｍ2 。它把多年生的灌木状白蜡和 1年生的作物结合起来 ,不但可以充分利用自然资源 ,生产大量的条子、白蜡杆等小型用材 ,而且还可以改善农田生态系统的结构 ,提高其多样性与稳定性 (王广钦等 ,1 987ａ;1 987ｂ ;1 990 ;ＷａｎｇＧｕａｎｇｑｉｎｅｔａｌ.,1 991 )。因此 ,把条农间作当作一个完整的人工生态系统 ,研究其物质的固定、消耗、分配、循环规律 ,对于进一步研究条农复… 相似文献
20.
D. J. Makus S. C. Tiwari H. A. Pearson J. D. Haywood A. E. Tiarks 《Agroforestry Systems》1994,27(2):121-127
Conventional planted okra in Booneville, Arkansas and Lorman, Mississippi were mulched with loblolly pine straw (Pinus taeda L.) and longleaf pine straw (P. palustris Mill.), respectively, at a rate of 11 t/ha or left bare. At Booneville, plant stand, season yields (18.6 t/ha), pod weight (16.3 g), plant dry weight (2.3 kg), or stem diameter (3.5 cm) were not affected by the loblolly pine mulch. However, mulch application increased pod number (1.22 vs. 1.06×106/ha) and plant height (1.5 vs. 1.6 m), while reducing weed competition (0.05 vs. 0.40 t/ha) and visible plant stress, during periods of soil moisture deficits. Soil temperatures at 5 and 15 cm depth were reduced by mulch until mid-August when plant canopies covered the rows. Seasonal moisture at 30 and 45 cm depths was similar between mulched and bare soils, based upon unreplicated neutron probe measurements. At Lorman, season okra yield (29.8 vs. 24.6 t/ha), number of pods per ha (1.24 vs. 1.07×106) and weed competition were reduced and soil pH lowered 0.56 units by longleaf pine straw mulch. Mulch reduced early season yield at both locations. 相似文献