Shade effects on forage crops with potential in temperate agroforestry practices

Thirty forages, including eight introduced cool-season grasses, four native warm-season grasses, one introduced warm-season grass, eight introduced cool-season legumes, five native warm-season legumes, and four introduced warm-season legumes, were grown in 7.6 L (two gallon) pots in full sun, 50%, and 80% shade created by shade cloth over a greenhouse frame. Experiments were conducted during summer--fall 1994, spring--early summer 1995, and summer--fall 1995. A complete randomized experimental design was used and above ground dry weight was measured in each shade environment. Tukey's studentized range test was used to compare mean dry weights (MDW) within a species. Warm-season grasses displayed significant reductions in MDW under shade regardless of growing season. All cool-season forages grown during spring--early summer showed a decrease in MDW under shade; however, the reductions in dry weights of ‘Benchmark’ and ‘Justus’ orchardgrass, ‘KY 31’ tall fescue, Desmodium canescens and D. paniculatum were not significant under 50% shade. Cool-season grasses showed more shade tolerance when grown during the summer--fall than when grown during the spring--early summer. Seven of the selected cool-season grasses grown during the summer--fall did not display significant reductions in MDW under 50% shade as compared to full sun. Smooth bromegrass grown under 50% shade showed a significantly increased MDW production compared to growth in full sun. With the exception of Justus orchardgrass and smooth bromegrass, growth of cool-season grasses was inhibited at 80% shade. Among the legumes harvested during the fall, the dry weights of both Desmodium species tested and hog peanut (Amphicarpaea bracteata L.) increased significantly under 50% and 80% shade. In addition, ‘Cody’ alfalfa, white clover, slender lespedeza and ‘Kobe’ lespedeza showed no significant reductions in MDW under 50% shade. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photosynthetically active radiation use efficiency of <Emphasis Type="Italic">Dactylis glomerata</Emphasis> and <Emphasis Type="Italic">Schedonorus phoenix</Emphasis> along a hardwood tree-induced light gradient

Photosynthetically active radiation use efficiency (PARUE) of orchardgrass (Dactylis glomerata L.) and tall fescue (Schedonorus phoenix (Scop.) Holub) was determined. Leaf mass was harvested for canopies at different shade levels when each reached 20 cm height with 5 cm residue for regrowth to simulate grazing. Total incident PAR at each site was summed for the growth period (S-PAR). Values for PARUE were calculated from dried leaf mass divided by S-PAR. The more highly shaded plants reached 20 cm at lower S-PAR. While overall leaf mass decreased linearly with shade induced decreases in S-PAR, PARUE increased exponentially. The coefficients for the equations representing this exponential increase vary for forage species and may represent a useful index for characterizing forage response to silvopastoral systems.     

Production and Economics of Native Pecan Silvopastures in Central United States

Riverine silvopastoral practices with native pecan (Carya illinoinensis) are a suitable land use for areas subjected to seasonal flooding in southern and central regions of the United States. Nut, timber and forage production, and the economics of managed pecan silvopastures were examined in southeastern Kansas. During 1981–2000, annual hulled nut production varied between 50 and 1600 kg ha⁻¹ in stands averaging 72 years of age, and ranging in density between 35 and 74 trees ha⁻¹. The nut crop had a pattern of biennial bearing with some exceptions. Tree stem diameter and stand basal area increased linearly with time. Nut production was not related to stand age or tree density, however, suggesting that nut production had reached a steady state level. Merchantable timber yield ranged between 0.25 and 1.35 m³ ha⁻¹ year⁻¹. In pecan silvopastures with a mean tree age of 37 years, forage production varied between 1500 and 4600 kg DM ha⁻¹ in 2001 and 2002. In 2001 only, grass production decreased with decreasing solar radiation within the range of 0.25–0.83 of fraction light transmitted. In both years, the grass understory had acceptable quality for cow-calf production with average crude protein content between 9 and 11.8%, and no evidence of excessive levels of ergoalkaloids from tall fescue. Twenty-seven vascular plants were identified in the understory of which nut sedge (Cyperus esculentus), tall fescue (Festuca arundinacea), wild oat (Avena fatua) and Canadian wild rye (Elymus canadensis) were the most abundant. Economic simulations obtained with the U.S. Agroforestry Estate Model indicated that pecan nut price is the main variable driving economic outputs under current production conditions. Annual cash flows from nut sales had smaller fluctuations than nut yields because of an inverse relation between nut price and yield. Improved timber production appears an option for increasing profitability of pecan silvopastures.     

Relationship between tree canopy height and the production of pasture species in a silvopastoral system based on alder trees

Silvopastoral systems in New Zealand that incorporate trees planted to control soil erosion on hills largely rely on the productivity of the pastoral system for financial returns. The effect on pasture productivity of increasing the tree canopy height by pruning Italian gray alder (Alnus cordata) was investigated by measuring the response of light, soil moisture, soil temperature, pasture production of major pasture species, and grazing behaviour of sheep. A split-plot design with four replicates was used. The main plot treatments were three levels of shade (81, 23, and 12% of available photosynthetic photon flux (PPF)), created by pruning 11 year old alder grown at the same density. The sub-plot treatments were four pasture mixes: perennial ryegrass (Lolium perenne), Yorkshire fog (Holcus lanatus), and cocksfoot (Dactylis glomerata), each sown with white clover (Trifolium repens), and cocksfoot sown with lotus (Lotus pedunculatus). Soil temperature was highest under light shade. Total herbage yield at 50 mm stubble height from October to May under heavy and medium shade was 60 and 80%, respectively, of the total herbage harvested under light shade. Cocksfoot had the greatest herbage yield, either with lotus or white clover. The tillering of perennial ryegrass was suppressed by shade more than for the other grass species making ryegrass unsuitable for use in this silvopastoral system. More sheep grazed in the light shade than in the heavy shade, but there was no difference in sheep preference for cocksfoot or Yorkshire fog. Lotus was grazed more frequently than white clover. Pruning of alder to increase canopy height has the potential to improve the productivity of the understorey pasture and its acceptability to sheep.     

Limits to recruitment of tall fescue plants in poplar silvopastoral systems of the Pampas,Argentina

Forage production in silvopastoral systems of the Flooding Pampa is based on cool season grasses with a relatively asynchronous phenology regarding their accompanying deciduous trees. However, the productivity of cool season grasses in these systems is usually low. The hypothesis of this work is that the low productivity of cool season grasses is caused by tree litter constraining plant recruitment. Emergence and establishment (reproductive propagation), and tillering (vegetative propagation) patterns of tall fescue, a cool season grass in the region, were studied in two pairs of adjacent non-afforested and afforested poplar stands (tree age 26–28 years, tree density 453–797 plants ha⁻¹). Observational and manipulative (i.e. addition of seeds, leaf litter removal) experiments indicated that the recruitment of tall fescue plants is strongly limited by the fall of poplar leaves over emerged seedlings, during autumn. Results suggest that any management practice capable of removing poplar litter, either through grazing or machinery, could neutralize this limitation enhancing the herbaceous primary production of the system.     

Nutritive quality and morphological development under partial shade of some forage species with agroforestry potential

The shade environment produced in agroforestry practices affects the morphology, anatomy and chemical composition of intercropped forages and, therefore, may affect forage quality. During the summer-fall growing season of 1994 and 1995, 30 forage cultivars were grown in 7.6 L (two gallon) pots in full sun, 50%, and 80% shade created by placing shade cloth over a greenhouse frame. Fifteen legumes and grasses that were similar in yield under full sun and shade treatments were selected for quality analysis. With the exception of 'Kobe' lespedeza, D. paniculatum and D. canescens, acid detergent fiber (ADF) was either not affected or was slightly increased by shade. Except for Kobe lespedeza and 'Martin' tall fescue, shade either did not affect or slightly increased the neutral detergent fiber (NDF) of the shade-tolerant forages. Crude protein (CP) percentage increased in most shade-grown forages; however, shade had less effect on CP of legumes than of grasses. Other than Kobe lespedeza, total mass of CP per pot (TCP) was unaffected or increased under 50% shade for all species. Total crude protein of hog peanut, D. esmodium paniculatum and D. canescens was greater under both 50% shade and 80% shade than in full sun. The decrease in ADF of Kobe lespedeza, D. paniculatum and D. canescens under the shade treatments might be associated with maintenance of a higher leaf:stem weight ratio under shade. However, the leaf:stem ratios of the same cultivars grown at different light intensities did not strongly correlate with NDF, CP, and TCP values. In general, on selected species, internodal length and leaf area increased while specific leaf dry weight decreased for plants grown in shade compared to those grown in full sun. The data indicated that forage quality of some species could be enhanced by shade. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pre-emergence herbicides affect seedling emergence of tropical forest tree species

Testing techniques to reduce weed infestation is a crucial step in developing direct tree seeding systems. The use of pre-emergence herbicides may be an alternative to manual weeding techniques, but so far, information on how they affect the seeds of native tree species is scarce. We established a greenhouse experiment to evaluate the effects of four pre-emergence herbicides (atrazine, diuron, isoxaflutole and oxyfluorfen) on weed suppression and seedling emergence and early growth of seven tropical forest tree species (Annona coriacea Mart., Citharexylum myrianthum Cham., Cordia ecalyculata Vell., Peltophorum dubium (Spreng.) Taub., Psidium guajava L., Pterogyne nitens Tul. and Schinus terebinthifolia Raddi). The experimental design was a randomized complete block design with five treatments and five replicates. The treatments consisted of a single dose of each pre-emergence herbicide and a control. Throughout the 60 days after sowing we evaluated weed cover and seedling emergence and early growth of tree species. Overall, our results suggest that all tested herbicides reduced weed cover; however, they also negatively affected tree species seedling emergence. Of the four herbicides tested, atrazine and diuron showed the greatest effects on tree seedling emergence, oxyfluorfen was least aggressive towards native species and isoxaflutole was most effective in weed control. Native tree species varied in their responses to herbicides, indicating that future experiments should increase the number of species tested as well as investigate how seed traits can affect the species responses to different herbicides.     

Establishment of genetic transformation system via Agrobacterium in tall fescue cultivar

Tall fescue (Festuca arundinacea Schreb.) is a cool-season turfgrass used on fairways in golf courses. The object of this study was to develop a more efficient, reliable, and repeatable approach in transforming the grass using Agrobacterium (EHA105), where β-glucuronidase gene (uidA) was used as a reporter and hygromycin phosphotransferase gene (hyg) as a selectable marker. An effective expression of transgene was observed in transforming 2-month-old calli derived from mature seeds (cv. Bingo) cultured on MS medium supplemented with 9 mg·L⁻¹ 2, 4-D. A two-step solid medium selection with increasing hygromycin concentration (from 30 to 50 mg·L⁻¹) was used to obtain resistant calli. Transgenic plants have been produced from many independent transformed calli. The presence of functional β-glucuronidase gene (uidA) was detected in hygromycin-resistant calli. Transgenic plants were regenerated and PCR and Southern blot confirmed transgene integration in the tall fescue genome. Biography: QIAN Hai-feng (1973–), male, Ph.D., associate professor in Zhejiang University of Technology.     

几种除草剂对金钟藤的杀灭效果初析

采用喷雾法研究9种药剂对金钟藤生长状况的影响,通过分析几种药剂对金钟藤绿枝条和老茎鲜重的抑制率,得出以下结果:对金钟藤绿枝条和老茎活性最高的均为2,4-滴丁酯,其抑制率分别为98.90%和81.06%,;其次为莠去津,抑制率分别为为95.07%和66.59%。     

Research methods for multistrata agroforestry systems with coffee and cacao: recommendations from two decades of research at CATIE

This paper reviews the research themes and methodologies used by CATIE in agroforestry research with shade trees over coffee (Coffea arabica) and cacao (Theobroma cacao) during the past 20 years. Initially research focused on characterization and production studies (of crop and timber including border areas) of traditional systems using temporary and permanent sample plots on private farms. The assessment area of traditional shade-coffee (or cacao) systems should be the whole plot, including the border areas, and not some subjectively selected central area which supposedly represents unit area productivity. Uncontrolled crop, tree, and management heterogeneity limited extrapolation of early on-farm research results to other farmers' fields. Replicated case studies of best bet technologies (traditional or experimental) on different farms are often preferable to the use of formal experimental designs. On-station research included the use of systematic spacing designs to test extreme shade tree density treatments of coffee. Most nutrient cycling studies were also carried out on-station, using service and timber shade species over coffee and cacao to evaluate the ability of these agroforestry systems to maintain nutrient reserves and diversify production. Plot size (even 36 × 36 m) was limiting for long term research because of inter-plot interference, both below- and above ground, when using fast growing, tall timber trees as shade. These experiences suggest a minimum plot size of 2,500 m². Individual tree designs and tree-crop interface studies (e.g. regression analysis of data taken along transects) are promising experimental/sampling approaches that need further development. The principal research thrusts proposed for the next five years are bio-physical process research on coffee responses to shade and competition with trees (growth, carbon allocation, phenology, disease-pest tolerance, yields and coffee quality effects) and socioeconomic analyses of both traditional and new or improved shade – coffee combinations vs. monocultures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of light availability and soil flooding on growth and photosynthetic characteristics of Genipa americana L. seedlings

Genipa americana L. (Rubiaceae) is a late successional neotropical fruit tree used in riparian forest restoration programs. We analyze the effects of light availability and soil flooding on the growth and photosynthetic characteristics of G. americana seedlings under nursery and natural light conditions. Two light levels (full sunlight and shade), and two levels of soil water (flooded and control) were used in the experiment. Flooding induced significant changes in the total seedling biomass (P < 0.01). The differences among water treatments were 70 and 10% at full sunlight and shade, respectively. These changes were explained by alterations in the maximum quantum efficiency of the photosystem 2 (Fv/Fm), light-saturated net photosynthetic rates (A _sat) and intrinsic water use efficiency (WUE). G. americana has high physiological plasticity in relation to the light availability and flooding, although significant interactive effects between high light exposure and soil flooding were observed in several photosynthetic and growth variables. The results highlight the importance of the synergistic effects between physical environmental variables on the establishment and growth of G. americana seedlings. In the practical point of view we can indicate that, in degraded riparian forests subjected to soil flooding, seedlings of this species should be planted under partially shaded environments.     

Tree establishment and growth using forage ground covers in an alley-cropped system in Midwestern USA

The integration of forage crops in an alley-cropped system was examined as a method of encouraging tree planting to increase farm income, improve soil quality, and enhance biodiversity on Midwestern U.S. farms. Crop and tree performance were evaluated in an alley-cropped system using four forage intercrops grown in tree alleyways to simulate a potential hay crop – oat (Avena sativa L.) and red clover (Trifolium pratense L.); oat, red clover, and red fescue (Festuca rubra L.); oat, red clover, and orchardgrass (Dactylis glomerata L.); and oat and hairy vetch (Vicia villosa Roth) – compared to a herbicide, mowing and control (no management) treatment. Five tree species, divided into fast-growing hardwoods of two poplar (Populus spp.) clones [Crandon (P. alba L. × P. grandidentata Michx.) and Eugenei (P. deltoids Bartr. × P. nigra L.)], and silver maple (Acer saccharinum L.) were compared with two high-value, slow-growing hardwoods planted from seed and as seedlings: red oak (Quercus rubra L.) and black walnut (Juglans nigra L.). Tree survival in the first year was greater for the fast-growing species, and by the fourth year, tree height among the four forage treatments was equivalent for all upland locations. The oat/hairy vetch ground cover was associated with the shortest trees in the bottomland site. Herbicide-treated trees were taller than the average of the four forage treatments for all four planting conditions. Tree height in the mowing and the control treatments was not significantly different for all four planting conditions. The nutritive value of the forage crop was excellent in the second year of tree establishment, with crude protein content and digestibility at 17 and 71%, respectively, in the oat/red clover/red fescue treatment, suggesting the viability of forage crops as alternatives to herbicides in alley-cropped systems.     

Influence of tree shelters on seedling success in an afforested riparian zone

The restoration of a natural riparian ecosystem is a key component to improving water quality and restoring stream health in a disturbed watershed. The rate and degree of riparian restoration, and hence stream restoration, depends in part upon afforestation practices. Successful afforestation is determined largely by the rates of survivorship and growth of the tree species planted or recruited in a riparian zone. This study was part of a project involving the restoration of a channelized section of Wilson Creek located in the Bernheim Arboretum and Research Forest, Nelson County, Kentucky. Riparian restoration activities focused on reestablishing a native riparian corridor using American sycamore (Platanus occidentalis), green ash (Fraxinus pennsylvanica var. subintegerrima), and pin oak (Quercus palustris). This study evaluated techniques for improving the growth and survivorship of planted seedlings along Wilson Creek. Specifically, two tree shelter types (Tubex^® vs. continental mesh), with or without herbicide treatments, were compared. Additionally, the influence of these techniques on debris retention within the riparian zone was also examined. Results showed that use of tree shelters significantly increased the growth of seedlings (but not survivorship), provided physical protection especially during heavy flooding events, and accelerated woody debris retention. Both Tubex^® and continental mesh tree shelters were effective in enhancing seedling growth, with Tubex^® shelters yielding significantly better growth when combined with herbicide to control competing vegetation. Thus, the most cost effective choice may depend on the environmental setting and ability to combine the shelters with other growth enhancing treatments.     

Restoring abandoned pasture land with native tree species in Costa Rica: Effects of exotic grass competition and light

Understanding the early establishment requirements and performance of tropical tree seedlings is essential to ensuring the success of restoration plantings. This study was designed to characterize growth and light requirements of six common neotropical tree species Pseudosamanea guachapele (Fabaceae), Tabebuia impetiginosa (Bignoniaceae), Ceiba pentandra (Bombacaceae), Pachira quinata (Bombacaceae), Dalbergia retusa (Fabaceae), and Tabebuia rosea (Bignoniaceae) in an abandoned pasture under contrasting light environments and grass competition. Field studies were conducted in the pastures of the Santa Ana Conservation Center in Costa Rica. Two differing grass competition sites were selected, one dominated by a tall grass, Hyparrhenia rufa and another dominated by a short grass, Cynodon mlenfluensis. Three light treatments were created (2, 37 and 100% light) using either neutral shade cloth (2 and 37%) or no shade cloth (100%). Growth characteristics and biomass partitioning of the seedlings were measured. Species differed in their relative growth rates (RGRs). The light × species interaction was significant at both sites. While all species had similar performance under 100% light on both short grass and tall grass sites, species growth differences were evident under 37 and 2% light levels. For example, at the short grass site, T. rosea had higher RGR than D. retusa and P. quinata under 2% light whereas both Tabebuia species performed better than other species at the tall grass site. The general trend was to increase root mass ratio and decrease leaf mass ratio with increasing levels of light. As an initial step for restoring abandoned pasture lands we recommend using all these species in direct and moderate light conditions. Incorporating all species will create a more heterogeneous environment. Choosing light demanding species that can tolerate grass competition may help ensure success in the early stage of restoration.     

Agroforestry and grass buffer effects on water quality in grazed pastures

Conservation practices including agroforestry and grass buffers are believed to reduce nonpoint source pollution (NPSP) from pastured watersheds. Agroforestry, a land management practice that intersperses agricultural crops with trees, has recently received increased attention in the temperate zone due to its environmental and economic benefits. However, studies are limited that have examined buffer effects on the quality of water from grazed pastures. Six treatment areas, two with agroforestry buffers, two with grass buffers, and two control treatments were used to test the hypothesis that agroforestry and grass buffers can be used to effectively reduce NPSP from pastured watersheds. Vegetation in grass buffer and pasture areas includes red clover (Trifolium pretense L.) and lespedeza (Kummerowia stipulacea Maxim.) planted into fescue (Festuca arundinacea Schreb.). Eastern cottonwood trees (Populus deltoides Bortr. ex Marsh.) were planted into fescue in agroforestry buffers. Soils at the site are mostly Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalfs). Treatments were instrumented with two-foot H flumes, water samplers, and flow measuring devices in 2001. Composite water samples were analyzed for sediment and total nitrogen after each runoff event to compare treatment differences. Treatments with agroforestry and grass buffers had significantly lower runoff volumes as compared to the control. The loss of sediment and total nitrogen were smaller for the buffered treatments. The results of this study suggest that establishment of agroforestry and grass buffers help reduce NPSP pollution from pastured watersheds. It is anticipated as trees grow and roots occupy more soil volume, the reduction in N in runoff will increase on the agroforestry watershed.     

Practical Developments in the Use of Chemicals for Forest Fire Control

The results of development work and practical use of chemicalfire retardants for control of vegetation fires are described.Viscous water, prepared using sodium alginate solution, hasproved highly successful for arresting flame spread in a varietyof fuel types, including heather, grass, and gorse. Field-scaleapplications over a 5-year period at more than 30 forests haveshown that the technique can be used reliably and economicallyfor controlled burning, and has also been used to contain wildfires.A satisfactory mixing/dispensing unit has been developed formixing and applying viscous water. This unit is light and versatileand can be used as a general purpose pump or sprayer for water,herbicides, etc., if required. Extension of earlier trials using herbicides to dry grass vegetationto permit safe and rapid controlled burning during the ‘green’season has confirmed the initial promise. Paraquat has provedthe most effective herbicide for this purpose, and can be usedto considerable practical advantage for fire-break formationin grass, and particularly Molinia vegetation, providing grazinganimals can be excluded for at least 24 hours after spraying.Recommendations are made on practical use of both these methods.     

Effect of post-planting applications of granulated atrazine and fertiliser on the early growth of Eucalyptus nitens

A factorial experiment was established in a plantation of Eucalyptus nitens in southern Tasmania on a site which had formerly carried native eucalypt forest. Before planting, the site had been cleared of weeds with foliar translocated and pre-emergence herbicides. The first factor of the experiment examined the effects on tree growth of no post-planting weed control, control by hand or with three levels of application of granulated atrazine, 0.9, 1.8 and 8 kg ha^–1. The second factor examined the effects of no fertiliser application or the application of nitrogen as urea at 200 kg ha^–1 N plus triple superphosphate at 120 kg ha^–1 P. Tree growth responses to treatments were examined at 11, 16, 23 and 29 months of age.Fertiliser application increased tree height and diameter growth. Application of atrazine generally reduced height and diameter growth, but this was statistically significant only at the highest rate of application. Growth reduction occurred even though atrazine reduced post-planting weed cover on the site and hence potential competition with the tree crop for site resources. Hand weeding reduced the weed crop on the site even more than atrazine, but this did not increase growth of the tree crop.Given satisfactory establishment practices which include the use of herbicides pre-planting, it was concluded that post-planting weed regeneration was not sufficiently vigorous to warrant post-planting weed control on these sites. The use of atrazine for post-planting weed control could even be deleterious to eucalypts.     

Prescribed burning and hexazinone herbicide as release treatments in a sapling hardwood-loblolly pine stand

To compare release treatments, a randomized complete block study was established in a 7-year-old hardwood-loblolly pine (Pinus taeda L.) stand in central Louisiana established using chopping and burning. There were 5 blocks of 3 treatments each: (1) check, (2) hexazinone applied once, and (3) prescribed backfiring applied twice. The first burn in December 1985 (7 years after site preparation) had a fire intensity of 90 kJ/s/m. The hexazinone herbicide was applied in April 1986 (the 8th year after site preparation) with a metered spotgun applicator at a rate of 3.0 kg active ingredient/ha. The second burn in March 1989 (the 11th year after site preparation) had a fire intensity of 106 kJ/s/m.The two prescribed burns increased the number of stems less than 1.5 m tall from 1,380 to 2,960/ha red maple (Acer rubrum L.), blackgum (Nyssa sylvatica var. bifora), and sweetgum (Liquidambar styraciflua L.). Burning reduced the number of loblolly pines less than 2.0 m tall, which resulted in a significant increase in average loblolly pine height and diameter. Loblolly pine comprised 62 and 59% of the basal area on the check and burn treatments, respectively, 11 years after site preparation. Hexazinone reduced the number of blackgum, sweetgum, and oak (Quercus spp.) from 6,100 to 4,560 stems/ha and resulted in significantly less hardwood tree basal area than found on the check or burn treatments. Therefore, the herbicide treatment resulted in principally a loblolly pine stand (over 80% of the total tree basal area was pine) four years after hexazinone application.     

Growth,dry matter production,phenotypic plasticity,and nutritive value of three natural populations of Dactylis glomerata L. under various shading treatments

Dactylis glomerata L. is a widespread perennial grass species, which has been reported to be adapted to shaded conditions. Its populations thrive in a variety of environments. However, little information is available concerning the comparative response of its natural populations from contrasting environments under the reduced light intensity conditions that exist in silvopastoral systems. The objective of the present study was to estimate the comparative ability of three populations of D. glomerata from northern, central and southern Greece to grow under full sun, 60 % shade and 90 % shade in terms of their growth characteristics, phenotypic plasticity, dry matter production and nutritive value. Shade reduced tillering and dry matter production, increased tiller height and modified leaf characteristics. Under shade fewer leaves were grown simultaneously on the same tiller, but these were longer and thinner compared to full sun. Differentiation in response to shade among the populations examined of D. glomerata was observed mainly for leaf characteristics. The population from Pertouli (central Greece) responded better, particularly to moderate shade as it had a higher leaf area, longer leaf and higher dry matter production, compared to the others. Evidence for adaptive phenotypic plasticity to moderate shade was suggested only for this population. Additionally, Pertouli had higher nutritive value compared to Taxiarchis (northern Greece) and Crete (southern Greece) under shade. The divergent responses of natural populations of D. glomerata could justify breeding germplasm with enhanced shade tolerance.     

Estimation of evapotranspiration with drainage lysimeters in the Taihang Mountain area, China

In this research, the evapotranspiration (ET) of three native vegetation communities were measured using drainage lysimeters in the Taihang Mountain area, China. They are a local grass, Themeda japonica, a local shrub, Vitex negundo var. heterophylla Rehd. and a mixture of both communities. The ET was measured using level lysimeters (with a slope of 0°) and slope lysimeters (with a slope of 25°). In general, the measured ET was higher in the level lysimeters than in the slope lysimeters because of the water loss of surface runoff from the slope lysimeter. The total ETs over the growing season for the grass, shrub, and the mixture were 730.4, 742.0 and 790.7 mm, respectively in the level lysimeters, and 535.5, 504.1 and 540.1 mm, respectively in the slope lysimeters. In addition, the monthly ET peaked in August and had close linear relationship with leaf area index. The drainage lysimeter is an effective tool to estimate plant ET in mountain areas. The results from this research would provide scientific information for the vegetation recovery and sustainable development of forestry in the TM areas.