Abstract
This review summarises current knowledge on root interactions in agroforestry systems, discussing cases from temperate and tropical ecosystems and drawing on experiences from natural plant communities where data from agroforestry systems are lacking. There is an inherent conflict in agroforestry between expected favourable effects of tree root systems, e.g. on soil fertility and nutrient cycling, and competition between tree and crop roots. Root management attempts to optimise root functions and to stimulate facilitative and complementary interactions. It makes use of the plasticity of root systems to respond to environmental factors, including other root systems, with altered growth and physiology. Root management tools include species selection, spacing, nutrient distribution, and shoot pruning, among others. Root distribution determines potential zones of root interactions in the soil, but are also a result of such interactions. Plants tend to avoid excessive root competition both at the root system level and at the single-root level by spatial segregation. As a consequence, associated plant species develop vertically stratified root systems under certain conditions, leading to complementarity in the use of soil resources. Parameters of root competitiveness, such as root length density, mycorrhization and flexibility in response to water and nutrient patches in the soil, have to be considered for predicting the outcome of interspecific root interactions. The patterns of root activity around individual plants differ between species; knowing these may help to avoid excessive competition and unproductive nutrient losses in agroforestry systems through suitable spacing and fertiliser placement. The possibility of alleviating root competition by supplying limiting growth factors is critically assessed. A wide range of physical, chemical and biological interactions occurs not only in spatial agroforestry, but also in rotational systems. In a final part, the reviewed information is applied to different types of agroforestry systems: associations of trees with annual crops; associations of trees with grasses or perennial fodder and cover crops; associations of different tree and shrub species; and improved fallows.
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References
Adesina FA (1991) Soil management with cultivated fallows in humid and subhumid Africa. Can J Soil Sci 71: 147–154
Alvim PT and Alvim R (1980) Environmental requirements of cocoa with emphasis on responses to shade and moisture stress. In: Proceedings of the International Conference on Cocoa and Coconuts, Kuala Lumpur, 1978, pp 93–111. The Incorporated Society of Planters, Kuala Lumpur
Atger C and Edelin C (1994) Stratégies d’occupation du milieu souterrain par les systèmes racinaires des arbres. Rev Ecol (Terre Vie) 49: 343–356
Atkinson D, Naylor D and Coldrick GA (1976) The effect of tree spacing on the apple root system. Hortic Res 16: 89–105
Atkinson D, Johnson MG, Mattam D and Mercer ER (1978) The effect of orchard soil management on the uptake of nitrogen by established apple trees. J Sci Food Agric 30: 129–135
Atkinson D and Last F (1994) Growth, form and function of roots and root systems. Scottish Forestry 48: 153–159
Bethlenfalvay GJ (1992) Mycorrhizae and crop productivity. In: Bethlenfalvay GJ and Linderman RG (eds) Mycorrhizae in sustainable agriculture, pp 1–27. American Society of Agronomy, Madison
Bowen GD (1984) Tree roots and the use of soil nutrients. In: Bowen GD and Nambiar EKS (eds) Nutrition of plantation forests, pp 147–179. Academic Press, London
Bowen GD (1985) Roots as a component of tree productivity. In: Cannell MGR and Jackson JE (eds) Attributes of trees as crop plants, pp 303–315. Institute of Terrestrial Ecology, Huntingdon
Buwalda JG (1993) The carbon costs of root systems of perennial fruit crops. Environ Exp Bot 33: 131–140
Caldwell MM (1994) Exploiting nutrients in fertile soil microsites. In: Caldwell MM and Pearcy RW (eds) Exploitation of environmental heterogeneity by plants, pp 325–347. Academic Press, San Diego
Caldwell MM, Manwaring JH and Durham SL (1996) Species interactions at the level of fine roots in the field: influence of soil nutrient heterogeneity and plant size. Oecologia 106: 440–447
Campbell CD, Mackie-Dawson LA, Reid EJ, Pratt S M, Duff EI and Buckland ST (1994) Manual recording of minirhizotron data and its application to study the effect of herbicide and nitrogen fertiliser on tree and pasture root growth in a silvopastoral system. Agrofor Syst 26: 75–87
César J and Coulibaly Z (1991) Le rôle des jachères et des cultures fourragères dans le maintien de la fertilité des terres. In: Savanes d’Afrique–terres fertiles? Actes des Rencontres Internationales, Montpellier, 10–14 Dec. 1990, pp 271–287. Ministère de la Coopération et du Développement, Paris
Chakly M and Berthelin J (1982) Rôle d’une ectomycorhize ‘Pisolithus tinctorius–Pinus caribea’ et d’une bactérie rhizosphérique sur la mobilisation du phosphore de phosphates minéraux et organiques insolubles. In: Gianinazzi SE (ed) Les Mycorhizes, partie intégrante de la plante: biologie et perspectives d’utilisation, pp 215–220. Institut National de la Recherche Agronomique, Paris
Chauvel A, Vital ART, Lucas Y, Desjardins T, Franken WK, Luizao FJ, Araguas LA, Rozanski K and Bedmar AP (1993) O papel das raizes no ciclo hidrologico da floresta Amazonica. Congresso Brasileiro de Meteorologia, 28 Sept–2 Oct 1992, vol. 1, pp 298–302. Sao Paulo
Chou C-H and Kuo Y-L (1986) Allelopathic research of subtropical vegetation in Taiwan III. Allelopathic exclusion of understory by Leucaena leucocephala(Lam.) de Wit. J Chem Ecol 12: 1431–1442
Cuenca G, Aranguren J and Herrera R (1983) Root growth and litter decomposition in a coffee plantation under shade trees. Plant Soil 71: 477–486
D’Antonio CM and Mahall BE (1991) Root profiles and competition between the invasive, exotic perennial, Carpobrotus edulis, and two native shrub species in California coastal scrub. Am J Bot 78: 885–894
Davet P (1996) Vie microbienne du sol et production végétale. Paris, Institut National de la Recherche Agronomique, 383 pp
Derouard L, Tondoh J, Vilcosqui L and Lavelle P (1997) Effects of earthworm introduction on soil processes and plant growth. Soil Biol Biochem 29: 541–545
Dissanayake SN and Waidyanatha UPD (1987) The performance of some tropical forage grasses interplanted with young Heveatrees and their effect on growth of the rubber. Trop Agric (Trinidad) 64: 119–121
Dupraz C, Dauzat M, Suard B, Girardin N and Olivier A (1995) Root extension of young wide-spaced Prunus aviumtrees in an agroforest as deduced from the water budget. In: Ehrenreich JH, Ehrenreich DL and Lee HW (eds) Growing a Sustainable Future, Proceedings of the Fourth North American Agroforestry Conference, July 23–28, 1995, pp 46–50. Boise, Idaho
Dupraz C, Simorte V, Dauzat M, Bertoni G, Bernadac A and Masson P (1998) Growth and nitrogen status of young walnuts as affected by intercropped legumes in a Mediterranean climate. Agrofor Syst this issue
Eastham J, Rose CW, Cameron DM, Rance SJ, Talsma T and Charles Edwards DA (1990) Tree/pasture interactions at a range of tree densities in an agroforestry experiment. II. Water uptake in relation to rooting patterns. Aust J agric Res 41: 697–707
Eissenstat D M (1992) Costs and benefits of constructing roots of small diameter. J Plant Nutr 15: 763–782
Eissenstat DM and Caldwell MM (1989) Invasive root growth into disturbed soil of two tussock grasses that differ in competitive effectiveness. Funct Ecol 3: 345–353
Emerman SH and Dawson TE (1996) Hydraulic lift and its influence on the water content of the rhizosphere: an example from sugar maple, Acer saccharum. Oecologia 108: 273–278
Ewel JJ (1986) Designing agricultural ecosystems for the humid tropics. Ann Rev Ecol Syst 17: 245–271
Ezenwa IV and Atta-Krah AN (1992) Early growth and nodulation in Leucaenaand Gliricidia and the effects of pruning on biomass productivity. In: Mulongoy K, Gueye M and Spencer DSC (eds) Biological nitrogen fixation and sustainability of tropical agriculture, pp 171–178. International Institute of Tropical Agriculture, Ibadan
Fernandes ECM, Davey CB and Nelson LA (1993) Alley cropping on an acid soil in the upper Amazon: mulch, fertilizer, and hedgerow root pruning effects. In: Technologies for sustainable agriculture in the tropics. ASA Special Publication 56, pp 77–96. American Society of Agronomy, Madison
Fiala K and Studeny V (1988) Cutting and fertilization effect on the root system in several grassland stands II. Vertical distribution of root biomass and changes in the carbohydrate content. Ekológia (CSSR) 7: 27–42
Foster LJ and Wood RA (1963) Observations on the effects of shade and irrigation on soil-moisture utilization under coffee in Nyasaland. Emp J Exp Agric 31: 108–115
Fownes JH and Anderson DG (1991) Changes in nodule and root biomass of Sesbania sesban and Leucaena leucocephalafollowing coppicing. Plant Soil 138: 9–16
Friend AL, Eide MR and Hinckley TM (1990) Nitrogen stress alters root proliferation in Douglasfir seedlings. Can J For Res 20: 1524–1529
Goss MJ, Miller MH, Bailey LD and Grant CA (1993) Root growth and distribution in relation to nutrient availability and uptake. Eur J Agron 2: 57–67
Grayston SJ, Vaughan D and Jones D (1996) Rhizosphere carbon flow in trees, in comparison with annual plants: the importance of root exudation and its impact on microbial activity and nutrient availability. Appl Soil Ecol 5: 29–56
Hauser S (1993) Effect of Acioa barteri, Cassia siamea, Flemingia macrophyllaand Gmelina arborealeaves on germination and early development of maize and cassava. Agric Ecosys Environ 45: 263–273
Hendricks JJ, Nadelhoffer KJ and Aber JD (1993) Assessing the role of fine roots in carbon and nutrient cycling. Trends Ecol Evol 8: 174–178
Herrera R, Mérida T, Stark N and Jordan CF (1978) Direct phosphorus transfer from leaf litter to roots. Naturwissenschaften 65: 208–209
Hulugalle NR and Lal R (1986) Root growth of maize in a compacted gravelly tropical alfisol as affected by rotation with a woody perennial. Field Crops Res 13: 33–44
IAEA (1975) Root activity patterns of some tree crops. Technical Report Series 170. Vienna, International Atomic Energy Agency, 154 pp
Ikram A, Jensen ES and Jakobsen I (1994) No significant transfer of N and P from Pueraria phaseoloidesto Hevea brasiliensisvia hyphal links of arbuscular mycorrhiza. Soil Biol Biochem 26: 1541–1547
Jackson RB and Caldwell MM (1992) Shading and the capture of localized soil nutrients: nutrient contents, carbohydrates, and root uptake kinetics of a perennial tussock grass. Oecologia 91: 457–462
Johnson NC and Pfleger FL (1992) Vesicular-arbuscular mycorrhizae and cultural stresses. In: Bethlenfalvay GJ and Linderman RG (eds) Mycorrhizae in sustainable agriculture, pp 71–99. American Society of Agronomy, Madison
Jones DL and Darrah PR (1996) Role of root exudates in plant nutrient acquisition in low input agricultural systems. Agroforestry Forum 7: 7–9
Jones M and Sinclair FL (1996) Differences in root system responses of two semi-arid tree species to crown pruning. Agroforestry Forum 7: 24–27
Kandeler E, Eder G and Sobotik M (1994) Microbial biomass, N mineralization, and the activities of various enzymes in relation to nitrate leaching and root distribution in a slurry-amended grassland. Biol Fertil Soils 18: 7–12
Kandiah S, Wettasinghe DT and Wadasinghe G (1984) Root influence on shoot development in tea (Camellia sinensis(L.) O. Kuntze) following shoot pruning. J Hortic Sci 59: 581–587
Kays JS and Canham CD (1991) Effects of time and frequency of cutting on hardwood root reserves and sprout growth. For Sci 37: 524–539
Knoop WT and Walker BH (1985) Interactions of woody and herbaceous vegetation in a southern African savanna. J Ecol 73: 235–253
Korwar GR and Radder GD (1994) Influence of root pruning and cutting interval of Leucaena hedgerows on performance of alley cropped rabisorghum. Agrofor Syst 25: 95–109
Krannitz PG and Caldwell MM (1995) Root growth responses of three Great Basin perennials to intra-and interspecific contact with other roots. Flora 190: 161–167
Kummerow J and Lages Ribeiro S (1982) Fine roots in mixed plantations of Hevea (Hevea brasiliensisH.B.K.Müll.Arg.) and cacao (Theobroma cacaoL.). Rev Theobr 12: 101–105
Kwesiga F and Coe R (1994) The effect of short rotation Sesbania sesbanplanted fallows on maize yield. For Ecol Manage 64: 199–208
Laycock DH and Wood RA (1963) Some observations on soil moisture use under tea in Nyasaland. Trop Agric (Trinidad) 40: 35–48
Le Roux X, Bariac T and Mariotti A (1995) Spatial partitioning of the soil water resource between grass and shrub components in a West African humid savanna. Oecologia 104: 147–155
Le Roux X and Bariac T (1998) Seasonal variations in soil, grass and shrub water status in a West African humid savannah. Oecologia 113: 456–466
Lifshitz R, Guilmette H and Kozlowski M (1988) Tn5-mediated cloning of a genetic region from Pseudomonas putidainvolved in the stimulation of plant root elongation. Appl Environ Microbiol 54: 3169–3172
Lim DHK (1980) New developments in shade for hybrid cocoa in Sabah. In: Proceedings of the International Conference on Cocoa and Coconuts, Kuala Lumpur, 1978, pp 122–142. The Incorporated Society of Planters, Kuala Lumpur
Linderman RG (1992) Vesicular-arbuscular mycorrhizae and soil microbial interactions. In: Bethlenfalvay GJ and Linderman RG (eds) Mycorrhizae in sustainable agriculture, pp 45–70. American Society of Agronomy, Macison
Lisanework N and Michelsen A (1993) Allelopathy in agroforestry systems: the effects of leaf extracts of Cupressus lusitanicaand three Eucalyptusspp. on four Ethiopian crops. Agrofor Syst 21: 63–74
Lyford WH and Wilson BF (1964) Development of the root system of Acer rubrumL. Harvard Forestry Paper 10: 1–17
MacDicken KG (1991) Impacts of Leucaena leucocephalaas a fallow improvement crop in shifting cultivation on the island of Mindoro, Philippines. For Ecol Manage 45: 185–192
Marschner H (1995) Mineral nutrition of higher plants, 2nd edition. London, Academic Press, 889 pp
McDonald PM (1986) Grasses in young conifer plantations–hindrance and help. Northwest Sci 60: 271–278
Mchowa JW and Ngugi DN (1994) Pest complex in agroforestry systems: the Malawi experience. For Ecol Manage 64: 277–284
Miller DE (1986) Root systems in relation to stress tolerance. HortScience 21: 963–970
Nair SK and Subba Rao NS (1977) Microbiology of the root region of coconut and cacao under mixed cropping. Plant Soil 46: 511–519
Nambiar EKS and Nethercott KH (1987) Nutrient and water availability to and growth of young radiata pine plantations intercropped with lupins. New Forests 1: 117–134
Nepstad DC, de Carvalho CR, Davidson EA, Jipp PH, Lefebvre PA, Negreiros GH, da Silva ED, Stone TA, Trumbore SE and Viera S (1994) The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures. Nature 372: 666–669
Newman EI (1978) Root microorganisms: their significance in the ecosystem. Biol Rev 53: 511–554
Page SLJ and Bridge J (1993) Plant nematodes and sustainability in tropical agriculture. Expl Agric 29: 139–154
Ramamoorthy M and Paliwal K (1993) Allelopathic compounds in leaves of Gliricidia sepium (Jacq.) Kunth ex Walp. and its effect on Sorghum vulgareL. J Chem Ecol 19: 1691–1701
Reeves M (1992) The role of VAM fungi in nitrogen dynamics in maize-bean intercrops. Plant Soil 144: 85–92
Rice EL (1968) Inhibition of nodulation of inoculated legumes by pioneer plant species from abandoned fields. Bull Torrey bot Club 95: 346–358
Rivera E, Silva S and Vicente-Chandler J (1983) Distribution of pigeon peas, cassava, coffee and grass roots in an ultisol. J Agric Univ Puerto Rico 67: 278–285
Robinson R K (1972) The production by roots of Calluna vulgarisof a factor inhibitory to growth of some mycorrhizal fungi. J Ecol 60: 219–224
Sanford RL, Jr. and Cuevas E (1996) Root growth and rhizosphere interactions in tropical forests. In: Mulkey SS, Chazdon RL and Smith AP (eds) Tropical Forest Plant Ecophysiology, pp 268–300. Chapman and Hall, New York
Schroth G (1995) Tree root characteristics as criteria for species selection and systems design in agroforestry. In: Sinclair FL (ed) Agroforestry: Science, Policy and Practice, pp 125–143. Kluwer Academic Publishers, Dordrecht
Schroth G, Kolbe D, Balle P and Zech W (1995a) Searching for criteria for the selection of efficient tree species for fallow improvement, with special reference to carbon and nitrogen. Fertilizer Res 42: 297–314
Schroth G, Poidy N, Morshäuser T and Zech W (1995b) Effects of different methods of soil tillage and biomass application on crop yields and soil properties in agroforestry with high tree competition. Agric Ecosys Environ 52: 129–140
Schroth G, Kolbe D, Balle P and Zech W (1996) Root system characteristics with agroforestry relevance of nine leguminous tree species and a spontaneous fallow in a semi-deciduous rainforest area of West Africa. For Ecol Manage 84: 199–208
Schroth G and Lehmann J (1995) Contrasting effects of roots and mulch from three agroforestry tree species on yields of alley cropped maize. Agric Ecosys Environ 54: 89–101
Schroth G and Zech W (1995a) Root length dynamics in agroforestry with Gliricidia sepiumas compared to sole cropping in the semi-deciduous rainforest zone of West Africa. Plant Soil 170: 297–306
Schroth G and Zech W (1995b) Above-and below-ground biomass dynamics in a sole cropping and an alley cropping system with Gliricidia sepiumin the semi-deciduous rainforest zone of West Africa. Agrofor Syst 31: 181–198
Sinclair FL, Verinumbe I and Hall JB (1994) The role of tree domestication in agroforestry. In: Leakey RRB and Newton A (eds) Tropical trees: potential for domestication and the rebuilding of forest resources, pp 124–136. HMSO, London
Skipper HD, Ogg AG, Jr. and Kennedy AC (1996) Root biology of grasses and ecology of rhizobacteria for biological control. Weed Techn 10: 610–620
Smucker AJM (1993) Soil environmental modifications of root dynamics and measurement. Ann Rev Phytopathol 31: 191–216
Springett J and Gray R (1997) The interaction between plant roots and earthworm burrows in pasture. Soil Biol Biochem 29: 621–625
Ssekabembe CK (1985) Perspectives on hedgerow intercropping. Agrofor Syst 3: 339–356
Taylor HM (1980) Modifying root systems of cotton and soybean to increase water absorption. In: Turner NC (ed) Adaptations of plants to water and high temperature stress, pp 75–84. John Wiley and Sons, New York
Theodorou C and Bowen GD (1993) Root morphology, growth and uptake of phosphorus and nitrogen of Pinus radiatafamilies in different soils. For Ecol Manage 56: 43–56
van Noordwijk M, Hairiah K, Ms S and Flach EN (1991a) Peltophorum pterocarpa (DC) Back (Caesalpiniaceae), a tree with a root distribution suitable for alley cropping on acid soils in the humid tropics. In: McMichael BL and Persson H (eds) Plant roots and their environment, pp 526–532. Elsevier, Amsterdam
van Noordwijk M, Widianto, Heinen M and Hairiah K (1991b) Old tree root channels in acid soils in the humid tropics: Important for crop root penetration, water infiltration and nitrogen management. Plant Soil 134: 37–44
van Noordwijk M, Lawson G, Soumaré A, Groot JJR and Hairiah K (1996) Root distribution of trees and crops: competition and/or complementarity. In: Ong CK and Huxley P (eds) Tree-Crop Interactions, pp 319–364. CAB International, Wallingford
Veresoglou DS and Fitter AH (1984) Spatial and temporal patterns of growth and nutrient uptake of five co-existing grasses. J Ecol 72: 259–272
Wilson JB (1988) Shoot competition and root competition. J Appl Ecol 25: 279–296
Wilson JB and Newman EI (1987) Competition between upland grasses: root and shoot competition between Deschampsia flexuosaand Festuca ovina. Acta Oecol Oecol Gener 8: 501–509
Wilson SD and Tilman D (1991) Components of plant competition along an experimental gradient of nitrogen availability. Ecology 72: 1050–1065
Wilson SD and Tilman D (1993) Plant competition and resource availability in response to disturbance and fertilization. Ecology 74: 599–611
Woods PV, Nambiar EKS and Smethurst PJ (1992) Effect of annual weeds on water and nitrogen availability to Pinus radiatatrees in a young plantation. For Ecol Manage 48: 145–163
Yocum W W (1937) Root development of young delicious apple trees as affected by soils and by cultural treatments. Univ Nebraska Agric Exp Stat Res Bull 95: 1–55
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Schroth, G. A review of belowground interactions in agroforestry, focussing on mechanisms and management options. Agroforestry Systems 43, 5–34 (1998). https://doi.org/10.1023/A:1026443018920
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DOI: https://doi.org/10.1023/A:1026443018920