1 suksesi tumbuhan dan kompetisi.ppt
TRANSCRIPT
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Plant Succession and Competition(Suksesi Tumbuhan dan Kompetisi)
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Ecological Succession = development of an ecosystem = changes in species structure and community composition over time
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Ecological SuccessionSuccession = change in species structure and community composition over time. BareHerbs,Small Mature groundgrasses Shrubstrees forest (climax)
ColonizersPersisters(adapt to new area)(relatively stable over time)Low diversityHigh diversityP>RPR
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Ecological SuccessionSuccession = change in species structure and community composition over time. BareHerbs,Small Mature groundgrasses Shrubstrees forest (climax)
Physical factors and climate (e.g., soil, fire) can dictate endpoint in succession
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Grassland end point due to fire, soils, moisture, etc
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Ecological SuccessionSuccession = change in species structure and community composition over time. BareHerbs,Small Mature groundgrasses Shrubstrees forest (climax)
Secondary succession occurs on cleared land
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Ecological Succession Application to AgricultureSecondary succession occurs on cleared landCertain herbaceous plants (grasses, nutsedge, etc.) are well adapted as colonizers become weeds in agricultural fields
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CompetitionTwo species occupying similar nicheCompete for water, nutrients, space, light, etc. Characteristics of the plant species (growth habits, genetics/variety, etc.) and environment (season, temp., moisture, etc.) determine which species will prevail
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Allelopathy = unusual advantage in some competitions
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Allelopathy -- some plants secrete chemicals that are suppressive to other plants
SunflowerWalnut trees (not much undergrowth)Oak tanninsGrains some cultivars of rye, wheat, oats
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CompetitionInterspecific competition between different species (crop plant vs. weeds)Intraspecific competition among plants of the same species (controlled in agriculture by planting rate plant density)
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Increased plant density (reduced row spacing) may increase yields to a point (more plants/ha)Increased plant population
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Increased plant density (reduced row spacing) may increase yields to a point (more plants/ha)Increased plant populationOptimum spacingLow yield due to low plant population
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Increased plant density (reduced row spacing) may increase yields to a point (more plants/ha)Increased plant populationOptimum spacingLow yield due to low plant populationLow yield due to competition, crowded plants
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Plant density depends on:Row spacing (previous example)Distance between plants in rows (e.g., if corn plant populations too high lodging, barren plants)Broadcast seeding rates (for plants not in rows)
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Effects of decreasing space between plant rows:+++ Increases plant population and yield (to a point)+++ Improved competition vs weeds (less open row space for weed colonization)- - - Difficult passage for equipment- - - Possible increase in plant diseases (mortality)
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Effects of decreasing space between plant rows:+++ Increases plant population and yield (to a point)+++ Improved competition vs weeds (less open row space for weed colonization)- - - Difficult passage for equipment- - - Possible increase in plant diseases (mortality)Important to know optimum plant spacing for each crop cultivar
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ReferencesText, pp. 30-31, 126-127, 134-137.Altieri, M.A. 1987. Agroecology. The Scientific Basis of Alternative Agriculture. Westview Press, Boulder, CO. Ch. 14.Begon et al., 1990.Carroll et al. 1990. Ch. 8.Odum, 1983. Ch. 8.Russo, V.M. 1995. HortScience 30:53-54.