Summary
The dwarf shrub Indigofera spinosa Forsk. (Papilionacea), a native forage species of arid Northwest Kenya, was propogated from seed, grown in a controlled environment, and subjected to three treatments of defoliation and watering frequencies in a factorial experimental design. Biomass production and nitrogen accumulation in tissue components were measured to determine defoliation responses in a water-limited environment. We hypothesized that plants would maintain biomass and nitrogen flows despite removal of aboveground meristems and tissues by defoliation. Principal experimental results included a slight reduction (11%; P=0.08) of total biomass production by clip** ca. 1/3 or 2/3 of new leaves and stems and all apical meristems every month. Total aboveground production was not affected by clip**, while final root biomass was reduced 17% by the 2/3 clip**. The least water stressed plants were affected most negatively by defoliation, and the unclipped plants responded more negatively to greater water limitation. Plants achieved partial biomass compensation through alterations in shoot activity and continued allocation of photosynthate to roots. A smaller fraction of leaf production was directed to litter in clipped plants although clip** only removed the youngest tissues, suggesting that clip** increased leaf longevity. In turn, each leaf probably contributed a greater total quantity of photosynthate. Photosynthetic rates were also likely to have been increased by clip** water-stressed plants. In contrast to biomass, plants overcompensated for nitrogen lost to defoliation. Total nitrogen uptake by individual plants was stimulated by defoliation, as there was more total nitrogen in leaves and stems. Increased nitrogen uptake was achieved by clip** stimulation of total uptake per unit of root rather than of total root mass.
Similar content being viewed by others
References
Bamberg IE (1986) Effects of clip** and watering frequency on production of the African dwarf shrub Indigofera spinosa. M.S. Thesis, Colorado State University, Ft. Collins, CO
Birch HF (1958) Patterns of humus decomposition in East African soils. Nature 181:788
Caldwell MM, Richards JH, Johnson DA, Nowak RS, Dzurec RS (1981) Co** with herbivory: photosynthetic capacity and resource allocation in two semiarid Agropyron bunchgrasses Oecologia 50:14–24
Chapin FS III (1980) Nutrient allocation and responses to defoliation in tundra plants. Arct Alp Res 12:553–563
Coppock DL, Ellis JE, Swift DM (1986) Livestock feeding ecology and resource utilization in a nomadic pastoral ecosystem. J Appl Ecol 23:573–583
Coughenour MB (1985) Graminoid responses to grazing by large herbivores: Adaptations, exaptations and interacting processes. Ann Mo Bot Gard 72:852–863
Coughenour MB (1990) Dwarf shrub and graminoid responses to clip**, nitrogen and water: simplified simulations of biomass and nitrogen dynamics. Ecol model (in press)
Coughenour MB, McNaughton SJ, Wallace LL, Ruess RR (1984a) Responses of nitrogen uptake, concentration and allocation in three Serengeti graminoids to clip**, water and nitrogen limitation. Bull Ecol Soc Am 65(2):141
Coughenour MB, McNaughton SJ, Wallace LL (1984b) Simulation study of Serengeti perennial graminoid responses to defoliation. Ecol Model 26:177–201
Coughenour MB, McNaughton SJ, Wallace LL (1985a) Adaptations of an African tallgrass (Hyparrhenia filipendula Stapf.) to defoliation and limitations of nutrients and water. Oecologia 68:50–56
Coughenour MB, McNaughton SJ, Wallace LL (1985b) Responses of an African graminoid (Themeda triandra Forsk.) to frequent defoliation, nitrogen and water—a limit of adaptation to herbivory. Oecologia 68:105–110
Coughenour MB, Ellis JE, Swift DM, Coppock DL, Galvin K, McCabe JT, Hart TC (1985c) Energy extraction and use in a nomadic pastoral ecosystem. Science 230:619–624
Coughenour MB, Coppock DL, Rowland M, Ellis JE (1990) Dwarf shrub ecology in Kenya's arid zone: Indigofera spinosa as a key forage resource. J Arid Environ (in press)
Detling JK (1988) Grasslands and savannas: regulation of energy flow and nutrient cycling by herbivores. In: Pomeroy LR, Alberts JJ (eds) Concepts of Ecosystem Ecology. Springer, Berlin Heidelberg New York, pp 131–148
Detling JK, Dyer MI, Winn DT (1979) Net photosynthesis, root respiration and regrowth of Bouteloua gracilis following simulated grazing. Oecologia 41:127–134
Herlocker DJ, Dolan RA (1980) Primary productivity of the herb layer and it's relation to rainfall. Integrated Project in Arid Lands Technical Report A-3. Man and the Biosphere Program, Nairobi
Jameson D (1963) Responses of individual plants to harvesting. Bot Rev 29:532–594
Jaramillo VJ, Detling JK (1988) Grazing history, defoliation, and competition: effects on shortgrass production and nitrogen accumulation. Ecology 69:1599–1608
Little MA, Dyson-Hudson N, Dyson-Hudson R, Ellis JE, Swift DM (1984) Human biology and the development of an ecosystem approach. In: Moran EF (ed) The Ecosystem Approach in Anthropology. Westview Press, Boulder, Colorado, pp 103–121
McCabe JT, Ellis JE (1987) Beating the odds in arid Africa. Nat Hist 96:32–41
McNaughton SJ (1979) Grazing as an optimization process: grassungulate relationships in the Serengeti. Am Nat 113:691–703
McNaughton SJ, Wallace LL, Coughenour MB (1983) Plant adaptation in an ecosystem context: effects of defoliation, nitrogen, and water on growth of an African C4 sedge. Ecology 64:307–318
McNaughton SJ, Chapin FS III (1985) Effects of phosphorous nutrition and defoliation on C4 graminoids from the Serengeti Plains. Ecology 66:1617–1629
Milchunas DG, Sala OE, Lauenroth WK (1988) A generalized model for the effects of grazing by large herbivores on grassland community structure. Am Nat 132:87–106
Mugambi M (1989) Responses of an African dwarf shrub (Indigofera spinosa) to competition, water stress, and defoliation: PhD. Dissertation, Colorado State University, Ft. Collins
Ruess RW (1984) Nutrient movement and grazing: experimental effects of clip** and nitrogen source on nutrient uptake in Kyllinga nervosa. Oikos 43:183–188
Ruess RW, McNaughton SJ, Coughenour MB (1983) The effects of clip**, nitrogen source and nitrogen concentration on the growth responses and nitrogen uptake of an East African sedge. Oecologia 59:253–261
Semb G, Robinson JBD (1969) The natural nitrogen flush in different arable soils and climates in East Africa. E Afr Agr For J 34:350–370
Wallace LL, McNaughton SJ, Coughenour MB (1983) Compensatory photosynthetic responses of three African grassland species to different fertilization, watering, and simulated grazing regimes. Bot Gaz 145:151–156
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Coughenour, M.B., Detling, J.K., Bamberg, I.E. et al. Production and nitrogen responses of the African dwarf shrub Indigofera spinosa to defoliation and water limitation. Oecologia 83, 546–552 (1990). https://doi.org/10.1007/BF00317208
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00317208