Progress 09/01/99 to 08/31/04
Outputs
OBJECTIVES: (1) Determine the relationship among plant diversity (taxa and functional form), plant community production and plant community stability; and (2) Determine the degree to which this relationship is driven by the interactions between the size, uptake rates, and scaling properties of plant root systems and the supply rate, mobility, and spatial distribution of soil nutrients. APPROACH: Two set of factorial experiments with the following factors. Factor 1 (common for both experiments) consisted of either N or P fertilization. Factor 2 (common for both experiments) consisted of high or low levels of N or P fertilization. Factor 3 (common for both experiments) consisted of two fertilization spatial distribution patterns for N and P: H=0.2 characterized by high spatial variability at short scales and low spatial variability at large scales, and H=0.8 low, short scale, and high, large scale, spatial variability. Factor 4 consisted of: (a) Experiment 1: 1, 2, 5, 10
or 20 plant species taxa randomly selected, with replacement, from 60 dominant grasses and forbs from the Great Plains; (2) Experiment 2: 1, 2, 3, 4 or 5 plant functional forms. The number of species taxa within each functional form treatment were 1, 2, 5, 10, and 20 respectively to allow for direct comparisons between results from experiments 1 and 2 (species taxa diversity vs. functional form diversity). Functional forms and specific plant species taxa within each functional form were selected randomly, with replacement, from the same list of species as in Experiment 1. SUMMARY OF RESULTS: Principal components (PC) decomposed the interaction between species diversity (SD) and functional form (FFD) diversity. PC1 represented the combined effects of SD and FFD while PC2 represented the unique effects of FFC. Above ground production (ANPP) was positively correlated with PC1 in the N treatments (R2=0.12, P<0.0001). In the P treatments ANPP was correlated with both PC1 and PC2 (R2=0.15
with P<0.0001 for PC1 and P<0.002 for PC2). The low N and P levels reduced ANPP but did not have an effect on diversity. There was a minimal H effect, with ANPP, SPD, and FFD been higher under H=0.8 than H=0.2 (P<0.1). The yearly variability in ANPP was reduced by SPD and FFD in both the N and P treatments (CV=0.51-0.097*PC1, R2=0.27 P<0.0001 for N; and CV=0.53-0.092*PC1, R2=0.26 P<0.0001 for P). Similarly minimum ANPP increased with SPD and FFD (Min ANPP=144+39*PC1, R2=0.31, P<0.0001 for N; and Min ANPP=117+31*PC1, R2=0.42, P<0.0001 for P). ANPP in the low and high N treatments was negatively correlated with root lateral spread (beta) and positively correlated with root density (nu) and relative growth rate (RGR). The additional ANPP in the high N treatment was positively correlated with N and P root uptake rates (Imax-N, Imax-P) and root to shoot ratio (R:S) and negatively correlated with N and P use efficiency (NUE and PUE). In the P treatments ANPP was positively correlated with
NUE and Imax-P. In the high P treatment ANPP was also positively correlated with R:S while in the low P treatments ANPP was positively correlated with RGR and negatively correlated with Imax-N.
Impacts
Results from this research should provide managers and policy makers with: (1) A scientific basis for policies designed to preserve and manage biodiversity on public and private lands. (2) A more accurate risk assessment of how a potential reduction in plant biodiversity can affect long term ecosystem productivity and stability.
Publications
- Fitzpatrick. C.P., K. K. Sedivec, and M. E. Biondini. 2003. Effects of wild fire on wooded draw composition in western North Dakota. Society for Range Management Annual Meeting, Casper WY (Abstract).
- Biondini, M. 2003. Answer to Xiaoxian Zhang comments on A three dimensional spatial model for plant competition in a heterogeneous soil environment. Ecological Modelling 166:187-189.
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Progress 10/01/02 to 09/30/03
Outputs
In the experiments involving species taxa diversity, both the low and high N treatments showed a quadratic relationship between species taxa diversity and above ground net primary production (ANPP). Peak ANPP was achieved at about 9 to 11 species. The P treatment showed no response differences between the high and low P levels, but like the N treatment there was a peak ANPP attained this time at about 11 to 13 species. The functional form diversity experiments showed a different pattern. The high N and both P treatments showed a linear response of ANPP to species functional form diversity. The low N treatment, on the other hand, responded in a similar way to its counterpart in the species taxa diversity experiments: a quadratic response with peak ANPP attained when 6 distinct species functional forms were present. There were no ANPP responses to the spatial patterns of soil nutrients. After 4 years of field measurements we have found that: (1) ANPP responds positively
to species taxa diversity up to a level of 9 to 13 species and declines afterward (the hypothesized saturation effect) with the response being contingent upon the level and type of nutrient supply; (2) Species functional form diversity, on the other hand, tends to generate a linear response in ANPP (the hypothesized linear response) with the specifics of the response again being contingent upon the level and type of nutrient supply; and (3) The community level combinations of plant growth rates, nutrient use efficiency, root architecture, and root physiology that correlate well with ANPP differ between the high and low nutrient treatments as well as between the N and P treatments.
Impacts
Results from this research should provide managers and policy makers with: (1) A scientific basis for policies designed to preserve and manage biodiversity on public and private lands. (2) A more accurate risk assessment of how a potential reduction in plant biodiversity can affect long term ecosystem productivity and stability.
Publications
- Sedevic, K. and M.E. Biondini. 2002. Sharp-tailed grouse monitoring, population trends, and visual obstruction reading monitoring on western North Dakota grasslands. Forest Service 01-CS-110118-00-070. 20p.
- Biondini, M. 2003. Answer to Xiaoxian Zhang's comments on A three dimensional spatial model for plant competition in a heterogeneous soil environment. Ecological Modelling 166:187-189.
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Progress 10/01/01 to 09/30/02
Outputs
In the summer of 2002 we conducted measurements of above-ground net primary production (ANPP) in the high (third year measurements) and low (second year measurements) nutrient treatments of experiment 1 (200 plots in total). We also conducted NPP measurements in experiment 2 (200 plots) but the data has not yet been analyzed. In the high nutrient treatment results followed a similar pattern to the one observed in 2001: (a) increase levels of ANPP with species taxa diversity in both the N and P treatments; and (b) no response to the spatial distribution patterns of N or P. In the low nutrient treatment results followed a somewhat different pattern: there was a significant increase of ANPP in response to species taxa diversity but only in the P treatment. As in the case of the high nutrient treatment there were no ANPP responses to the spatial patterns of soil nutrients. After 3 years of field measurements we have found that: (1) in general ANPP responds positively to
species taxa diversity but the response is contingent upon the level and type of nutrient supply; and (2) the community level combinations of plant growth rates, nutrient use efficiency, root architecture, and root physiology that correlate well with ANPP differ between the high and low nutrient treatments as well as between the N and P treatments. Plans for the coming year: in 2003 we will add 2 new sets of field measurements designed to investigate the relationship among species taxa or functional form diversity, mycorrhizal infection, and soil nitrate leaching.
Impacts
Results from this research should provide managers and policy makers with: (1) A scientific basis for policies designed to preserve and manage biodiversity in public an private lands. (2) A more accurate risk assessment of how a potential reduction in plant biodiversity can affect long term ecosystem productivity and stability.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
Objectives: (1) Determine the relationship among plant diversity (taxa and functional form), plant community production and plant community stability; and (2) Determine the degree to which this relationship is driven by the interactions between the size, uptake rates, and scaling properties of plant root systems and the supply rate, mobility, and spatial distribution of soil nutrients. Results: In 2000 we completed the planting of experiment 2. The experiment consists of 200 plots organized as a completely randomized factorial design with 4 factors and 5 replications. Factor 1 represents functional form diversity: 1 functional form (FF) and 1 species (sp) per FF, 2 FF and 1 sp per FF, 3 FF and 2 sp per FF, 4 FF and 3 sp per FF, and 5 FF and 4 sp per FF. The number of species taxa within each functional form treatment were 1, 2, 5, 10, and 20 respectively. This arrangement allows for direct comparisons between results from experiments 1 and 2 (species taxa diversity
vs. functional form diversity) by avoiding the confounding factor of different number species taxa per functional form treatment. Factor 2 consists of the application of either N or P. Factor 3 consists of 2 mean supply rates of N and P, High: 20 g/m2 of N and 4 g/m2 of P; Low: 2 g/m2 of N and 0.4 g/m2 of P. Factor 4 consists of 2 spatial patterns characterized by fractal scaling constants of H=0.2 and H=0.8. H=0.2 is characterized by high spatial variability at short scales and low spatial variability at large scales, while H=0.8 has the opposite structure: low, short scale, and high, large scale, spatial variability. In the summer of 2001 we measured above and below ground biomass, net primary production, and total plant N and P uptake in experiment 1. Results show a definite increase in total above ground biomass productions with species taxa diversity under both the N & P treatments. The spatial patterns of N application did not affect results, in fact the regression line were the
same for both treatments. The spatial patterns of P applications, however, did affect plant responses to species taxa diversity: biomass was higher under H=0.8 than under H=0.2 for high species diversity but lower for low species diversity. Plans for the Coming Year: In the Fall of 2002 we will sample for the first time all the 400 plots of experiments 1 and 2.
Impacts
Results from this research should provide managers and policy makers with: (1) A scientific basis for policies designed to preserve and manage biodiversity in public an private lands. (2) A more accurate risk assessment of how a potential reduction in plant biodiversity can affect long term ecosystem productivity and stability.
Publications
- Biondini, M. E. 2001. A three dimensional spatial model for plant competition in a heterogeneous soil environment. Ecological Modelling 142:189-225.
- Levang-Brilz, N. and M.E. Biondini. 2001. Growth rate, root development and nutrient uptake of 55 plant species from the Great Plains Grasslands, U.S.A. Plant Ecology (in press).
- Johnson, H. and M.E. Biondini. 2001. Root morphological plasticity and nitrogen uptake of 59 plant species from the Great Plains grasslands, U.S.A. Basic and Applied Ecology 2:127-143.
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Progress 10/01/99 to 09/30/00
Outputs
Objectives:(1) Determine the relationship among plant diversity,plant community production and plant community stability; and (2) Determine the degree to which this relationship is driven by the interactions between the size, uptake rates, and scaling properties of plant root systems and the supply rate, mobility, and spatial distribution of soil nutrients. In 1999 we completed the planting of experiment 1. The experiment consist of 200 plots organized as a completely randomized factorial design with 4 factors and 5 replications. Factor 1 represents species taxa diversity and consisted of treatments with 1, 2, 6, 12 or 20 plant species taxa randomly drawn, without replacement, from a list of 55 species common to the Great Plains grasslands. Factor 2 consisted of the application of either N or P. Factor 3 consist of 2 mean supply rates of N and P, High: 20 g/m2 of N and 4 g/m2 of P; Low: 2 g/m2 of N and 0.4 g/m2 of P. Factor 4 consist of 2 spatial patterns
characterized by fractal scaling constants of H=0.2 and H=0.8. H=0.2 is characterized by high spatial variability at short scales and low spatial variability at large scales, while H=0.8 has the opposite structure: low, short scale, and high, large scale, spatial variability. In the summer of 2000 we conducted field measurements designed to determine above and below ground biomass, net primary production, and total plant N and P uptake in experiment 1. In addition, we (a) conducted a survey of the spatial variability of soil N and P prior to plot establishment; and (b) collected rainfall and soil moisture data on a routine basis. Field data collection was completed in September of 2000, and will be statistically analyzed in the Winter of 2001 when laboratory measurements are completed. We constructed plant functional form groups, to be used in experiment 2 (see below), using data collected in the previous USDA funding cycle (NRICGP 930051). Plants were separated into grasses and
forbs/shrubs and then classified into functional form groups with cluster analysis using the following parameters: (1) Maximum relative growth rate; (2) root:shoot ratio; (3) Saturation N and P use efficiency; (3) Saturation N and P root uptake per unit of root surface area; (4) the allometric scaling constants relating root biomass to root lateral spread, and root surface area; (5) the scaling constant that relates total root biomass to root biomass by depth; and (6) root plasticity (redirection of root growth to areas with high nutrient concentration). Experiment 2 was established in October of 2000 and consisted of another 200 plots arranged as in experiment 1. The only difference was that Factor 1 represented functional form diversity: 1 functional form (FF) and 1 species (sp) per FF , 2 FF and 1 sp per FF, 3 FF and 2 sp per FF, 4 FF and 3 sp per FF, and 5 FF and 4 sp per FF. The number of species taxa within each functional form treatment were 1, 2, 5, 10, and 20 respectively.
The design allows for direct comparisons between results from experiments 1 and 2 (species taxa diversity vs. functional form diversity) by avoiding the confounding factor of different number species taxa per functional form treatment.
Impacts
(1) A scientific basis for policies designed to preserve and manage biodiversity in public an private lands. (2) A more accurate risk assessment of how a potential reduction in plant biodiversity can affect long term ecosystem productivity and stability. This knowledge should provide policy makers with better information to evaluate the potential environmental impact of economic development programs.
Publications
- Biondini, M.E. 1999. Use of Parallel Computing in Ecological Modeling. Internet 2 Regional Conference. Fargo, North Dakota. (Abstract--Invited)
- K. Ringwall, M.E. Biondini, and C.E. Grygiel. 2000. Effects of nitrogen fertilization in leafy spurge root architecture. J. of Range Mgt. 53:228-232.
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