Comparingthe Influence of Precipitation, Fire, and Topography

onPlant Productivity in the Tallgrass Prairie

Comparingthe Influence of Precipitation, Fire, and Topography on PlantProductivity in the Tallgrass Prairie

Theobservation is based on determining the different factors that play arole in influencing the annual rate of growth of the prairies. TheAmerican prairies are estimated to occupy an area of land of morethan 240,000 acres. It is a natural ecosystem that is a habitat formany species of birds, reptiles and insects. It is, however, vital tonote that the grassland is not only affected by natural factor butalso by human factors that result from different human activitiesthat take place in the area (Barbour, &amp Billings, 2000). One ofthe problems that is associated with the habitat is periodic firesthat destroy a huge part of the prairies, thereby causing a greatshift in the ecosystem that is sustained by the area. The factorsthat play a role in determining the annual growth rate of plants inthe prairies are properly measured through the analysis of the plantbiomass per area (Collins et al., 2012). This is basically the weightof a plant after it has been cut and dried so as to remove any formof moisture that could be contained in the plant. Biomass ispreferred as an indicator since it has a high probability ofproviding data that is valid and reliable. Another factor that isquite vital while trying to determine the annual growth rate of theprairies is the inclusion of all the indicators that are crucial.

Thisexperiment is quite important and interesting since it providesecologists with ways through which the factors that affect thesurvival of the prairies could be harnessed so as to increase itssustainability. The one great lesson that could be learned from theexperiment is that there are much better and cost effective methodsthat could be put into the protection of natural habitats. The onegeneral area of Biology that the experiment aims to address is waysthrough which the ecosystem could be made to be self-sustaining withlittle or no input from human activities (Collins, &amp Calabrese,2012). The specific hypothesis that the study will test is thefactors that are associated with the growth of plants in the Midwestprairies play a huge role in the survival of the grassland. Thishypothesis will be tested statistically for correlation with theindependent variables.

Materialsand methods

Thestudy shall rely on secondary data of the prairies indicating theindependent variable reports such as the total precipitation in thearea, annual burning, and 20-year burning cycle. The data for thedependent variable shall include information regarding the growthrate of the upland, lowland, grass, and forbs. The data shall rangefrom the year 1984 to 1999 (Myers, Well &amp Lorch, 2010). This16-year period shall be vital for showing any trend that may berelied upon as it relates to the influence of the independentvariables upon the dependent ones. It shall also be crucial forensuring that the hypotheses set for the experiment is properlytested.

Thestudy shall involve the testing of the following hypotheses in orderascertain whether they have an influence on the growth rate of plantsin the prairies

H0Precipitation has no influence on plant productivity in the tallgrass Prairie.

H0Firehas no influence on plant productivity in the tall grass Prairie.

H0Topographyhas no influence on plant productivity in the tall grass Prairie.

Thethree hypotheses shall be tested using correlation at 95% confidencelevel. A p-value shall be obtained, which will be key in determiningwhether the researcher will reject or fail to reject the nullhypothesis and adopt the alternative hypothesis, instead. Theresearcher will reject the null hypothesis if the p-value is nearerto 1 or -1 compared to 0, at 95% confidence level. The study shallalso compare the findings of the different hypotheses so as todetermine the one that has more influence over the others.


Theresults of the experiment conducted relied heavily on the analysisthat the researcher conducted in a bid to answer the three hypotheseshighlighted. The findings showed that the correlation coefficient(p-value) of the association between total precipitation and thelength of grass was 0.788. Since this value is nearer to positive 1than 0, we, therefore, reject the null hypothesis and state thatprecipitation has a significant influence on the length of grass(Myers et al., 2010). The results also indicated that the p-value ofthe association between precipitation and forbs was -0.189. Sincethis value is nearer to 0 than -1, it shows that precipitation has nosignificant influence on the growth of forbs.

Theresults also showed that the correlation coefficient of theassociation between annual burning and the length of grass was 0.927.Since this value is nearer to 1, it shows that the burning rate hadan influence on the length of grass in general. Another featuretested was a topographical influence on the growth rate andproductivity of plants in the prairies (Ferreira, 2011). One of thecorrelation test done between the uplands and the growth of the forbsindicated that the correlation coefficient was -0.306. Since thisvalue is closer to 0 than -1, it shows that the upland feature has nosubstantial effect on the growth rate of the forbs in the grassland.The lowland feature was also tested for correlation with the growthof grass it clearly showed a correlation coefficient value of 0.992showing a very big influence of upland on the growth rate of thegrass in the area.


Thefindings clearly show that the different independent variablesprecipitation, burning and topography have different responses to thegrowth and productivity of plants in the prairies. For instance, thetopography is seen to have a great level of influence on the growthof grass more than fire and precipitation. Fire also appears to havea high level of influence on the growth and productivity of plants inthe grassland compared to precipitation. This comes as a surprise tomany people who would believe that precipitation is the most vitalfactor in the growth and development of plants in the prairies.Another element that may be established from the experiment is thefact that different plants respond differently to the factors in thegrassland. For instance, while precipitation seems to have a positiveinfluence on the growth of grass in the prairies, it fails to haveany significant influence on the growth of the forbs. In fact, thelittle influence that it has on the growth of the forbs is negative.This is interpreted as the more the rainfall, the lower the rate ofgrowth of the forbs.

Fireis an important factor in the growth rate and productivity of plantsin the prairies. It indicates that the more the fire, the higher therate of growth of plants in the prairies. This is because the burntdeposits of the plants do provide the much-needed nutrients to aid inthe growth of other plants found in the grassland. However, theburning needs to be hugely controlled otherwise, it will greatlyinterfere with the natural ecosystem found in the ecosystem, a factorthat could have far-reaching consequences on the survival of thegrassland.

Fromthe findings obtained in the analysis, it is clear that they supportthe hypothesis highlighted and go a long way in attempting to answerthem. In all the three hypotheses, we reject the null hypothesis andstate that precipitation, fire, and topography have an influence onplant productivity in the tall grass prairie. The results go a longway in showing that proper measures need to be taken to ensure thatthese three elements need not be affected so that the productivity ofplants in the tall grass prairies will be sustained. The one questionthat remains unexplored is why there is a difference of the effect ofthe three factors upon grass and forbs. There is, therefore, the needfor further research in the area so as to determine the main reasonthat could be behind such a difference. Table 1.0 below shows theassociation between precipitation and the growth of grass in theprairies between the years 1984 and 1999.

Figure1.0 Precipitation and growth of grass in the prairies.


Barbour,M. G. &amp Billings, W. D. (2000). North American TerrestrialVegetation. (2nd ed.). : Cambridge University Press.

Collinset al. (2012). Stability of tallgrass prairie during a 19-yearincrease in growing season precipitation. FunctionalEcology, 26,1450-1459.

Collins,S. L., &amp Calabrese, L. B. (2012). Effects of fire, grazing andtopographic variation on vegetation structure in tallgrassprairie.&nbspJournalof Vegetation Science,&nbsp23(3),563-575.

Ferreira,D. F. (2011). Sisvar: a computer statistical analysis system.Ciênciae agrotecnologia,&nbsp35(6),1039-1042.

Myers,J. L., Well, A., &amp Lorch, R. F. (2010).&nbspResearchdesign and statistical analysis.Routledge.