Publications


Submitted

Parton, WJ, Scurlock JMO, Ojima DS, Gilmanov TG, Scholes RJ, Schimel DS, Kinyamario JI.  Submitted.  Observations and modeling of biomass and soil organic matter dynamics for the grassland biome worldwide. AbstractObservations and modeling of biomass and soil organic matter dynamics for the grassland biome worldwide

Century is a model of terrestrial biogeochemistry based on relationships between climate, human management (fire, grazing), soil properties, plant productivity, and decomposition. The grassland version of the Century model was tested using observed data from 11 temperate and tropical grasslands around the world. The results show that soil C and N levels can be simulated to within ±25% of the observed values (100 and 75% of the time, respectively) for a diverse set of soils. Peak live biomass and plant production can be simulated within ± 25% of the observed values (57 and 60% of the time, respectively) for burned, fertilized, and irrigated grassland sites where precipitation ranged from 22 to over 150 cm. Live biomass can be generally predicted to within ±50% of the observed values (57% of the time). The model underestimated the live biomass in extremely high plant production years at two of the Russian sites. A comparison of Century model results with statistical models showed that the Century model had slightly higher r2 values than the statistical models. Data and calibrated model results from this study are useful for analysis and description of grassland carbon dynamics, and as a reference point for testing more physiologically based models prediction's of net primary production and biomass. Results indicate that prediction of plant and soil organic matter (C and N) dynamics requires knowledge of climate, soil texture, and N inputs.

2013

Kinyamario, JI, Squires VR.  2013.  Rangeland Ecophysiology.

2011

Macharia, PN;, Gachene CKK;, Mureithi JG;, Kinyamario JI;, Ekaya WN;, Thuranira EG.  2011.  The effect of introduced forage legumes on improvement of soil fertility in natural pastures of semi-arid rangelands of Kajiado District, Kenya. Abstract

A two phase study was carried out from 2002 to 2005 in the semi-arid rangelands of Kajiado District, Kenya to determine the effect of introduced forage legumes on soil fertility improvement of natural pastures. During legume evaluation phase, Neonotonia wightii (Glycine), Macroptilium atropurpureum (Siratro), Lablab purpureus cv. Rongai (Dolichos), Mucuna pruriens (Velvet bean) and Stylosanthes scabra var. Seca (Stylo) were screened for adaptability and growth performance under the semi-arid conditions for two years. Results of soil analysis showed there were significant increases in soil pH (4.92 to 5.36), organic carbon (1.17 to 2.57%) , nitrogen (0.17 to 0.22%) and potassium (1.23 to 1.68 me%) probably due to the large amounts of organic residues produced by the legumes (particularly Glycine, Siratro and Stylo which are perennials). The calcium content decreased significantly from 7.97 to 4.50 me% (which was attributed to plant uptake) while the decrease of phosphorus was not significant. During the second phase of study for 1½ years Glycine, Siratro and Stylo were integrated into natural pastures. The results showed that only the soil pH significantly increased from 5.23 to 5.31 while all the other nutrients decreased results, which were attributed to production of less organic residues by the legumes compared to the residues produced during the legume evaluation phase. The study concluded that Glycine, Siratro and Stylo were capable of improving the soil fertility of semi-arid natural pastures only if the respective dry matter production was 10.31, 7.81 and 3.52 tha-1, amounts which were able to produce large amounts of organic residues.

2009

Otuoma, J, Kinyamario J, Ekaya W, Kshatriya M, Nyabenge M.  2009.  Effects of human–livestock–wildlife interactions on habitat in an eastern Kenya rangeland.

2008

Awitia, AO, Walsha MG, Shepherd KD, Kinyamario J.  2008.  Soil condition classification using infrared spectroscopy: A proposition for assessment of soil condition along a tropical forest-cropland chronosequence. AbstractWebsite

Abstract Soil fertility depletion in smallholder agricultural systems in sub-Saharan Africa presents a formidable challenge both for food production and environmental sustainability. A critical constraint to managing soils in sub-Saharan Africa is poor targeting of soil management interventions. This is partly due to lack of diagnostic tools for screening soil condition that would lead to a robust and repeatable spatially explicit case definition of poor soil condition. The objectives of this study were to: (i) evaluate the ability of near infrared spectroscopy to detect changes in soil properties across a forest-cropland chronosequence; and (ii) develop a heuristic scheme for the application of infrared spectroscopy as a tool for case definition and diagnostic screening of soil condition for agricultural and environmental management. Soil reflectance was measured for 582 topsoil samples collected from forest-cropland chronosequence age classes namely; forest, recently converted, RC (17 years) and historically converted, HC (ca.70 years). 130 randomly selected samples were used to calibrate soil properties to soil reflectance using partial least-squares regression (PLSR). 64 randomly selected samples were withheld for validation. A proportional odds logistic model was applied to chronosequence age classes and 10 principal components of spectral reflectance to determine three soil condition classes namely; “good”, “average” and “poor” for 194 samples. Discriminant analysis was applied to classify the remaining 388 “unknown” samples into soil condition classes using the 194 samples as a training set. Validation r2 values were: total C, 0.91; total N, 0.90; effective cation exchange capacity (ECEC), 0.90; exchangeable Ca, 0.85; clay content, 0.77; silt content, 0.77 exchangeable Mg, 0.76; soil pH, 0.72; and K, 0.64. A spectral based definition of “good”, “average” and “poor” soil condition classes provided a basis for an explicitly quantitative case definition of poor or degraded soils. Estimates of probabilities of membership of a sample in a spectral soil condition class presents an approach for probabilistic risk-based assessments of soil condition over large spatial scales. The study concludes that reflectance spectroscopy is rapid and offers the possibility for major efficiency and cost saving, permitting spectral case definition to define poor or degraded soils, leading to better targeting of management interventions.

PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology, 2 (1), 15-21. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology Vol. 2 (6), pp. 127-133.. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology, 2 (1), 15-21. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology Vol. 2 (6), pp. 127-133.. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology, 2 (1), 15-21. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology Vol. 2 (6), pp. 127-133.. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology, 2 (1), 15-21. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology Vol. 2 (6), pp. 127-133.. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology, 2 (1), 15-21. : EAMJ
PROF. KINYAMARIO, JENESIOI.  2008.  J. I. Kinyamario, T. P. Wang. African Journal of Environmental Science and Technology Vol. 2 (6), pp. 127-133.. : EAMJ

2007

Ngari, AN, Kinyamario JI, Ntiba MJ, Mavuti KM.  2007.  Factors affecting abundance and distribution of submerged and floating macrophytes in Lake Naivasha, Kenya. AbstractWebsite

Macrophytes have been shown to perform important ecological roles in Lake Naivasha. Consequently, various studies regarding the impact of biotic factors on the macrophytes have been advanced but related studies on environmental parameters have lagged behind. In an attempt to address this gap, sampling on floating species and submergents was carried out in eight sampling sites in 2003 to investigate how they were influenced by a set of environmental factors. Soil texture (sandy sediments; P < 0.05, regression coefficient = −0.749) and wind were the most important environmental parameters influencing the distribution and abundance of floating macrophytes. Combination of soil texture and lake-bed slope explained the most (86.3%) variation encountered in the submergents. Continuous translocation of the floating dominant water hyacinth to the western parts by wind has led to displacement of the submergents from those areas. In view of these findings, the maintenance and preservation of the steep Crescent Lake basin whose substratum is dominated by sand thus hosting most submergents remain important, if the whole functional purpose of the macrophytes is to be sustained

2006

Mnene, WN;, Ekaya WN;, Kinyamario JI;, Hanson J.  2006.  Effect of method of harvesting, storage container type and duration on seed germination of four rangeland grasses. Abstract

The study tested 2 techniques of harvesting pasture grass seed (hand stripping and cutting with stalks), 4 storage containers (Aluminium tins, Polythene, Cotton cloth and brown paper bags), and 10 post harvest periods of storage (0-72 weeks) of four species seed lots harvested in two different seasons during 2001-2002 at Kiboko, Kenya. The species were C. roxburghiana, C. ciliaris, E. superba and E. macrostachyus and seeds were stored from 0 to 72 weeks post harvest. The Germination (percentage) test using caryopses extracted with sandpaper and placed in covered Petri dishes lined with moist filter paper was used for duration of 14 days. The overall mean daily germination (percentage) was 3.61+ 0.060, ranging from 2.5percentage for C. ciliaris to 6.4percentage for E. macrostachyus. Harvesting by cutting with stalks resulted in superior seeds than by stripping them. Seeds stored in aluminium tins germinated better than those in plastic, cloth or brown paper bags. Seeds stored for less than eight weeks had lower germination percentage which then increased with storage.

2004

Olukoye, GA;, Wakhungu JW;, Wamicha, W.N.;, Kinyamario JJ;, Mwanje JL.  2004.  Livestock Versus Wildlife Ranching In Kenyan Rangelands: A Case Study Of Laikipia District Ranches..

2003

Macharia, PN, Kinyamario J, Ekaya WN, Gachene CKK.  2003.  Screening forage legumes for integration into natural pastures of semi-arid rangelands of Kenya.

2002

Mnene, WN;, Ekaya WN;, Kinyamario JI;, Jamnadass RH;, Hanson J;, Stuth. JW.  2002.  http://profiles.uonbi.ac.ke/wekaya/publications.

2001

Wakhungu, JW, Olukoye GA, Wamicha WN, Kinyamario JI, Mwanje JI.  2001.  Environmental impacts of livestock-wildlife ranching in Laikipia District, Kenya.

1999

Jenkinson, DS, Meredith J, Kinyamario JI, Warren GP, Wong MTF.  1999.  Estimating net primary production from measurements made on soil organic-matter. Website

1996

Ojima, DS, Parton WJ, Coughenour MB, Scurlock JMO, Kirchner TB, Kittel TGF, Van Veen JA, Kinyamario JI.  1996.  Impact of climate and atmospheric carbon dioxide changes on grasslands of the world.

1993

1992

Kinyamario, JI, Imbamba SK.  1992.  Savanna at Nairobi National Park, Nairobi. Website
Kinyamario, JI, Imbamba SK.  1992.  Dry savanna, Kenya. Website

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