Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya
Identifieur interne : 001650 ( Istex/Corpus ); précédent : 001649; suivant : 001651Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya
Auteurs : George A. KeyaSource :
- Agriculture, Ecosystems and Environment [ 0167-8809 ] ; 1998.
Abstract
A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. Efforts to understand and tackle the desertification problem in this area must therefore take this fact into account.
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DOI: 10.1016/S0167-8809(98)00096-6
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Keya</name><affiliation><mods:affiliation>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</mods:affiliation></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:F60EFD26E76DB908085D72550399ED1E25DA9942</idno><date when="1998" year="1998">1998</date><idno type="doi">10.1016/S0167-8809(98)00096-6</idno><idno type="url">https://api.istex.fr/document/F60EFD26E76DB908085D72550399ED1E25DA9942/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">001650</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Corpus" wicri:corpus="ISTEX">001650</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a">Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</title><author><name sortKey="Keya, George A" sort="Keya, George A" uniqKey="Keya G" first="George A" last="Keya">George A. Keya</name><affiliation><mods:affiliation>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Agriculture, Ecosystems and Environment</title><title level="j" type="abbrev">AGEE</title><idno type="ISSN">0167-8809</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998">1998</date><biblScope unit="volume">69</biblScope><biblScope unit="issue">1</biblScope><biblScope unit="page" from="55">55</biblScope><biblScope unit="page" to="67">67</biblScope></imprint><idno type="ISSN">0167-8809</idno></series><idno type="istex">F60EFD26E76DB908085D72550399ED1E25DA9942</idno><idno type="DOI">10.1016/S0167-8809(98)00096-6</idno><idno type="PII">S0167-8809(98)00096-6</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0167-8809</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. Efforts to understand and tackle the desertification problem in this area must therefore take this fact into account.</div></front></TEI><istex><corpusName>elsevier</corpusName><author><json:item><name>George A Keya</name><affiliations><json:string>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>Grasses</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Forbs</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Dwarf shrubs</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Offtake</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Herbivores</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Desertification</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Nomads</value></json:item></subject><language><json:string>eng</json:string></language><originalGenre><json:string>Full-length article</json:string></originalGenre><abstract>A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. 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Appl. Ecol.</title></host><title>Primary production of a grassland in Nairobi National Park</title></json:item><json:item><author><json:item><name>J.E. Ellis</name></json:item><json:item><name>D.M. Swift</name></json:item></author><host><volume>41</volume><pages><last>459</last><first>450</first></pages><author></author><title>J. Range Manage.</title></host><title>Stability of African pastoral ecosystems: Alternate paradigms and implications for development</title></json:item><json:item><host><author></author></host></json:item><json:item><host><author></author></host></json:item><json:item><host><author></author></host></json:item><json:item><author><json:item><name>C.F. Hutchinson</name></json:item></author><host><volume>33</volume><pages><last>524</last><first>519</first></pages><author></author><title>J. Arid Environ.</title></host><title>The Sahelian desertification debate: A view from the American south-west</title></json:item><json:item><author><json:item><name>G.A. Keya</name></json:item></author><host><volume>66</volume><pages><last>111</last><first>101</first></pages><author></author><title>Agric. Ecosy. and Environ.</title></host><title>Effects of herbivory on the production ecology of the perennial grass Leptothrium senegalense (Kunth.) in the arid lands of northern Kenya</title></json:item><json:item><host><author></author></host></json:item><json:item><author><json:item><name>H.F. Lamprey</name></json:item><json:item><name>H. Yussuf</name></json:item></author><host><volume>10</volume><pages><last>134</last><first>131</first></pages><author></author><title>Ambio.</title></host><title>Pastoralism and desert encroachment in northern Kenya</title></json:item><json:item><host><author></author></host></json:item><json:item><host><author></author></host></json:item><json:item><author><json:item><name>W.J. Lusigi</name></json:item><json:item><name>E.R. Nkurunziza</name></json:item><json:item><name>S. Masheti</name></json:item></author><host><volume>37</volume><pages><last>548</last><first>542</first></pages><author></author><title>J. Range. Manage.</title></host><title>Forage preference of livestock in the arid lands of northern Kenya</title></json:item><json:item><author><json:item><name>S.J. McNaughton</name></json:item></author><host><volume>55</volume><pages><last>294</last><first>259</first></pages><author></author><title>Ecol. Monogr.</title></host><title>Ecology of a grazing ecosystem: The Serengeti</title></json:item><json:item><author><json:item><name>D.G. Milchunas</name></json:item><json:item><name>W.K. Lauenroth</name></json:item></author><host><volume>63</volume><pages><last>366</last><first>327</first></pages><author></author><title>Ecol. Monogr.</title></host><title>Quantitative effects of grazing on vegetation and soils over a wide range of environments</title></json:item><json:item><author><json:item><name>M.L.A. Owaga</name></json:item></author><host><volume>18</volume><pages><last>5</last><first>1</first></pages><author></author><title>Kenya. Afr. J. Ecol.</title></host><title>Primary productivity and herbage utilization by herbivores in Kaputei Plains</title></json:item><json:item><host><author></author></host></json:item><json:item><host><author></author></host></json:item><json:item><host><author></author></host></json:item><json:item><author><json:item><name>M. Westoby</name></json:item><json:item><name>B. Walker</name></json:item><json:item><name>I. Noy-meir</name></json:item></author><host><volume>42</volume><pages><last>274</last><first>266</first></pages><author></author><title>J. Range Manage.</title></host><title>Opportunistic management for rangelands not at equilibrium</title></json:item><json:item><host><author></author></host></json:item></refBibs><genre><json:string>research-article</json:string></genre><host><volume>69</volume><pii><json:string>S0167-8809(00)X0039-4</json:string></pii><pages><last>67</last><first>55</first></pages><issn><json:string>0167-8809</json:string></issn><issue>1</issue><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><title>Agriculture, Ecosystems and Environment</title><publicationDate>1998</publicationDate></host><categories><wos><json:string>science</json:string><json:string>environmental sciences</json:string><json:string>ecology</json:string><json:string>agriculture, multidisciplinary</json:string></wos><scienceMetrix><json:string>applied sciences</json:string><json:string>agriculture, fisheries & forestry</json:string><json:string>agronomy & agriculture</json:string></scienceMetrix></categories><publicationDate>1998</publicationDate><copyrightDate>1998</copyrightDate><doi><json:string>10.1016/S0167-8809(98)00096-6</json:string></doi><id>F60EFD26E76DB908085D72550399ED1E25DA9942</id><score>1.8121028</score><fulltext><json:item><extension>pdf</extension><original>true</original><mimetype>application/pdf</mimetype><uri>https://api.istex.fr/document/F60EFD26E76DB908085D72550399ED1E25DA9942/fulltext/pdf</uri></json:item><json:item><extension>zip</extension><original>false</original><mimetype>application/zip</mimetype><uri>https://api.istex.fr/document/F60EFD26E76DB908085D72550399ED1E25DA9942/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/F60EFD26E76DB908085D72550399ED1E25DA9942/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a">Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>ELSEVIER</publisher><availability><p>©1998 Elsevier Science B.V.</p></availability><date>1998</date></publicationStmt><notesStmt><note type="content">Fig. 1: Map showing location of the study area and sites.</note><note type="content">Fig. 2: (a) Monthly rainfall distribution at Kargi (eco-zone 7) during the study period; (b) monthly rainfall distribution at Ngurunit (eco-zone 6) during the study period.</note><note type="content">Fig. 3: (a) Mean graminoid standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean graminoid standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b</note><note type="content">Fig. 4: (a) Mean forb standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean forb standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Fig. 5: (a) Mean dwarf shrub standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean dwarf shrub standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Fig. 6: (a) Mean total herbaceous standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean total herbaceous standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Table 1: Vegetation type and use description of the study sites</note></notesStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a">Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</title><author xml:id="author-1"><persName><forename type="first">George A</forename><surname>Keya</surname></persName><note type="correspondence"><p>Corresponding author. Tel.: 49 651 2014538; fax: 496512013980; e-mail: Keya@uni-trier.de</p></note><affiliation>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</affiliation></author></analytic><monogr><title level="j">Agriculture, Ecosystems and Environment</title><title level="j" type="abbrev">AGEE</title><idno type="pISSN">0167-8809</idno><idno type="PII">S0167-8809(00)X0039-4</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998"></date><biblScope unit="volume">69</biblScope><biblScope unit="issue">1</biblScope><biblScope unit="page" from="55">55</biblScope><biblScope unit="page" to="67">67</biblScope></imprint></monogr><idno type="istex">F60EFD26E76DB908085D72550399ED1E25DA9942</idno><idno type="DOI">10.1016/S0167-8809(98)00096-6</idno><idno type="PII">S0167-8809(98)00096-6</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1998</date></creation><langUsage><language ident="en">en</language></langUsage><abstract xml:lang="en"><p>A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. Efforts to understand and tackle the desertification problem in this area must therefore take this fact into account.</p></abstract><textClass><keywords scheme="keyword"><list><head>Keywords</head><item><term>Grasses</term></item><item><term>Forbs</term></item><item><term>Dwarf shrubs</term></item><item><term>Offtake</term></item><item><term>Herbivores</term></item><item><term>Desertification</term></item><item><term>Nomads</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1998">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/F60EFD26E76DB908085D72550399ED1E25DA9942/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Elsevier, elements deleted: ce:floats; body; tail"><istex:xmlDeclaration>version="1.0" encoding="utf-8"</istex:xmlDeclaration><istex:docType PUBLIC="-//ES//DTD journal article DTD version 4.5.2//EN//XML" URI="art452.dtd" name="istex:docType"><istex:entity SYSTEM="gr1" NDATA="IMAGE" name="gr1"></istex:entity><istex:entity SYSTEM="gr2" NDATA="IMAGE" name="gr2"></istex:entity><istex:entity SYSTEM="gr3" NDATA="IMAGE" name="gr3"></istex:entity><istex:entity SYSTEM="gr4" NDATA="IMAGE" name="gr4"></istex:entity><istex:entity SYSTEM="gr5" NDATA="IMAGE" name="gr5"></istex:entity><istex:entity SYSTEM="gr6" NDATA="IMAGE" name="gr6"></istex:entity></istex:docType><istex:document><converted-article version="4.5.2" docsubtype="fla"><item-info><jid>AGEE</jid><aid>1320</aid><ce:pii>S0167-8809(98)00096-6</ce:pii><ce:doi>10.1016/S0167-8809(98)00096-6</ce:doi><ce:copyright year="1998" type="full-transfer">Elsevier Science B.V.</ce:copyright></item-info><head><ce:title>Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</ce:title><ce:author-group><ce:author><ce:given-name>George A</ce:given-name><ce:surname>Keya</ce:surname><ce:cross-ref refid="CORR1">*</ce:cross-ref></ce:author><ce:affiliation><ce:textfn>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</ce:textfn></ce:affiliation><ce:correspondence id="CORR1"><ce:label>*</ce:label><ce:text>Corresponding author. Tel.: 49 651 2014538; fax: 496512013980; e-mail: Keya@uni-trier.de</ce:text></ce:correspondence></ce:author-group><ce:date-received day="8" month="7" year="1997"></ce:date-received><ce:date-accepted day="5" month="2" year="1998"></ce:date-accepted><ce:abstract><ce:section-title>Abstract</ce:section-title><ce:abstract-sec><ce:simple-para>A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0<ce:hsp sp="0.25"></ce:hsp>kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1<ce:hsp sp="0.25"></ce:hsp>kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. Efforts to understand and tackle the desertification problem in this area must therefore take this fact into account.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:keywords class="keyword"><ce:section-title>Keywords</ce:section-title><ce:keyword><ce:text>Grasses</ce:text></ce:keyword><ce:keyword><ce:text>Forbs</ce:text></ce:keyword><ce:keyword><ce:text>Dwarf shrubs</ce:text></ce:keyword><ce:keyword><ce:text>Offtake</ce:text></ce:keyword><ce:keyword><ce:text>Herbivores</ce:text></ce:keyword><ce:keyword><ce:text>Desertification</ce:text></ce:keyword><ce:keyword><ce:text>Nomads</ce:text></ce:keyword></ce:keywords></head></converted-article></istex:document></istex:metadataXml><mods version="3.6"><titleInfo><title>Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</title></titleInfo><titleInfo type="alternative" contentType="CDATA"><title>Herbaceous layer production and utilization by herbivores under different ecological conditions in an arid savanna of Kenya</title></titleInfo><name type="personal"><namePart type="given">George A</namePart><namePart type="family">Keya</namePart><affiliation>Department of Geography and Geosciences, Trier University, P.O Box 3825, D-54286TrierGermany</affiliation><description>Corresponding author. Tel.: 49 651 2014538; fax: 496512013980; e-mail: Keya@uni-trier.de</description><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="Full-length article"></genre><originInfo><publisher>ELSEVIER</publisher><dateIssued encoding="w3cdtf">1998</dateIssued><copyrightDate encoding="w3cdtf">1998</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract lang="en">A three-year study was done to determine herbaceous biomass production and its utilization by herbivores in an arid zone inhabited by a largely nomadic population in northern Kenya. The indicator selected for study was aboveground live standing biomass of grasses, forbs, dwarf shrubs and the total sum biomass of these vegetation categories (total herbaceous layer). Sampling was done along grazing gradients in order to estimate the utilization levels in the arid zone 7 and the semi-arid zone 6. Mean peak standing biomass for grasses, forbs, dwarf shrubs and total herbaceous layer under non-grazed conditions was 184.4, 374.2, 1094.4 and 1504.0kg/ha in eco-zone 7, respectively. In the zone 6, mean peak standing biomass was 55.3, 98.8, 4259.1 and 4320.1kg/ha under non-grazed conditions, respectively. Results indicated graminoid removal to be respectively 57.1–99.8% and 24.2–87.2% of mean peak standing aboveground live biomass in the zone 7 and 6. Forb utilization in zone 7 was estimated to be 51.5–99.3%. Mean peak forb standing biomass however, showed a general increase on grazed sites compared to the non-grazed plot in zone 6. The corresponding utilization of the dwarf shrub layer was estimated to be in the range 40.5–80.0% and 76.6–92.3% in zone 7 and 6 respectively. Total herbaceous layer consumption of 39.3–85.3% and 74.0–90% was estimated for zone 7 and 6 respectively. These findings suggest that herbivores exert considerable control over biomass dynamics of the herbaceous layer in this zone and contribute to degradation in heavily utilised areas. Efforts to understand and tackle the desertification problem in this area must therefore take this fact into account.</abstract><note type="content">Fig. 1: Map showing location of the study area and sites.</note><note type="content">Fig. 2: (a) Monthly rainfall distribution at Kargi (eco-zone 7) during the study period; (b) monthly rainfall distribution at Ngurunit (eco-zone 6) during the study period.</note><note type="content">Fig. 3: (a) Mean graminoid standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean graminoid standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b</note><note type="content">Fig. 4: (a) Mean forb standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean forb standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Fig. 5: (a) Mean dwarf shrub standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean dwarf shrub standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Fig. 6: (a) Mean total herbaceous standing biomass along grazing gradients in eco-zone 7. NG1: non-grazed exclosure site; SG1: seasonally grazed site 14/15a; SG2: seasonally grazed site 14b; HG1: yearlong grazed site 14/30a; HG2: yearlong grazed site 5a/32a; (b) Mean total herbaceous standing biomass along grazing gradients in eco-zone 6. NG2: non-grazed exclosure site; SG3: seasonally grazed site 75b; SG4: seasonally grazed site 17b; HG3: yearlong grazed site 17bi; HG4: yearlong grazed site 74b.</note><note type="content">Table 1: Vegetation type and use description of the study sites</note><subject><genre>Keywords</genre><topic>Grasses</topic><topic>Forbs</topic><topic>Dwarf shrubs</topic><topic>Offtake</topic><topic>Herbivores</topic><topic>Desertification</topic><topic>Nomads</topic></subject><relatedItem type="host"><titleInfo><title>Agriculture, Ecosystems and Environment</title></titleInfo><titleInfo type="abbreviated"><title>AGEE</title></titleInfo><genre type="journal">journal</genre><originInfo><dateIssued encoding="w3cdtf">19980511</dateIssued></originInfo><identifier type="ISSN">0167-8809</identifier><identifier type="PII">S0167-8809(00)X0039-4</identifier><part><date>19980511</date><detail type="volume"><number>69</number><caption>vol.</caption></detail><detail type="issue"><number>1</number><caption>no.</caption></detail><extent unit="issue pages"><start>1</start><end>88</end></extent><extent unit="pages"><start>55</start><end>67</end></extent></part></relatedItem><identifier type="istex">F60EFD26E76DB908085D72550399ED1E25DA9942</identifier><identifier type="DOI">10.1016/S0167-8809(98)00096-6</identifier><identifier type="PII">S0167-8809(98)00096-6</identifier><accessCondition type="use and reproduction" contentType="copyright">©1998 Elsevier Science B.V.</accessCondition><recordInfo><recordContentSource>ELSEVIER</recordContentSource><recordOrigin>Elsevier Science B.V., ©1998</recordOrigin></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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