Have southern Texas savannas been converted to woodlands in recent history?

Research output: Contribution to journalArticle

325 Citations (Scopus)

Abstract

Discrete clusters of woody plants form in herbaceous clearings following the invasion of mesquite Prosopis glandulosa var. glandulosa, an arborescent legume. The growth rate of these clusters varies with precipitation and size. A simulation model was developed in which the establishment of other woody species beneath invading Prosopis occurred within 10-15 yr. As a cluster developed around the Prosopis nucleus, species richness increased rapidly for 35-45 yr and became asymptotic at 10 species per cluster. Estimated age of the oldest Prosopis plant found in clusters was 172-217 yr, but model-derived size-age relationships predicted that 90% of clusters and mesquite plants at the site are <100 yr old. A lack of field evidence of mortality among large clusters and Prosopis plants suggests that populations are young and expanding geometrically. There was no evidence of density-dependent restrictions on recruitment or expansion. Thus, as new clusters are initiated and existing clusters expand, coalescence to continuous canopy woodlands may eventually occur. Predicted long-term mean radial trunk growth of Prosopis (0.8-1.9 mm.yr) was reasonable in comparison with short-term field measurements on Prosopis in other, more-mesic systems (2-4 mm/yr). Model output was consistent with historical observations suggesting that the conversion of savannas to woodlands in the Rio Grande Plains has been recent and coincident with both heavy grazing by livestock and seasonal shifts in precipitation that began in the late 1800s. -from Author

Original languageEnglish (US)
Pages (from-to)545-561
Number of pages17
JournalAmerican Naturalist
Volume134
Issue number4
DOIs
StatePublished - 1989
Externally publishedYes

Fingerprint

Prosopis
savanna
savannas
woodlands
woodland
history
young population
woody plant
coalescence
livestock
grazing
species richness
canopy
mortality
Prosopis glandulosa var. glandulosa
simulation
plant architecture
woody plants
tree trunk
simulation models

ASJC Scopus subject areas

  • Ecology

Cite this

Have southern Texas savannas been converted to woodlands in recent history? / Archer, Steve.

In: American Naturalist, Vol. 134, No. 4, 1989, p. 545-561.

Research output: Contribution to journalArticle

@article{41ff609a7d9e48e5a50864e4d4c15197,
title = "Have southern Texas savannas been converted to woodlands in recent history?",
abstract = "Discrete clusters of woody plants form in herbaceous clearings following the invasion of mesquite Prosopis glandulosa var. glandulosa, an arborescent legume. The growth rate of these clusters varies with precipitation and size. A simulation model was developed in which the establishment of other woody species beneath invading Prosopis occurred within 10-15 yr. As a cluster developed around the Prosopis nucleus, species richness increased rapidly for 35-45 yr and became asymptotic at 10 species per cluster. Estimated age of the oldest Prosopis plant found in clusters was 172-217 yr, but model-derived size-age relationships predicted that 90{\%} of clusters and mesquite plants at the site are <100 yr old. A lack of field evidence of mortality among large clusters and Prosopis plants suggests that populations are young and expanding geometrically. There was no evidence of density-dependent restrictions on recruitment or expansion. Thus, as new clusters are initiated and existing clusters expand, coalescence to continuous canopy woodlands may eventually occur. Predicted long-term mean radial trunk growth of Prosopis (0.8-1.9 mm.yr) was reasonable in comparison with short-term field measurements on Prosopis in other, more-mesic systems (2-4 mm/yr). Model output was consistent with historical observations suggesting that the conversion of savannas to woodlands in the Rio Grande Plains has been recent and coincident with both heavy grazing by livestock and seasonal shifts in precipitation that began in the late 1800s. -from Author",
author = "Steve Archer",
year = "1989",
doi = "10.1086/284996",
language = "English (US)",
volume = "134",
pages = "545--561",
journal = "American Naturalist",
issn = "0003-0147",
publisher = "University of Chicago",
number = "4",

}

TY - JOUR

T1 - Have southern Texas savannas been converted to woodlands in recent history?

AU - Archer, Steve

PY - 1989

Y1 - 1989

N2 - Discrete clusters of woody plants form in herbaceous clearings following the invasion of mesquite Prosopis glandulosa var. glandulosa, an arborescent legume. The growth rate of these clusters varies with precipitation and size. A simulation model was developed in which the establishment of other woody species beneath invading Prosopis occurred within 10-15 yr. As a cluster developed around the Prosopis nucleus, species richness increased rapidly for 35-45 yr and became asymptotic at 10 species per cluster. Estimated age of the oldest Prosopis plant found in clusters was 172-217 yr, but model-derived size-age relationships predicted that 90% of clusters and mesquite plants at the site are <100 yr old. A lack of field evidence of mortality among large clusters and Prosopis plants suggests that populations are young and expanding geometrically. There was no evidence of density-dependent restrictions on recruitment or expansion. Thus, as new clusters are initiated and existing clusters expand, coalescence to continuous canopy woodlands may eventually occur. Predicted long-term mean radial trunk growth of Prosopis (0.8-1.9 mm.yr) was reasonable in comparison with short-term field measurements on Prosopis in other, more-mesic systems (2-4 mm/yr). Model output was consistent with historical observations suggesting that the conversion of savannas to woodlands in the Rio Grande Plains has been recent and coincident with both heavy grazing by livestock and seasonal shifts in precipitation that began in the late 1800s. -from Author

AB - Discrete clusters of woody plants form in herbaceous clearings following the invasion of mesquite Prosopis glandulosa var. glandulosa, an arborescent legume. The growth rate of these clusters varies with precipitation and size. A simulation model was developed in which the establishment of other woody species beneath invading Prosopis occurred within 10-15 yr. As a cluster developed around the Prosopis nucleus, species richness increased rapidly for 35-45 yr and became asymptotic at 10 species per cluster. Estimated age of the oldest Prosopis plant found in clusters was 172-217 yr, but model-derived size-age relationships predicted that 90% of clusters and mesquite plants at the site are <100 yr old. A lack of field evidence of mortality among large clusters and Prosopis plants suggests that populations are young and expanding geometrically. There was no evidence of density-dependent restrictions on recruitment or expansion. Thus, as new clusters are initiated and existing clusters expand, coalescence to continuous canopy woodlands may eventually occur. Predicted long-term mean radial trunk growth of Prosopis (0.8-1.9 mm.yr) was reasonable in comparison with short-term field measurements on Prosopis in other, more-mesic systems (2-4 mm/yr). Model output was consistent with historical observations suggesting that the conversion of savannas to woodlands in the Rio Grande Plains has been recent and coincident with both heavy grazing by livestock and seasonal shifts in precipitation that began in the late 1800s. -from Author

UR - http://www.scopus.com/inward/record.url?scp=0024880609&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0024880609&partnerID=8YFLogxK

U2 - 10.1086/284996

DO - 10.1086/284996

M3 - Article

AN - SCOPUS:0024880609

VL - 134

SP - 545

EP - 561

JO - American Naturalist

JF - American Naturalist

SN - 0003-0147

IS - 4

ER -