Defoliation and woody plant (Prosopis glandulosa) seedling regeneration: Potential vs realized herbivory tolerance

Jake F. Weltzin, Steve Archer, Rodney K. Heitschmidt

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Herbivory by rodents, lagomorphs and insects may locally constrain woody plant seedling establishment and stand development. Recruitment may therefore depend either upon plant tolerance of herbivory, or low herbivore abundance, during seedling establishment. We tested potential herbivory tolerance by quantifying growth, biomass allocation, and survival of defoliated Prosopis glandulosa seedlings under optimal abiotic conditions in the absence of competition. Realized tolerance was assessed by clipping seedlings of known age grown in the field with and without herbaceous competition. At 18-d (= 'young') or 33-d (= 'old') of age, seedlings in the growth chamber were clipped just above the first (cotyledonary) node, above the fourth node, or were retained as non-clipped controls. Potential tolerance to defoliation was high and neither cohort showed evidence of meristematic limitations to regeneration. Clipping markedly reduced biomass production relative to controls, especially belowground, but survival of seedlings defoliated 5 times was still ≥75%. Contrary to expectations, survival of seedlings defoliated above the cotyledonary node 10 times was greater (P < 0.10) for 'young' (75%) than 'old' (38%) seedlings. Under field conditions, survival of defoliated 11-month-old P glandulosa seedlings was ≤59% after one defoliation and only ≤ 13% after six defoliations. Results indicate P. glandulosa is potentially tolerant of repeated shoot removal early in its life cycle. Seedling tolerance to defoliation under field conditions therefore appears dependent upon abiotic stresses or resource limitations rather than a lack of intrinsic adaptations for shoot replacement or a depletion of the seedlings' bud bank. Curtailment of root growth, a consequence of top removal observed in the growth chamber experiment, may reduce the capacity of P. glandulosa seedlings to acquire soil resources needed for meristem activation and shoot growth under field conditions. The importance of resource availability to post-defoliation regeneration was implicated in the field experiment, where survival, shoot elongation, and aboveground productivity of clipped seedlings was greatest in plots without herbaceous interference. In light of the marked increases in P glandulosa abundance in grasslands in recent history, our results suggest that (1) utilization of Prosopis seedlings by herbivores may be infrequent or sporadic, (2) Periodic episodes of seed production and germination may satiate herbivore populations, and/or (3) Prosopis seedling establishment occurs during periods of low herbivore density.

Original languageEnglish (US)
Pages (from-to)127-135
Number of pages9
JournalPlant Ecology
Volume138
Issue number2
DOIs
StatePublished - 1998
Externally publishedYes

Fingerprint

Prosopis glandulosa
defoliation
woody plant
woody plants
herbivory
herbivores
regeneration
tolerance
seedling
seedlings
herbivore
seedling establishment
clipping
shoot
Prosopis
shoots
growth chambers
lagomorph
seed productivity
shoot growth

Keywords

  • Browsing
  • Clipping
  • Competition
  • Honey mesquite
  • Survival
  • Texas
  • Top removal

ASJC Scopus subject areas

  • Forestry
  • Plant Science
  • Ecology

Cite this

Defoliation and woody plant (Prosopis glandulosa) seedling regeneration : Potential vs realized herbivory tolerance. / Weltzin, Jake F.; Archer, Steve; Heitschmidt, Rodney K.

In: Plant Ecology, Vol. 138, No. 2, 1998, p. 127-135.

Research output: Contribution to journalArticle

@article{016721ac5db8400597ab1f40066f7def,
title = "Defoliation and woody plant (Prosopis glandulosa) seedling regeneration: Potential vs realized herbivory tolerance",
abstract = "Herbivory by rodents, lagomorphs and insects may locally constrain woody plant seedling establishment and stand development. Recruitment may therefore depend either upon plant tolerance of herbivory, or low herbivore abundance, during seedling establishment. We tested potential herbivory tolerance by quantifying growth, biomass allocation, and survival of defoliated Prosopis glandulosa seedlings under optimal abiotic conditions in the absence of competition. Realized tolerance was assessed by clipping seedlings of known age grown in the field with and without herbaceous competition. At 18-d (= 'young') or 33-d (= 'old') of age, seedlings in the growth chamber were clipped just above the first (cotyledonary) node, above the fourth node, or were retained as non-clipped controls. Potential tolerance to defoliation was high and neither cohort showed evidence of meristematic limitations to regeneration. Clipping markedly reduced biomass production relative to controls, especially belowground, but survival of seedlings defoliated 5 times was still ≥75{\%}. Contrary to expectations, survival of seedlings defoliated above the cotyledonary node 10 times was greater (P < 0.10) for 'young' (75{\%}) than 'old' (38{\%}) seedlings. Under field conditions, survival of defoliated 11-month-old P glandulosa seedlings was ≤59{\%} after one defoliation and only ≤ 13{\%} after six defoliations. Results indicate P. glandulosa is potentially tolerant of repeated shoot removal early in its life cycle. Seedling tolerance to defoliation under field conditions therefore appears dependent upon abiotic stresses or resource limitations rather than a lack of intrinsic adaptations for shoot replacement or a depletion of the seedlings' bud bank. Curtailment of root growth, a consequence of top removal observed in the growth chamber experiment, may reduce the capacity of P. glandulosa seedlings to acquire soil resources needed for meristem activation and shoot growth under field conditions. The importance of resource availability to post-defoliation regeneration was implicated in the field experiment, where survival, shoot elongation, and aboveground productivity of clipped seedlings was greatest in plots without herbaceous interference. In light of the marked increases in P glandulosa abundance in grasslands in recent history, our results suggest that (1) utilization of Prosopis seedlings by herbivores may be infrequent or sporadic, (2) Periodic episodes of seed production and germination may satiate herbivore populations, and/or (3) Prosopis seedling establishment occurs during periods of low herbivore density.",
keywords = "Browsing, Clipping, Competition, Honey mesquite, Survival, Texas, Top removal",
author = "Weltzin, {Jake F.} and Steve Archer and Heitschmidt, {Rodney K.}",
year = "1998",
doi = "10.1023/A:1009743130922",
language = "English (US)",
volume = "138",
pages = "127--135",
journal = "Plant Ecology",
issn = "1385-0237",
publisher = "Springer Netherlands",
number = "2",

}

TY - JOUR

T1 - Defoliation and woody plant (Prosopis glandulosa) seedling regeneration

T2 - Potential vs realized herbivory tolerance

AU - Weltzin, Jake F.

AU - Archer, Steve

AU - Heitschmidt, Rodney K.

PY - 1998

Y1 - 1998

N2 - Herbivory by rodents, lagomorphs and insects may locally constrain woody plant seedling establishment and stand development. Recruitment may therefore depend either upon plant tolerance of herbivory, or low herbivore abundance, during seedling establishment. We tested potential herbivory tolerance by quantifying growth, biomass allocation, and survival of defoliated Prosopis glandulosa seedlings under optimal abiotic conditions in the absence of competition. Realized tolerance was assessed by clipping seedlings of known age grown in the field with and without herbaceous competition. At 18-d (= 'young') or 33-d (= 'old') of age, seedlings in the growth chamber were clipped just above the first (cotyledonary) node, above the fourth node, or were retained as non-clipped controls. Potential tolerance to defoliation was high and neither cohort showed evidence of meristematic limitations to regeneration. Clipping markedly reduced biomass production relative to controls, especially belowground, but survival of seedlings defoliated 5 times was still ≥75%. Contrary to expectations, survival of seedlings defoliated above the cotyledonary node 10 times was greater (P < 0.10) for 'young' (75%) than 'old' (38%) seedlings. Under field conditions, survival of defoliated 11-month-old P glandulosa seedlings was ≤59% after one defoliation and only ≤ 13% after six defoliations. Results indicate P. glandulosa is potentially tolerant of repeated shoot removal early in its life cycle. Seedling tolerance to defoliation under field conditions therefore appears dependent upon abiotic stresses or resource limitations rather than a lack of intrinsic adaptations for shoot replacement or a depletion of the seedlings' bud bank. Curtailment of root growth, a consequence of top removal observed in the growth chamber experiment, may reduce the capacity of P. glandulosa seedlings to acquire soil resources needed for meristem activation and shoot growth under field conditions. The importance of resource availability to post-defoliation regeneration was implicated in the field experiment, where survival, shoot elongation, and aboveground productivity of clipped seedlings was greatest in plots without herbaceous interference. In light of the marked increases in P glandulosa abundance in grasslands in recent history, our results suggest that (1) utilization of Prosopis seedlings by herbivores may be infrequent or sporadic, (2) Periodic episodes of seed production and germination may satiate herbivore populations, and/or (3) Prosopis seedling establishment occurs during periods of low herbivore density.

AB - Herbivory by rodents, lagomorphs and insects may locally constrain woody plant seedling establishment and stand development. Recruitment may therefore depend either upon plant tolerance of herbivory, or low herbivore abundance, during seedling establishment. We tested potential herbivory tolerance by quantifying growth, biomass allocation, and survival of defoliated Prosopis glandulosa seedlings under optimal abiotic conditions in the absence of competition. Realized tolerance was assessed by clipping seedlings of known age grown in the field with and without herbaceous competition. At 18-d (= 'young') or 33-d (= 'old') of age, seedlings in the growth chamber were clipped just above the first (cotyledonary) node, above the fourth node, or were retained as non-clipped controls. Potential tolerance to defoliation was high and neither cohort showed evidence of meristematic limitations to regeneration. Clipping markedly reduced biomass production relative to controls, especially belowground, but survival of seedlings defoliated 5 times was still ≥75%. Contrary to expectations, survival of seedlings defoliated above the cotyledonary node 10 times was greater (P < 0.10) for 'young' (75%) than 'old' (38%) seedlings. Under field conditions, survival of defoliated 11-month-old P glandulosa seedlings was ≤59% after one defoliation and only ≤ 13% after six defoliations. Results indicate P. glandulosa is potentially tolerant of repeated shoot removal early in its life cycle. Seedling tolerance to defoliation under field conditions therefore appears dependent upon abiotic stresses or resource limitations rather than a lack of intrinsic adaptations for shoot replacement or a depletion of the seedlings' bud bank. Curtailment of root growth, a consequence of top removal observed in the growth chamber experiment, may reduce the capacity of P. glandulosa seedlings to acquire soil resources needed for meristem activation and shoot growth under field conditions. The importance of resource availability to post-defoliation regeneration was implicated in the field experiment, where survival, shoot elongation, and aboveground productivity of clipped seedlings was greatest in plots without herbaceous interference. In light of the marked increases in P glandulosa abundance in grasslands in recent history, our results suggest that (1) utilization of Prosopis seedlings by herbivores may be infrequent or sporadic, (2) Periodic episodes of seed production and germination may satiate herbivore populations, and/or (3) Prosopis seedling establishment occurs during periods of low herbivore density.

KW - Browsing

KW - Clipping

KW - Competition

KW - Honey mesquite

KW - Survival

KW - Texas

KW - Top removal

UR - http://www.scopus.com/inward/record.url?scp=0031698584&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031698584&partnerID=8YFLogxK

U2 - 10.1023/A:1009743130922

DO - 10.1023/A:1009743130922

M3 - Article

AN - SCOPUS:0031698584

VL - 138

SP - 127

EP - 135

JO - Plant Ecology

JF - Plant Ecology

SN - 1385-0237

IS - 2

ER -