Termite mounds as islands: woody plant assemblages relative to termitarium size and soil properties

Joseph, Grant S., Seymour, Colleen L., Cumming, Graeme S., Cumming, David H.M., and Mahlangu, Zacheus (2013) Termite mounds as islands: woody plant assemblages relative to termitarium size and soil properties. Journal of Vegetation Science, 24 (4). pp. 702-711.

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Abstract

Questions: We investigated whether soils of small mounds resembled large mound or matrix soils, whether changes in plant composition reflected changes in soils, and the sequence in which plants colonize and disappear from mounds of increasing size.

Location: Miombo woodland in northwest Zimbabwe.

Methods: Macrotermitinae termitaria vary in size and soil nutrient concentrations, harbouring distinct woody plant assemblages, making them foci for plant and animal diversity, and also influencing primary, secondary and tertiary productivity. In spite of the importance of termitaria to heterogeneity and diversity, no studies have investigated changes in plant species assemblages as mound surface area increases to the point where mound vegetation is distinct from that of the matrix. We compared woody plant assemblages on 43 matrix plots with 95 Macrotermes termitaria across a range of surface areas, using ANOSIM, cluster analysis and MDS ordination. We compared soil nutrients, pH and clay, from ten large and ten small termitaria, and ten matrix sites. We also assessed how relative representation of large mound or matrix indicator species changed with mound area.

Results: Change was apparent even at mound sizes of >10 m2, where both soils and plant assemblages on mounds were significantly different to those of the matrix. Plant assemblages fell into two main groups at 20% similarity; the first comprised of matrix plots, mounds <10 m2 and some mounds between 10 and 30 m2; the second, the remainder of the mounds between 10 and 30 m2 and all mounds >30 m2. At 40% similarity, four groups emerged: matrix, mounds <10 m2, mounds 10-30 m2 and mounds >30 m2. Woody plant composition changed gradually as mound area increased. On termitaria <10 m2, only 25% of indicators were mound indicator species, but on mounds between 10 and 30 m2 in size, 62.5% were mound indicators. On termitaria >30 m2 in surface area, only mound indicator species were found.

Conclusions: Through termite activities in concentrating nutrients and clay, termitaria provide habitat for species usually excluded from the matrix. The process of mound building and the nature of the plants that establish on them seem to establish a positive feedback for establishment of other non-woodland matrix species.

Item ID: 40951
Item Type: Article (Refereed Research - C1)
Keywords: biodiversity, indicator species, macrotermes, miombo, savanna tree patch dynamics, termite mound
ISSN: 1654-1103
Funders: National Research Foundation of South Africa, Southern African Develpoment Community, DST/NRF Centre of Excellence at the Percy FitzPatrick Institute
Date Deposited: 18 Nov 2015 00:24
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050104 Landscape Ecology @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060202 Community Ecology (excl Invasive Species Ecology) @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060299 Ecology not elsewhere classified @ 34%
SEO Codes: 96 ENVIRONMENT > 9613 Remnant Vegetation and Protected Conservation Areas > 961308 Remnant Vegetation and Protected Conservation Areas at Regional or Larger Scales @ 50%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
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