Philip Ayres, F Siebert & SJ Siebert School of Environmental - - PowerPoint PPT Presentation

Philip Ayres, F Siebert & SJ Siebert School of Environmental Sciences and Development North-West University

Channel type

Browsing and animal movement Anthropogenic Landscape Geology Patch history (Floods, fire, anthropogenic) Hydrology Geomorphology Climate

Riparian Vegetation structure

Changes in vegetation structure may affect:

Riparian vegetation

Habitat & heterogeneity Transpiration Nutrient cycle Large Woody Debris Flow velocity Sedimentation Bank stability Water temperature Water table Aesthetic value

Linkage between geomorphology and Riparian vegetation

• Changes in vegetation composition is caused by a change in the combination of

geomorphological factors

• Two distinct morphological units
• MCB (Macro Channel Bank) – stable infrequently flooded (only large

floods-LID; 2000), less vegetation impact

• MCF (Macro Channel Floor) – less stable, frequently flooded, geomorphic

and hydrological dynamic, higher vegetation impact (high energy zone)

• 4 Channel types (van Coller, 1997):
• Bedrock Anastomosing (BA)
• Pool Rapid (PR)
• Mixed Anastomosing (MA )
• Braided (Br)

Mixed Anastomosing. Adapted from McLoughlin C.A. et al., 2007

Research History

Wits (1990) Wits (2004) NWU (2010)

Woody species Woody species Woody species Environmental data Environmental data Environmental data 11 Transects, 20 m wide 24 Transects, 30 m wide 4 Transects, 30 m wide (Masters Project) Transects selected in stratified-random fashion (based on geology and channel type) 6 Transects in each of the four channel types 1 Transect in each of the four channel types Belt-transect across entire MC, perpendicular to river Belt-transect across entire MC, perpendicular to river Same as CWE & Wits (2004)

• The purpose of this study (SANPark’s registered project):
• Continue with long-term monitoring of riparian vegetation
• Investigate patterns of floristic and structural change (since 2000 flood).
• The objectives of this project:
• correspond with the Post-flood Program of monitoring riparian vegetation change along
• the Sabie River

Study design: CWE and Wits (2004)

• Results and conclusions by previous studies CWE &

Wits (1990 and 2004) were considered during the analysis of the results and study design

• Parsons, M., Mcloughlin, C.A., Rountree, M.W. and Rogers, K.H. 2006. The

Biotic and Abiotic Legacy of a Large Infrequent Flood Disturbance in the Sabie River, South Africa. River Research and Applications 22: 187 – 201.

• Van Coller, A.L., Rogers, M.W. and Heritage, G.L. 1997. Linking riparian

vegetation types and fluvial geomorphology along the Sabie River within the Kruger National Park, South Africa. African Journal of Ecology 35: 194 – 212.

Study design…

Belt-transect no Latitude Longitude

2 (BA) 24°59'21.398" 31°17'13.814" 3 (PR) 24°58'54.565" 31°18'03.106" 4 (MA) 25°01'30.035" 31°47'24.932" 5 (Br) 24°58'22.848" 31°32'31.006"

• Pre-selected (SANParks

and CWE)

• Represents the four main

river channel types:

• Bedrock Anastomosing

(BA)

• Pool Rapid (PR)
• Mixed Anastomosing (MA )
• Braided (Br)

Study area:

Study design…

MCB MCB MCF MCF Belt-transect 2 (BA)

• 13 (30m x 5m) plots
• MCB = 5 plots
• MCF = 8 plots
• 24°

59'21.398" S 31° 17'13.814" O Belt-transect 3 (PR)

• 26 (30m x 5m) plots
• MCB = 4 plots
• MCF = 22 plots
• 24°

58'54.565" S 31° 18'03.106" O

Study area:

Study design…

MCB MCB MCF MCF Belt-transect 4 (MA)

• 12 (30m x 5m) plots
• MCB = 4 plots
• MCF = 8 plots
• 25°

01'30.035" S 31° 47'24.932" O Belt-transect 5 (Br)

• 12 (30m x 5m) plots
• MCB = 7 plots
• MCF = 5 plots
• 24°

58'22.848" S 31° 32'31.006" O

Study area:

Field surveying…

Data sampling (SOP):

S

Statistical Analyses

• SPSS (PASW Statistics 18, Release Version 18.0.0. )
• 3-way Anova (height)
• Cross tabulation (number of stems)
• Significant change

729 957 346 356 200 400 600 800 1000 1200

Total number of individual trees/shrubs

Shrubs & Trees

Total number of tree and shrub counts from 2004 to 2010

Shrubs 2004 Shrubs 2010 Trees 2004 Trees 2010

3 72 60 27 77 118 87 34 234 151 75 107 208 144 114 175

50 100 150 200 250 1 2 3 4 Total number of individual shrubs Belt-transect

Total number of shrubs counts on the MCF & MCB: 2004 - 2010

MCF (2004) MCF (2010) MCB (2004 MCB (2010)

3 72 60 27 19 22 28 26 100 42 74 77 51 35 70 105

20 40 60 80 100 120 1 2 3 4 Total number of individual trees Belt-transect

Total number of trees counts on the MCF & MCB: 2004 - 2010

MCF (2004) MCF (2010) MCB (2004) MCB (2010)

Results: Descriptive

2 (BA) 3 (PR) 4 (MA) 5 (Br) 2 (BA) 3 (PR) 4 (MA) 5 (Br)

Increase

Results

Shrubs avg. height Trees avg. height

1.397 1.306 1.627 2.014 2.118 2.110 1.978 2.059 .000 .500 1.000 1.500 2.000 2.500

1 2 3 4

• Avg. height (m)

Belt-transect

Average shrub height (m) for Belt-transects on the MCB: 2004 - 2010

MCB 2004 MCB 2010 2 (BA) 3 (PR) 4 (MA) 5 (Br)

1.190 1.157 1.135 1.378 1.883 2.191 1.484 2.714 .000 .500 1.000 1.500 2.000 2.500 3.000

1 2 3 4

• Avg. height (m)

Belt-transect

Average shrub height (m) for belt-transects on the MCF: 2004 - 2010

MCF 2004 MCF 2010

1.460 2.058 1.952 2.177 2.481 3.224 2.341 2.170 .000 .500 1.000 1.500 2.000 2.500 3.000 3.500

1 2 3 4

• Avg. height (m)

Belt-transect

Average tree height (m) for belt-transects on the MCB: 2004 - 2010

2004 MCB 2010 MCB 2 (BA) 3 (PR) 4 (MA) 5 (Br)

2.470 1.287 1.241 2.441 3.570 1.827 1.760 2.709 .000 .500 1.000 1.500 2.000 2.500 3.000 3.500 4.000

1 2 3 4

• Avg. height (m)

Belt-transect

Average tree height (m) for belt-transect on the MCF: 2004 - 2010

2004 MCF 2010 MCF 2 (BA) 3 (PR) 4 (MA) 5 (Br) 2 (BA) 3 (PR) 4 (MA) 5 (Br)

Stable

33% 32% 20% 7% 8%

Distribution of shrub stem classes on the MCF for 2010

1 2 – 3 4 – 6 7 – 10 11 – 55

35 : 65

30% 52% 14% 2% 2%

Distribution of shrub stem classes on the MCF for 2004

1 2 – 3 4 – 6 7 – 10 11 – 55 1 2 – 3 4 – 6 7 – 10 11 – 55 45% 38% 11% 3% 3%

Distribution of shrub stem classes on the MCB for 2004

1 2 – 3 4 – 6 7 – 10 11 – 55 29% 27% 22% 6% 16%

Distribution of shrub stem classes on the MCB for 2010

1 2 – 3 4 – 6 7 – 10 11 – 55

44 : 56 17 : 83

Shrubs: distribution of stem classes

Results

18 : 82

2004 2010

66% 21% 10% 2% 1%

Distribution of tree stem classes on the MCB for 2010

59% 33% 6% 2%

Distribution of tree stem classes on the MCB for 2004

57% 34% 9%

Distribution of tree stem classes on the MCF for 2004

65% 22% 9% 2% 2%

Distribution of tree stem classes on the MCF for 2010

Results

Trees: distribution of stem classes

1 2 – 3 4 – 6 7 – 10 11 – 55 1 2 – 3 4 – 6 7 – 10 11 – 55 1 2 – 3 4 – 6 7 – 10 11 – 55 1 2 – 3 4 – 6 7 – 10 11 – 55

9 : 91 8 : 92 13 : 87 13 : 87

2004 2010

Conclusion

Height Number of stems Shrubs Trees

The way forward

• Structural change
• Basal area
• Investigating compositional change
• Alien invasive
• Functional types
• Most abundant and successful functional type
• Regeneration, recruitment and

nursing effect

• Reed associated
• Large Woody Debris
• Termite mounds

Acknowledgements

• CWE (Wits) for providing GIS-based data and other relevant

information regarding re-sampling in 2010

• Karen Kotschy (CWE) and Craig McCloughlin (SANParks) for

valuable discussions on the project

• SANParks scientific services for logistic support
• Hugo Bezuidenhout for valuable inputs into the project and for

acting as SANParks coordinator for die registered research project

• North West University for financial support
• Suria Ellis for providing valuable guidance concerning the statistical

analysis of the data

• Pieter Kloppers and Madeleen Struwig for assisting in the fieldwork
• Thomas (SANParks field guide) for keeping us safe in the veld and

sharing is knowledge of the environment