Vegetation survey in a swamp forest of Mpumalanga, South Africa

View of upstream riverine vegetation in the Sand River catchment

Olivier Flores 2001

Contents 1 Introduction

3

2 Presentation of the Working for Water programme 2.1 The issue of invasive plant species in South Africa . . . . . . . . . . . 2.2 What is the Working for Water programme? . . . . . . . . . . . . . . 2.3 WfW in Mpumalanga and the Save the Sand project . . . . . . . . .

3 3 3 4

3 Vegetation survey in a swamp forest of the srsc 3.1 Ecological features of the srsc and presentation of the forest 3.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Vegetation sampling . . . . . . . . . . . . . . . . . . 3.2.2 Site characterization . . . . . . . . . . . . . . . . . . 3.2.3 Data analysis . . . . . . . . . . . . . . . . . . . . . . 3.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Species identity and status . . . . . . . . . . . . . . . 3.3.2 Life forms . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 Overstorey composition and diameter distribution . . 3.3.4 Ordination analyses . . . . . . . . . . . . . . . . . . .

4 4 6 6 7 7 8 8 8 8 9

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4 Discussion – Conclusion 10 4.1 Conservative value of the swamp forest in the Welgevonden area . . . 10 4.2 Species response to environmental variables . . . . . . . . . . . . . . 11 4.3 About this work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2

1

Introduction

Wetlands are particular terrestrial ecosystems essentially dependent on soil waterlogging. Among these, riparian formations occur along streams and are strongly influenced by flood regime (Kingsford, 2000; Richter and Richter, 2000). Riverine ecosystems have high conservation value since they buffer flooding, provide habitat to numerous species (Darveau et al., 2001) and serve as corridors for animal movements (De Lima and Gascon, 1999). In South Africa, swamp forest cover 4834 ha over the 1.2 million square kilometres of the total area of the country. Very little literature exists on swamp forest in South Africa and these ecosystems remain weakly known. The aim of the present project was to study of the composition and organisation of a swamp forest in the Mpumalanga province in South Africa. This work was realized in collaboration with the governmental Working for Water programme. The first aim was to draw up an inventory of species present in a river catchment being rehabilitated by the programme. In order to present the context and content of the project, this report is divided in two parts. In the first part, a presentation deals with the purpose of WfW in South Africa. The second part presents a field survey of riverine vegetation in the upper Sand River catchment area, part of the Sabie River catchment in Mpumalanga. The data obtained from this survey concerns sampling of occurring plant species from which diameter distributions of woody species and species assemblage are studied. While surveying species, I also characterized species response to four qualitative environmental variables in order to investigate their influence on species distribution. Comparisons are drawn with a similar study done in the Santa Lucia Lake area (Kwazulu-Natal, South Africa, Wessels, 1991).

2 2.1

Presentation of the Working for Water programme The issue of invasive plant species in South Africa

In South Africa, one hundred and sixty one species have been identified as invasive. They cover around 10% of the area of the country (Fig.1.a). Their ability to spread and establish in sensible ecosystems is a serious threat to South African biodiversity, whereas the country is one of the hotspors with regard to the world biodiversity (Myers et al., 2000). Invasive species can increase fire frequency due to the addition of natural combustible, especially under dry conditions which are common in South Africa. They also cause trouble in terms of water management: infested catchment show severe decrease in runoff due to water use by invading species. Water loss from invasive species in South Africa has been estimated to 7% of the total water ressources. Agriculture is also affected since the land needs to be cleared before being suitable. Each year, billion of dollars are spent on fighting biological invasions. Left uncontrolled, effect of these invasions are supposed to double within twenty years or less.

2.2

What is the Working for Water programme?

WfW is a multi-departmental programme of the South African government. It was launched in 1995 in order to tackle the problem of invasive species and unemployment in South Africa. The map on figure 1 displays the locations of about three 3

hundred projects run by WfW, as well as level of infestation by invasive species. The goal of the programme are multiple: • Ecological aims The principal activity of the programme is the clearing of invasive species in order to improve the sustainability of water ressources and protect the biodiversity of the country. Different methods are employed: hand-cutting, herbicides, ring-barking to kill trees without cutting them, and biological control using predators and pathogens of invasive species. • Social aims The programme acts on a social ground to create jobs for people from the local communities and improve water supply conditions. Projects are conducted in the nine South African provinces. In each province, area managers are responsible for a given part of the territory. Each manager employs local contractors from the communities and each contractor is responsible for a team of twenty people chosen by himself. Among the 42,000 workers employed by WfW at its peak, 54% were women, 26% were young people, and 1% were disable people. Created jobs essentially include alien plants clearing and rehabilition of stream catchments, but the programme also developps secondary industries such as crafts from alien wood. Environmental awareness as well as disease prevention against cholera and AIDS are also conducted among the local contractors and private owners.

2.3

WfW in Mpumalanga and the Save the Sand project

In Mpumalanga, WfW is implied in the rehabilitation of the Sand River subcatchment which is part of the more important Sabie River catchment (Fig.1). The Sabie River catchment (src) covers around 7,000 km2 at the border between South Africa and Mozambique. Included in this area, the Sand River sub-catchment (srsc) which represents 27% of the src (1910 km2 . The Sand River contributes up to 2023% of the Sabie River runoff, depending on estimations, and over 336,000 people depend on the src for their water supply. In the src, population density, estimations range from 176 to less than 2 people per km2 , depending on wether the total area or only residential areas are considered. These physical and demographical conditions make water management a critical issue in this area. Among other things, the Save the Sand project include maintenance of access roads and stream management in the srsc.

3 3.1

Vegetation survey in a swamp forest of the srsc Ecological features of the srsc and presentation of the forest

The srsc lies eastward of the Drakensberg escarpment (Fig.1.b). The climate in the region of srsc is sub-tropical and strongly influenced by topography with altitudes varying from over 1700 m westward to 200 m above sea-level eastward. The precipitation pattern shows a strong eastward gradient in annual rainfall decreasing from 2000 mm to 550 mm per year over a distance of 80 kms. Due to this pattern, the upper part of the srsc provides water to the rest of the catchment: 50% of the Sand 4

a.

b.

Figure 1: a. Infestation level by invasive species in South Africa and locations of WfW projects (circles). b. Localization of the Sabie River Catchment (src).

5

River runoff is actually generated on 25% of the catchment area. Precipitations are highly seasonal and mainly occur during summer, with 75% of the annual amount falling between October and March. The studied swamp forest occurs in this upper part of the catchment along river streams including the Sand River and its tributaries. Pine plantations also occur in this part of the catchment above the 1100 mm isohyet. Three state-owned plantation cover about 3% of the catchment area, among which the Welgewonden forestry where the survey was conducted. In this area, plantations sometimes a common edge with the indigenous fores. The width of the swamp forest (across the drainage line) ranges from 5 m on each side up to 100-200 m. The forest cover is fragmented by open areas. These areas may occur naturally or correspond to highly perturbated areas (clearcut forestry). Slopes in the forest are low (120

110−120

100−110

DBH (cm) >120

110−120

100−110

80−90

70−80

60−70

50−60

40−50

30−40

>120

110−120

100−110

90−100

DBH (cm)

90−100

80−90

70−80

60−70

50−60

40−50

30−40

20−30

10−20

80−90

70−80

60−70

50−60

40−50

30−40

20−30

10−20

>120

110−120

100−110

90−100

80−90

70−80

60−70

50−60

40−50

30−40

20−30

10−20

5−10

>120

110−120

100−110

90−100

DBH (cm)

90−100

DBH (cm)

80−90

2

70−80

1.5

60−70

2.0

4

50−60

5

40−50

Cryptocarya woodii 20−30

Breonardia microcephala

30−40

0.0 5−10

%

Syzygium cordatum

20−30

5

10−20

15

5−10

10

%

>120

110−120

100−110

0

10−20

3

%

>120

110−120

100−110

80−90

70−80

60−70

50−60

40−50

30−40

20−30

10−20

5−10

0

5−10

>120

110−120

100−110

DBH (cm) 90−100

DBH (cm)

90−100

80−90

70−80

60−70

50−60

40−50

30−40

20−30

10−20

5−10

DBH (cm)

90−100

DBH (cm)

80−90

70−80

60−70

50−60

40−50

30−40

20−30

0

10−20

% 60 50 40 30 20 10 0

5−10

%

%

%

3.0 2.5 2.0 1.5 1.0 0.5 0.0

5−10

%

Maesa lanceolata Canthium mundianum

5

4

3

2

1

10

Anthocleista grandiflora

8

6

4

2

Tricalysia lanceolata

1.0

0.8

0.6

0.4

0.2

Tabernaemontana ventricosa

1.0

2

2 R.sa.(c) A.mo.(f)

C.sp.(h) P.af.

A.la.(c)

A.fa.(c)

1

Ox.sp.(h)

1

* *

*

A.sp.(h)

* * * 11* 5 und.(h) * und.(h) und.(h)

0

-1

Axis 2

* 13 * * 21 14 * O.spe. * 12 und.(h) P.ma.(f) A.ae.(f) * E.ca. 15 35 * * ** ** 36 * * * **** 16 * 33 * C.af. * * * 18 * 29 37 * 27 * * * 22 * C.dr.(f) 34 * ** * S.um. 6 3 9 ** und.(h) *17 * *** *** *26 ** * * und.(h) 8 7 *10 ** * * 28 * * C.an. * P.po.(f) C.li. * * * und.(h) * 25 Tr.sp.(c) * 2 *1* Pl.sp.(h) 23 4 30 M.fr.(f) 24 32 * A.di. 31 * * * E.ho.(h) * * * * * 38 * G.oc. C.na. C.tr. D.dr.(c) L.ja.(f) O.na. B.fl.(h)

0

-1

N.flo. H.sp.(h)

-2

Pe.sp.(c) S.an.

R.gl.(sd)

A.ph.(f)

-2

-3 -1.6

-1.1

-0.6

-0.1 Axis 1

0.4

0.9

1.4

1.9

-1.6

-1.1

-0.6

-0.1

0.4 Axis 1

Axis 3

0

1.4

1.9

und.(h)

A.ph.(f)

und.(h)

2

* * * * *N.flo. D.dr.(c) und.(h)E.ho.(h) * * 31 16 ** * H.sp.(h) *6 * * * * *C.sp.(h) B.fl.(h) * 3 28 L.ja.(f) * P.ma.(f) A.ae.(f) C.na.* * 15 35 P.af.* *** * *13 * 2938 *S.an. * und.(h) 30 und.(h) 14 54 * ** 1 E.ca. ** * A.la.(c) * 2** * 2212 1817 * *** * * 34 32 C.af.P.po.(f) * *C.an. Tr.sp.(c) ** 25* * *2021 * * * * 37 36 * * * * * * C.tr. 26 * * * * 27* 33 * ** * * A.mo.(f) Ox.sp.(h) 11 * * A.sp.(h) S.um. * ** * * R.sa.(c)24 * ** O.spe. * * 19 * 23 Pe.sp.(c) A.fa.(c) 7 10 G.oc. Pl.sp.(h) 9

und.(h) T.la.

O.na.

und.(h)

1

T.la.(sd)

Pe.sp.(c) * * * 10 Pl.sp.(h) 23 24 * R.ch. * * * 20 S.an. * * * 25 * O.spe. * * ** *** 27** **26 C.tr.(sh) G.oc. C.wo. * * * 21 * *12 17 A.sp.(h) *22 ****34 ******* 28 * ***33 * * R.sa.(c) P.lo.(sh) 18 * *15 C.an. 32 H.sp.(h) 11 * ** **37 ** 30* * 38 N.flo. C.wo.(sd) * E.ma.(sh) * und.(h) C.af.(sh) * 5 *3**** 4 2* **35 C.wo.(sh) * 14 P.lo. und.(h) * * E.ly.(sh.) P.af.(sh) * * 16* * ** ** ** * 1 P.po.(f) * * 13 31 36 * * * * H.lu.(sh) 6 * 29 C.af. und.(h) ** Tr.sp.(c) * * E.ho.(h) S.um.(sh) A.ph.(f) * L.ja.(f) * B.fl.(h) C.sp.(h) * * * * A.gr.(sd) D.dr.(c) M.fr.(f)S.rh.(sd) und.(h)E.ca. und.(c) T.em. P.ma.(f) A.ae.(f) A.mo.(f)

O.na.

8

-1

-2 und.(h) A.di. und.(h)

T.ve. C.tr.(sd)

7

A.fa.(c)

R.gl.(sd)

0

-1 C.li. und.(h)

A.di.

C.li.(sh) 8

Axis 3

1

0.9

A.di.(sh)

M.fr.(f) C.dr.(f)

9

P.lo.(sd) 19 H.lu.

S.um.

-2

-3

-3

-2

-1

0

1

2

Axi s 2

-1.6

-1.1

-0.6

-0.1 Axis 1

0.4

0.9

1.4

1.9

A.di.(sh)

M.fr.(f)

und.(h)

C.dr.(f) und.(h)

A.ph.(f)

2

* * * * * N.flo.D.dr.(c) E.ho.(h) und.(h) * * 31 16 H.sp.(h) * * * ** * * C.sp.(h) * 28 * 36 B.fl.(h) * L.ja.(f) * * A.ae.(f) 29 P.ma.(f) C.na. 15 * 35 S.an. P.af. * * * * * 38 und.(h) * 13 30 * 14 * *und.(h) * 1 **5*E.ca. 42 18 * * ** A.la.(c) * 22 32 * P.po.(f) * *17 * ** C.af. 12 * *****34 25 Tr.sp.(c) *C.an. *37*36 * 21 * 20 * C.tr. * * * **** ***27 *26 * 33*** *11 A.mo.(f) Ox.sp.(h) * 24 * A.sp.(h) *O.spe. * * S.um. R.sa.(c) * * ** 19 * 23 G.oc. Pe.sp.(c) A.fa.(c) 710 Pl.sp.(h) 9

0

und.(h) T.la.

T.la.(sd)

Pe.sp.(c) 9 * * * 10 Pl.sp.(h) 23 24 * R.ch. 25* * S.an. ** *** * *** *26 * * O.spe. * * 27* * C.tr.(sh) G.oc. C.wo. * * * 21 * *12 17 A.sp.(h) *22 ****34 ******* 28 * ***33 * * R.sa.(c) P.lo.(sh) 18 * *15 C.an. 32 H.sp.(h) 11 * ** **37 ** 30* * 38 N.flo. C.wo.(sd) * E.ma.(sh) * und.(h) C.af.(sh) * 5 *3**** 4 2* **35 C.wo.(sh) * 14 P.lo. und.(h) * *E.ly.(sh.) P.af.(sh) * * 16* * ** ** ** * 1 P.po.(f) * * 13 31 36 * * * * H.lu.(sh) 6 * 29 C.af. und.(h) ** Tr.sp.(c) * * E.ho.(h) S.um.(sh) * L.ja.(f) * A.ph.(f) B.fl.(h) C.sp.(h) * * * * A.gr.(sd) D.dr.(c) E.ca. M.fr.(f)S.rh.(sd) und.(h) und.(c) T.em. A.mo.(f)

P.lo.(sd) 19 H.lu.

S.um.

20

0

8

-1

-2

T.ve. C.tr.(sd)

7

A.fa.(c)

R.gl.(sd)

und.(h)

C.li.

O.na.

und.(h)

1

-1 O.na.

A.di.

C.li.(sh) 8

Axis 3

1

Axis 3

Axis 2

*

* 2019

Pe.sp.(c) O.na. D.dr.(c) H.sp.(h) S.an. S.um.(sh) C.tr.(sd) C.tr.(sh) E.ly.(sh.) T.ve. G.oc. A.ph.(f) N.flo. A.di. R.ch. * * * 38 Tr.sp.(c) * * * * * 24 L.ja.(f) P.ma.(f) A.ae.(f) * * ** 2332 *C.af. * P.po.(f) C.an. E.ho.(h) * * * 2 29 E.ca. 25 4 *1* * 26 Pl.sp.(h) 28 * 30 * * A.di.(sh) 36 * C.li.(sh) * * * *** * *34 A.gr.(sd) ****27 ** * und.(h) 3* * * 78* * 10 * * * * und.(h) * 22 H.lu.(sh) und.(h) * C.af.(sh) 18 * * S.rh.(sd) und.(h) 59 6 ** * *31 * * * 17 33 und.(h) B.fl.(h) ** 37 *11* ** ***12 35 * * * ** * * * ** * * **** und.(c) * * 16 M.fr.(f) * * P.lo. S.um. * * und.(h) * E.ma.(sh) O.spe. T.la.(sd) 14 15 13 ** T.em. A.sp.(h) * * * 20 * T.la. * 21 * P.lo.(sh) * P.lo.(sd) C.wo.(sh) 19 H.lu. C.sp.(h) A.fa.(c) P.af.(sh) C.wo.(sd) C.wo. A.mo.(f) R.sa.(c)

und.(h)

P.ma.(f) A.ae.(f)

A.di. und.(h)

-2

-3

-3

-2

-1

0

1

Axi s 2

-2

-1

0 Axis 2

1

2

Figure 4: Factorial maps of Canonical Analysis (CA) on species presence – absence. Left: overall analysis without layer distinction. Right: detailed analysis of presence – absence in three vegetation strata. Numbers refer to sampling sites. Labels are initials of scientific names for species with scores higher than 1 on one axis. (sh) shrubs, (se) seedlings, (c) creepers, (f) ferns, (h) herbs.

14

2

1.8

3

und.(h) und.(h) A.di.

9 8 7 A.di.(sh)

2

1.3 *

*

und.(h) und.(h)

*

*

D.dr.(c) P.po.(f) Tr.sp.(c) und.(h) * * C.af. * * *29 E.ho.(h) 2 ** A.ph.(f) Z.mu. N.flo. 25 * 28* 26 4 1* H.sp.(h) * * * 30 * * * * * * 36 C.na. 78 ** * * 27 ** * * ** 3 ** L.ja.(f) 22* ** *10 31 C.an. * *18* ** *** * 34 59 6 33 * * * 35 * * * 11 17* * PER C.tr. 37 ** S.um. * ** ** ** * * * * * C.dr.(f) * * 12 * * ** * * 16 * * S.an. G.oc. * * * und.(h)und.(h) * * WAT* DIS 13 Pe.sp.(c) * * 15 14 * * * * 20 * 21 O.na. B.fl.(h)

-0.2

-0.7

24

23 32

Axis 2

0.3

T.ve.(sd) Pl.sp.(h)

und.(h)

* 2 1 C.na.(sd) L.ja.(f) * und.(h) 4 10 und.(h) 18 A.gr.(sd) H.lu.(sh)11 * * 12 * 6B.fl.(h) 17 16 *

0

-1

-0.5

0.0

P.ma.(f) A.ae.(f) E.ca. * * 30 * C.in. 37 36 D.dr.(c) 33 28 Tr.sp.(c) A.di. 32 A.ph.(f) * P.po.(f) * N.flo. H.sp.(h) * ** S.um.(sh) ** * * ** *34 * Z.mu. * C.af.(sh) * * * * ** *** 38 ** * * PER C.an. C.tr.(sh) ** * ** * *** * **R.ch. ** ***** * *** * ***** * * ** ** ** * * ***35* * C.dr.(f) * * * ** ** * WAT * * S.an. * * * ** * * ** DIS * G.oc. * * Pe.sp.(c) 14 * * * * 13 25 24 C.tr.(sd) * ** * O.na. 15 23 26 * 19R.gl.(sd)21 T.ve. E.cr. A.mo.(f) 20

*

* und.(h) E.ho.(h)

5

22

-2

-1.0

*

27

19

-1.2

-1.5

C.af. 31

RIV C.li.(sh) *

1

E.cr.

A.mo.(f)

-2.0

29

38

*

und.(h)

Axis 2

P.ma.(f) A.ae.(f) E.ca.

RIV

Pl.sp.(h)

0.8

0.5

1.0

-1

0 Axi s 1

1.5

1

2

Axi s 1

3

A.di.(sh)

35

35

und.(h) 5

2 5

2

A.di.

und.(h)

6

28

C.li.(sh)

28 34

B.fl.(h)

1

C.dr.(f) **

30

WAT RIV *

32

38

1

33

* * P.po.(f) * * A.ph.(f) D.dr.(c) Tr.sp.(c) * 27 S.um. ** * C.af. und.(h) ** E.ca. * * * * und.(h) * * * * * * * *** * ** ** * Z.mu. E.ho.(h) * * * 11 * * * * * C.an. * * * * * * * * P.ma.(f) A.ae.(f) *15 * * ** *31 3 ** * * * *** * * S.an. 29 8 und.(h) 7 * * 19 * 20 DIS 9 * * A.mo.(f) ** 22 21 * PER und.(h) * Pl.sp.(h) Pe.sp.(c)C.tr. ** 4 * A.di. * 18 12 * 10 ** * L.ja.(f) 14 * 13 C.na. 23 26 E.cr. G.oc. 2 1

und.(h)

0

-1

und.(h)

*

*16 17 *

*

38

O.na.

*

N.flo. H.sp.(h)

Axis 3

Axis 3

6

* **

37 36

33

*

T.ve.C.tr.(sd) 34 * Pe.sp.(c) R.gl.(sd) * RIV E.cr. * 11 30* * WAT 37 36 32 Pl.sp.(h) * A.mo.(f) * R.ch. * * ** * * * S.an. T.ve.(sd) * * ** * ** * **21 27 **G.oc. * C.tr.(sh) * * * ** * *10* * * *** * * * * ** *** * ** * * ** * * C.an. ** * H.sp.(h)* * * * ** * ** N.flo. * * und.(h) C.af.(sh) * * * *14 * *** * * und.(h) 9 * * 29* * * * *13* 15 * * * * *C.dr.(f) P.po.(f) ** Z.mu.DIS 19 * 20 4 * * * * H.lu.(sh) 22 C.af. und.(h) * C.in. Tr.sp.(c) * * E.ho.(h) * 18 12 S.um.(sh) A.ph.(f) PER L.ja.(f) 3 C.na.(sd) B.fl.(h) * * * * * 8 7 D.dr.(c) 2 A.gr.(sd)1 * E.ca. * und.(h) 26 23 31 * * P.ma.(f) A.ae.(f) 17 16

0

-1

O.na.

25 24

25 24

-2

-2 -2

-1

0 Axis 1

1

2

-2

-1

3

0 Axi s 1

1

2

35 35

5

2 28

5

2

6

B.fl.(h)

28 34

6

38 H.sp.(h) N.flo.

B.fl.(h)

1

Axis 3

Axis 3

C.dr.(f) 30 32 33 * WAT * **und.(h) RIV * * und.(h) P.po.(f) * A.ph.(f) D.dr.(c)27* * * * Tr.sp.(c) S.um. * * C.af. und.(h) * ** * ** und.(h) * * E.ca. *** * * ** ************ Z.mu. * *37 36 * E.ho.(h) * ** 11*****C.an. * P.ma.(f) A.ae.(f) und.(h) 15 * *********** *** 19 S.an. 31 29 * 20 * DIS** **PER 22 A.mo.(f)21 ** * und.(h) Pl.sp.(h) A.di. Pe.sp.(c) * * 4C.tr. * * * 12 * 10 * * 18 * 14 L.ja.(f) C.na. 13* 23 26 E.cr. G.oc. 2 1 O.na.

1

17 16 *

0

-1

H.lu.(sh)

8 7

C.dr.(f)

38

N.flo. H.sp.(h) 33 S.um.(sh) 34 P.po.(f)

16 17 *

* * * RIV und.(h) C.af.(sh) 11 30 WAT * 37 * D.dr.(c) 3236 * Tr.sp.(c) * * * ** * * und.(h) A.gr.(sd) * * *R.ch. * * * * *und.(h) C.in. und.(h) *** Z.mu. * A.ph.(f) * * * 21 * * 27 * * * ** * * 10** * C.tr.(sh) P.ma.(f) A.ae.(f) E.ca. C.li.(sh) * * ******* ****E.ho.(h) * * * * ** * ** *** *C.an. * ** S.an. * C.af.und.(h) * * *** ***** * R.gl.(sd)* 14 A.mo.(f) * * ** * * * * * * * 13* * * 29und.(h) DIS * 15* * Pl.sp.(h) Pe.sp.(c) 19 * ** * 20 * 4 * 22 * * 12 18 ** * PER * * * L.ja.(f) T.ve.(sd) 2 1 C.na.(sd) A.di. G.oc. 23 26 31 T.ve. E.cr. *

0

3 9

-1

9

A.di.(sh) 8 7

O.na. 24 25 C.tr.(sd)

24 25

-2

-2

-2

-1

0

1

2

3

Axis 2

-1

0

1 Axis 2

Figure 5: Factorial maps of Canonical Correspondance Analysis (CCA) on species presence – absence. Left: overall analysis without layer distinction. Right: detailed analysis of presence – absence in three vegetation strata. Variables are: WAT , water, PER, perturbation, RIV , river. Numbers refer to sampling sites. Labels are initials of scientific names for species with scores higher than 1 on one axis. (sh) shrubs, (se) seedlings, (c) creepers, (f) ferns, (h) herbs.

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2

3

References Darveau, M., Labb´e, P., Beauchesne, P., B´elanger, L., and Huot, J. (2001). The use of riparian forest strips by small mammals in a boreal balsam fir forest. Forest ecology and Management, 143(95-104). De Lima, M. and Gascon, C. (1999). The conservation value of linear forest remnants in central amazonia. Biological Conservation, 91:241–247. Gauch, H. (1982). Multivariate analysis in community ecology. Cambridge Studies In Ecology. Cambridge University Press. Kingsford, R. (2000). Ecological impacts of dams, water diversions and river management on floodplains wetlands in australia. Austral Ecology, 25:109–127. Myers, N., Mittermeier, R., Mittermeier, C., da Fonseca, G., and Kent, J. (2000). Biodiversity hotspots for conservation priorities. Nature, 403:853–858. Richter, B. and Richter, H. (2000). Prescibing flood regimes to sustain riparian ecosystems along meandering rivers. Conservation Biology, 14(5):1467–1478. Sagers, C. and Lyon, J. (1997). Gradient analysis in a riparian landscape: contrasts among forest layers. Forest ecology and Management, 96:13–26. Wessels, N. (1991). The syntaxonomy and synecology of swamp forests in the lake st lucia area. Technical report, Department of Water Affairs and Forestry (South Africa).

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List of Figures . . . . . . . a. Infestation level by invasive species in South Africa and locations of WfW projects (circles). b. Localization of the Sabie River Catchment (src). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Species composition of the canopy layer. a. All trees included, b. Trees with DBH ≥20 cm, c. Trees with DBH ≥60 cm. . . . . . . . . Diameter distribution of the most abondant species in the overstorey.b. Localization of the Sabie River Catchment (src). . . . . . . . . . . . Factorial maps of Canonical Analysis (CA) on species presence – absence. Left: overall analysis without layer distinction. Right: detailed analysis of presence – absence in three vegetation strata. Numbers refer to sampling sites. Labels are initials of scientific names for species with scores higher than 1 on one axis. (sh) shrubs, (se) seedlings, (c) creepers, (f) ferns, (h) herbs. . . . . . . . . . . . . . . . Factorial maps of Canonical Correspondance Analysis (CCA) on species presence – absence. Left: overall analysis without layer distinction. Right: detailed analysis of presence – absence in three vegetation strata. Variables are: WAT , water, PER, perturbation, RIV , river. Numbers refer to sampling sites. Labels are initials of scientific names for species with scores higher than 1 on one axis. (sh) shrubs, (se) seedlings, (c) creepers, (f) ferns, (h) herbs. . . . . . . . .

View of upstream riverine vegetation in the Sand River catchment

1

2 3 4

5

17

1

5 12 13

14

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Appendix Table 3: Checklist of sampled species in the Welgevonden area with names and status. Scarcity: number of sites where the species occurs over total. Abundance: mean abundance over sampling sites. Scientific name

Family

Common name

Scarcity

Abundance

0.03 0.66 0.11 0.18 0.03 0.61 0.95 0.18 0.24 0.18 0.03 0.16 0.29 0.21 0.08 0.29 0.03 0.82 0.08 0.32 0.16 0.05 0.08 0.61 0.05 0.16 0.03 0.58 0.03 0.58 0.03 0.03 0.08 0.05 0.13 0.21 0.11 0.26 0.03 0.18 0.11 0.18 0.03 0.13 0.08 0.50 0.05 0.13 0.92 0.42 0.39

1 49 4 25 5 72 107 14 28 17 1 22 14 11 5 38 1 325 3 42 10 2 7 45 1 9 1 54 1 94 1 6 5 3 7 13 17 18 1 6 4 38 1 5 6 51 1 13 289 28 16

Trees and shrubs Anacardium occidentale Anthocleista grandiflora Apodytes dimidiata Argyrolobium tomentosum Brachylaena transvaalensis Breonardia microcephala Bridelia micrantha Canthium inerme Canthium mundianum Celtis africana Cephalanthus natalensis Citrus limon Clausena anisata Combretum krausii Cryptocarya transvaalensis Cryptocarya woodii Dracaena aletriformis Dyospyros whyteana Ekebergia capensis Englerophytum magalismontanum Erythrina lysistemon Euclea crispa Ficus burkei Ficus sur Grewia occidentalis Halleria lucida Heteropyxis natalensis Keetia guenzii Kiggelaria africana Maesa lanceolata Maytenus undata Monanthotaxis caffra Nuxia floribunda Ochna natalita Oxyanthus speciosus Pavetta gardeniifolia Peddiea africana Prothorus longifolia Psycothria capensis Rhus chirindensis Rhus pyroides Rothmannia globosa Rubus sp. Sapium ellipticum Schfflera umbellifera Sida rhombifolia Solanum anguivii Solanum panduriforme Syzygium cordatum Tabernaemontana ventricosa Toddalia asiatica

Anacardiaceae Loganiaceae Icacinaceae Fabaceae Compositae Rubiaceae Euphorbiaceae Rubiaceae Rubiaceae Ulmaceae Rubiaceae Rutaceae Rutaceae Combretaceae Lauraceae Lauraceae Agavaceae Ebenaceae Meliaceae

Forest fever tree White pear Wild silver oak Matumi Mitserie Turkey-berry White stinkwood Tree strawberry Lemon tree Horsewood Forest bushwillow Cape laurel Bladder-nut Cape ash

Papilionoideae Ebenaceae Moraceae Moraceae Tiliaceae Scrophulariaceae Myrtaceae

Cross-berry Tree-fuchsia Lavender tree

Flacourticeae Myrsinaceae Celastraceae Annonaceae Loganiaceae Ochnaceae Rubiaceae Rubiaceae

Wild peach Maesa Kokoboom Dwaba-berry Forest nuxia Natal plane Wild loquat Common bride’s bush

Anacardiaceae Rubiaceae Anacardiaceae Anacardiaceae Rubiaceae Rubiaceae Euphorbiaceae Araliaceae

Red beech Cream psychotria Bostaaibos Common taaibos

Jumping seed tree Bastard cabbage tree

Solanaceae Solanaceae Myrtaceae Apocynaceae

Water berry Forest toad tree

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common coral tree Blue guarri Common wild fig

Table 3: (continued) Trema orientalis Tricalysia lanceolata Trichilia emetica Trimeria grandiflolia Zanthoxylum davyi Ziziphus mucronata

Ulmaceae Rubiaceae Meliaceae Flacourtiaceae Rutaceae Rhamnaceae

Pigeonwood Rock alder Natal mahogany Mulberry-leaf trimeria Knobwood Buffalo-thorn

0.08 0.66 0.03 0.08 0.03 0.18

Ferns Acliantum philippense Anemia dregeana Arthropteris monocarpa Asplenium aetheiopicum Cheilanthes viridis var. macrophylla Cyatea dregei Diplazium zanzibarum Doryopteris concolor Lunathyrium japonicum Marattia fraxinea var. salicifolia Microlepia speluncae Pleopettis macrocarpa Polypodium polypodioides Pteridium aquilinum Pteris friesii Thelypteris confluens Thelypteris dentata var. buchananii Thelypteris interrupta

0.11 0.05 0.05 0.05 0.66 0.05 0.08 0.03 0.05 0.05 0.26 0.05 0.55 0.18 0.03 0.03 0.55 0.68 Creepers

Abrus laevigatus Acacia ataxacantha Asparagus falcatus Cissampelos torulosa Cyphostema sp. Dalbergia armata Desmodium repandum Diosorea dregeani Domatia villosa Hibiscus calyphyllus Mikania spicata Momordica sp. Peniplocoea sp. Rhoicissus rhomboides Rhoicissus tomentosa Rhynchosia caciber Rhynchosia caribia Rumex sagitatia Secanoni sp. Smilax anceps Stephania abyssinica Tragia sp.

0.05 0.32 0.08 0.66 0.03 0.32 0.03 0.05 0.03 0.34 0.32 0.11 0.08 0.08 0.45 0.18 0.03 0.05 0.18 0.68 0.24 0.05 Herbs

Ageratum houstonianum Alocasia sp. Asclepia fructicosa Asparagus sp. Bideus pilosa Bradypodium flexum Carex pseudoleptocladum Centella sp.

0.21 0.03 0.03 0.16 0.03 0.08 0.13 0.05

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3 76 1 5 1 11

Table 3: (continued) Commelia africana Commelia benghualensis Cyathula cylindrica Desmodum repandum Dissotis canescens Equisetum ramosissimum Eulophia horsfallii Gallium sp. Helichrysum sp. Hemizgia sp. Hibiscus sp. Impatiens sylvicola Justicia sp. Kalanchoe rotundifolia Oplismenus sp. Orchidacea sp. Oxalis sp. Pennisetum clandestinum Persicaria puchrum Phragmites mauritianus Plectranthus fructicosus Plectranthus laxiflorus Plectranthus sp. Plectranthus verticillaris Richardsia sp. Selaginela mittenii Senecio pandaniforme Senecio polyanthemoides Senecio sp. Setaria megaphylla Solanum nigrum Triumphetta sp. Verbena brasiliensis Xanthium strumarium

0.61 0.66 0.76 0.92 0.03 0.13 0.16 0.18 0.03 0.03 0.08 0.47 0.87 0.03 0.95 0.03 0.05 0.03 0.29 0.16 0.55 0.76 0.13 0.32 0.03 0.50 0.03 0.29 0.68 0.71 0.21 0.37 0.05 0.03

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