Distribution, diversity and abundance of invasive plant species within Ngorongoro rangelands

Full text

1
Distribuon, diversity and abundance
of invasive plant species within
Ngorongoro rangelands
Technical Book
Tanzania Wildlife Research Institute

Distribuon, diversity and abundance of invasive
plant species within Ngorongoro rangelands
Technical Book
2023
Tanzania Wildlife Research Instute

iv
Execuve Summary
Rangelands within the Ngorongoro Conservaon Area (NCA) was assessed to determine
the distribuon, abundance and diversity of invasive and non-invasive plant species.
also, to idenfy suitable plant species for biomass briquee producon and explain
exisng paerns of forage use by wild herbivores. The study fullls the objecve 1
of the project whose targets is to determine available raw material for producon of
biomass briques.
Intensive transect sampling was carried out whereby line transects were established both
inside and outside the crater area. Transects crossed dierent ecological habitats and
administrave wards. Data was systemacally collected from 1m2 quadrants established
3 km apart. The types and frequency of occurrence of both invasive and non-invasive
plants were recorded. Invasive plants suitable as raw materias for producon of biomass
briquee were idened. Addionally, presence of large herbivores in sampling points
were recorded based on indirect and direct observaons.
A total of six (6) invasive plant species (IPS) were recorded inside the crater while 34
species were reported in rangelands outside the crater area. The coverage of IPS within
the crater oor ranged from 17% to 23%, with Bidens schimperi and Lippia Javanica
being the most dominant species. On the contrary, invasion of the rangelands outside
the crater was 30%–40%. Notably, eleven invasive (11) plant species were recognized
as the most notorious outside the crater area. A larger number of invasive plant species
suitable for briquee producon were found outside the crater (n = 7) compared to
inside (n = 2), but the dierence in their abundance was not signicant (W = 10614,
P-value > 0.05).
Herbivore abundance and diversity on non-invaded plots far exceeded those on invaded
plots. The populaons of Gutenbergia cordifollia and L. javanica increased inversely with
the populaon of herbivores, while the trend of other IPS was posively correlated. This
implies that the response of herbivore biodiversity and rangeland quality was variable
across dierent IPS species during the dry season in NCA.
Moreover, rangelands in NCA habors high abundance and diversity of IPS, some of them
very suitable rich in wooden content. This implies that rangelands in NCA can oer a
huge supply of raw materials for biomass briquees producon. Therefore, the study
recommend establishment of a small- size factory for briquee producon within the
NCA.

This technical book has been produced through
collaboraon between the Tanzania Wildlife
Research Instute (TAWIRI) and the Ngorongoro
Conservaon Area Authority (NCAA). The work is
parally supported by the Tanzania Commission
for Science and Technolgy (COSTECH) through
the MAKISATU Iniave.
Citaon
Jerome Kimaro, Hillary Mushi, Richard Lyamuya
Peter Nyanswi and Victoria Shayo; Distribuon,
diversity and abundance of invasive plants
species in Ngorongoro rangelands (2023).
Publisher informaon:
Tanzania Wildlife Research Instute
Box 661, Arusha Tanzania
barua@tawiri.or.tz
www.tawiri.or.tz
ISBN 978 9976 5378 14
All rights reserved, no part of this publicaon
may be produced without a prior permission
from TAWIRI

vi
Execuve summary
1.0 Introducon
1.1 Purpose of study
1.2 Specic objecves
2.0 Materials and Methods
2.1 Study area
2.2 Data collecon
3.0 Key results
3.1 Within crater area
3.2 Outside crater area
4.0 Conservaon implicaons of ndings
5.0 Recommendaons and conclusion
6.0 References
Contents
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1.0 Introducon
The rapid increase of invasive plant species (IPS) is currently a crical conservaon
challenge in Ngorongoro Conservaon Area (NCA) (Bukombe et al., 2021). Owing to
that, rangelands ecosystem oen fail to maintain various biophysical funcons like
decreasing quanty and quality of feed and water which are important resources for
herbivores metabolism. Moreover, loss of nutrive value or exncon of palatable
forage in rangelands inuence herbivores to extend their range, somemes beyond
protected area protected areas boundaries. This escalates human-wildlife conucts
(DeFries et al., 2007).
Given that high populaons of IPS are sll persistent in NCA, a serious lbiodiversity and
decline in tourism acvies will be noced in the near future. Nonetheless, invesment
in sustainable management of controling IPS is not well advanced yet in NCA to contain
afromenoned challenges. Much eorts including mechanical mowing by tractors
and manual uproong has been has aempted in the crater area and few villages like
Erkapus and Nainokanoka.
To ll the gap in sustainable management of IPS in NCA, collecve eorts are required to
promote more aordable, parycipatory and reliable approaches. In turn, such eorts
should reward increasing market value of rangelands resources, enhance biodiversity
conservaon, and create employment among local people. Given that consideraon,
the Tanzania Wildlife Research Instute (TAWIRI) in collaboraon with the Ngorongoro
Conservaon Area Authority (NCAA), seek to exploit IPS in NCA as raw materials for
producon of biomass briquees.
1.1 Purpose of study
This study was conducted to determine the distribuon, diversity and abundance of
invasive plant species in wildlife rangelands within the NCA. The study forms the baseline
informaon for objecve one of this project, which focuses on the quancaon and
characterizaon of available stock for biomass briquee producon.
1.2 Specic objecves
• Determine the spaal variaon in distribuon, abundance, richness and diversity of
dierent IPS within the rangelands.
• Idenfy IPS that can be used as a suitable raw material for biomass briquee
producon.

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• Establish a relaonship between herbivore distribuon and the spread of IPS within
the rangelands.
The main outputs of the study:
• Variaon in distribuon, abundance and diversity of IPS across dierent habitats and
administrave wards in NCA established.
• Variaon in coverage of invasive plants within rangelands in NCA established
• Suitable species as raw materials for biomass briquee producon idened
• Relaonship between herbivore distribuon and the spread of IPS within rangelands
in NCA established
2.0 Material and Method
2.1 Study area
The Ngorongoro Conservaon Area (NCA) is located in Northern Tanzania (Figure 1). It
is a mulple land-use area where Maasai pastoralists co-exist with wildlife. One of its
prominent features is Ngorongoro Crater, which covers an area nearly 260 km2, and it is
recognized as one of the UNESCO World Heritage Sites, the Man and Biosphere Reserve,
and one of the African Seven Wonders (Masao et al., 2015). Major vegetaon types
in the NCA include grassland, forest, bush land, shrubs, and swamp patches (Foxcro
et al., 2006). NCA is home to various large mammal species like African elephants
(Loxodonta africana), wildebeests (Connochaetes taurinus), zebras (Equus quagga),
common elands (Taurotragus oryx), African bualos (Syncerus caer), Grant’s (Nanger
gran), Thomson’s gazelles (Eudorcas thomsonii), spoed hyenas (Crocuta crocuta) and
lions (Panthera leo). The climate is characterized by wet and dry seasons with diurnal
temperatures ranging from 7.4 °C–14.5 °C and from 10.6 °C–19.6 °C, respecvely and an
annual rainfall ranging from 300 to 630 (Foxcro et al., 2006).
The study was conducted in rangelands located both inside and outside the Ngorongoro
crater (Fig. 1) during the dry season (September–October 2022) and completed
in February 2023. The study area comprises six wards, namely: Enduleni, Kakesio,
Nainokanoka, Misigyo, Ngorongoro and Olbalbal. Also, ve major habitats characterize
the foraging area of rangelands: grassland, woodland, wooded grassland, wetlands and
forest.

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Figure 1: Study area

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2.2 Data collecon and sampling design
A total of 40 transect lines were systemacally established across the enre study area.
Out of these, 10 transects were inside the crater, while 30 transects were laid outside
the crater. Along each transect, sampling points were established aer each 3 km (Fig.
2). Sampling plots were replicated three mes (0 m, 25 m and 50 m) in an alternang
right-le direcon. Both transects and sampling points were mapped using Google
Earth-Pro soware and veried by ground truthing. During data collecon, transects
were tracked using GPS. At each sampling point, a quadrant (1m by 1m) was used.
Figure2 : Transect lines and sampling plots in the crater area

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Figure 4: Project team collecng data from sampling plots
Figure 3: Sampling design

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2.2.1 Vegetaon data
Within a quadrant, the research team collected informaon on types of both invasive
and non-invasive plant species and idened them to species level. Addionally, their
frequency and coverage were assessed and documented (Fig. 5).
2.2.2 Wildlife data
Aer obtaining vegetaon informaon, direct observaon was conducted within a
15-meter radius from the center of the quadrant to count all wild animals and birds that
were present at the sampling site. Visual signs like dung, tracks, feathers and nests were
also idened and recorded (Fig. 6).
Figure 6: Dungs from dierent wild animals species
Figure 5: Dungs from dierent wild animals species
2.2.3 Modulus elascity of plant stems
To idenfy species suitable for briquee producon, the strength of various plant stems
was tested. All species with wooden stems were idened through visual observaon.
By using hands, stress was placed to compare the extent of deformaon that the stem
exhibits along its length. All species that were less resistant to breakage were considered
rich in lignin content.

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Figure 7: Distribuon of invasive plant species across dierent ecological habitats
within the crater area
2.3 Data analysis
We analyzed the distribuon of IPS using QGIS soware and mapped their spread on
the crater oor. We calculated the abundance of each IPS and non-invasive based on
the frequency of their presence. Species diversity was measured using the Simpson
Diversity Index (SDI).
A one-way ANOVA test was used to determine the variaon of species abundance across
dierent surveyed wards and major ecological habitats. T-test was used to compare
ecological indices of individual invasive species between grassland and bushland
ecosystems. Results were presented in tables, graphs and maps. All calculaons were
computed in R stascal soware (Team, 2019).
3.0 KEY RESULTS
3.1 Within the Ngorongoro Crater area
3.1.1 Species distribuon, abundance and diversity
Our survey idened a total of six invasive plant species, namely: Bidens schimperi,
Gutenbergia cordifolia, Lippia javanicum, Targetes minuta, Solonum incunam and
Verben ocinalis. All invasive plant species were found in grassland and bush land only,
and their abundance was variable (Figs. 7 and 8). The dierence in species abundance
between the two habitats was signicant (W = 1821.5, p-value < 0.05). Based on the
Simpson Diversity Index, bush land indicated higher species diversity (D = 0.26) compared
to grassland (D = 0.3).

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Figure 8: Variaon in abundance of IPS dominated the crater oor in NCA
L. Javanica was the most abundant among other IPS (mean = 11.9). It was located at
the foot of the crater rim, especially in the northern and eastern parts (Fig.10). The
higher populaon of L. Javanica was found in bush land (93.1%) compared to grassland
habitats (6.9%) (Figs. 3 and 4). However, the dierence in species abundance between
the two habitats was not signicant (W = 21, p-value > 0.05).
B.schimperi was the most dominant IPS in grassland habitat and the second most
dominant in bush land. It was found both in the central and northern parts of the crater
oor (Fig. 11). More than half of its populaon was found in grassland (68.8%) and
partly in bush land (31.3%), but the dierence was not signicant (W = 82, p > 0.05).
S.incanum was the second dominant IPS in the grassland habitat. About 77% of its
populaon was found in grassland, while 23.7% was in bushland, but the dierence
was not signicant (W = 45, p-value > 0.05). Within the crater oor, it is located in the
northwestern and central parts (Fig. 12).
G. cordifolia was about 50% less abundant than B. schimperi in the grassland and the
least dominant in the bushland. Its populaon was about six mes higher in grassland
(84.5%) compared to bushland (14.5%), but the dierence was not signicant (w = 15.5,
p-value > 0.05). Similar to B. schimperi, its hotspot locaon is in the northern part of the
crater oor, with a few patches in the central part (Fig. 13).

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S. minuta was about one-ninth as abundant as B. schimperi and represented the least
dominant IPS within grassland habitat. Its populaon was twice as high in bush land
(66.7%) as in grassland (33.3%), but the dierence was not signicant (W = 1, P-value
> 0.05). The plants were conned only to the northern part of the crater oor (Fig. 11).
V. ocinalis was not present in grassland habitat and was among the least abundant IPS
in bush land too (Fig. 12). It was only found in the southwestern part of the crater oor.
Figure 9: Common invasive plant species dominated the crater oor in NCA

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Figure 10: Distribuon of L. Javanica in the crater oor in NCA

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Figure 11: Distribuon of B. schimperi in the crater oor in NCA

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Figure 12: Distribuon of S. incunum in the crater oor in NCA

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Figure 13: Distribuon of G. cordifolia in the crater oor in NCA

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Figure 14: Distribuon of T. iminuta in the crater oor in NCA

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Figure 15: Distribuon of V. ocinalis in the crater oor in NCA

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3.1.2 Distribuon of IPS Percentage Cover
Invasive plant species covered nearly 17% of the crater area (CI = 13.7%, 32.2%).
Notably, B.schimperi covered the largest part of the landscape, followed by L. javanica.
Addionally, G.cordifolia covered nearly half of the surface area occupied by B.schimperi.
Addionally, T.minuta and V. ocinalis sll covered only a small part (< 1%) of the crater
oor. In contrast, a large part of the crater oor (82.7%) was not invaded by any invasive
plants (Fig 16).
Figure 16: The proporon of invaded and non-invaded crater surface area
Figure 17: Variaon of IPS cover (%) between grass and bush land habitats

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The percentage cover of all invasive species indicated a signicant dierence between
grassland and bushland (t = 4.9496, df = 67.197, P-value = < 0.05). Under bush land habitat,
L. javanica indicated the highest percentage cover (median = 70%), followed by V. ocinalis
(median = 30%), while the least was T. minuta (median = 5%). Under the bushland habitat,
L. javanica indicated the highest percentage cover (30%). The proporons of B. schmiperi,
G. cordifolia and S. incanum were nearly comparable (median = 10%–12%) (Fig. 17).
3.1.3 Species suitable for briquee producon
The survey determined only two plant species within crater area could be suitable for
briquee producon, namely L. Javanicum and S. incunam. The former was more abundant
(abundance = 336) compared to the laer (abundance = 59).
3.1.4 Rangelands Ulizaon by wildlife
All herbivore species were more abundant in areas un-invaded compared to areas
invaded by invasive plants within rangelands, and their dierence was highly signicant
(df = 1, F = 35.68, p-value < 0.05). Bualo, eland, wildebeest and zebra were present
in all sampling plots that were invaded by invasive species. Seemingly, these four
herbivore species could be more tolerant than other species. The largest number of
bualo (n = 10) was present in plots aected by L. javanica while the fewest (n = 1)
were present under V. ocinalis and T. minuta. Zebra were more abundant (n = 18)
under B. schimperi and under S.incanum (n = 11). Eland ranged between moderate
and large (n = 1–5) with the largest populaon under L.javanica. On the other hand,
baboons and warthogs were rarely observed within the invaded parts of rangelands (n
= 1). The former was present under L. javanica while the laer was under G. cordifolia
(Table 1).
Within invaded areas, between 3 and 7 herbivore species were observed. Locaons
aected by B. schimperi and S. incanum indicated the highest herbivore species
richness (n = 7 and n = 6), while those under V. ocinalis and S. incanum indicated
comparable levels (n = 5). However, the lowest herbivore species richness (n = 3) was
noted in locaons under T. minuta. However, most herbivores could tolerate foraging
in invaded bush land compared to invaded grassland (H = 630.89, df = 357, P-value <
0.05). Bualos and zebras were the most dominant (N > 20%), while warthogs (1.1%)
and hartebeests (0.8%) were the least. Herbivores’ abundance varied signicantly
across dierent invasive plants (df = 5, F = 0.884, p < 0.05). The highest was noted
under B. schimperi (n = 30), L. javanica (n = 26), and S. incunum (n = 20). But, the least
abundant were noted under T. minuta and V. ocinallis (n < 6) (Fig. 18).

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Figure 18: Spaal variaon of herbivore abundance under dierent habitat types

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A linear relaonship between herbivore populaons and the abundance of IPS was
noted. The increasing populaon of G. cordifollia and L. javanica decreases the
populaon of herbivores, while other IPS indicate a posive correlaon (Fig. 19)
Figure 19: Relaonship between the extent of G.vcorfolia(A) B.vschimperi (B) V.
ocinalis (C) L. javanica (D), T. minuta and S. incanum (E) and the populaon of
various large herbivores in the crater oor

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Table 1: Frequency of occurrence of large herbivores across sampling points dominated by dierent IPS
Animal B. schimperi G. cordifolia L. javanica S. incunum T. minuta V. ocinalis Not invaded
Baboon 0 0 1 0 0 0 0
Bualo 5 30 5 1 1 110
Dik dik 0 0 0 0 0 0 11
Eland 21 5 1 1 1 22
Elephant 0 0 0 1 0 0 72
G.gazelle 1 0 0 1 0 1 33
Hartebeest 0 0 0 0 0 0 4
Hippo 0 0 0 0 0 0 10
Rhino 0 0 0 0 0 0 1
T.gazelle 1 0 0 0 20 52
Warthog 0 1 0 0 0 0 5
Wildebeest 1 1 1 1 0 0 58

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3.2 OUTSIDE THE CRATER AREA
3.2.1 Distribuon of invasive and non-invasive plants species
The survey idened a total of 34 invasive plant species outside the Ngorongoro crater
area which have covered between 30% to 40% of rangelands area. The distribuon of its
coverage across dierent wards in NCA is presented in Table 2. Nevertheless, the coverage
contributed by invasive and non-invasive plants species within rangelands indicated a
signicant dierence (P-value <0.05, F = 1, df = 4). The most aected areas with invasive
species were Enduleni and Ngorongoro wards. Two wards, namely Nainokanoka, and
Kakesio indicated comparable extent of coverage (33% to 37%). In contrary, relavely the
least aected ward was Olbalbal (27%) (Table 2).
Ward Invasive plants (%) Non-invasive (%)
1Enduleni 40 60
2Olbalbal 27 73
3Nainokanoka 33 67
4Kakesio 34 66
5Ngorongoro 37 67
3.2.1 Diversity and richness of invasive plants
The diversity of invasive plants were relavely higher in Nainokanoka and Kakesio wards
(D = 0.37 - 0.45)(D = 0.37–0.45). Ngorongoro and Olbalbal indicated only a slightly
dierence (0.21 and 0.27). The lowest values were observed in Enduleni (D = 0.16). On
other hand, wooded grassland indicated a slightly higher diversity of invasive plants (D =
0.16), while grassland and woodland were comparable (D = 0.14). Habitats with higher
species richness were grassland (n = 29), while the least was woodland (n = 11) (Tables
3 and 4).
Ward Species diversity
(Simpson-Index)
Species richness
1Enduleni 0.16 60
2Olbalbal 0.27 9
3Nainokanoka 0.45 5
4Kakesio 0.37 9
5Ngorongoro 0.21 10
Table 3: Diversity and species richness of IPS outside Ngorongoro crater
Table 2: Distribuon (% cover) of invasive and non-invasive plants outside crater

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Ward Species diversity
(Simpson-Index)
Species richness
1Grassland 0.14 29
2Woodland 0.16 11
3Wooded-grassland 0.14 16
3.2.2 Abundance of invasive plant species
The abundance of invasive plant species indicated a signicant dierence across the
ve study wards (H = 80.39, df = 58, P < 0.05). The most dominant species were Juscia
exigua (n = 197), Gutenbergia cordifolia (n = 107), and Solanum incanum (n = 96). Others
were Indigofera spinosa (n=49), Eleusine jaegeri (n = 38), Tagetes minuta (n = 38), and
Heliotropium indicum (35) (Tables 5 and 6). Enduleni ward indicated the highest number
of invasive plant species (n = 22), while the fewest were recorded in Nainokanoka ward
(n = 5). The rest of the three wards, namely Kakesio, Ngorongoro and Olbalbal indicated
nearly the same number of invasive plants (n = 9–10). The abundance of invasive species
was signicantly dierent across the three ecological habitats (H = 70.54, df = 58, P-value
< 0.05). In grassland, the abundance was about twice (n = 29) that recorded in wooded
grassland (n = 16), but was slightly higher than that recorded in woodland (n = 11).
Table 4: Diversity and species richness of IPS across major habitats
Figure 20: Rangelands dominated by E.Jaegeri in upland areas

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Ward Species name Count
1Nainokanoka Eleusine jaegeri 28
Conocarpus erectus 9
Cerasum glomeratum 4
Juscia exigua 2
Heliotropium indicum 1
Enduleni Juscia exigua 120
Gutenbergia cordifolia 90
Solanum incanum 65
Indigofera spinosa 42
Tagetes minuta 25
Leucas aspera 14
Amaranthus spinosus 11
Heliotropium steundrr 10
Lippia javanica 10
Heliotropium indicum 7
Leonos nepefolia 7
Heliotropium steudneri 6
Datura stramonium 5
Xanthium strumarium 4
Bidens schimperii 3
Cuscuta campestris 3
Indigofera.sp 2
Cassia didymobotrya 1
Indigofera gaora 1
Table 5: Abundance of invasive plants species outside Ngorongoro crater

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Lippia ucambeusis 1
Ononis spinosa 1
Withania somnifera 1
Kakesio Gutenbergia cordifolia 17
Juscia exigua 16
Biden schirmperii 13
Tagetes minuta 12
Leucas aspera 11
Solanum incanum 7
Amaranthus spinosus 2
Datura stramonium 2
Leonos nepefolia 2
Ngorongoro Eleusine jaegeri 10
Uca masaica 4
Juscia exigua 2
Amaranthus spinosus 1
Cirsium arvense 1
Conocarpus erectus 1
Leucas aspera 1
lantago afra 1
Pteridium exculantum 1
Tagetes minuta 1
Olbalbal Juscia exigua 57
Heliotropium indicum 27
Solanum incanum 24
Indigofera spinosa 7
Withania somnifera 5

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Chenopodium.sp 4
Ipomoea.sp 3
Amaranthus spinosus 2
Argemon mexicana 1
Habitat Plant name Count
1Grassland Juscia exigua 118
Solanum incanum 62
Gutenbergia cordifolia 54
Indigofera spinosa 39
Eleusine jaegeri 38
Heliotropium indicum 20
Tagetes minuta 13
Amaranthus spinosus 10
Conocarpus erectus 10
Heliotropium steundri 9
Leucas aspera 7
Heliotropium steudneri 6
Cerasum glomeratum 4
Datura stramonium 4
Leonos nepefolia 4
Uca masaica 4
Bidens schimperi 5
Cuscuta campestris 3
Ipomoea.sp 3
Xanthium strumarium 3
Cirsium arvense 1
Indigofera gaora 1
Indigofera.sp 1
Lippia ucambeusis 1
Ononis spinosa 1
Plantago afra 1
Pteridium exculantum 1
Withania somnifera 1
Table 6: Abundance of IPS across major habitats

26
2Woodland Juscia exigua 18
Gutenbergia cordifolia 11
Lippia javanica 5
Withania somnifera 5
Chenopodium.sp 4
Leucas aspera 3
Tagetes minuta 3
Biden schirmperii 2
Leonos nepefolia 2
Argemon mexicana 1
Heliotropium indicum 1
3Wooded-grassland Juscia exigua 61
Gutenbergia cordifolia 42
Solanum incanum 34
Tagetes minuta 22
Leucas aspera 16
Heliotropium indicum 14
Indigofera spinosa 10
Biden schirmperii 9
Amaranthus spinosus 6
Lippia javanica 5
Datura stramonium 3
Leonos nepefolia 3
Cassia didymobotrya 1
Heliotropium steundrri 1
Indigofera.sp 1
Xanthium strumarium 1
3.2.3 Diversity and richness of nave forage
The survey found that the dominance of nave forage species was signicantly dierent
across the ve wards (H = 131.64, df = 107, P-value 0.05), but only 11 species were
most dominant. These included Cynadon. dactylon (n = 269), Euphorbia. prostrata (n
= 131), Kyllinga. alata (n = 116), Cyperus. rotundus (n = 89), Indigofera. volkensii (n =
88), Brachiaria. semiundulata (n = 77), Brachiaria. brizantha (n = 68), Tribulus. terestris
(68), Eragross.tenuifolia (n = 67), Chloris. pycnothrix (n = 61), Digitaria. abbysinica (n =
50). Likewise, the dominance of nave forage species indicated a signicant dierence
across the three ecological habitats (H = 184.64, df 107, P - value < 0.05).

27
Generally, all surveyed wards indicated low diversity of nave forage species, which
ranged from 0.04 to 0.09. Almost all surveyed wards indicated comparable values of
species diversity (D = 0.04–0.05), except in Olbalbal (D = 0.09) (Table 7). However, nave
forage species diversity was only slightly dierent across the major ecological habitats
(D = 0.03–0.04) (Table 8).
Nave forage species richness was relavely high in the Enduleni ward. The value
dropped by nearly 50% in each of the other four surveyed wards. Across habitats,
grassland was the richest in species numbers, followed by wooded grassland. On the
contrary, woodland indicated the least number of species (Table 9).
Ward Species diversity
(Simpson-Index)
Species richness
1Enduleni 0.04 94
2Olbalbal 0.05 44
3Nainokanoka 0.05 48
4Kakesio 0.05 37
5Ngorongoro 0.09 47
Table 7: Diversity and species richness of nave forage outside Ngorongoro crater
Ward Species diversity
(Simpson-Index)
Species richness
1Grassland 0.04 110
2Woodland 0.03 46
3Wooded-grassland 0.04 80
Table 8: Diversity and species richness of nave forage across major habitats
Figure 21: The most dominant nave forage species outside the crater area

28
Ward Species name Count
1Nainokanoka Alchemillia alpina 29
Bacopa crenata 28
Cyperus rotundus 26
Eragross tenuifolia 26
Cynodon dactylon 19
Dichondra repens 17
Leontodo hispidus 17
Setaria pumila 17
Sporobolus africanus 16
Tephrosia pumila 15
Alysicarpus vaginalis 14
Euphorbia prostrata 12
Brachiaria brizantha 11
Oxalis corniculata 9
Pennisetum clandesnum 8
Carum carvi 7
Dicondra repens 6
Eragross superba 5
Geranium molle 5
Geranium.sp. 4
Kyllinga alata 4
Aeschynomene indica 3
Dactyloctenium aegypum 3
Fimbristylis.sp. 2
Commelina benghalensis 2
Table 9: Abundance of nave forage species outside Ngorongoro crater

29
Ward Species name Count
Indigofera volkensii 2
Pennisetum mezianum 2
Alchemill alpina 1
Bidens pilosa 1
Brachiaria semiundulata 1
Cenchrus clandesnum 1
Commelina africana 1
Crepis bursifolia 1
Digitaria abbysinica 1
Geranium.sp 1
Ipomoea sinensis 1
Lathyrus tuberosus 1
Leontodon.sp 1
Orthosiphon.sp. 1
Portulaca quadrifolia 1
Ruelia patula 1
Sennecio gallicus 1
Solanum nigrum 1
Alchemillia alpina 29
Bacopa crenata 28
Cyperus rotundus 26
2Enduleni Abulon pannosum 2
Achyranthes aspera 5
Alchemillia alpina 1
Alternanthera pungens 1
Alysicarpus vaginalis 2

30
Ward Species name Count
Enduleni cont... Arisda kenyensis 1
Barleria cristata 7
Bidens pilosa 6
Brachiaria brizantha 56
Brachiaria semiundulata 1
Chenopodium murale 1
Chlori gayana 37
Chloris pycnothrix 3
Combretum.sp. 12
Commelina africana 4
Commelina benghalensis 1
Craterosgma plantagineum 1
Crotalaria.sp. 3
Crotalaria spinosa 5
Crotolaria.sp. 9
Crotolaria spinosa 1
Cucumis anguria 2
Cucumis.sp 1
Cyanthula.sp 2
Cyathula prostrata 31
Cymbopogon.sp. 1
Cynodon dactylon 111
Cyperus rotundus 39
Dactyloctenium aegypum 15
Digitaria scala 2
Digitaria scalarum 24

31
Ward Species name Count
Enduleni cont... Digitaria valuna 3
Digitaria vercilata 17
Digitaria abbysinica 2
Eleusine indica 30
Ephoprostrata.spp 1
Eragross aspera 1
Eragross superba 11
Eragross aspera 7
Eragross tenella 1
Eragross teunifolia 2
Eragross superba 21
Eragross tenuifolia 9
Euphorbia prostrata 60
Galinsoga parviora 4
Gilinsoga parymidalis 1
Glebionis coronaria 1
Harpachne schimperi 1
Hermania.sp. 4
Indigofera basiora 1
Indigofera volkensii 64
Ipomoea sinensis 26
Kalanchoe.sp. 1
Kyllinga.alata 36
Lepidium.sp. 2
Microchloa kunthii 4
Oldenlandia.sp 3

32
Ward Species name Count
Enduleni cont... Oldenlandia.sp. 2
Orthosiphoa.sp 1
Oxygonum sinuatum 21
Pennisetum mezianum 24
Portulaca quadrifolia 17
Rhynchosia minima 6
Rhynchosia volubilis 1
Ruelia patulla 1
Sanecio gallicus 1
Senecio abbysinica 1
Senna obtusifolia 1
Sennecio abbysinica 1
Sennecio gallicus 15
Setaria homonima 5
Setaria sphacelata 17
Setaria vercilata 19
Setaria pumila 10
Sida cuneifolia 2
Sida ovata 25
Solanum nigrum 1
Sonchus asper 2
Sporobolas pyramidalis 1
Sporobolus africanus 1
Sporobolus iocladus 1
Sporobolus pyramidalis 1
Sporoborus africanus 1

33
Ward Species name Count
Enduleni cont... Sporoborus africanus 1
Tragus berteronianus 13
Tribulus terestris 49
Vachellia torlis 3
3Olbalbal Cynodon dactylon 117
Kyllinga alata 72
Tribulus terestris 44
Eragross tenuifolia 27
Euphorbia prostrata 23
Brachiaria semiundulata 20
Sida ovata 19
Alysicarpus aginalis 17
Sporobolus ioclados 16
Grangea maderaspatana 12
Sennecio gallicus 12
Achyranthes aspera 10
Digitaria abbysinica 10
Cyperus rotundus 9
Digitaria macroblephara 8
Ipomoea sinensis 8
Portulaca quadrifolia 8
Eragross superba 6
Ruelia patulla 6
Sporobolus ioclodus 6
Alternanthera pungens 5
Indigofera volkensii 4

34
Ward Species name Count
Olbalbal cont... Sida cuneifolia 4
Craterosgma plantagineum 3
Tephrosia pumila 3
Tribulus terrestris 3
Boeharvia diusa 2
Crotolaria.sp. 2
Malva neglecta 2
Orthosiphoa.sp 2
Oxygonum sinuatum 2
Vachellia mellifera 2
Vachellia torlis 2
Barleria sp 1
Chloris pycnothrix 1
Commelina benghalensis 1
Digitaria veluna 1
Eragross teunifolia 1
Indigofera spinosa 1
Ocimum suave 1
Pennisetum mezianum 1
Setaria vercilata 1
Sinapis arvensis 1
Sporobolus loclodus 1
Viburnum dentatum 1
4Ngorongoro Cynodon dactylon 18
Euphorbia prostrata 15
Bacopa crenata 14

35
Ward Species name Count
Ngorongoro cont... Cyperus rotundus 14
Alchemillia alpina 13
Sporobolus africanus 13
Brachiaria brizantha 12
Setaria pumila 12
Oxalis corniculata 9
Carum carvi 8
Commelina. benghalensis 7
Dichondra repens 7
Eragross tenuifolia 5
Geranium molle 5
Leontodon hispidus 4
Crotalaria.sp. 3
Cynodon plectostachyus 2
Digitaria abbysinica 2
Fimbristylis.sp. 2
Solanum.nigrum 2
Aeschynomene indica 1
Anchusa ocinalis 1
Astragalus pelecinus 1
Bacopa.sp. 1
Calopogonium mucunoides 1
Crotolaria spinosa 1
Cyathula prostrata 1
Galinsoga parviora 1
Geranium.sp 1

36
Ward Species name Count
Ngorongoro cont... Indigofera volkensii 1
Ipomoea sinensis 1
Medicago sava 1
Rhynchosia mimina 1
Salvia.sp. 1
Salvia nemorosa 1
Sonchus.asper 1
Vachellia.torlis 1
5 Kakesio Chloris.pycnothrix 23
Dactyloctenium aegypum 19
Euphorbia prostrata 19
Indigofera volkensii 17
Eragross aspera 9
Brachiaria brizantha 8
Digitaria abbysinica 7
Tragus berteronianus 6
Eragross superba 5
Sennecio abbysinica 5
Tribulus terrestris 5
Cenchru ciliaris 4
Cyathula prostrata 4
Cynodon dactylon 4
Glebionis coronaria 4
Kyllinga alata 4
Pennisetum mezianum 4
Setaria pumila 4

37
Ward Species name Count
Kakesio cont... Achyranthes aspera 3
Ruelia patulla 3
Sporobolus ioclados 3
Abulon pannosum 2
Barleria.sp. 2
Commelina. benghalensis 2
Commiphora africana 2
Digitaria scalarum 2
Panicum maximum 2
Senecio abbysinica 2
Setaria vercilata 2
Sporobolus africanus 2
Sporobolus loclodus 2
Vachellia torlis 1
Acacia torlis 1
Brachiaria brizanza 1
Couchrus cilians 1
Crotolaria.sp. 1
Cyanthula.sp. 1
Cynodon plectostachyus 1
Cyperus rotundus 1
Digitaria vercilata 1
Eragross superba 1
Eragross tenella 1
Ipomoea sinensis 1
Oxygonum sinuatum 1

38
Ward Species name Count
1Nainokanoka Alchemillia alpina 29
Bacopa crenata 28
Cyperus rotundus 26
Eragross tenuifolia 26
Cynodon dactylon 19
Dichondra repens 17
Leontodo hispidus 17
Setaria pumila 17
Sporobolus africanus 17
Tephrosia pumila 16
Alysicarpus vaginalis 15
Euphorbia prostrata 14
Brachiaria brizantha 12
Oxalis corniculata 11
Pennisetum clandesnum 9
Carum carvi 8
Dicondra repens 7
Eragross superba 6
Geranium molle 5
Geranium.sp. 5
Kyllinga alata 4
Aeschynomene indica 3
Dactyloctenium aegypum 3
Fimbristylis.sp. 3
Commelina benghalensis 2
Indigofera volkensii 2

39
Ward Species name Count
Nainokanoka cont... Pennisetum mezianum 2
Alchemill alpina 1
Bidens pilosa 1
Brachiaria semiundulata 1
Cenchrus clandesnum 1
Commelina africana 1
Crepis bursifolia 1
Digitaria abbysinica 1
Geranium.sp 1
Ipomoea sinensis 1
Lathyrus tuberosus 1
Leontodon.sp 1
Orthosiphon.sp. 1
Portulaca quadrifolia 1
Ruelia patula 1
Sennecio gallicus 1
Solanum nigrum 1
Alchemillia alpina 29
Bacopa crenata 28
Cyperus rotundus 26

40
Habitat Plant name Count
1Grassland Cynodon dactylon 196
Kyllinga alata 83
Euphorbia prostrata 82
Cyperus rotundus 62
Eragross tenuifolia 61
Brachiaria brizantha 56
Brachiaria semiundulata 48
Alchemillia alpina 42
Bacopa crenata 42
Indigofera volkensii 38
Setaria pumila 38
Alysicarpus vaginalis 33
Sporobolus africanus 32
Tribulus terestris 29
Chloris pycnothrix 28
Digitaria scalarum 25
Dichondra repens 24
Sennecio gallicus 23
Digitaria abbysinica 22
Cyathula prostrata 21
Eragross superba 21
Leontodon hispidus 21
Oxalis corniculata 20
Ipomoea sinensis 19
Sida ovata 18
Tephrosia pumila 17
Carum carvi 16
Dactylocteniumaegypum 16
Sporobolus ioclados 16
Tribulus terrestris 16
Commelina benghalensis 15
Portulaca quadrifolia 13
Oxygonum sinuatum 12
Pennisetum mezianum 10
Table x: Abundance of IPS across major habitats

41
Habitat Plant name Count
Grassland cont... Geranium molle 10
Setaria sphacelata 10
Achyranthes aspera 9
Commelina africana 9
Pennisetum clandesnum 9
Digitaria. veluna 8
Digitaria.macroblephara 8
Dicondra. repens 7
Ruelia.patulla 7
Setaria. vercilata 7
Barleria.cristata 6
Sporobolus. ioclodus 5
Fimbristylis.sp. 5
Geraniu.sp. 5
Glebionis. coronaria 5
Tragus. berteronianus 5
Aeschynomene. indica 4
Crotalaria sp 4
Sida.cuneifolia 4
Solanum nigrum 4
Alternanthera pungens 3
Bidens pilosa 3
Crotalaria spinosa 3
Crotolaria spinosa 3
Eragross aspera 3
Eragross teunifolia 3
Galinsoga.parviora 3

42
Habitat Plant name Count
Grassland cont... Microchloa. kunthii 3
Orthosiphoa.sp 3
Crotolaria.sp. 2
Cynodon. plectostachyus 2
Digitaria. valuna 2
Geranium.sp 2
Hermania.sp. 4
Lepidium.sp. 2
Rhynchosia. mimima 2
Senecio.gallicus 2
Sennecio. abbysinica 2
Sonchus.asper 2
Sporobolus. ioclodus 2
Abulon. pannosum 1
Alchemilla. alpina 1
Anchusa. ocinalis 1
Arisda. kenyensis 1
Astragalus. pelecinus 1
Bacopa sp. 1
Calopogonium. mucunoides 1
Cenchrus. clandesnum 1
Couchrus.cilians 1
Craterosgma.plantagineum 1
Crepis bursifolia 1
Cucumis anguria 1
Cyanthula.sp. 1
Cymbopogon. sp. 1

43
Habitat Plant name Count
Grassland cont... Digitaria vercilata 1
Eragross superba 1
Eragross tenella 1
Harpachne schimperi 1
Indigofera. basiora 1
Kalanchoe.sp. 1
Lathyrus tuberosus 4
Leontodon.sp. 1
Medicago sava 1
Orthosiphon.sp. 1
Rhynchosia mimina 1
Rhynchosia volubilis 1
Ruelia patula 1
Salvia.sp. 1
Salvia nemorosa 1
Sanecio gallicus 1
Senna obtusifolia 1
Setaria spacelata 1
Sporobolus iocladus 1
Sporobolus.locladus 1
Vachellia.torlis 1
Woodland Digitaria abbysinica 10
Cynodon dactylon 8
Indigofera.volkensii 8
Sida ovata 6
Chloris pycnothrix 5
Euphorbia prostrata 5

44
Habitat Plant name Count
Woodland cont... Tribulus terestris 5
Cyathula prostrata 4
Cyperus rotundus 4
Eragross superba 4
Dactyloctenium aegypum 3
Rhynchosia mimima 3
Ruelia patulla 3
Sennecio abbysinica 2
Achyranthes.aspera 2
Barleria.sp. 2
Brachiaria semiundulata 2
Digitaria scala 2
Digitaria Scalarum 2
Eragross aspera 2
Ipomoea sinensis 2
Malva neglecta 2
Oxygonum sinuatum 2
Panicum maximum 2
Portulaca quadrifolia 2
Setaria pumila 2
Tephrosia pumila 2
Boeharvia diusa 1
Brachiaria brizanza 1
Brachiaria brizantha 1
Combretum.sp. 1
Commiphora africana 1
Cyanthula.sp. 1

45
Habitat Plant name Count
Woodland cont... Cynodon plectostachyus 1
Digitaria veluna 1
Eragross tenella 1
Gilinsoga parymidalis 1
Indigofera spinosa 1
Kyllinga alata 1
Pennisetum mezianum 1
Setaria homonima 1
Sporobolus loclodus 1
Sporobolus pyramidalis 1
Tragus berteronianus 1
Tribulus terrestris 1
Vachellia torlis 1
3Wooded-grassland Cynodon dactylon 65
Euphorbia prostrata 44
Indigofera volkensii 42
Tribulus terestris 34
Kyllinga alata 32
Chloris pycnothrix 28
Brachiaria semiundulata 27
Cyperus rotundus 23
Sida ovata 20
Dactyloctenium aegypum 18
Digitaria abbysinica 18
Pennisetum mezianum 18
Tribulus terrestris 17
Ipomoea sinensis 16

46
Habitat Plant name Count
Wooded grassland cont... Setaria vercilata 15
Eragross superba 13
Tragus. berteronianus 13
Grangea maderaspatana 12
Brachiaria brizantha 11
Cyathula prostrata 11
Eragross aspera 11
Digitaria veluna 9
Oxygonum sinuatum 9
Portulaca quadrifolia 8
Eragross.aspera 7
Achyranthes aspera 7
Crotolaria spinosa 7
Eragross superba 7
Crotolaria.sp. 6
Eragross tenuifolia 6
Vachellia torlis 5
Setaria sphacelata 5
Bidens pilosa 4
Cenchrus ciliaris 4
Commelina africana 4
Sennecio abbysinica 4
Sennecio gallicus 4
Setaria homonima 4
Abulon pannosum 3
Alternanthera pungens 3
Craterosgma plantagineum 3

47
Habitat Plant name Count
Wooded grassland cont... Digitaria scalarum 3
Glebionis coronaria 3
Senecio abbysinica 3
Setaria pumila 3
Sporobolus ioclados 3
Combretum.sp. 2
Cucumis.sp 2
Digitaria vercilata 2
Gilinsoga parviora 2
Oldenlandia.sp 2
Sida cuneifolia 2
Vachellia mellifera 2
Acacia torlis 1
Alchemillia alpina 1
Alysicarpus vaginalis 1
Barleria cristata 1
Barleria.sp. 1
Boeharvia diusa 1
Chenopodium murale 1
Chloris gayana 1
Commelina benghalensis 1
Commiphora africana 1
Digitaria valuna 1
Eleusine indica 1
Ephoprostrata.spp 1
Microchloa kunthii 1
Ocimum suave 1

48
Habitat Plant name Count
Wooded grassland cont... Oldenlandia.sp. 1
Rhynchosia minima 1
Senecio gallicus 1
Setaria spacelata 1
Seteria vercilata 1
Sida avata 1
Sinapis arvensis 1
Sonchus asper 1
Sporobolas pyramidalis 1
Sporobolus africanus 1
Sporoborus africanus 1
Viburnum dentatum 1
3.2.4 Plant species suitable for briquees producon
A total of seven plant species were found to indicate desirable traits for briquee
producon (Table 10, Fig. 17). Their distribuon and abundance varied across the study
sites and showed signicant dierences (H = 60.637, df = 6, P-value < 0.05). Nearly 60%
of idened species indicated that they were abundant within rangelands. Seemingly,
L. javanica is poorly established outside the crater. Moreover, J. exigua was the most
widespread species, followed by S. incunm. On the contrary, L. javanica was only found
in Enduleni Ward.

49
Plant species name Frequency of occurrence
1J. exagua 3050
2S. incunam 856
3E. jaegeri 304
4W. somifera 303
5I. spinos 138
6C. eractus 20
7L. javanica 3
Table 10: Indened IPS suitable for producon of biomass briquees
Figure 22: Idened IPS suitable for biomass briquees producon

50
4.0 Conservaon implicaons of research ndings
4.1 Importance of conserving diverse habitats in the NCA
The results have revealed that rangelands within the crater area are relavely less
aected by invasive plant species compared to those located outside. This is based on
observaons of surface coverage and the exisng number of species. This dierence is
inferred from current management pracces against invasive plants. According to the
Head of Wildlife Management and Research Department (Pers.com), eorts to control
invasive plants in the NCA focus more on the crater area compared to other locaons
within the NCA. This priorizaon was based on the fact that the crater area has unique
biodiversity value and also plays an important role in tourism acvies. On the other
hand, there is a shortage of manpower, working gear, and funds to allow one-me
control of invasive plants across the enre ecosystem.
Grassland and bushland could be the most vulnerable habitats to IPS within the NCA.
This is aributed to ongoing over ulizaon of these habitats by large herbivores and
Maasai livestock which leads to dierent degrees of ecosystem disturbance. Notably,
increased trampling in rangelands triggers the loss of nave grass species and inuences
the dominance of invasive plants on the soil surface (Obiri, 2011).
Spaal variaon in diversity and abundance of IPS across habitats explains why ecologists
should always be updated on the ecological status of rangelands. This is important to
avoid increased threats in special habitats or locaons that need conservaon aenon.
For example, above 90% of the L. javanica populaon was recorded on the slope of
the crater rim, which is an important refuge for black rhino. Likewise, the increased
populaons of E . jaegeri in Nainokanoka and Ngorongoro wards were reported to
enhance human-wildlife conicts (HWC). According to Mr. Maura, Nainokanoka Ward
Chairman (Pers. comm). E. jaegeri are not oen eaten by livestock, thus creang
corridors for small stock predators like hyenas and leopards.
Given that the extent of the spread of IPS could vary over me scales, ecologists
should conduct regular monitoring, mapping and mely sharing of results with other
conservaonists and local people.

51
4.2 A need to integrate innovave conservaon eorts
Although there is no full assessment of the eecveness of current control methods
conducted in NCA (Pers. comm, H-WMR), exisng literature suggests that non-
parcipatory methods for controlling IPS are not sustainable (Rodrigues et al., 2017).
We are opmisc that exploing invasive plants as raw materials for economically
valuable products could be an impacul measure against ongoing degradaon. Thus,
through the Rangeland Care Project, a newly collaborave iniave between TAWIRI
and NCAA is expected to speed up the removal of various IPS from rangelands.
Reportedly, Rangeland-Care Project has successfully developed biomass briquees from
E. jaegeri, one of seven idened IPS in NCA with the potenal to provide raw materials
for biomass briquee producon. Interesngly, local pastoralists in NCA indicated a
posive response when conducng community tests. Likewise, laboratory tests on the
combuson properes of briquees from E. jaegeri have indicated that they fall within
the recommended range for alternave sources of energy in households by the Tanzania
Bureau of Standards (TBS). While the Rangeland-Care Project connues to assess the
energy properes of the other six IPS, parallel eorts should be implemented to idenfy
the potenal use of other IPS that are not suitable for briquee producon.
4.2.3 Protecon beyond NCA boundaries
We detected that a reasonable number of IPS were extensively spread within the
boundaries of the NCA. For example, G. cordifolia and S. incunum in Enduleni and Kakesio
wards have extended to Mwiba and Makao villages. Likewise, the massive abundances
of J. exagua and I.spinosa in Olbalbal have extended to Serenge Naonal Park. These
ndings highlight that a ght against IPS should not concentrate inside NCA boundaries.
Given that human acvies are the major drivers of spreading IPS, care is needed where
rangelands are connected to culvated or livestock grazing areas in adjacent villages.

52
5.0 Recommendaons and suggesons
Based on our ndings, we recommend the following:
• The reported high abundance and diversity of IPS in rangelands calls for the most
ecient approach to controlling the populaon of invasive plants in the NCA.
• The suggested migaon measures should be supported by detailed scienc data
from accredited laboratories and community percepons about their eciencies
• This exercise should be repeated during the wet season in order to capture temporal
variaons in the ecology of invasive plants in the NCA
• Given that this study assessed herbivore distribuon only within the crater area, we
suggest that the recent report of an aerial census of large mammals conducted by
TAWIRI could be useful for rangelands located outside the crater
6.0 References
1. Bukombe J.K., Nkwabi A.K., Mangewa L.J., Sweke E.A., Kavana P.Y., Liseki S.D., Kija H.H. (2021) Alien
Invasive Species in Tanzania. Invasive Alien Species: Observaons and Issues from Around the
World 1:263-290.
2. DeFries R., Hansen A., Turner B., Reid R., Liu J. (2007) Land use change around protected areas:
management to balance human needs and ecological funcon. Ecological applicaons 17:1031-
1038.
3. Foxcro L., Loer W., Runyoro V., Maay P. (2006) A review of the importance of invasive alien
plants in the Ngorongoro Conservaon Area and Serenge Naonal Park. African Journal of Ecology
44:404-406.
4. Masao C.A., Makoba R., Sosovele H. (2015) Will Ngorongoro Conservaon Area remain a world
heritage site amidst increasing human footprint?
5. Obiri J.F. (2011) Invasive plant species and their disaster-eects in dry tropical forests and rangelands
of Kenya and Tanzania. Jàmbá: Journal of Disaster Risk Studies 3:417-428.
6. Rodrigues A.J., Odero M.O., Kerich D., Odundo F., Akuno W. (2017) Up Scaling Invasive Plant Biomass
Briquee Producon: Case of Kendu Bay, Lake Victoria, Kenya.
7. Team R.C. (2019) R: a language and environment for stascal compung, version 3.0. 2. Vienna,
Austria: R Foundaon for Stascal Compung 2013.

Rangelands Care Project, Technical Report 02
www.tawiri.or.tz