An Assessment of Lantana Camara Distribution and Its Effects on Selected Soil Properties in Ward 1 of Zvimba District, Zimbabwe

BINDURA UNIVERSITY OF SCIENCE EDUCATION

DEPARTMENT OF ENVIRONMENTAL SCIENCE

AN ASSESSMENT OF LANTANA CAMARA DISTRIBUTION AND ITS EFFECTS ON SELECTED SOIL PROPERTIES IN WARD 1 OF ZVIMBA DISTRICT, ZIMBABWE

ELIZABETH GULUGULU (B1128987)

A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS OF THE BACHELOR OF ENVIRONMENTAL SCIENCE HONOURS DEGREE IN NATURAL RESOURCES MANAGEMENT

DATE OF SUBMISSION: 31 OCTOBER 2014 DEDICATION

I dedicate this dissertation to Mrs. Goromonzi for her love and financial support through my academic journey, my granny Ambuya Kaunda who passed away when I was in the middle of data collection of this project and to the late Litah and Sandress, you will always have a special place in my heart mum and dad.

ACKNOWLEDGEMENTS

I thank the almighty God for his strength and guidance for with him the impossible were made possible. My sincere gratitude goes to Mr. T. Nyamugure and Mr. A. Kundhlande my project supervisors who took their time and worked beyond hours assisting me with my project. In a special way I would like to thank Mr. G. Chikorowondo for his advice and assistance, Mr. W. Mhlanga, Mr. L. Jimu, Mr. T. Kaseke, Mr. P. Makumbe, Miss. T. Makuku for their contributions and corrections concerning this project. I extend my acknowledgements to Environmental Management Agency (EMA) for giving me an opportunity of doing this project on their behalf. My special gratitude goes to Mr. A. Chigona for his encouragement, Mr. M. Tendaupenyu District Environmental Officer of Zvimba whom I worked closely with on this project, Mr. L. Hwengwere Quality Environmental Officer of Mashonaland West for assisting me with the selection of soil parameters and literature concerning this study, Melissa Maenza my colleague for assisting me with information for my literature and Mr. K. Kabesa District Environmental officer of Kadoma for giving me time to work on my project during working hours, Mr. M. Nhariswa District Environmental Officer of Chegutu for his assistance towards selection of my project topic. I also want to thank my brother Jah, Godwin for his encouraging words towards my school work, my two lovely sisters Lucia and Liness for their support and prayers towards my school work, God bless you ladies. Lastly I want to thank Mr. and Mrs. Chikwanha for taking their time to assist me with my project and my fiancé Tarisai Emmanuel for assisting me with this dissertation and encouraging me to work hard.

ABSTRACT

This study was conducted in Ward 1 of Zvimba District in Zimbabwe with the aim of assessing the distribution of Lantana camara and its effects on selected soil properties (N, P, K, Mg, Ca, C, pH, soil texture and Na). Field reconnaissance using a Garmin GPS version 2.40 was used to mark areas invaded with L. camara and data were entered in ArcGIS version 10.1 for analysis of the production of a L. camara distribution map. Stratified random sampling was employed for field soil sample collections. Replicate soil samples were collected from different strata which included heavily invaded, moderately invaded and uninvaded, using a soil augur. Soil analyses were done using standard methods at the Department of Research and Specialist Services (DR&SS) in Harare for the determination of various mineral elements which included N, P, K, Mg, Ca, C, Na, pH and soil texture. Oneway ANOVA was used for data analysis and the LSD test was used to separate means of measured parameters at 95% confidence interval. Lantana camara invaded 14.3% of the total land in Ward 1, covering an area of 992.73 ha. Lantana camara was mainly distributed along riverine areas. Results showed that L. camara generally improved soil fertility in areas it had invaded (in terms of N, P, Mg, C and Na) except for K, Ca and clay content, despite the fact that there was low species richness within its environment due to its allelopathic effects. Future studies should focus on other soil properties which were not covered in this study. Researchers are also encouraged to continuously map land cover changes to help monitor areas affected by L. camara within the Ward.

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TABLE OF CONTENTS

DEDICATION ...... i

ACKNOWLEDGEMENTS ...... ii

ABSTRACT ...... iii

LIST OF FIGURES ...... vi

LIST OF TABLES ...... vii

LIST OF ACRONYMS AND ABBREVIATIONS...... viii

CHAPTER 1...... 1

INTRODUCTION...... 1 1.1 BACKGROUND TO THE STUDY ...... 1 1.2 PROBLEM STATEMENT ...... 2 1.3 JUSTIFICATION...... 2 1.4 AIM ...... 3 1.5 OBJECTIVES ...... 3 1.6 RESEARCH QUESTIONS ...... 3

CHAPTER 2...... 4 LITERATURE REVIEW ...... 4 2.1 DISTRIBUTION OF LANTANA CAMARA IN ZIMBABWE ...... 4 2.1.1 IMPACTS OF LANTANA CAMARA ON SOILS ...... 5 2.1.2 IMPACTS OF INVASIVE SPECIES ON SOIL ...... 5 2.1.3 SOIL NUTRIENTS ...... 6 2.1.4 SOILS IN ZVIMBA ...... 6 2.2 EFFECTS OF LANTANA CAMARA ...... 7 2.2.1 IMPACTS ON RURAL AGRICULTURE ...... 7 2.2.2 LOSS OF PASTURE ...... 7 2.2.3 TOXICITY ON ANIMALS ...... 7 2.2.4 DEPLETION OF NATURAL VEGETATION ...... 8 2.2.5 MANAGEMENT OF LANTANA CAMARA ...... 8

CHAPTER 3...... 10 METHODOLOGY...... 10 3.1 DESCRIPTION OF THE STUDY AREA ...... 10 3.1.1 DEMOGRAPHY AND RAINFALL...... 11 3.2. EXPERIMENTAL DESIGN ...... 11 3.4 METHODS OF DATA ANALYSIS ...... 12

CHAPTER 4...... 13 RESULTS...... 13 4.1 DISTRIBUTION AND AREA OCCUPIED BY LANTANA CAMARA ...... 13 4.2 EFFECTS OF LANTANA CAMARA ON SOIL PROPERTIES ...... 14

CHAPTER 5...... 16 DISCUSSION ...... 16 5.1 DISTRIBUTION OF LANTANA CAMARA ...... 16 5.2 EFFECTS OF LANTANA CAMARA ON SOIL PROPERTIES ...... 17

CHAPTER 6...... 19 CONCLUSION AND RECOMMENDATIONS...... 19 6.1 CONCLUSION ...... 19 6.2 RECOMMENDATIONS ...... 19

REFERENCES ...... 20

APPENDICES......

LIST OF FIGURES

Figure 3.1 Location map of Ward1 Zvimba district………………………….. 10 Figure 3.2 Steps taken to produce distribution map of L. camara…………….12 Figure 4.1 Distribution map of L. camara in Ward 1, Zvimba district………. 13

LIST OF TABLES

Table 4.1 Influence of L. camara on soil properties across strata…………..14

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LIST OF ACRONYMS AND ABBREVIATIONS

ANOVA Analysis of variance CBD United Nations Convention on Biological Diversity EMA Environmental Management Act GIS Geographical Information Systems GISP Global Invasive Species Programme GIS Geographical Information Systems GPS Global Positioning System ha Hectare ISMF Invasive Species Management Framework L. camara Lantana camara SPSS Statistical Package for the Social Scientists WoNS Weed of National Significance ZAWA Zambia Wildlife Authority

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CHAPTER 1 INTRODUCTION

1.1 BACKGROUND TO THE STUDY

Exotic species have spread from target areas and replaced the original tree biodiversity on the earth’s surface and are one of the biggest threats to ecosystems and biodiversity worldwide (Chenje et al., 1998; CBD, 2001). Their threat to biodiversity is considered second only to that of habitat loss, according to D’Antonic et al. (1992). Over a long period of time, invasive alien species can cause significant and often irreversible environmental and socio-economic impacts from the gene to the ecosystem level (CBD, 2001).

An invasive alien species is defined as species introduced deliberately or unintentionally outside their natural habitats where they have the ability to establish themselves, invade, out compete natives and take over the environments (CBD, 2001). According to GISP (2003) Lantana camara is believed to be one of the most exotic plants and is in the top 100 of highest impacting invasive species globally in Africa L. camara is believed to have been introduced in the 1930’s in Africa and has deleterious impacts on human enterprises such as fisheries, agriculture, grazing and forestry (Pimentel, 2000; Verdcourt, 1992). The costs associated with such impacts of Invasive alien species have been put at US$ 1.4 trillion per year, approximately 5% of global GDP (Pimental, 2000).

In Zimbabwe studies have been done on the impacts of L. camara on vegetation in Northern Gonarezhou and its effects in Victoria Fall World Heritage Site (Chatanga, 2007; Nang’alelwa, 2010). Lantana camara is believed to be a threat in the rainforest of the Eastern Highlands in Zimbabwe (Timberlake and Musokonyi, 1994). According to the Noxious Weed Act of Zimbabwe (19:07) L. camara is believed to be a fast growing shrub encroaching cultivated lands at an alarming rate. This species was introduced for commercial and ornamental purposes in Africa and is now widespread in Zimbabwe where it grows on wastelands, along major roads, waterways and on cultivated farmlands (Chikuvire et al., 2013).

Lantana camara is believed to have a dense population in Zvimba district and is rapidly spreading becoming a problem as it threatens agriculture and pastoral production, forestry and toxicity to livestock (Nyabeza, 2006). As the density of L. camara in forest increases, species richness decreases (Fenshan et al., 1994). Its allelopathic qualities can reduce vigor of plant species nearby and reduce productivity in orchards (Day et al., 2003). According to Mellow et al. (2005) L. camara poisoning has caused severe economic losses and is the major cause of livestock mortality and morbidity. Lantana camara has been found to drastically reduce above ground biomass by smothering native species thus impacting negatively on the abundance of wildlife forage and consequent loss of biodiversity (Witt, 2010). Its invasion is implicated in widespread loss of native species diversity via recruitment, limitation, competition and alteration of ecosystem structure and function (Bhatt et al., 1994). Lantana camara readily invades rangelands outcompeting native species, resulting in reduction of pasture land whilst its impenetrable thickets impede access to desired plant species by herbivores (Witt, 2010).

1.2 PROBLEM STATEMENT

The proliferation of L. camara in Zvimba district has increased over the past years (EMA, 2014). The distribution and subsequent effects on soil quality is not yet documented in Ward 1 of Zvimba. There have been reports of reduced grain yields on crops grown on land infested by L. camara and it is yet unknown how this phenomenon has developed in Zvimba district where peasant farming is practiced.

1.3 JUSTIFICATION

Traditionally, agriculture, especially smallholder farming, has been the cornerstone of Zimbabwe’s economy (Rukuni et al., 2006). Soil is a major source of nutrients needed by plants for growth, therefore there is need for scientifically justified research on soil nutrients concerning crop yields. By identifying the distribution of L. camara in Ward 1, this will provide information to policy makers, such as the Zvimba Rural District Council, for them to make informed decisions in planning.

1.4 AIM

To map the distribution and assess the effects of L. camara on selected soil properties in Ward 1 of Zvimba district.

1.5 OBJECTIVES 1.5.1 To assess the spatial distribution of L. camara in Ward 1 of Zvimba district.

1.5.2 To determine the impacts of L. camara on selected soil chemical properties that is (N, P, K, pH, Mg, Ca, Na, C) and texture.

1.6 RESEARCH QUESTIONS

1.6.1 What is the spatial distribution of L. camara in Ward 1, Zvimba district?

1.6.2 What are the effects of L. camara on the selected soil chemical properties?

CHAPTER 2

LITERATURE REVIEW

2.1 DISTRIBUTION OF LANTANA CAMARA IN ZIMBABWE

The spread of L. camara is still increasing with many of the countries and islands that were listed in 1974 as not having L. camara being infested more recently (Thaman, 1974). According to Sharm et al. (2005) L. camara species pose a great threat to the ecosystem in hotspot areas. Lantana camara is known to have invaded the riparian zone of the Victoria Falls World Heritage Site ecosystem covering an extent of 524 ha (Masocha and Ndaimani, 2010). According to a research in Gonarezhou National Park by Chatanga (2007), the distribution of L. camara is within riparian vegetation, especially along Save, Runde and Mwenezi rivers and the low lying areas. Lantana camara appears to be associated with wet areas and high rainfall increases its spread (Nang’alelwa, 2010). The moist evergreen rain forest of the Eastern highlands of Zimbabwe are being threatened by alien invasive plant species such as L. camara, wattle (Acacia mearnsii), Mauritius thorn (Caesalpinia decapetala) and eucalyptus species, to the detriment of biodiversity of the forests (Timberlake and Musokonyi, 1994).

2.1.1 DISPERSAL OF LANTANA CAMARA

Lantana camara colonizes large areas because its seed dispersal system is via birds and also it produces allelochemicals, which causes it to out compete other plants (Mabasa et al., 2013). Seed dispersal is primarily by fruit eating birds, and to a lesser extent by rodents, foxes and other vertebrates forages (Day et al., 2003). Much research has been done on the movement of seed by animals (Milton et al., 1981) which all play a role in the spatial distribution of seeds within certain areas, but the dominant transport medium for seeds in the riparian environment remains water (Goodson et al., 2001). Lantana camara grows on all types of well-drained soils and in wide rainfall range (from seasonal dry forests to rainforest) but is also very drought resistant (Prasad, 2011). According to Mabasa et al. (2013) L. camara grows mainly in non arable terrestrial habitats and farmers are reluctant to control it because it is not a threat to crop production. However, it has been reported that the leaves and unripe berries of L. camara can produce high levels of poisonous alkaloids which are toxic to livestock and humans. It rarely 4 invades undisturbed, closed- canopy forest but rapidly colonizes edges and disturbed or logged habitats (Prasad, 2011).

2.1.2 IMPACTS OF INVASIVE SPECIES ON SOIL

Invasive species affect plants, animal communities, soil properties and nutrient fluxes and affect the native species within that ecosystem (Eherenfeld and Scott, 2001). They also alter the ecosystem for they are different from natives in ecophysiology such as growth and allocation patterns (Braithwaite et al., 1989). Invasive species growth is usually limited by low soil nutrient availability especially Nitrogen and Phosphorus (Sankaran, 1971). According to Gordon (1998) and Eherenfeld et al. (2003), invasive species cause major changes within the ecosystem, they change nutrient cycling, modify ecosystemic functionality and fire regimes. In Canada the establishment of invasive species increase with the increase amount of light reaching the ground and amount of exposed mineral soil (Reader and Bricker, 1994). Most studies seem to indicate that the invasions of exotic species are most likely to cause changes in nutrient cycling process (Chapin et al., 2000; Tilman et al., 1997; Hector et al., 1999; Hooper and Vitousek, 1998). Invasive alien species can increase carbon assimilation rates, change soil nutrients status, increase flammability, threaten plant species and change habitat suitability for native animal species (Higgins et al., 1999; Dukes and Mooney, 2004; Hiremath and Sundaram, 2005). Invasive species may have different soil effect depending on local conditions (Benalp and Philips, 2001; Meyerson et al., 2000; Stock et al., 1995; Scott et al., 2001).

2.1.3 IMPACTS OF LANTANA CAMARA ON SOILS

Lantana camara has impacts on soil ecosystem and this could be because of its allelopathic and litter accumulation effects (Simba et al., 2013). This species is capable of improving soil fertility and influence nutrient cycling result to making the ground conducive for its growth (Osunkoya et al., 2010; Simba et al., 2013). Lamb (1988), identified an increase in soil nitrate in eucalyptus woodland following L. camara invasion, to the benefit of L. camara and other weeds, whilst to some native species there was a decline in some nutrients. A study which was done in China by Fan et al. (2010) indicated that soils underneath the canopy of L. camara had higher pH, total N,

5 total P, available N, and available K than the soils on the edge of the canopy and 2-5 m away from the L. camara plant. Dense stands of L. camara reduce the vegetation and the capacity of soil beneath to absorb rain which could potentially increase the amount of runoff and the subsequent risk of soil erosion in areas infected by L. camara (Day et al., 2003). Most studies have indicated that major and trace elements by N and P have been significantly higher in invasive plants than non invasive (Barber and Lee, 1974; Chacon et al., 2009; Ehrenfeld et al., 2001; Fan et al., 2010; Hawkes et al., 2005; Levine et al., 2003).

2.1.4 SOIL NUTRIENTS

Kelly (2004) highlights that soil is a major source of nutrients needed by plants for growth and lack of those nutrients may cause stunted growth to crops or diseases. Soil nutrients are grouped into three categories according to Duggin et al. (2010). These categories include primary nutrients referred to as major nutrients by Kelly (2014). This category includes nitrogen (N), phosphorus (P) and potassium (K) these three nutrients are required in large quantities than other nutrients (Yost and Uchida, 2000). Secondary nutrients include calcium (Ca), magnesium (Mg) and sulphur (S) and finally the micronutrients which include iron (Fe), manganese (Mn), boron(Bo), molybdenum (Mo), copper (Cu), zinc (Zn), chlorine (Cl), nickel (N) and cobalt (Co), these micronutrients are required in very small quantities, the uptake of micronutrients is expressed in parts per million (ppm). If any nutrient is deficient, the growth of the entire plant will not reach maximum yield (Walworth, 2006).

2.1.5 SOILS IN ZVIMBA

Geological formations found in the area include the Greenstone Belt, granitoids, Great Dyke rocks, the Lomagundi and the Piriwiri Group of rocks. The Greenstone Belt (early Precambrian) comprises meta sediments, meta volcanic and ultramafic lavas. The area is characterized by red clay soils with relatively low porosity. Patches of soils found in the area are black clay soils which could have emanated from granite rocks. Sandy soils are also found in Zvimba these soils are well drained and low in organic content (Arex Mashonaland West Province, 2006). People

6 depend on subsistence farming because of the types of soils in Zvimba district (PASS report, 2006).

2.2 EFFECTS OF LANTANA CAMARA

2.2.1 IMPACTS ON RURAL AGRICULTURE

Lantana camara infestation has impacts on the environment, forestry management, agriculture, recreation and transport (Feller, 1983). This species is known to affect agriculture in various ways. In some parts of East Asia and the pacific communities L. camara has reduced crop productivity and disturbed harvesting (Thomas and Ellison, 1991). According to Priyanka et al. (2013) this species has invaded traditional agricultural areas of Himalaya in India and farmers have changed their attitudes on agriculture because the species seem to invaded everywhere. Lantana camara reduces crop productivity, interferes with harvesting and may affect economic viability of crops such as coffee, oil palm, coconuts and cotton (ISSG, 2006).

2.2.2 LOSS OF PASTURE

In Queensland, loss of pasture is the greatest cost of L. camara invasion in grazing areas (A$ 3Mm per year at 1985 values), (Day et al., 2003). Its dominance in invaded areas and possession of poisonous components like triterpenes leads to forage scarcity and bad health or deaths of animals (Sharma et al., 2005). Lantana camara greatly reduces pasture productivity it readily invade pastures, particularly when they are poorly managed. If left uncontrolled, it spreads and excludes useful native grasses and improved pastures. Lantana camara along roadsides, riparian zones and fence lines also increase the loss of available pasture and spoils scenery ( Feller, 1983; Simelane, 2005).

2.2.3 TOXICITY ON ANIMALS

According to Chatanga (2007) L. camara contains toxic compounds (triterpenoids) that have been implicated in the killing of animals such as buffalo, through poisoning and photosensitivity.

The above statement also agree with the findings of Sharma et al. (1988) who says L. camara has been implicated in the poisoning of a number of animals including cattle, buffalo, sheep and goats. Lantana camara has serious deleterious effects on some of endemic animals (Sharma et al., 2007). Ensbey (2008) says L. camara poisoning in cattle is quite common and causes major economic losses. Most cases of poisoning occur in animals newly introduced into areas where toxic forms of lantana are already growing.

2.2.4 DEPLETION OF NATURAL VEGETATION

Lantana camara is reported to have contributed towards the depletion of indigenous plant species and biodiversity in general on the Zimbabwean side of the Zambezi river which forms the southernmost part of the Victoria Falls World Heritage Site (Nang’alelwa et al., 2010). A study that was done in Nothern Gonarezhou National Park by Chatanga (2007) shows that L. camara invasion is negatively affecting elements of vegetation structure. It competes with tree seedlings for light and nutrients and also interferes with plantation access and general management (Feller, 1983). As the density of L. camara in forest increases species richness decreases (Fensham et al., 1994). Often, alien species recolonize previously invaded areas after clearing and become dominant during early succession stages, altering conditions for seedling establishment of native species (Belnap et al., 2001).

2.3 MANAGEMENT OF LANTANA CAMARA

A number of efforts have been made in several countries worldwide including Australia, South Africa and Zambia to clear invasive alien plants in riparian areas (Groves, 1989; Richardson et al., 1989; ECZ, 2004). The key to good management of L. camara is constant vigilance (Day et al., 2003). In Australia L. camara is recognized as a Weed of National Significance due to its invasiveness, potential distribution range and impacts on primary industries conservation and biodiversity. The Weed of National Significance strategy developed in 2001 set out plans for the management and control of L. camara across Australia. The strategy is designed to coordinate with state, regional, and local weed and pest management strategies in order to confront the problem posed by L. camara in an integrated manner. In India an invasive Species management framework (ISMF) has been adopted (Priyanka et al., 2013). The invasive management

8 framework (ISMF) is a systematic process intended for use by governments, private companies, and individuals to identify the steps that need to be taken to minimize the harmful ecological, economic and human health impacts for efficient and effective management of invasive species (United State National Invasive Species Council Management Plan, 2001). This framework include the aspects of Research by formulating complimentary research projects aligning to ISMF transferring research projects outcomes identifying gaps in ISMF and suggesting measures to overcome. It also has the aspects of Education and Outreach by developing specific and targeted information and awareness programmes, information determination through seminars, workshops, films, popular publication and teaching materials (Priyanka et al., 2013).In Zambia L. camara is classified under the Noxious Weeds Act No 233 of 1984. This Act define noxious weeds as ‘aquatic or terrestrial plants, that when translocated into a new area and freed from control over their spread, explode into growth to such an extent that they suppress all other plant species’(ECZ,2004a). According to Nanga’lelwa (2010) Zambia Wildlife Authority (ZAWA) set up experimental plots where chemical control of Lantana was attempted but however these trials were futile because no long term monitoring or follow up mechanisms were put in place. The Wildlife Environmental Conservation Society of Zambia (WECSZ) and Environmental Clubs from local schools have also participated in mass L. camara clearing activities in the past. In Zimbabwe the Environmental Management Agency (EMA), has encouraged communities to use mechanical methods through clearing and destroying each plant. This method is encouraged to be practiced in dry season not in rainy season so as to avoid early germination of seeds which might have fallen on the ground.

CHAPTER 3

METHODOLOGY

3.1 DESCRIPTION OF THE STUDY AREA

Fig 3.1 Location map of study area Ward 1, Zvimba district.

3.1.1 DEMOGRAPHY AND RAINFALL

Zvimba Rural District is located in Mashonaland West Province in central northern Zimbabwe about 95 km west of Harare on the Highveld, with altitude ranging between 1500-1800 m above sea level. According to Parliament Research Department (2011) Zvimba west has 13 wards, the constituency has a total population of approximately 41 626, which is female dominated with 22 327 females against 19 299 males and ward 1 has a total population of approximately 6 500 people. The area lies within the agro ecological region IIA and receives mean annual rainfall of about 750 - 1000mm/yr. The rainy season stretches from mid-November to March and rainfall often occurs in the form of 10 to 15 day wet spells that are followed by dry spells of similar duration. The rain comes mostly in the form of convective thunderstorms. The rest of the year from May to early November is dry. Slopes around the project are relatively gentile with others being undulating.

3.2. EXPERIMENTAL DESIGN

Stratified sampling was used to take into account different areas (or strata) which are identified within the main body of the area. Ward 1 was stratified into 3 categories which are 1) heavily invaded area of L. camara 2) moderately invaded and 3) uninvaded areas of L. camara. Three soil samples where randomly selected from each stratum which was 50m by 50m at different sampling sites.

3.3 DATA COLLECTION

Distribution of L. camara was marked by a Garmin Global Positioning System (GPS) version 2.40, this device was used to take coordinates of area infested by L. camara. Distance of area infested by L. camara was obtained through the use of a measuring wheel and Geographical Information Systems (GIS). Soil samples were collected using a soil auger and samples were collected in replicate from each sampling site at a depth of 15cm below as done by Chatanga, (2007), Simba et al. (2013), Stolhgren et al. (1995) This is where most biological activity takes place (Simba et al., 2013). A total of three sampling sites were selected thus in total 9 samples were collected from the study. Samples were collected from the top to bottom soil using a soil auger. The soil samples were then taken to Department of Research laboratory for analysis.

Samples were analyzed for texture, pH, Carbon, Calcium, Magnesium, Sodium, Potassium, Phosphorus and Nitrogen.

3.4 METHODS OF DATA ANALYSIS

Micro-Soft Excel and Statistical Package for Social Scientists (SPSS) were used for entry and analysis of data. One way ANOVA and Post hoc where used to determine the significance of differences across the measured parameters. Geographical information system and remote sensing were used to produce a distribution map. Arc GIS version 10.1 was used and LAN Sat image 8 combined clear imagery with the use of band 1, 2, 3. Digital data was applied and pre processing which includes the fitting of coordinates of the study areas. Feature Extract was used through the selection of training data which was unsupervised. Decision and classification was done the supervised way resulting to classification output where all noise of L. camara was removed leaving the one in study area which led to the output of a distribution map as indicated by figure 3.2. Percentage of area affected by L. camara was calculated using the formula below Total area of classified L. camara ×100 Total area of ward

Fig 3.2 Steps taken to produce distribution map of L. camara in Zvimba

CHAPTER 4 RESULTS

4.1 DISTRIBUTION AND AREA OCCUPIED BY LANTANA CAMARA

Fig 4.1 Distribution of L. camara in Ward 1 of Zvimba distribution

The above map shows the distribution of L. camara in Ward 1 of Zvimba District. Approximately 992.73 ha out of 6953.59 ha has been affected by L. camara making a percentage of 14.3% infested by L. camara.

4.2 EFFECTS OF LANTANA CAMARA ON SOIL PROPERTIES

Table 4.1 Influence of L. camara on soil properties across strata

Parameter Mean and Standard Error Heavily invaded Moderately invaded Uninvaded Soil pH 5.4±0.1 a 5.47±0.033 ab 4.73±0.12 c Magnesium (me %) 1.27±0.033 a 0.27±0.067b 0.4±0.1bc Sodium (me %) 0.16±0.032 a 0.09±0.009 b 0.07±0.009bc Potassium (me%) 0.22±0.026 a 0.17±0.034 ab 0.34±0.032 c Total Nitrogen (ppm) 11.67±0.882 a 6.33±0.667 b 1.67±0.667 c Avail Phosphorus (ppm) 13.67±1.202a 9.67±1.202 b 5.33±0.882 b Fine Sands % 37.33±0882 a 43.33±0 .882b 38.33±1.45ac Organic Carbon % 1.38±0.18 a 0.44±0.116 b 0.16±0.007 c Calcium (me %) 4.77±0.145a 4.20±0.100a 3.70±0.755a Clay % 3.33±0.333a 3.33±0.333a 3.67±0.667a Means within the same row with different superscripts are significantly different at P< 0.05

4.1.1 Soil pH Table 4.1 is showing a significant difference in soil pH between heavily invaded site and uninvaded site, there was also a significant difference between moderately invaded site an uninvaded site at (P<0.05). However, there was no significant difference of pH levels between heavily invaded and moderately invaded at (P>0.05).

4.1.2 Magnesium There was a significant difference of magnesium in heavily invaded and moderately invaded, heavily invaded and uninvaded at (P<0.05).There was no significant difference in magnesium between moderately invaded site and uninvaded site at (P>0.05).

4.1.3 Sodium There was a significant difference of sodium in heavily invaded and moderately invaded site and a significant difference between invaded site and uninvaded site at (P<0.05). Results indicate no difference between moderately invaded site and uninvaded site at (P>0.05).

4.1.4 Potassium There was a significant difference of potassium in heavily invaded and uninvaded sites and a significant difference between moderately invaded and uninvaded sites at (P<0.05) but however there was no significant difference of potassium between heavily invaded and moderately invaded sites at (P>0.05).

4.1.5 Nitrogen There was a significant difference of total nitrogen on all sites at (P<0.05).

4.1.6 Phosphorus There was a significant difference of phosphorus on all sites at (P<0.05).

4.1.7 Fine Sands Fine sands indicated on the table to be significantly different in the heavily invaded and moderately invaded sites and between the moderately invaded and uninvaded sites at (P<0.05), but however there was no significant difference fine sands between heavily invaded and uninvaded sites at (P>0.05).

4.1.8 Organic Carbon There was a significant difference of organic carbon on all sites at (P<0.05).

4.1.9 Calcium and Clay There was no significant difference of calcium and clay amongst the three sites at (P>0.05).

CHAPTER 5

DISCUSSION

5.1 DISTRIBUTION OF LANTANA CAMARA

Results clearly indicate that L. camara has invaded Ward 1 of Zvimba district. These findings are similar to those of Chatanga (2007) who observed that more than 50% of Gonarezhou National Park was affected by L. camara. The varying distribution could be a result of several factors which include low temperatures, its low tolerance to saline soils, insufficient water due to low rainfall and coralline soils with poor water holding capacity (Thaman, 1974). Seed dispersal contributing to the distribution of L. camara is caused by fruit eating birds and animals (Day et al., 2003; Chatanga, 2007; Swarbrick et al., 1998). Zvimba district is a farming and ranching district, were cattle are kept for dairy products this could possibly contribute to the dispersal of L. camara in the Ward.

Lantana camara infestation within the Ward is mainly along the rivers. This could be possibly due to floods which contribute to propagule dispersal, water availability, moisture and favorable conditions for plant growth (Naiman et al., 1993; Goodson et al., 2001; Galatowitsch and Richardson et al., 1997). These findings agree with the findings of Cilliers and Neser (1991) who observed L. camara to generally survive along rivers. Findings of the current study also agree with findings of Chatanga (2007), Thomas and Ellison (2000), Meek et al. (2010) who observed L. camara to be largely restricted to riparian zones. The findings of the current study agree with the theory of invasibility imposed by Davis et al. (2000) who assume that invasive species must have access to available resources e.g. light, water and nutrients so as to enjoy greater success in invading a community. The distribution of L. camara in Zvimba district Ward 1 if not controlled might increase and this may change soil microhabitat through shading, self mulching, increase in soil nitrate, decline in other nutrients and out compete native species(Lamb, 1988; Swarbrick et al.,1995; Gentle et al., 1997).

5.2 EFFECTS OF LANTANA CAMARA ON SOIL PROPERTIES

The alteration of L. camara on soil chemical properties in Ward1, Zvimba district agree with Sharma et al. (2005) who observed that invasive species alter soil nutrients. In addition L. camara litter had been identified to have an effect on the alteration of soil nutrients. High levels of nitrogen and phosphorus in the invaded area are consistent with the results reported by Chatanga (2007) in Northern Gonarezhou who observed nitrogen and phosphorus increased with the increase of L. camara intensity. Sharma et al. (2005) and Osunkoya (2010) also agreed with the results of the current study, Fan et al. (2010) indicates that L. camara accelerates nitrogen and phosphorus cycles. The increase of nitrogen and phosphorus can be caused by the accumulation of litter beneath the canopy of L. camara which builds up soil organic matter and account for the elevated nitrogen and phosphorus this agrees with the findings of Chatanga (2007).

Higher concentrations of magnesium and sodium agree with the findings of Simba et al. (2013) whose assumption was based on the heaped organic matter that mulches on the soil surface beneath L. camara species thereby preventing the leaching of nutrients from the soil surface. Findings in this study indicate high levels of organic carbon and this concurs with the findings of Osunkoya (2010) who identified high organic carbon in L. camara infested patches. The cause of increase of organic carbon could be the accumulated thick layer of litter under the canopy of L. camara that builds up organic carbon. Soils with low organic matter content and sparse vegetation cover which are invaded by invasive plants with high biomass may accumulate carbon through higher litter returns (Dassonville, 2008). These finding also agree with Ehrenfeld et al. (2001) and Marchante et al. (2008).

High pH levels in the invaded area are consistent with the findings of Gentle and Duggin (1997b), Osunkoya et al. (2010) and Simba et al. (2013). It is not clear if the increase of pH in his study was due to L. camara invasion or it favoured the site with high soil pH as observed by Simba et al. (2013) and Osunkoya et al. (2011). Changes in pH could be because of the parent material where soils are made from, the type of rock dictates the natural pH of the soil, basic rock like limestone creates alkaline soil and rocks containing more silica create acidic soil.

Findings in this study however, indicate low levels of potassium in heavily invaded site and high in uninvaded site these results agree with the findings of Chatanga (2007) who observed a decrease of potassium in invaded area. This could be due to the prolific flowering and large seed number production by L. camara therefore resulting to low levels of potassium in the heavily invaded area (Thomas and Ellison, 2000; ISSG, 2006). Observing the table, findings from the current study indicate that calcium was high in heavily invaded site and clay percentage appeared to be high in uninvaded site but however, statistically there was no significant difference of calcium and clay on all sites. These findings agree with Simba et al. (2013) who did not find major variations in soil texture on invaded and uninvaded sites but however soils consisted of more sands than clay contradicting with Simbal et al. (2013). The results also agree with Fan et al. (2010) who recorded high levels of calcium in heavily invaded site.

Contrary to the findings of the current study Eherenfeld (2003) and Simba et al. (2013) observed low concentrations of nitrogen and phosphorus in invaded sites than uninvaded site. The current studies also contradict with the findings of Duda et al. (2003), Fan et al.(2010), Sharma et al. (2011) and Simba et al. (2013) who observed high levels of potassium in heavily invaded sites whilst Osunkoya et al. (2010) did not find a significant difference of potassium between invaded and uninvaded sites.

CHAPTER 6

CONCLUSIONS AND RECOMMENDATIONS

6.1 CONCLUSIONS

Results of the study indicated that L. camara is mainly distributed along the riverine areas because there are favorable conditions of water and nutrients. As run off flows into the river, it carries with it fine sediments and leached nutrients which will be deposited on river banks. These will then become favourable conditions for plant growth. However, due to the aggressive nature of L. camara and its allelopathic nature, it outcompetes other species and hence colonise the riverine areas. The study findings showed that L. camara is slowly invading Ward 1 of Zvimba District since the colonization is still at its early stages as compared to other areas in Zimbabwe. Lantana camara has the effect of improving soil fertility. The research findings show that magnesium, organic carbon, sodium, phosphorus, nitrogen and sodium where high in the heavily invaded site of L. camara. The increase in nutrients in heavily invaded areas is as a result of dead organic matter which when decomposed release nutrients through various biochemical reactions which occurs during decomposition of organic matter which forms part of the biogeochemical cycles. This indicates that L. camara alters soil chemical properties which are essential for the growth of certain plants.

6.2 RECOMMENDATIONS

Researchers are encouraged to map cover changes resulting from the presence of L. camara within the ward. Future studies should also look at other soil properties which were not covered in this study. The adoption of a framework on the management of L. camara should be taken into consideration as suggested by Priyanka (2013) in India and the following recommendations should be considered and adopted at national level, prevention through identification of known and potential pathways of invasion, early detection and response this can be done through developing strike team to curtail invasion. The frameworks also include early detection and response, control and management, education and outreach programmes.

REFERENCES

Arex Mashonaland West Province, (2006). Types of Soils found in Zimbabwe suitable for agriculture. Zvimba district.

Barber D.A, Lee R.B. (1974). The effect of micro-organisms on the absorption of manganese by plants. New Phytol 73:97–106.

Belnap J and Phillips S. (2001). Soil biota in an ungrazed grassland: response to annual grass (Bromus tectorum) invasion. Ecol Applic 11:1261–75, (5, O).

Bhatt Y.D, Rawat Y.S and Singh S.P (1994). Changes in ecosystemfunctioning after replacement of forest by Lantana shrub land in Kumaun Himalaya. J Veg Sci 5:67–70.

Braithwaite R.W, Lonssdale W.M and Eastbergs J.A. (1989). Alien vegetation and native biota in tropical Australia: the spread and impact of Mimosa pigra. Biological Conservation 48: 189-210.

Chacón N, Herrera I, Flores S, González J.A, Nassar J.M. (2009). Chemical, physical, and biochemical soil properties and plant roots as affected by native and exotic plants in neotropical arid zones. Biol Fertil Soils 45:321–328.

Chapin FS III, and others (2000). Consequences of changing biodiversity. Nature 405:234–42.

Chatanga P. (2007). Impacts of the Alien Species. L camara (L.) On vegetation in Northern Gonarezhou National Park Zimbabwe, MSc Thesis, University of Zimbabwe 1-84.

Chenje M., Sola L and Paleczyn D. (1998). The State of Zimbabwes Environment Government of the Republic of Zimbabwe, Ministry of Mines, Environment and Tourism, Harare, Zimbabwe.

Chikuvire T. J, Karavina C, Parwada C and Maphosa B.T (2013). Lantana camara and Tithonia diversifolia leaf teas improve the growth and yield of Brassica napus. African Journal of agricultural research 8(48) p 6220-6225.

Cilliers C.J, Nesser S. (1991). Biological control of Lantana camara (Verbenaceae) in South Africa. Agriculture , Ecosystems and Environment 37: 57-75.

Convention on Biological Diversity (2001). Global Diversity Outlook. Convention of Biological Diversity on line. www.biodiv.org/handbook/ [08/04 /2014].

Davis J, Mark A, Grime P and Thompson K,(2000). Fluctuating Resources in plant communities: a general theory of invisibility. Journal of Ecology 88: 528-534

D’ Antonio C. M and Vitousek P. M. (1992). Biological invasions by exotic grasses,the grass/fire cycle, and global change. Annual Review of Ecology and Systematics, 23: 63-8

Dassonville N, Vanderhoeven S, Gruber W and Meerts P. (2008). Invasion by Fallopia japonica increases topsoil mineral nutrient concentrations. Ecoscience. 14(2):230-240.

Day M, Wiley C.J, Playford J and Zaluck M.P. (2003). Lantana Current Management Status and Future Prospectus. ACIAR Monograph 1-125

Digging (2010). Anderstanding soil nutrients, hand book for soil scientist and Agricultural activities. Carlifonia, 156-165.

Duda JJ, Freeman DC, Emlen JM, Belnap J, Kitchen SG, Zak JC, Sobek E, Tracy M, Montante J (2003). Differences in native soilecology associated with invasion of the exotic annual chenopod,

Duggin, J.A and Gentl, C.B. (1998). Experimental Evidence on the Importance of Disturbance Intensity for Invasion of L. camara L. in Dry Rainforest Ecotones in North Eastern NSW Australia. Forest Ecology Management.

Dukes J.S. and Mooney H.A.(2004). Disruption of ecosystem processes in western North America by invasive species. Rev. Chil. Hist. Nat. 77: 411-437.

ECZ. 2004. Implementation of invasive plant prevention and control programmes in Zambia. Report submitted to the CAB International Africa Regional Centre under the PDF-B phase of the UNEP/GEF Project: Removing Barriers to Invasive Plant Management in Africa (RBIPMA), ECZ, Lusaka, Zambia

Ehrenfeld J.G and Scott N. (2001). Invasive species and the soil: effects on organisms and ecosystem processes. Ecol Applic 11:1259–60.

Ehrenfeld J.G, Kourtev P and Huang W. ( 2001). Changes in soil functions following invasions of exotic understory plants in deciduous forests. Ecol Applic 11:1287–300, (22, O, EP).

Ehrenfeld J.G. (2003). Effects of exotic plant invasions on soil nutrient cycling processes. Ecosystems 6:503-523. Environmental Management Act (20:27) of 2002 section 123

Environmental Management Agency Report (unpublished).

Fan L, Chen Y, Yuan J and Yang Z. (2010). The effect of Lantana camara Linn. invasion on soil chemical and microbiological properties and plant biomass accumulation in southern China. Geoderma. 154:370-378. Feller MC. (1983). Effects of an exotic conifer (Pinus radiata) plantation on forest nutrient cycling in southeastern Australia For Ecol Manage 7:77–102, (27, O).

Fensham R. J, Fairfax R. J. and Carnell R. J. (1994). The invasion of Lantana camara L. in Forty Mile Scrub National Park, north Queensland. Australian Journal of Ecology 19: 237-305

Gentle C.B. and Duggin J.A (1997b). Allelopathy as a Competitive Strategy in Persistent Thickets of L.camara L. in Three Australian Forest Communities. Plant Ecology 132: 85-95

GISP (2003). The Invasive Alien Species problem. The Global Invasive Species Programme. http://www.gisp.org . [08/10/ 2013].

Goodson, J.M., Gurnell, A.M., Angold, P.G., Morrisey, I.P. 2001. Riparian seed banks: Structure, process and implications for riparian management. Progress in Physical Geography 25: 301-325

Gordon D.R. (1998). Effects of invasive, non-indigenous plant species on ecosystem processes: lessons from Florida. Ecol Applic 84:975–89, (28, R).

Parliament Research Department (2011). Zvimba West Constituency Profile

Poverty Assessment Study Survey Summary (PASS) Report, Government of Zimbabwe (2006). Zimbabwe 2003 Ministry of Service, Labor and Social Welfare, July 2006, Harare.

Groves, R. H. (1989). Ecological control of invasive terrestrial plants. In: Drake, J., Mooney, H. A., di Castri, F, Groves, R., Kruger, F., Rejmanek, M., Williamson, M. (Eds). Biological Invasions: A Global Perspective. John Wiley and Sons, Chichester,pp 215-255 Halogeton glomeratus. Biol Fertil Soils 38:72–77

Hawkes C.V, Wren I.F, Herman D.J and Firestone M.K. (2005). Plant invasion alters nitrogen cycling by modifying the soil nitrifying community. Ecol Lett 8:976–985

Hector A, and others (1999). Plant diversity and productivity experiments in European grasslands. Science 286:1123–7.

Higgins, S.I., Richardson, D.M., Cowling, R.M and Trinder-Smith, T.H (1999). Predicting the Landscape- Scale Distribution of Alien Plants and Their Threats to plant Diversity. Conservation Biology 13(2), 303-313.

Hiremath, A.J and Sundaran, B. (2005) The Fire-L.camara Cycle Hypothesis in India Forests Conservation and Society 3(1) 26-42.

Hooper DU, Vitousek PM. (1998). Effects of plant composition and diversity on nutrient cycling. Ecol Monogr 68:121–49.

ISSG (2006) One hundred of the Worlds Worst Invasive Allien Speceis.A selection from the Global Invasive Database. ISSG. Auckland, Newzealand.

Kelly L.R (2014). Plant nutrients in the soil, Primary Industries Agriculture. www.dpi.nsw.gov.au/agriculture/resources/soils/improvement/plant-nutrient. [05/09/2014] Lamb D. (1988). Ecological and perceptual changes to scrubland associated with lantana invasion. Caring for Warringah’s bushland. Shire of Warringah , Sydney.

Lavine J.M, Vila M, D’Antonio C.M, Dukes J.S, Grigulis K and Lavorel S. (2003). Mechanisms underlying the impacts of exotic plant invasions. Proc R Soc Lond B 270:775–778

Mabasa S. Kwembeya A. Rugare J.T. (2013). Allelopathic Effects of (Lantana. C) on Blackjack (Bidens pilosa) and Pearl Millet (Pennisetum Glaucum). Assian Journal of Agriculture and Rural Development 3(8) 543-553.

Masocha M. and Ndaimani H.(2010). Mapping of the priority Invasive Alien Plant

Mello F.B, Jacobus D., Carvalho J.R.B (2005). Effects of Lantana camara (Verbenaceae) on general reproductive performance and teratology in rats. 45 p 459-466

Meyerson LA, Saltonstall K, Windham L, Kiviat E, Findlay S. (2000). A comparison of Phragmites australis in freshwater and brackish marsh environments in North America. Wetl Ecol Manage 9:89–103, (44, R).

Milton S. J. and Hall A. V. (1981) Reproductive biology of Australian acacias in the South western Cape Province, South Africa. Transactions of the Royal Society of

Naiman, R. J., Decamps H and Pollok, M. (1993). The role of riparian corridors in maintaining regional biodiversity. Ecological Applications 3: 209-212

Nang’ alelwa (2010) Effects of treatment on Lantana camara (L.) and the restoration potential of riparian seed banks in cleared areas of the Victoria Falls World Heritage Site, Livingstone, Zambia.

Noxious Weeds Act (1996) Chapter 19: 07 Government printers. Harare.

Nyabeza S.(2006). Zimbabwe Zvimba farmers strive to destroy toxic plant http://www.allAfrica.com. [20/06/2014].

Osunkoya O.O, Perret C (2011). Lantana camara L. (Verbenaceae) invasion effects on soil physicochemical properties. Biol. Fertil. soils. 47:349-355.

Osunkoya O.O, Perrett C and Fernando C. (2010). Population viability analysis models for Lantana camara L. (Verbenaceae): a weed of national significance. In: Zydenbos SM (ed) Proceedings of the 17th Australasian weeds conference. New Zealand Plant Protection Society, New Zealand Christchurch, pp 99–102

Pimentel, D., Lach, L., Zuniga, R., and Morrison, D. (2000). Environmental and economic costs of non-indigenous species in the United States. BioScience 50: 53-65

Prasad A.E (2011) Landscape –scale relationship between the exotic invasive shrub Lantana camara and native plants in a tropical deciduous forest in Southern India.J. Trop. Ecology 28: 55-64

Priyanka N, Shiju M.V and Josh P.K (2003). A framework for management of Lantana camara in India, International academy of ecology and environmental science 3(4) 306-323.

Reader R.J and Bricker B.D (1974). Barriers of Establishment of Invading Non- Forest Plants in Decidious Forest Nature Reserves. Environmental conservation 21: 62-66

Richardson DM, Macdonald IAW, Hoffmann JH, Henderson L (1997). Alien plant invasion. In: Cowling RM, Richardson DM, Pierce SM (eds) Vegetation of Southern Africa. Cambridge UniversityPress, Cambridge, pp 535–570

Rukuni M, Eicher C.K and Blackie (2006). Zimbabwe’s Agricultural Revolution, Revisited. University of Zimbabwe publications, Harare.

Sankaran T. (1971). Biological control of weeds in India a review of introductions and current investigations of natural enemies. Proceedings of the II International Symposium on Biological Control of Weeds. 82-88,Rome, Italy

Scott AN, Sagger S, McIintosh DP (2001). Biogeographical impact of Hieracium invasion in New Zealand’s grazed tussock grasslands: Sustainability implications. Ecol. Appl. 11(5):13111322

Sharm G.P and Raghubanshi A.S (2005). Tree population Stracture, Regeneration and Expected Future Composition at Different Levels of L. camara. Lantana camara Invassion in the Vindhyon Tropical Dry Deciduous Forest of India. Australian Journal of Ecology 17:167-179

Sharm G.P, Raghubanshi A.S and Singh J.S (2007). L. camara Invasion. An Overview Weed biology and Management. 5: 157-165

Sharm GP and Raghubanshi A.S (2011). Lantana camara L. invasion and impact on herb layer diversity and soil properties in a dry deciduous forest of India. Appl. Ecol. Environ. Res. 9(3):253-264.

Sharma O.P. (1988). How to combat lantana ( Lantana camara L) menace? Current perspective. Journal Scientific Industrial Research 47: 611-616

Simba Y.R, Kamweya A.M , Mwangi P.N and Ochora J.M (2013). Impact of the invasive shrub, Lantana camara L. on soil properties in Nairobi National Park, Kenya. International Journal of Biological Diversity and Conservation 5(12) p803-809.

Simelane D.O. (2005). Biological control of Lantana camara in South Africa: targeting a different niche with a root- feeding agent, Longitarsus sp. BioControl 50: 375-387

Stock WD, Wienand KT, Baker AC (1995). Impacts of invadingN2-fixing Acacia species on patterns of nutrient cycling in two Cape ecosystems: evidence from soil incubation studies. Stohlgren T.J, Falkner M.B and Schell L.D (1995). A Modified Whittaker Nested Vegetation Sampling Method. Vegetation. 117(2):113-121.

Swarbick, J. T., Willson, B.W., Hannan-Jones, M. A. (1998). Lantana camara L. In: Panetta, F. D., Groves, R. H., and Shepherd, R. C. H. (Eds). The Biology of Australian Weeds, Melbourne, pp. 119-140

Thaman R.R (1974) Lantana camara its introduction, dispersal and impact on Islands of the tropical Pacific Ocean. Micronescia 10: 17-39.

Thomas, S. E. and Ellison, C. A. (1991). A Century of Classical Biological Control of Lantana camara: Can Pathogens Make a Significant Difference? In: Spencer, N. R.(Ed) Proceedings of the X International Symposium on Biological Control of Weeds, Montana State University, Bozeman, Montana USA, pp 97-104

Tilman D, Knops J, Wedin D, Peter B, Ritchie M and Siemann E. (1997) .The influence of functional diversity and composition on ecosystem processes. Science 277:1300–2.

Timberlake J and Musokonyi C. (1994). Forest conservation and utilization. Chirinda forest- a visitor guide. Forestry Commission Harare.

United States National Invasive Species Council Management Plan (2001). http://www.invasivespecies.gov/ [30/07/2014].

Verdcourt B (1992). Flora of Tropical East Africa. Verbenaceae. Rotterdam, Netherlands. pp. 37-47.

Vitousek P.M, Walker L.R, Whiteaker L.D, Mueller-Dombois D. and Matson P.A. (1987). Biological invasion by Myrica faya alters ecosystem development in Hawaii. Science 238:802–804, (65, O).

Walworth J.L. (2006). Soil Sampling and Analysis, College of Agriculture and life sciences, University of Arizona. Arizona

Weidenhamer JD, Callaway RM (2010). Direct and indirect effects of invasive plants on soil chemistry and ecosystem functions. J. Chem. Ecol. 36:59-60.

Witt A (2010). Impacts of invasive plants and their sustainable management in agro-ecosystems in Africa: a review. CABI Africa. pp. 1102-1109.

Yost R.S and Uchida R. (2000). Interpreting Soil Nutrients Analysis Data definition of the ‘Low,’ ‘Sufficient’ and ‘High’ Nutrient levels Charpter 7. College of Tropical Agriculture and Human Resources, University of Hawaii at Monoa.