Human Perceptions on Degradation of Wetland Ecosystems : The Case of Magwenzi Wetland in Chivi District ; Zimbabwe Hove Crecious and *

Wetlands are critical natural resources that serve various purposes including environmental, hydrological and socioeconomic functions. However, this important resource is so fragile and has suffered deterioration due to human activities such as cultivation, grazing, water abstraction among others. Several current studies have studied wetland ecosystem changes using GIS and remote sensing and other scientific methods. These studies lack information on people’s perceptions. In this study, degradation of Magwenzi wetland ecosystem was assessed based on local people’s perceptions. The Story Telling Approach (STA), questionnaire surveys, interviews and field observations were used to collect data. Stratified random sampling technique was used in the selection of respondents. The study found that human activities such as wetland cultivation, water abstraction and cattle grazing have resulted in the alteration of ecosystem functions and interactions. There have been reported changes in land cover, species richness, species evenness and the hydrology of the wetland. We conclude that humans perceive themselves as the critical driving force behind ecosystem degradation as their activities negatively affect wetland ecosystems by changing the type, number and interactions of vegetative and animal species on the wetland.


INTRODUCTION
Wetlands are important resources which play many functional purposes (Mutyavaviri, 2006).They vary in size and type and are thus differently defined.The most commonly adopted definition for wetlands is that of the RAMSAR Convention (1971) which defines wetlands as, areas of marsh, fern, peat land or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water, the depth of which at low tide does not exceed six metres (Mutyavaviri, 2006;Msipa, 2009;Cherry, 2012;Tsujii and Sasagawa, 2012).
In Zimbabwe these include dambos (Mapane), flood plains, artificial impoundments and pans (Mutyavaviri, 2006).They are estimated to cover an area of about 1.28 million hectares of the country, with 20% of them in the communal areas (Mharapara et al, 1997).Wetlands share a common feature of retaining excess water, long enough to influence land uses, soil characterisation and life forms that flourish them.They support many water bird species, hippopotamus, buffalos and waterbuck.They also provide spawning ground for riverine and anadromous fishes and critical dry season grazing lands for domesticated livestock and wildlife (Beilfuss and Davies, 1999).
Wetlands play critical functions ranging from environmental, hydrological and socio-economic benefits to the local communities (Dixon and Wood, 2003).They recharge rivers and serve as reservoirs for dry water supply (du Toit, 1994).In addition, they serve to purify and improve river water quality (Bowden, 1987;Breen et al., 1997;Smith;2013).They also provide important habitats for many bird and animal species (Bowden, 1987, Smith, 2013).They are home to large numbers of both terrestrial and amphibious organisms.Wetlands serve as a mini-ecosystem and without such areas; populations of countless species would be threatened.The loss of wetlands poses dangers to wildlife as well as human populations both in terms of protection of terrain and in a broader economic sense (Smith, 2013).
Despite the importance of wetlands to humanity, they have been largely degraded and rather treated as wastelands.Excessive pressure on wetlands results in degradation and eventual loss (Mharapara et al, 1997;Bedford, 1999).Degradation has been largely a result of human activities that include overgrazing, housing development, cultivation, groundwater extraction and artificial drainage among others.As a result of population growth, many thousands of swampland have been logged and drained for residential and agricultural purposes.
Much of the once mucky land has been filled in and developed for growing crops, grazing livestock, building homes or citrus orchards (http://www.attrakt.com,2012).Land development leads to land clearance or erosion (Mclnnes, 2009).This cause chemical changes in the chemical makeup of wetlands which results in the whole ecosystem being thrown off track (Mclnnes, 2009).Waste dumping pollutes wetlands, thereby disturbing the life forms that depend on them.Macrophyte exploitation, brick making, medicinal plant harvesting, crop production and fishing are some of the human activities behind wetland degradation (Cherry, 2012).Farming is undertaken without due consideration to sustainable land use practices, with large tracts of land being cleared for farming and infrastructural development at the expense of valuable wildlife habitat.The important roles of wildlife in the ecosystem food web as pollinators, predators, seed dispersers or prey species of other animals did not seem to have been appreciated by a majority of land users (Wuver, 2006).
However, very little has been done in as much as policy making and protection of wetlands is concerned, probably because they are wrongly regarded as wastelands that can be sacrificed for the sake of social welfare (Seyam et al., 2001;Mutyavaviri, 2006;Wuver, 2006) or as natural resources with no need for management (Mharapara et al, 1997;Mutyavaviri, 2006).The environmental importance of the resource has been eclipsed by uses of the wetlands outlined above.Government policies on the use of wetlands are not sound that this important resource continues to be degraded at alarming levels.Some of the policies were designed not based on the perceptions of the people residing around the wetlands.Thus, they tend to contradict what people ought to know and this result in poor implementation of policy recommendations.The lack of attention is predominant in communal areas where either very little research has been done or researches have been too unrealistic by ignoring local peoples' perceptions.It is in view of this gap that a qualitative assessment of impacts of human activities on wetland ecosystems merits attention.Thus this research will focus on the impacts of anthropogenic activities on wetlands based on local people's perceptions.

Study Area
Magwenzi wetland (Figure 1.1) is situated in ward 15 of Chivi district, about 78 kilometres from Masvingo, some 6 kilometres south of Chivi growth point.The ward has a total of 1,725 people while about 245 people living around the wetland area (AGRITEX Chivi, 2013).The area has an average annual temperature of 19 0 C and an annual rainfall amount of 450mm.The key economic activities in the wetland include gardening, crop cultivation, brick moulding, orchards, grazing and dipping.

Sampling procedure
In this study, the stratified random sampling method was used.The population was stratified into three classes.The first class comprised those who had spent a minimum of 20years in the area.This group provided historical information on wetland change, land use change and change in land cover.The second group involved those who are in the practice of gardening on Magwenzi wetland.Finally, the last group comprised of members of the community who had no direct interaction with the wetland but are aged 20years and above.From these groups, respondents were randomly selected using the formula 10% + 1 to reduce the error of inclusion and exclusion and for spatial representation.

Data collection
Data was collected through key informant interviews, questionnaire surveys, focus group discussions and personal observations.These tools were used to gather data pertaining to the activities that are carried out on and around Magwenzi wetland and how they affect the wetland ecosystem.

Questionnaire surveys
25 questionnaires were distributed in the area with a population of 250.Questionnaires were employed to collect data from different people because it is time saving to the researcher and the respondents.Moreover, data collected through questionnaires is easy to analyse quantitatively using statistical software.

Key Informant interviews
We held interviews with Mrs Duve, former district head Zvishavane Water Project.This non-governmental organisation developed wells (elephant pumps and funded gardening projects in the area).Mr Mututuvari the Rural District Council Administrator highlighted the council by laws, the problems faced in implementing them as well as the measures taken by council officers to reduce the impacts of human activities on the wetland.Finally, Mrs Hwititi the EMA District Officer emphasised the need for a synoptic approach to wetland utilisation between developers and conservationist.

Focus group discussions
Two focus group discussions were conducted.Focus group A involved members of Takashinga garden.Group B consisted of members from Magwenzi garden.These groups provided information relating to the effects of human activities on the wetland ecosystem and their impact on the society.They also provided information on other causes of wetland change other than human activities.

Story Telling Approach (STA)
Local people and key stakeholders were tasked to tell stories on human activities and their impacts on the wetland.It is understood that story telling captures some information that would otherwise have been left out in a formal guided interview or a questionnaire survey (Chapungu, 2013).From the stories related, important data was synthesized and conclusions drawn.

Data analysis
The data was analysed to determine the relationship between population (as a proxy for human activities) and wetland degradation.Also, data analysis helped determine the activities that impact negatively on the wetland system.

Human activities and ecosystem changes.
The interaction between human beings and the environment is the driving force behind ecosystem changes over time.Thus, an increase in an area's population would mean an increase in the interactions and therefore ecosystem changes (Roberts, 1988;Mutyavaviri, 2006).In Magwenzi wetland , the population has increased significantly over the years.The growth in population means increased pressure on limited environmental resources as households continuously exploit the environment to meet the demands of the growing household size.Thus, population growth can be used as proxy indicator for increased human impact on wetland ecosystem (Roberts, 1988).This is demonstrated in figure 4.2 which shows that as the population around Magwenzi wetland increased, the estimated area under cultivation within the wetland also increased.

Figure 4.2 The relationship between population and land cultivation in Magwenzi
As shown in figure 4.2, It was observed that there is a significant (p=0.001α=0.05) relationship between population and size of land under cultivation.Thus, we expect the number of people involved in land cultivation and other activities such as gardening, grazing, water abstraction, brick moulding, bee keeping to increase as the population grows.This is illustrated in figure 4.3 which compares land use intensity changes between 1997 and 2012.This has profound effects on the wetland ecosystem as cultivation alters natural vegetation, modifies soil chemical parameters and its physical structure.These disturbances result in the alteration of interactions between and among microbial and other fauna species.Figure 4.3 illustrates that an increase in population resulted in an increase in the number of people involved in some of the activities that use environmental resources.This has resulted in significant ecosystem changes.
It is shown that the activities that are carried out on Magwenzi wetland increased in intensity and coverage due to an increase in the number of people involved between 1997 and 2012.Thus, ecosystem changes could be the resultant outcome for the increase in activity intensity and coverage.It is also shown that water abstraction is the key activity on the wetland with an average of 87 people involved in direct abstraction of water for various purposes including gardening, brick moulding and consumption.Other activities that significantly increased in intensity include land cultivation, plantation, gardening, grazing, orchards and brick moulding.New projects such as bee keeping were also introduced and contributed to the ecosystem changes within the wetland.Hugget et al, (2004) postulated that excessive water abstraction due to gardening activities in communal areas depletes ground water and disturbs the hydrology of an area.Thus, water abstraction on the wetland has an impact on the wetland's hydrology.This in turn affects land cover which consequently influences species richness and evenness.Table 4.1 shows the perceptions of the respondents concerning the impacts of gardening activities on wetland ecosystems in Magwenzi.

SA=Strongly agree, A=agree, DA=Don't agree, DK=Don't know
The respondents highlighted that gardening has had effects on Magwenzi wetland ecosystem.Land cover and hydrology were reported to be the most affected.The clearance of land in preparation for gardening, cutting of thorn bushes to fence the gardens have reduced land cover.Impact on land cover has significantly contributed to the impact on species richness and species evenness.Replacement of natural vegetation with crops and other vegetative plants have affected the interactions and energy flows within the wetland.The abstraction of water from the wetland for watering the garden heavily depletes the ground water.The clearance of vegetation reduces transpiration and humidity, thus negatively impacting the hydrological cycle.The use of pesticides has been reported to have resulted in the elimination of selected species.This affects species richness and evenness.Land clearance destroys the habitat of wetland faunal species; as a result such organisms like frogs, fish, matapi and aquatic snakes have been reported to have either died or migrated downstream.Moreover pesticides pollute the water and affect aquatic species diversity.The use of fertilisers changes the chemical properties of the soil and affects microbial diversity.

Impacts of cultivation
Area under cultivation has increased between 1960 and 2012.This was due to the increase in population which led to an increased demand for food.Fragile wetland area has been converted to crop farming.Cultivation has been reported to be contributing to the impacts on wetland ecosystems.Figure 4.4 shows the perceptions of the people concerning impacts of cultivation on various aspects of the ecosystem.shows the perceptions about impacts of cultivation on the aspects of the ecosystem.About 29% of the people indicated that land cover is the most affected of the ecosystem aspects discussed.This was a result of agricultural expansion to increase the yields and a response to population growth creating an increased demand for agricultural land.
Cultivation also impacted negatively on the wetland hydrology according to the views of 24 percent of the respondents in the area.By clearing land for cultivation, there was a direct reduction in evapotranspiration.This reduces water vapour and hence precipitation.The respondents indicated that bare grounds promote surface runoff, reduce infiltration and groundwater recharge as well.Coupled with excessive drawing of groundwater for gardening purposes, the resource is never replenished.
The clearance of land had direct impacts on both species richness and evenness.Various tree, grass and animal species were affected by farming.It was reported that some small animal species have significantly reduced in number.Farming also introduced some alien species in the area resulting in the alteration of ecosystem functions.

Impacts of water abstraction
The abstraction of water if done excessively can lead to the depletion of wetland ecosystems (kling et al, 2003(kling et al, , Hugget et al, 2004)).This is because it lowers the water table, dries the surface disturbing the microbial habitat and activity.Figure 4.5 illustrates the views of the people concerning impacts of water abstraction on the wetland.

Figure 4.5 Perceptions about impacts of water abstraction
Respondents view land cover as the most affected aspect of the ecosystem.This also affects other ecosystem functions that depend on land cover such as vegetation.It was reported that abstraction depletes the water tables and cause plants and vegetation that relied on that water to wilt.It was observed that due to depleting water levels, some vegetation species could no longer survive leading to their extinction.
Moreover, Chivi Mission pumps water from this wetland to supply the school, mission and the clinic.This poses great strain on groundwater.The rate of extraction by far surpasses the rate of recharge and thus the water table is greatly lowered and this consequently affects wetland ecosystems.
Information from respondents suggests that Species richness declined by approximately 25% due to water abstraction.As the rate of groundwater extraction exceeds the recharge, the area dries and water loving plants die.This strongly reduces the number of aquatic species -both fauna and flora.It was learnt from the respondents that animal species such as snakes and frogs have significantly been reduced in abundance.The same was said about vegetation species such as the Ficus Carica.This means the total size of herd that graze on the wetland has increased.It was found that grazing is reducing land cover and altering ecosystem interactions.Excessive grazing has been reported in the area and it is resulting in the depletion of specific graminae species in the wetland.Respondents indicated that animal tracks are causing habitat fragmentation which significantly alters some species interaction in the wetland as their ecological niche is disturbed.Figure 4.7 shows ecosystem aspects that have been affected due to grazing on the wetland.

Figure 4.7 Perceptions about impacts of grazing
According to the views of the people in the wetland, land cover is the most affected aspect of the ecosystem and this consequently affects vegetation species richness and evenness.Hydrology has also been affected as compaction and grazing increased the rate of surface runoff affecting recharge of the water table .A dip tank built on the wetland also contributed to the problem of soil compaction and overgrazing on the wetland.Animal tracks have encouraged rill erosion which also exacerbates ecological disturbances on the wetland.

Land cover and land use changes
The changes in land cover and land uses are a proxy indicator for impacts of human activities on wetland ecosystems.This is because human activities were seen to be the driving force behind all ecosystem changes on the wetland.However, it was also noted that climatic changes, frequent droughts and occasional floods have also contributed but respondents played down the impacts of natural factors on the wetland's ecosystem.Figure 4.9 shows land cover changes based on respondents' estimation between 1970 and 2012.As human activities increased in number and size, there was a corresponding reduction in natural vegetation.In 1990, about 75% of the wetland was woodland; however.by 2012 only 50% remained as woodland.This was in response to the increase in the size of orchards, plantation, gardens, cultivation and the introduction of settlements in the wetland area.

Discussion
This study established that, based on views of the people in Magwenzi area, human activities have significant impacts on wetland ecosystems.Ecosystem aspects mainly affected include landcover which consequently affects vegetation species richness and evenness.Cultivation of land has been identified as the key activity that influenced land cover changes.It was reported that woodlands have been converted into settlement and cultivated areas.This confirms earlier studies by Robberts (1988) which show that human activities such as wetland cultivation significantly influences changes in land cover type.He propounded that these changes in land cover type also affect existing ecosystem interactions within the wetland.This affects the number and type of species in the wetland.Mutyavaviri (2006) also confirms this when she claimed that cultivation on wetlands have far reaching impacts on wetland ecosystems including interactions at microbial level to large ecosystem components.She says cultivation improves aeration of soils, mixes organic material with inorganic materials and this consequently changes the existing microbial interactions within the soils.
The growth in average herd size of cattle meant an increase in the impacts on land cover as the grazing intensity increases.Middleton (2003), Hugget (2004) and Champion et al. (2001) concur with the respondents' view that land grazing significantly alters ecosystem functions and interactions.Excessive grazing has resulted in erosion of soils on the wetland.Treading by animals have also added to the compaction of soils The hydrology of Magwenzi wetland was also significantly affected and this affected animal species diversity, especially those whose ecological niche is water based.Some animal and plant species survive optimally under wet conditions.The drying up of wetland due to excessive water abstraction and climatic changes have significantly affected the existince of these species.This affects ecosystem interactions that previously existed in the wetland.Hugget et al (2004) and kling et al ( 2003) also contend with the view that water abstraction in a wetland causes significant ecosystem changes

CONCLUSION
This study, through a qualitative assessment, established that population size can be used as a proxy indicator for the extent of human impacts on wetland ecosystems.As the population of an area increases, the demand for ecological resources increases and land use intensity increases leading to changes on wetland ecosystems.We also found that a wide range of human activities have significant consequences on wetland ecosystems.The main activities that affect wetland ecosystems include land cultivation, water abstraction and grazing.Other activities such as brick moulding and bee keeping also contribute to the changes in ecosystem functions and interactions.Local people have proved to be knowledgeable about the impacts of their activities on ecosystem functions and interactions.It is therefore the conclusion of this study that humans perceive themselves as the critical driving force behind wetland ecosystem degradation as activities significantly influence ecosystem functions and interactions on wetlands.

Figure 4 . 3
Figure 4.3 Land use and changes between 1997 and 2012

Figure
Figure 4.4 Perceptions on impacts of cultivation

Figure 4 .
Figure 4.6 shows the changes in average herd size per household in Magwenzi wetland.It is shown that generally, herd size has increased over time although there was a decline during the 1992 drought.

Figure 4 . 6
Figure 4.6 Average herd size over time

Figure 4 . 8 :
Figure 4.8: Land cover and land use changes between 1970 and 2012.

Fig 4 .
Fig 4.8a and b illustrate the change in land use over time from 1990 to 2012.As human activities increased in number and size, there was a corresponding reduction in natural vegetation.In 1990, about 75% of the wetland was woodland; however.by 2012 only 50% remained as woodland.This was in response to the increase in the size of orchards, plantation, gardens, cultivation and the introduction of settlements in the wetland area.