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A study of how fragmentation affects distribution
and diversity among Nymphalidae, Papilionidae
and Pieridae (Lepidoptera)
in native and exotic forest fragments in southern
Brazil
Emma Andersson
A study of how fragmenta2on affects distribu2on and diversity
among Nymphalidae, Papilionidae and Pieridae (Lepidoptera) in
na2ve and exo2c forest fragments in southern Brazil
Content
1 Introduction 3
1.1 Fragmentation 3
1.2 Atlantic forest biome 5
1.3 Eucalyptus plantation 5
1.4 Butter=ly ecology and their ability to act as indicators 6
2 Aim 7
3 Materials and methods 7
3.1 Study sites 7
3.2 Sampling 10
3.3 Analyzing the data 11
4 Results 11
5 Discussion 13
6 Conclusion 17
7 Acknowledgements 17
1 Introduc-on
The global dimensions of fragmenta2on has lead to great loss of ecosystems and biodiversity, not least in the tropics and subtropics (Broadbendt et al. 2008; Jorge and Garcia, 1997; Pütz, et al., 2011). The most common effects caused by fragmenta2on are drier soils, more light availability, higher wind disturbance and in many tropical regions the community structure and vegeta2on dynamics are highly disturbed. Small fragments (<25ha) have a higher risk of decreased diversity and may also lead to decreasing biomass of up to 50%, especially in isolated areas (Pütz, et al., 2011). On the other hand, edge effects can be beneficial for certain species and can in some cases increase specia2on (Campbell, 2008). Small fragments have shown to have a nega2ve effect on core-‐adapted species, further suppor2ng the fact that areas of small fragments are unfavorable for the diversity (Campbell, 2008; Ewers & Didham, 2007). At present, a global ex2nc2on is occurring par2ally caused by fragmenta2on, as opposed natural factors causing the previous mass ex2nc2ons (Burnie, 2007).
The Atlan2c forest of southern Brazil has been vastly affected by deforesta2on during the last five centuries (Pütz, et al., 2011) and the con2nuous reduc2on of forest area, caused by both anthropogenic and natural processes, (Wulder, et al., 2009) leads to fragmenta2on and thereby larger edge effects. This will inevitably lead to changes in flora and fauna
composi2on. These edge effects usually reach about one km into the forests, though in some rare cases they might reach up to 5-‐10 km (Broadbendt, et al., 2008).
1.1 Fragmenta-on
The forests of the world have for a long 2me been exploited by humans due to the need of firewood, logging and cul2vated areas (Primack, 1993). Fragmenta2on in terrestrial
ecosystems generally begins with a gap forma2on in the matrix of the natural habitat. These gaps are commonly a result of the development of infrastructure (Smith & Smith, 2001; Groom, et al., 2006). As these gaps con2nue to increase in size they will eventually become the matrix itself and only a small amount of the original habitat remain (Johansson, 2013). These gaps create barriers in the landscape, which may limit species dispersal, migra2on and coloniza2on of new habitats. Many species are adapted to their specific habitat and will not cross open areas due to the risk of predators (Primack, 1993). Species with large
geographical range are more resistant to habitat loss and fragmenta2on as they have a greater amount of metapopula2ons within their geographical range (Smith & Smith, 2001). Forest fragmenta2on causes interrup2ons of natural paaerns of dispersal and migra2on (Tabarelli, et al., 1999), and also the elimina2on of species, altered predatory-‐prey rela2onships and introduc2on of invasive and non-‐invasive species (Groom, et al., 2006; Tabarelli, et al., 1999). The outcome of fragmenta2on can be very diverse as some species might thrive in the new environment and others struggle to adapt to the new condi2ons, leading to metapopula2ons, migra2on or even ex2nc2on (Groom et al., 2006). When fragments decrease in size the edge effect increases and the original vegeta2on struggles to sustain itself in the decreasing core area. This process also increases the risk of invasive species sealing down (Tabarelli, et al., 1999). As edges usually consists of sparse vegeta2on, these areas are more exposed to sunlight, higher temperatures, wind speed and light availability, which will inevitably lead to lower air and soil humidity around the edge.
small fragments (Tabarelli, et al., 1999). Light and temperature are important factors affec2ng the flora and fauna composi2on in forests. In dense forests only about 1% of the sunlight may reach the ground, which means that it keeps cool, moist and shaded (Primack, 1993). When deforesta2on occurs, more sunlight will reach the ground, leading to higher temperature and dryer soils. This will also prevent heat from being trapped in the forest during night and the air will no longer be as humid as before. These effects will be strongest at the edges. As the forest size decreases, the wind will have a greater effect. In larger forests tree trunks will reduce the wind speed, leading to only small amounts of wind reaching the inner area (Primack, 1993). Moisture and temperature affect species and popula2ons in many ways, such as survival, reproduc2on, interac2ons between organisms and not least their geographical distribu2on (Krebs, 2001).
It is important to compare habitat destruc2on between countries and poli2cal borders as this gives an indica2on of how the natural resources are u2lized in different parts of the world, and may lead to knowledge about how to prevent further destruc2on of habitats (Primack, 1993). Ecosystems have changed quicker and more extensively during the last 50 years, due to anthropogenic ac2vity, than during any other comparable 2me in human history
(Millennium Ecosystems Assessment, 2005). The original habitat of many species has been destroyed and only small areas are protected (Primack, 1993). Na2onal protec2on of habitats is important, as well as on an interna2onal scale, as certain habitats extend over more than one country. (Primack, 1993). As habitat destruc2on is one of the biggest threats to biodiversity loss, habitat protec2on can be the most important ac2on towards saving species in risk of ex2nc2on. In countries with high anthropogenic ac2vity rela2ve to the land area, most of the original habitats have been destroyed. In 1993 65% of the wildlife habitat in the tropical parts of Asia had been lost In the 1970s deforesta2on became a huge threat to biodiversity in Malaysia and Indonesia, resul2ng in the establishment of numerous
preserva2on ac2ons. In 1993 the areas had about half of their wildlife habitats lef, while a total of 65% had been lost in the tropical parts of Asia. (Primack, 1993; WWF, 2013). Since 1973, WWF has supported the research for the protec2on of the Atlan2c forest in Brazil by limi2ng unsustainable use of the forest, increasing public awareness and numerous other solu2ons to maintain the scarce amount of Atlan2c forest that remains. In 1993, an area of 5,843 km2 had been suffering from deforesta2on in Brazil. Today, UNESCO has listed 25 areas
of the southeast Atlan2c forest as part of their World Heritage sites, covering an area of 470,000 ha (World Wildlife Found, 2013; UNESCO, Visited 2014). The United Na2ons Food and Agricultural Organiza2on (FAO) states that the global net loss of forest area in Brazil during the 1990’s was es2mated at 94 million ha, which is equivalent to 2.4% of the forest area in the world (Smith & Smith, 2006).
Fragmenta2on of a biome will limit migra2on and establishment in new areas and the
possibility for species to cope with the new environment will be reduced, leading to declining popula2on sizes and in some cases ex2nc2on (Primack, 1993; Tabarelli, et al., 2005). When a popula2on size decreases due to fragmenta2on, the size and isola2on of the fragment determines the scale of the decrease (Krohne, 1998). Andrén (1996) studied the rela2onship between size, isola2on and biodiversity in fragments to determine if there is a similar paaern
1.2 Atlan-c forest biome
The Atlan2c forest in South America stretches from the northeast of Brazil down to the southern parts of the country and also covers northern Argen2na and southeastern Paraguay (The nature conservancy, 2011) At the beginning of the European coloniza2on in the 16th
century, the Atlan2c forest covered an area of 1,300,000 km2, stretching along the coast of
Brazil from the northeast to the south (Morellato, 2000). Today only 100,000 km2 (about 7%)
of the original forest remains, though it is s2ll considered to be the second largest rainforest on the South American con2nent (Tabarelli, et al., 2005; World Wildlife Found, 2013). The reduc2on is mainly a result of the extrac2on of 2mber, firewood, agriculture and other anthropogenic ac2vi2es (Morellato, 2000), which have divided the forest into several thousand small fragments (Tabarelli, et al., 1999). The Atlan2c forest contains many old fragments (>50 years old) and has one of the highest plant and animal endemisms of any con2nental tropical forest (Tabarelli, et al., 1999). The soil types, climate and vegeta2on composi2ons are also highly diverse since it contains tropical rainforest in the north, followed by Lauraceae and Araucaria forests further south, with deciduous and semi-‐
deciduous forest inland (Johansson, 2013). Today, 3,000 ci2es are situated in the area of the Atlan2c forest, inhabited by 100 million Brazilians (Morellato, 2000). In total, around 20,000 plant species have been found in the Atlan2c forest, and the number is con2nuously rising. About 8,000 of these species are endemic, and at present, the Atlan2c forest is one of 25 areas proclaimed as biodiversity hotspots (Conserva2on interna2onal, 2013; The nature conservancy, 2011). This high diversity of the vegeta2on includes mul2ple lianas, orchids, bromeliads, ferns, mosses and epiphytes. 5% of the world’s vertebrates can be found in this area, which accounts for around 2,200 amphibians, rep2les, birds and mammals (The nature conservancy, 2011). Most of the fragments of the Atlan2c forest are small, usually smaller than 30 ha. When fragments are smaller than 10 ha it is not uncommon that it only consists of edge habitat, and therefore core specialized species are absent from these fragments (Tabarelli, et al,. 1999). Illegal logging, land conversion and expansion of urban areas are some of the anthropogenic factors causing these fragmenta2ons. Since 1991 The Nature Conservancy has been working to restore and protect 30 million acres of the Atlan2c forest, with the goal set at the year 2015. This project focuses a lot on developing forest corridors and increasing the chances of gene2c flow between popula2ons (The nature conservancy, 2011). Maintaining high gene2c flow is important, especially in small fragments where popula2ons ofen are small as well since the risk of inbreeding increases, crea2ng homozygosity (Krohne, 1998).
1.3 Eucalyptus planta-on
Eucalyptus (Eucalyptus oblique) is at present the most common species within industrial reforesta2on due to its high quality, rapid growth and high adaptability (Cirad, 2011; Luzar, 2007). An introduc2on of the eucalyptus in Brazil was made as the species was believed to reduce pressure on exis2ng forests, but it was soon discovered that the wide roots of eucalyptus extract large amounts of water and nutrients from the soil and would eventually increase soil acidity. Eucalyptus has a tendency to out-‐compete surrounding flora, which creates a bare landscape, increasing the risk of erosion (Luzar, 2007). In some cases forest planta2ons of any kind may support biodiversity by working as corridors between na2ve fragments, increasing chances for organisms to cross the landscape matrix (Barlow, et al., 2007)
of this area while pine accounts for 37%. In 1967 several afforesta2on programs started to emerge afer a symposium held by FAO called World symposium on Man-‐Made forests and
their Industrial Importance. Within 20 years 4 million ha had been planted (Food and
Agruculture Organiza2on, 2003; Evans, 2009). Products such as paper and pulp became important for the interna2onal economy, consuming around 400,000 ha of planta2on. Brazil accounts for 2.4% of the global market of forest products and in 2001 this amounted to approximately 3,200 million USD (Food and Agriculture Organiza2on, 2003). The produc2vity of eucalyptus planta2ons in the world has increased by 10-‐20% every decade during the last 40 years (Cirad, 2011). Depending on the purpose of the eucalyptus planta2on, the forest is usually harvested within 7-‐14 years afer it has been planted (Wilcken, et al., 2008). When deforesta2on occurs, animal and plant communi2es will be disrupted and ecological
succession will take place. Pioneer species will be the first new organisms to enter the area, and are usually adapted to the specific disturbance that has occurred. The characteris2cs of the area will change over 2me, and new species will con2nue to enter un2l equilibrium is reached. In the beginning the succession is very produc2ve, as the area can exploit more sunlight than the previously covered ground (Duram, 2010).
1.4 Bu@erfly ecology and their ability to act as indicators
Buaerflies are the most frequently studied taxa, and in tropical habitats, buaerflies have ofen been used as indicators to determine the conserva2on value of a specific area (Barlow, et al., 2007; Robinson, et al., 2012). Most buaerfly species have rela2vely short life-‐cycles, which combined with their sensi2vity to climate change gives scien2sts the possibility to study changes and condi2ons of the environment in their habitat more easily. This may in long term give scien2sts knowledge about how other terrestrial organisms may be affected by these changes as well (Robinson, et al., 2012; Bonebrake, et al., 2010). Examining how communi2es differ among habitats may help to determine the preferred habitat of a specific group of organisms as well as understanding the vulnerability of certain areas when it comes to environmental change (Robinson, et al., 2012). Due to their sensi2vity for weather
changes buaerflies have frequently been used as indicators to determine the conserva2on value of tropical habitats and consequences of disturbances and land-‐use (Barlow, et al., 2007). The more favorable the habitat is, the greater chance there will be for the individuals to successfully produce numerous offspring (Krebs, 2001).
The study of buaerflies has led to great understanding of ecology and conserva2on (Bonebrake, 2010). Geographical distribu2on of species can be restricted by species compe22on. In a habitat, species A and species B might co-‐exist, though the presence of species A may cause species B to decrease in popula2on size due to, for example,
compe22on of food. In some cases the presence of species A might be an indicator of total absence of species B since the compe22on between these two species are too big (Krebs, 2001). When compe22on for resources occurs between two species, one species will always have a greater ability to gather or u2lize the resource, leading to migra2on or adap2on of the weaker species (Krebs, 2001).Canopy dwellers are usually more adapted to open areas while species occupying the ground floor are more dependent on the characteris2c forest
Buaerflies are extremely sensi2ve to severe weather, and changes in precipita2on and temperature may disturb their abundance and distribu2on. These kinds of changes may also affect nectar sources and their food plants (Robinson, et al., 2012). Many studies have been made of the correla2on between buaerfly diversity and habitat disturbance (Bonebrake, 2010). A study made by Robinson, et al., (2012) show that a combina2on of higher temperature and lower precipita2on in 2002 led to a decrease in both abundance and species richness among buaerfly communi2es in dry and temperate ecosystems. This decrease show the vulnerability among buaerflies when it comes to changes in weather condi2ons due to different factors, one among them being the availability and quality of food, which in this case were supposed to have been affected by the weather, due to less precipita2on leading to less water availability for plants and plants were therefore not growing as much as other years (Robinson, et al., 2012). The occurrence of a buaerfly
species depend more on the co-‐occurrence of a host plant and a suitable microclimate rather than on the absolute abundance of the host plant. The choice of host plants varies greatly among families and species. Therefore it is more convenient to rely on local data of the host plants of the specific species or family (Lindman, et al., 2012). Habitat selec2on is one of the ecological processes we have the least knowledge about (Campbell, 2008).
2 Aim
The aim of this project was to inves2gate the diversity and distribu2on of three buaerfly families in two forest fragments. By comparing buaerfly diversity in two forest
fragmenta2ons; one preserved na2ve forest and one eucalyptus planta2on, this study will contribute to the understanding of how species diversity is affected by fragmenta2on. The two fragments differ in shape, plant composi2on and amount of human disturbance. The purpose of this study is to establish a value of the diversity both within and between the fragments and draw conclusions of the factors that may have caused the result. The families chosen for this project are Nymphalidae, Papilionidae and Pieridae. These families were chosen for this project as they are some of the more common families in the area. Not only are they usually easy to iden2fy but also commonly flies at a catchable range, which makes these families beneficial for this study due to the method of inventory that was chosen. They can be found both in the edge and core area and are easy to iden2fy even when flying. A list of the plant composi2on in the na2ve and exo2c fragment was received from the botanical department at Univates university to dis2nguish possible correla2ons between plants and buaerfly diversity in the area (appendix 2 & 3), (Périco, unpublished data).
3 Materials and methods
3.1 Study sites
The two sites chosen for this project are situated in the state of Rio Grande do Sul in southern Brazil (figure 1), an area with elements of Atlan2c forest. The na2ve fragment is located one kilometer outside of the town Colinas, situated close to the Taquari River and is surrounded by crops and a small sealement (figure 2). This sealement consists of gardens in which flowers and vegetables are grown. This could affect the result of the inventory as the flowers and vegetables may aaract buaerflies that would otherwise not be found in the area, as their only food source can be found in the gardens, and not in the actual forest area where the na2ve flora grows. This fragment consists of na2ve flora (appendix 2) and has a
wild-‐growing character. It is not certain for how long this area has been preserved, but due to the diameter of the tree trunks, it is es2mated to have been protected for 15-‐20 years (Périco, pers. comm, 2014). Due to the dense vegeta2on, light availability is scarce in the core area, and at the edges, vegeta2on is less dense, which enables more light to penetrate through the sparse canopies. The edge in the southern part of the fragment has presumably been harvested and does therefore today consist of low-‐growing bushes while the amount of trees is higher in the rest of the edge. The exo2c fragment, located close to the town
Lajeado, is a planta2on of eucalyptus trees (Eucalyptus obliqua) (figure 3). The plant diversity of the exo2c fragment is low compared to the na2ve fragment (appendix 3). With few bushes and lianas, the exo2c fragment is significantly less dense than the na2ve fragment. Though, different parts of the fragment is frequently harvested, leading to open patches or areas with vegeta2on in early successional state. Parts of the edge of the fragment has been es2mated to have been harvested somewhere between May 2013 and April 2014, according to Google earth maps.
These two structurally different fragments were chosen to analyze the differences of the diversity and distribu2on of Nymphalidae, Papilionidae and Pieridae in a preserved area of na2ve flora and a planted eucalyptus forest. The fragments are both rather small and the amount of disturbance from the surroundings, such as roads, houses and agricultural ac2vity is approximately the same. In the region of our study area, the rainfall is es2mated to reach 100-‐150cm3/year (Krebs, 2001). By analyzing the maps of Google earth from 2006 to 2014, it
is evident that the exo2c fragment has been exposed to deforesta2on at several occasions. When analyzing the na2ve fragment, no significant changes have been made during the last eight years, except for a small frac2on in the southern part of the edge, which used to be a field but has now over-‐grown, becoming a part of the edge (Google earth, 2014). When this study was executed the size of the na2ve fragment was approximately 5 ha, with a cross sec2on of 0.30km × 0.20km, and the exo2c fragment were 3.5 ha with a cross sec2on at 0.30km × 0.12km.
Figure 1. The two fragments in which the inventories was carried out are situated in the state Rio Grande do Sul in southern Brazil. The area consists of fields and villages, resul2ng in a fragmented landscape. Retrieved from Google earth, 2014-‐01-‐10.
Figure 2. The na2ve fragment is situated 1 km from Colinas, Rio Grande do Sul, Brazil, and is a protected area that consists of na2ve flora. This fragment is approximately 5 ha big, surrounded by crops and a small sealement, close to the Taquari River. Retrieved from Google earth, 2014-‐01-‐10.
Figure 3. The exo2c fragment is a eucalyptus planta2on situated close to Lajeado, Rio Grande do Sul, Brazil. This fragment, consis2ng of exo2c flora, was approximately 3,5 ha big when the research was carried out. As this is a planta2on, the fragment is con2nuously exposed to deforesta2on and the fragment size is constantly changing. Note: When the research was executed, the yellow area in the figure had not been harvested yet. Retrieved from Google earth, 2014-‐01-‐10.
3.2 Sampling
In 2013, data was gathered between April and the end of May consis2ng of 5 inventories at each site. The fragments were divided into 4 research areas: na2ve edge, na2ve core, exo2c edge and exo2c core. The inventories started at 9 am with sampling of the edge followed by the core. The next fragment was sampled at 1 pm the same day, working the same plan of inventory. A quan2ta2ve method was used during this research to determine the amount of species that was found within the families Nymphalidae, Papilionidae and Pieridae. Using a net, uniden2fied buaerflies were collected and brought back to the lab for iden2fica2on. The species that were iden2fied in the field were released immediately afer iden2fica2on or collected for Univates University’s buaerfly collec2on. The buaerflies were iden2fied using literature of the buaerfly species in South America (Canals, 2003; D’Abrera, 1984; Smart, 1989) but also by comparing the species to specimens that had been gathered and iden2fied in previous studies. Considering the size of the fragments, the edge area was es2mated to reach approximately 10 meters into the forest at both sites. Walking the same path each 2me with a serpen2ne paaern, samples were collected immediately when they were spoaed. In the cores, serpen2ne paths were followed as well.
3.3 Analyzing the data
Data was analyzed in the program PAST where both Shannon diversity index and Ward’s cluster analysis was calculated for each fragment. Shannon diversity index was also calculated for the edge and core at each fragment. Ward’s cluster analysis was used to establish the similari2es and differences of species composi2on in the two fragments by looking at species existens and non-‐existens. The analysis was made on all four sites (edge and core at fragments 1 and 2). Thereafer, the results were compared between the four sites, but also between the two fragments to establish the amount of species found in the different areas. The species were also grouped into the families to determine wither some families thrived more than the others in the different areas.
4 Results
39 species of Nymphalidae, Papilionidae and Pieridare were found, 33 of them exis2ng in the na2ve fragment and 23 species in the exo2c fragment (appendix 1). Figure 4 shows that the area with the highest diversity among buaerflies was the na2ve edge, where 31 species was found, followed by the exo2c edge with 21 species, the na2ve core with 17 species and last the exo2c core with 15 species. 4 of the species found during the study were not iden2fied, though it was s2ll possible to categorize them into the correct family and include them in the research. 9 species were found at all sites and 19 species occurred only at one of the four sites. 17 species were found in both the na2ve and exo2c fragment. The most common family during the study was Nymphalidae, followed by Pieridae and last Papilionidae (appendix 1). The na2ve and exo2c edge had 15 species in common, while the na2ve and exo2c core had 10 common species (appendix 2). Didonis biblis was the only species what was found only at one of the four sites, the na2ve core. Agraulis vanillae maculosa could only be found in the edges of the fragments, while Eurema deva was found only in the na2ve fragment, though both in the edge and core (appendix 2). During the inventory of the exo2c edge it was noted that many species could be found par2cularly in an area consis2ng of small bushes, lots of grass and small trees, which suggests that the area had been harvested not long before the inventory took place.
Figure 4. Number of species found at the different sites within the families Nymphalidae,
Papilionidae and Pieridae, and the number of species found in total.
Shannon diversity index show that the na2ve fragment has a higher value in total (3.871) than the exo2c fragment (3.584), hence has a higher diversity (table 1). The na2ve edge and core also has a higher value compared to the exo2c edge and core. Shannon diversity index was also calculated on the plant composi2on at the two fragments, which resulted in a value of 4.682 in the na2ve fragment and 3.497 in the exo2c fragment.
Table 1. Shannon diversity index of the buaerfly species of Nymphalidae, Papilionidae and
Pieridae at the two fragments and in their edge and core.
Shannon diversity index Na2ve
fragment Na2ve edge Na2ve core Exo2c fragment Exo2c edge Exo2c core
3.871 3.434 2.833 3.584 3.045 2.708 0 10 20 30 40
Both fragments Native Native core Native edge Exotic Exotic core Exotic edge
Ward’s cluster analysis show that the na2ve edge differ most in buaerfly composi2on from the other sites, with a value at 4.9 (figure 5), while the na2ve core differ a bit less with a value at 3.5. The exo2c core and exo2c edge are similar in species composi2on, both ending up with a value at 2.5.
Figure 5. Ward’s cluster analysis was used to compare the composi2on of buaerfly species of
Nymphalidae, Papilionidae and Pieridae in the edge and core of the na2ve and exo2c
fragments, to determine the uniqueness of the four sites.
5 Discussion
The na2ve edge consisted of a significantly higher amount of species of Nymphalidae,
Papilionidae and Pieridae than the exo2c edge (figure 4). As edges are more exposed to light,
this will increase the possibility for plants to grow, flourish and aaract insects (Tabarelli, et al., 1999). The high light availability in the edges might be one of the major reasons for the large amount of species exis2ng in these areas, as buaerflies are dependent on sunlight to maintain a proper body temperature (Gilbert & Singer, 2013). Though, other factors must also be considered, as the diversity according to shannon diversity index is higher in the na2ve edge (3.434) than in the exo2c edge (3.045). The difference in diversity is larger between the edges than between the cores of the fragments, which suggests that there are important factors in the na2ve edge that might not be as strong or even exist in the exo2c edge. The na2ve and exo2c edge each consists of one area that has earlier been harvested, and does today consist of low-‐growing plants, which could consist of both na2ve and exo2c flora (Meiners, 2007), and differs from the characteris2cs of the rest of the edge. The harvested area of the na2ve edge aaracted a lot of buaerfly species, which might be due to the high light availability and the flourishing plants. The area in the exo2c edge has earlier been a part of the eucalyptus planta2on, but has been lef alone since the harvest, which took place some 2me between May 2012 and the beginning of April 2013 (Google earth,
2014), which has allowed other species than eucalyptus to grow. As more species were caught in this par2cular area, the new plants seems to have aaracted more buaerfly species than the eucalyptus, as there were not as many species caught in the rest of the edge where eucalyptus was domina2ng and other plants were scarcer. The na2ve edge consisted of a small sealement surrounded by gardens, containing large amounts of blooming plants, providing buaerflies with nectar and has probably aaracted large amounts of buaerflies to the area.
When comparing the values received from the Shannon diversity index, it is evident to say that the buaerfly diversity of the core areas did not differ a lot compared with the edges. Both cores contained approximately the same amount of species, which probably led to the similar shannon diversity index. Light seemed to be an important factor affec2ng the amount of buaerflies found in the areas. Though in the exo2c edge, less species were found
compared to the na2ve edge, even though the light availability were approximately the same, meaning that there are other factors in the eucalyptus planta2on that limits the diversity. The low amount of plants in the area is probably a major factor to the scarce amount of buaerflies, as this limits the possibility that host plants can be found in the fragment. Due to the low light availability, the air is likely to be colder, which might repel buaerflies, as they need to maintain a certain body temperature for their fer2lity and flight ability (Gilbert & Singer, 2013).
The fact that the na2ve fragment aaracts more buaerflies is clear, which Shannon diversity index supports with a higher value in the na2ve fragment (3.871) than in the exo2c fragment (3.584). Except for the light availability, plant diversity is an important factor to consider. Shannon diversity index of the plants show a value at 4.682 in the na2ve fragment, and 3.497 in the exo2c fragment. The fact that the plant diversity is higher in the na2ve fragment has most likely affected the diversity of buaerflies, as it is crucial for buaerflies to have access to nectar to survive, produce offspring and maintain a sustainable popula2on (Gilbert & Singer, 1999). The Shannon diversity index of both buaerflies and plants is higher in the na2ve fragment and lower in the exo2c fragment. In the na2ve fragment, buaerfly diversity is 3.871 and plant diversity 4.682. In the exo2c fragment, buaerfly diversity is 3.584 and plant
diversity 3.497. As these two indexes follow each other, this could support the fact that buaerfly diversity is dependant on plant diversity. The monotonous vegeta2on in the exo2c fragment might also have affected the buaerfly diversity, as this lowers the possibili2es that host plants exist in the area. As eucalyptus is an invasive species, it would probably not be a host plant for any buaerfly in the area. The low amount of bushes and low-‐growing trees in the exo2c fragment may result in increased wind speed, which might lower the amount of buaerflies in the area due to their sensibility for changes in weather condi2ons (Robinson, et al., 2012).
The exo2c fragment is con2nuously exposed to deforesta2on, which reduces the chances for buaerflies to seale down in the fragment. When deforesta2on occurs in the area, only small frac2ons of the fragment is harvested at each occasion (Google earth, 2013), which allows species to move to other parts of the fragment to survive, and several plants and animals can
the pioneer organisms probably are na2ve to the area, the chances for them being host plants for the buaerflies increases. Sadly, new trees of eucalyptus are con2nuously planted, preven2ng succession to reach equilibrium and destroying the possibili2es for a more diverse vegeta2on to seale down, which probably would increase buaerfly diversity (Duram, 2010). As the choice of host plants of a specific buaerfly species may differ depending on the geographical loca2on (Lindman, et al., 2012), further studies of the host plants of the buaerflies in this area may increase the understanding of why certain species are more adaptable to the exo2c area than others. This would also supply more knowledge about which species could be considered indicators for good environments, giving scien2sts greater understanding of how much disturbance the planta2on suffers from, as the absence of species that occur in the na2ve fragment could demonstrate if the na2ve or exo2c area suffers from severe disturbance or not.
Ward’s cluster analysis states that the exo2c edge and core have similar species composi2on among buaerflies, which was expected as the exo2c fragment consists of monotonous vegeta2on throughout the whole fragment and would therefore aaract similar species. The analysis also states that species composi2on between the na2ve edge and exo2c edge + eco2c core are very different, with a value at 3,5 in Ward’s cluster analysis (figure 5). The na2ve edge consisted of more blooming plants, bushes and trees than in the exo2c edge, which means that the habitats were very different from each other. Though the areas s2ll had 15 species in common (appendix 2). As the exo2c core had the same species
composi2on as the exo2c edge, this means that the exo2c core is equally different from the na2ve edge.
Broadbendt, et al., (2008) states that edge effects may reach 1 km into a fragment, which would indicate that both fragments used during this research consist exclusively of edge habitat. Despite this, it was possible to dis2nguish differences in structure of vegeta2on, light availability and buaerfly diversity in the na2ve fragments edge and core. Edge and core in the exo2c fragment seem thus to be very similar in my study, which might be due to its size and shape. The exo2c fragment has a rectangular and slim shape (figure 3) while the na2ve fragment has an oval shape (figure 2). A narrow shape minimizes the possibility for a core habitat to exist in the fragment, especially if the fragment is small. This suggests that
fragmenta2on is unfavorable for core-‐adapted buaerflies. Though, comparing the amount of species found in the two cores (figure 4), the number of species does not differ a lot,
sugges2ng that both cores are equally beneficial for buaerfly diversity. As the exo2c core did not have a significant core habitat, this suggests that the whole exo2c fragment might consist exclusively of edge habitat. Increased amount of edge in a fragment might cause changes in temperature and wind, and could have damaging effects on ecological processes (Debinski & Holt, 2000) As the na2ve fragment is also rather small, it is possible that the characteris2cs of the na2ve core does not differ enough from the na2ve edge to aaract other species than the once found in the edge. The low differences do therefore not aaract as many core-‐adapted species as it would in a larger forest, where the core would be more defined. A possible reason for this similar result might be that the small size of the fragments forces edge species into the center of the fragment, causing a crowding affect which increases the compe22on between and within a species. As generalists are more adaptable to changes than specialists, this would mean that generalists will cope with the changes beaer while the specialists either die or disperse from the area (Campbell, 2008).
The constant deforesta2on has probably also affected the diversity of buaerflies in the exo2c fragment, Every 7th to 14th year, frac2ons of the forest are harvested (Google earth, 2014;
Wilcken, et al., 2008), con2nuously exposing the fragment to anthropogenic stress. This causes succession to take place, introducing new species un2l eucalyptus once again is planted in the area (Duram, 2010). The differences of buaerfly diversity in the exo2c edge and exo2c core is probably due to the vegeta2on sprou2ng around the fragment, which is more diverse and the possibility for host plants to exist outside of the fragment is higher than inside the fragment as other plants most likely are out-‐competed by the eucalyptus in the fragment. Some species might adapt to the high density of eucalyptus as long as there are a certain amount of their host plants to be found in the same area, while other
buaerflies need the na2ve environment of southern Brazil, to which they are adapted. In the exo2c edge, a few other tree species has managed to sprout without being outcompeted by the eucalyptus.
There are corridors connected to the naive fragment, which might increase the chances of dispersal of individuals and species. Not only might this lead to more gene2c exchange, but also increases the possibili2es for species to move between habitats in search of food and mates for breeding. The presence of numerous larger fragments in the surroundings might increase the possibili2es for species to migrate, but unfortunately the corridors connected to the na2ve fragment are rather narrow, which decreases the chances for species to use them as pathways. Fields and roads in the surroundings limit the use of many corridors. Some species will not be en2rely limited by these anthropogenic factors, while some species refuse to cross even short distances of areas that for them are considered non-‐habitable (Primack, 1993), and dispersal of the popula2on will completely stop. Heliconius erato, which was found during this study, has shown to be very sedentary while many other Heliconius species are rather migratory (Gilbert & Singer, 2013). As there are numerous larger fragments in the surroundings of the na2ve fragment, this increases the chances for species to migrate between different habitats. The corridors connected to the exo2c fragment are also rather narrow, and as the surrounding does not consist of any larger fragments, the possibility for species to migrate between habitats is limited.
Nymphalidae had by far the superior diversity among families throughout the research, with
19 species in the na2ve fragment and 15 in the exo2c fragment. As the amount of
Papilionidae and Pieridae were low in both fragments (figure 4), it is possible that small
fragments are disadvantageous for them. Papilionidae was the family that seemed to cope the least to the monotonous environment in the exo2c fragment, with only two species occurring, compared to the five species in the na2ve fragment. The occurrence of Pieridae in the na2ve fragment was rather equal to Papilionidae, with a number of six species. Though,
Pieridae seemed to have higher possibility of survival as five species was found in the exo2c
fragment. Nymphalidae is the most common family occurring in both fragments and 8 of the 9 species found at all sites belonged to the family Nymphalidae. This suggests that the species found within this family are more adaptable to changes in both na2ve and exo2c environments than the species found of Papilionidae and Pieridae. This could mean that many species of Nymphalidae are generalists, as resent studies show that specialists usually
harvested, consis2ng of other species than eucalyptus, which would imply that eucalyptus forests decrease buaerfly diversity.
6 Conclusion
Both the na2ve and exo2c fragment has suffered from fragmenta2on due to anthropogenic factors, though the areas have responded rather differently. The highest diversity among buaerflies was found in the na2ve edge (3.434), followed by the exo2c edge (3.045), the na2ve core (2.833) and the exo2c core (2.708). The results of this study show that eucalyptus planta2ons are unfavorable for buaerfly diversity, as the monotonous vegeta2on of the exo2c fragment lowers the possibili2es for buaerflies to find host plants in the area, decreasing the diversity due to lack of food. The monotonous vegeta2on in the exo2c fragment, combined with the fragments small size and slim shape, has probably also led to the absence of core habitat, which has most likely decreased the possible amount of core-‐ adapted buaerflies in the area. The habitat of the na2ve fragment has shown to be more beneficial for buaerfly diversity compared to the habitat of the exo2c fragment, as Shannon diversity index resulted in a higher value of buaerfly diversity in the na2ve fragment (3.871) than in the exo2c fragment (3.584). The plant diversity in the na2ve fragment (4.682) was higher than in the exo2c fragment (3.497), which might increase buaerfly diversity due to the increased chances for host plants to exist in the area.
7 Acknowledgements
I want to show my gra2tude to Camila Schmidt at Univates, Lajeado, Brazil, for all the help with the inventories, fieldwork and iden2fica2on of the buaerflies. You have been of great importance for me during this project. I also want to thank Samuel Renner for helping out in the field and ac2ng as a personal driver to the sites. Marie Magnheden, supervisor at
Halmstad University for supervising and guiding me through my research, and Eduardo Perico, my supervisor at Univates, Brazil. I am grateful to Halmstad University and the s2pendium Linneus-‐Palme, handed out by Universi2es to students to be able to study abroad, for giving me the opportunity to travel and study in Brazil, which has given me great knowledge and a wonderful experience.
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