- May 12, 2020
Possible Climate Change Impacts on Agricultural Ecosystem Services by Bats
PossibleClimate Change Impacts on Agricultural Ecosystem Services by Bats
PossibleClimate Change Impacts on Agricultural Ecosystem Services by Bats
Anecosystem can be described as the interdependence and interactionbetween living organisms and the non-living environment, bothphysical and chemical (Kunz et al., 2011). Research by KassoandBalakrishnan(2013)explains that bat species have existed on the earth for a million ofyears. During this period, bats have evolved to over 1200 extantspecies. Many species of bats are found in dark places such as tombs,caves and big holes in the ground. Others find shelter in treecavities and undergrowth (Heimetal., 2015). Bat species play important role in agriculturalecosystems by providing various services such as insect and pestcontrol, pollination and seed dispersal, redistribution of nutrientsfrom guano, among others (Kunzet al., 2011). Despite the various ecosystem services provided bybats, these species have become increasing threatened as a result ofclimate change resulting from human factors such as urbanization,mining, deforestation, air pollution to name but a few. This paperwill focus on the various ecosystem services provided by bat in theUnited States and the possible impacts resulting from climate change.
Accordingto Boyles,Cryan,McCrackenandKunz(2011),bats are some of the creatures that have been overlooked by manystudies that have explored endangered species of the world. Often,bat biologists encounter the question as to why people should careabout bats. From the evidence gathered from various studies, it isobvious that bat biologists care about the wellbeing and future ofthese animals because they provide a number of ecological andeconomic benefits to human beings (Kasso& Balakrishnan, 2013).It is very unfortunate that as technology advances and the worlddevelops climate on the other hand is deteriorating and consequentlyaffecting many of the natural ecosystems of the world and bats arenot an exception. Therefore, if these animals are not monitored andprotected, the services that humans directly and indirectly enjoyfrom bats will be weakened or ceased completely causing severeimpacts to the ecological units in which they live.
Agriculturalecosystem services provided by bats in the United States
Manyparts of the United States such as the South Western regions andSouth-central Texas are homes to a rich diversity of various speciesof bats (Kunz et al., 2011). Some of these species feed on insects,others on fruits, nectar, and flowers. There are also some bats thatfeed on arthropods and some crop pests. Current research also explainthat there are carnivorous bats that feed on frogs, fish, blood andother small mammals and these play a significant role as predators orprey in sustainable ecosystems(Heimetal., 2015).Through their eating habits and way of living, bats provide variousecosystem services. Bats are very important not only in the U.S. butalso in all places that they occur because they offer services toecosystem in various ways. In the following section of this paper,the various ecosystem services provided by bats such as insectand pest control, pollination and seed dispersal, redistribution ofnutrients from guano will be discussed
Batsas insect and pest control agents
Amongthe estimated over 1,200 extant bats, two thirds are either coercedor natural insectivores(Kasso& Balakrishnan2013).Some of the bat species glean insects from vegetation and on watersurfaces in clustered forests, grasslands and other agriculturallandscapes. Studies such as the one carried by WhitakerandClem(1992) recognize that, bats have insatiable appetites for nocturnalinsects. However, insectivorous bats are wide-ranging predators, whofeed on a variety of animal groups. When opportunities arise,insectivorous bats consume small sized prey according to availabilitywithin the habitat. According to Heimetal. (2015), insectivorous bat activity and variety are stronglylinked the availability of arthropod, implying that bats search forhabitats rich in prey sources.
Theinsectivorous bats play significant role agriculture by suppressingthe number of arthropods (Boyles et al., 2011). Research by Boylesand his colleagues suggest that herbivorous arthropods destroy almosthalf of the world’s crops. The mechanism to fight arthropods bymany farmers in the United States and many other countries has beenthe use of synthetic pesticides. Studies in this field show that theuse of synthetic pesticides has various negative impacts such ashuman health risks, soil toxicity, increased resistance by pests andother severe changes on climate(Clevelandet al., 2006). Theuse of synthetic pesticides in the United states has increased overthe years but despite that, the number of crops being destroyed hasgone up to 13% from 6% recorded in the 1940s (Kunz et al., 2011).
Theincreased use of pesticides has diminished the benefits offered byinvertebrate and vertebrate predators such as the bats andconsequently insect species that initially were not considered croppest have gained the status of pests (Boyles et al., 2011). Accordingto Kasso& Balakrishnan(2013),recent efforts to reduce the use of synthetic pesticides include theadoption of organic controls. Kunz et al. (2012) point out thatalmost 100% possible pests are restricted by organic ecosystems, ofwhich some of them can be attributed to predation by bats. The UnitedStates invests millions of dollars annually to pest control. However,most of these resources are lost since use of synthetic pesticideshas proven to be inefficient causing reductions in agricultureoutput. Therefore, as various studies suggest, the use of bats asbiological pest control should be encourage not only in the UnitedStates, but all over the world to reduce cost, avid negative impactsof synthetic pesticides and increase crop production (Boyleset al., 2011 Kasso& Balakrishnan,2013Kunz et al., 2011).
Batsfor pollination and seed dispersal
Inaddition to acting as biological pest and insect control, batecosystems also provide the service of pollination and seed dispersalin most of the tropical and sub-tropical parts of the United States.For bats to feed on nectar and pollen, they require some certainmorphology as sharp and long mouth and tongues. According toGasbarrini(2016), because of such morphological specialization, very fewspecies of the bats i.e. 15 species in six genera can feed on nectar.Most of the other members are primarily fruit-eaters. Unlikepredation, an interaction in which only the predator benefits at theexpense of the prey, pollination and seed dispersal are mutualrelations in which both the plants and bats gets some benefits. Batsget food from the plants while the latter benefits by beingpollinated and seeds dispersed. According to Gasbarrini (2016), batswith other flower visiting and fruit-eating animals play asignificant role not only in agriculture but in other naturalecosystem such as forests in the United States.
Generally,bat pollination in the United States is not as common as bird orinsect pollination. However, as Kunz et al. (2011) and Sherwin,Montgomery and Lundy (2012) point out, bat pollination involves aremarkable a variety of plants, which are of significant economic andecological value. There are two families of bats namely the Agavaceaeand Cactaceae, which offer vast economic and ecological value. Manyspecies of paniculate Agave depend so much on bats for pollinationand many of these bats pollinate and disperse seeds of columnarcacti, which are common in Southwestern United States (Gasbarrini,2016). Originally, in the United States, bats pollinated large-scalecrops such as nonnative bananas and mangos. MaineandBoyles(2015)explain that bats have played a significant role agro ecologicalinteractions in corn not only in the United States but all parts ofthe world where corn is grown. Upto date, the United States continues to derive benefits from batpollination and seed dispersal in ensuring the spread and dominanceof important tree, fruit, and flower species.
Redistributionof nutrients from guano
Historically,guano from bats has been sourced from caves to be used asagricultural fertilizer for a variety of crop species owing to itsrich content of nitrogen and phosphorous (Kunz et al., 2011). Kunzand his colleagues explain that nitrogen and phosphorous are not onlyimportant nutrients but are the primary limiting nutrients for mostplant life. However, Kunz et al. (2011) posit that not many studieshave clearly investigated the effects of guano on plant growth. Thecommon habitats of bats are the caves and hence are thought toprovide organic input to the ecosystems found in these places. Forinstance, the salamander, fish population and other invertebratecommunities that reside in caves highly depend on the nutrients frombat guano (Kunz et al., 2011). Currently, there are severalresearches being carried out to determine the potential ecologicalrole of guano in nutrient redistribution in various ecosystems.
Insectivorousbats require high amounts of energy to sustain themselves especiallyfor flight purposes. As bats fly across various heterogeneoushabitats searching for preys, it is expected that guano beredistributed over the countryside throughout the night (Boyles etal., 2011). Through their night movements, bats play a significantrole in nutrient redistribution from the ecosystems rich in nutrientssuch as lakes and rivers to those poor in nutrients such as arid andupland areas. The study by Kunz and others also reveal that whenguano is applied moderately in guarded greenhouse experiments, itpromotes growth in a grass species that is mainly found in Texas.According to Heim et al. (2015), the fact that bats can enhancenutrient distribution, which is essential for agriculture, makes themimportant animals for conservation. Kunz and other argue that guanofrom bats may have specific advantageous effects on plant communitiesand hence there is need for further in-depth investigations and fieldstudies to authenticate the argument.
Possibleimpacts of climate change in the U.S.
Climatechange plays a significant role in driving changes in the currentglobal ecosystems. According to (Sherwin et al., 2012), increasingtemperatures, changes in amounts of rainfall, and altered weatherpatterns are likely to have adverse impacts on biodiversity, thoughsome few species may benefit depending on their occurrence in theworld. As climate changes, various species are expected to migratefrom their traditional ecosystems to find new locations withfavorable and suitable climatic conditions favorable areas for theirsurvival. It means that, some areas will experience significantreductions in the number of specifies as they migrate to favorableareas. Climate change will also cause the death of many otherspecies, which lack the ability to move. According to Jones,et al. (2009),climate change will result in alterations of timing when speciesbreed, migrate due to winter seasons or food availability, all ofwhich will have significant impacts on their populations. So howmight climate change affect the agricultural ecosystem servicesprovided by bats in the United States?
Researchshows that bat population are tremendously declining worldwide in thelast few decades (Sherwin et al., 2012). Since bats have lowreproductive rates, their populations are highly vulnerable toelevated mortality resulting from negative impacts of climate change.There is a developing concern that if bats are not conserved, many oftheir species will continue to be increasingly affected by humanactivities such as urbanization and ecosystem pollution (Russo &Ancillotto, 2015). As discussed in the previous section of the paper,bats depend on a variety of insects occurring in agriculturalecosystems. Bat species that depend on nectar, pollen, fruits, andflowers are argued to depend on the availability and abundance ofplant resources. Moreover, many bats depend on plants especiallytrees as roosting locations for varying periods of time (Kunz et al.,2011). Climate change has been found to adversely affect thephenology, occurrence, and distribution of plant species. Therefore,it is inevitable that the agricultural ecosystem services provided bybats will also be affected.
Batsare affected by climate change at all stages of their annual cycle(Russo & Ancillotto, 2015). Research by Sherwin et al. (2012)show that changes in temperature may affect hibernation of bats, bothin the accessibility of appropriate locations and behavior, span andtiming of hibernation. When temperature and precipitation change, itnegatively affects the successful breeding of some female bats due tochanges in the availability of prey. Temperature and precipitationare two important factors that affect the occurrence and availabilityof insects, which are the main prey for insectivorous bats. Asdiscussed earlier, insectivorous bats play an important role inagricultural ecosystem by acting as pest and insect control agents.Furthermore, bats acts as pollinators and insect dispersers as wellas agents to redistribute nutrients in agricultural ecosystems.Therefore, when bat population and cycles are affected b climatechange, the services that they offer to the agricultural ecosystemswill either diminish or cease completely.
Accordingto Russo and Ancillotto (2015), climate change may also affect thetype of habitats and insect preys available for bats for foraging,which could have indirect impacts on bat population and consequentlytheir agricultural ecosystem services. The distribution of bats inthe U.S. is expected to change due to climatic changes hence someagricultural ecosystem will enjoy fewer or no benefits offered bybats. Moreover, it is expected that as temperature rises with changesin climate, most of the bat species found in the United States willshift or move northwards or to higher altitudes (Jones,et al,2009).When these bat species reach their northern limit, they are expectedto migrate to other countries with suitable climatic conditions.However, these studies assume that there will be countries withsuitable roosts and habitats and that bat species will successfullymigrate to these new areas (Sherwin ET AL., 2012).
Sherwinet al. (2012) point out that by 2012, there was evidence that a batspecies by the name Nathusius’pipistrelleis already showing some responses to climate change. In the recentyears, studies in this particular species of bat have increased andits expansion in the Northern parts of the United States has beenattributed to climate change. According to Kasso and Balakrishnan(2013), bats are among the most overlooked species despite theirvarious ecological and economic benefits. Therefore, the fact thatclimate change is affecting bat occurrence, distribution, andsurvival means that the various agricultural ecosystem services willdiminish or cease all together not only in the United States but inthe various parts of the world where these animals are found.
Thereare over 1,200 bat species occurring in various parts of the world.Texas and many northern parts of United States are common groundswhere various species of bats seek refuge due to favorable climaticconditions and abundance of food. Many of the bat species in theUnited States are insectivorous hence acts as pest and insect controlagents in agricultural ecosystems. Moreover, many bats feed on nectarand pollen hence aid in the processes of pollination and seeddispersal, which are vital in agricultural ecosystems. However, asthe paper has already discussed, bat populations in the U.S. aredeclining tremendously because of climate change. Changes in climateaffect the abundance and occurrence of insects, which determine theoccurrence of bats. Moreover, changes in climate such as increase intemperature are argued to affect many species of bats forcing them tomigrate to other locations with favorable climatic conditions. It isimportant that the United States stop overlooking bats and find waysto protect these species from negative impacts of climate change tocontinue enjoying the various agricultural benefits offered by theserare animals. However, more research is needed to monitor batpopulation changes in the United States to fully understand how thesespecies and the various services they offer agricultural ecosystemsare impacted by the current and future climate changes.
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