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Effects of agriculture on terrestrial biodiversity
Due to anthropogenic activities such as agriculture and logging, terrestrial biodiversity
around the world has been declining. It is more prominent in “biodiversity hotspots” which are
rich in biodiversity that are experiencing large amounts of habitat loss (Newbold et al.) The loss
of biodiversity can be traced back to habitat loss, overexploitation, and pollution. (GEO5). These
effects may be amplified by climate change as well as socioeconomic situations of different
countries.
Biodiversity can be understood as the biodiversity of life and its components, like genes,
species, community, and ecosystems (Noss and Cooperrider). Terrestrial biodiversity would refer
to the biodiversity on land. Many logging practices can cause certain changes in the communities
by reducing places to live and hide, changing the age distribution of certain species, and the
number of species and their populations (Venier et al.). By changing the demographics of the
population there could be shifts for the worst. If the young are wiped out, there will not be a next
generation. If the adults are gone, the young may die. Some agriculture methods can be more
damaging than others. In many of the cases in Southeast Asia, a biodiversity hotspot, one of the
largest problems there is the conversion of forests to agricultural land (Wilcove et al.). This
conversion causes major losses in biodiversity. In some studies, there can be a loss of
approximately 75% of bird species (Aratrakorn et al., Peh et al.), and 80% of butterflies (Koh
and Wilcove, Hamer et al., Dumbrell and Hill). By changing the methods of modern agriculture
there is hope. For example, mono-cropping, pesticide use, and fertilizer use, to incorporate
traditional knowledge as well as keeping in mind of the economic drivers of agriculture. Then we
can begin to reduce the stresses we are currently putting on the environment.
Before the exportation of different species of plants and animals around the world,
indigenous peoples of different environments, understood the behaviors of their crops. They have
co-evolved with their food and building sources (Srivastava et al.). They have developed
methods for harvest and management, such as certain cropping patterns to limit pests (Srivastava
et al.). This knowledge can sometimes be lost when plants are taken to new countries with
similar environments to be grown. The crops may also be exposed to new pests which may thrive
on the crop. This could lead to increase pesticide and fertilizer use in the new region since the
knowledge is not there. This could result in a progress trap. The increase of pesticide use can
help pests develop resistances, which would lead to the development of more chemicals and
other short term solutions that could ultimately end up in the environment of surrounding biota.
The chemicals may have negative effects on biota and could cause a decline in animal
populations and even in beneficial insects and microorganisms that could have benefited crops
(Srivastava et al.). This ends up with two stages of biodiversity loss; the initial stage during the
conversion of the land to farm land, then the exposure of agricultural chemicals to the natural
environment.
Along with the loss of indigenous knowledge, there is also the development of
monoculture crops. This farming practice allows farmers to be more productive in a confined
space and untimely make more profit. In areas with increasing population, monocrops seem like
the only solution, but in monoculture crops, there is little species variation compared to the
original unconverted land. Not all animals can survive in the area when their land is converted
into a crop that they do not consume (Srivastava et al.). Organisms are then displaced and have
to move, given they are still alive. Areas that are converted into farm land are not just a small
patch at the edge of a forest. In parts of Southeast Asia alone there has been a 0.1-5.2% loss of
forests cover from 2000-2010 (Wilcove et al.). Considering that the conversion of forests has
occurred before 2000, this relatively recent loss of 0.1-5.2% is a lot. This causes habitat loss and
in some areas habitat fragmentation. This could make it difficult for animals to migrate or reach
a certain resource. The conversion of forests to agricultural land would cause problems for not
only animals in the converted area but also the surrounding environment.
For many modern agricultural practices, like monoculture, the main focus is on the short
term economic gain (Srivastava et al.). There is not much consideration for the native biota, the
care of the soil and surrounding environment due to economic cost. From a traditional economic
stand point, conserving the environment would not be profitable and therefore would not be
pursued. Fertilizers and chemicals would destroy any unwanted pests, are relatively cheap, and
do not involve much as much man power. This progress trap can lead to many environmental
problems in the long term, including degradation of the soil and fertilizer runoff that can further
the loss of biodiversity due to the pollution of water and food sources in the wild. Once humans
realized the role biodiversity plays in the ecosystem services that people rely on, there has been
increased attention to the topic of biodiversity; although not much has resulted from this to date
(GEO5).
Biodiversity can be measured by the Biodiversity Intactness Index (Newbold et al.). The
Biodiversity Intactness Index looks at the average abundance of the original species in the area
of interest, relative to the original average abundance without anthropogenic changes (Newbold
11). The main problem with this measure is the number of species in the area both before and
after anthropogenic changes. It is often difficult to keep track of all species. Data about
biodiversity or even just an inventory of species in the past may not have been recorded in
certain areas or in great detail. There are always new species being discovered as well as species
that are harder to find than others. Surveying methods may also differ depending on the
environment and which part of the world the surveys are conducted in. Scale would be very
important when looking at biodiversity data. If a survey was done in a small area, the data may
be more detailed and accurate, relative to worldwide data. There are also areas with less human
settlement and as a result may lead to less surveying being done.
To look at the change in biodiversity we need to consider the time series data but this has
been difficult; as shown by Hudson et al.’s introduction about the PREDICTS (Predicting
Responses of Ecological Diversity In Changing Terrestrial Systems) project (Hudson et al.).
There is often little geographic and taxonomic coverage in some older databases and they are not
detailed enough. Some only recorded the absence or presence of certain species (Hudson et al.).
Another problem is whether certain species are contributing, harming, or not having an impact
on the environment they are in. Because of the extent of biodiversity on earth, it is very difficult
to have great data. We need to work with what can be collected and hope that the assumptions
made reflect at least part of what may be observed.
There have been more response to the decrease in biodiversity since the start of the
concerns, but little results have been observed (GEO5). There is much discussion about how
humans are destroying biodiversity, but what usually is not discussed is that biodiversity can also
benefit humans. There may be plants in the wild that could contribute economically in the future,
they may not have been discovered or used as a resource just yet (Hudson et al.). Many of the
medicines we have today are derived from plants used by local peoples. They understood the
properties of the plants through knowledge that has been passed down for generations. There is
still the potential to discover new medicines either from uncontacted civilizations, or through the
discovery of new plants. We do not know where the plants could be found, so with the
preservation of habitats, we will have the time to discover new plants. With many advances in
gene technology, positive traits from one species can be taken to benefit others (Hudson et al.).
This could help with crop resistance to certain pests and promote growth. Even without gene
technology, biodiversity in agricultural fields could be increased to benefit the crops. There can
be microorganisms and insects that can be incorporated into agricultural systems. Throughout
history, certain food crops that did not have as large of a market in its original habitat could be
brought to a new place with similar climate and be grown there. For example, mangoes are
originally from tropical Asia but are more commercially grown for the international market in
parts of Latin America (Srivastava et al.).
There is still a decline in worldwide biodiversity. With a decrease in biodiversity, there
will also be a decrease in ecosystem services. These services usually go unnoticed in day to day
life: trees and large forests can sequester large amounts carbon dioxide, insects pollinate crops,
and provide beautiful views and landscapes. With a decrease in these services, there would also
be a decrease in quality of life. A reduction in ecosystem services impact poor regions the most
where communities reply on them more. With fewer infrastructures, there is a greater
dependence on natural systems for necessities like water purification and soil nutrient
cycles.Wilcove et al. ran two models based on the increase of forest conversion from 2000-2010.
The first one, business as usual (BAU), assumed the rates of loss stay the same. This resulted in a
29% median decrease in lowland forest bird species and 24% median lowland forest mammal
extinction. The second model (CONS) assumed that the rates were halved. This model saw a
16% median for birds and 13% median for mammals. Although these medians show a large
difference, the confidence intervals in this study were very large as seen in the figure below.
Nevertheless this study was based on fairly current data and show some truth to what could
happen in the future depending on our actions.
The Strategic Plan for Biodiversity 2011-2010 contains five main goals, containing 20
targets. These goals include mainstreaming biodiversity, promoting sustainable land use,
protecting species and genetic diversity, demonstrate the benefits of ecosystem services,
inclusivity from stakeholders in planning, and management and implementation of certain
strategies (GEO5). The Global Biodiversity Outlook reports on how the world is doing according
to the goals that are in place (GEO5). Currently the goals have not been met, but there have been
some actions taken, showing that with the resources and the will of governments, we could
reduce biodiversity loss (GEO5). The goals that have been set out are very ambitious, but at the
same time, we need to act on this quickly so we can stop the extinction of species. The faster
these goals and target are met, the better the environment and the lives of all organisms will be.
There are many responses that can help slow down or even lower terrestrial biodiversity
loss. We can develop new policies but we also need to look at the ecosystem as a whole and
understand the impact our industries have on life on earth. Agriculture to some extent needs
biodiversity. With the gene modification technologies that we have now, and the potential for
more development in the future we can make crops more efficient, and have certain resistances
to pests. Without the variety of genes available in wild populations, there may be one gene that
could change agriculture as we know it, but would die off with the species due to our current
agricultural practices. With the help of biodiversity, we may also be able to reduce the amount of
fertilizers and pesticides used. We can use a variety of microorganisms to restore soil nutrients
and small birds or insects to control pest populations. We need to keep these options in mind
when thinking about sustainable agriculture. This will help to decrease the amount of toxic
chemicals in the environment and reduce the number of species affected by agricultural
chemicals. This is one way of using biodiversity to protect biodiversity.
There are also other forms of ecoagriculture. Current agriculture practices can displace
local plants and animals and fragments ecosystems. This not only affects biota, but also the
ecosystem services they provide. This could severely impact agriculture. For example, if rivers
were feeding and purifying a water source that local farmers used, a dying off in plants and
microorganisms contributing to purification would result in a need for farmers to filter water
before use. Ecoagriculture would consider biodiversity conservation as well as keeping in mind
that farmers still need to be able to use and develop agricultural land. Crop rotation is one
method that can be used to increase crop yields as well as conserving biodiversity and the
wellbeing of biota in general. Different types of crops may need different nutrients from the soil.
Some plants, like certain legumes, may even contribute nutrients to the soil. This leads to less
soil degradation, lowered fertilizer use, and less fertilizers polluting the surrounding
environment.
Sometimes there can be premiums that come with agricultural practices that conserve
biodiversity. This could allow companies to change the ways they farm and cover any losses that
may come with a more environmental form of agriculture (Wilcove et al.). One form of
monocrops could be plantations. In cases in Sundaland, there has been the disappearance of 15
out of 16 IUCN Red-listed species, mainly due to rubber plantations. There is evidence that
“jungle rubber”, rubber harvested from the understory of secondary forests is not as damaging as
the plantation method (Wilcove 21). When people are told that a certain method of harvest or
farming occurred that is environmentally friendly, they may choose to purchase this product
instead, even if there is a premium to be paid. To jump start this shift there could be government
subsidies to help companies use more ecofriendly methods. If this shift in consumption occurs,
there may be more consumer demand for ecofriendly materials which could lead to a change in
the entire industry.
With biodiversity conservation, as with many environmental problems, we need to keep
in mind the stakeholders. We need to find a compromise between stakeholders where everyone
would be satisfied to some extent. This could be done with the development of new genetic
technologies and a shift from the view that agriculture and the environment cannot work together
to solve biodiversity loss while keeping the economics steady. We need to start seeing
biodiversity and agriculture as interconnected fields that are able to positively impact each other.
Only with a shift in these views, can the real problem solving begin.
References
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conversion of lowland forest to oil palm and rubber plantations in southern Thailand. Bird
Conservation International, 16(1), 71-82.
Dumbrell, A.J., Hill, J.K. (2005). Impacts of selective logging on canopy and ground
assemblages of tropical forest butterflies: Implications for sampling. Biological Conservation,
125(1), 123-131.
Hamer, K.C., Hill, J.K., Benedick, S., Mustaffa, N., Sherratt, T.N., Maryati, M., Chey, V.K.
(2003). Ecology of Butterflies in Natural and Selectively Logged Forests of Northern Borneo:
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