Usando especies nativos
PLANTING WITH NATIVE SPECIES
What does it mean to be native?
Every geographic region has its own unique makeup of native plant species. These regions are called ecotones, and are categorized by the predominant type of vegetation found there (see map: http://mapserver.inegi.org.mx/geografia/espanol/estados/chis/agri.cfm?c=444&e=07). Plants native to a particular area are those that have been growing there naturally for a long time before people began traveling long distances and introducing plants from other areas. They have evolved over thousands of years to thrive in a particular climate, adapting to its unique soil, moisture, temperature, rainfall, drought, and frost conditions. They have also evolved to exist in natural balance with the region’s animals, birds, insects, fungi, and diseases, with each component of the ecosystem relying on others for food, shelter, and breeding requirements.
This process of evolving together is called coevolution. An example is the monarch butterfly and milkweed coevolving as plant and pollinator, with both relying on one another to survive. Milkweed is the primary food source for monarchs, which only eat a particular species of milkweed. In fact, the entire life cycle of a monarch revolves around the milkweed plant. Monarchs lay their eggs on its leaves, and the hatched caterpillars eat the leaves for nutrition, gaining protection from bird predators from the toxins in the sap. The caterpillar then pupates on the milkweed plant, and when the pupa emerges as a butterfly, it returns the favor to the milkweed by pollinating it and ensuring its reproduction.
Why are non-native species sometimes problematic?
Non-native species run the potential of becoming invasive species, which pose a serious threat to biodiversity. When a plant is introduced from another region, it establishes itself in its new home and enjoys freedom from natural controls that normally keep it in check. Without competitors or insect pests, and provided the climate is suitable, introduced plants can thrive and multiply, outcompeting and displacing native species. This disrupts the natural balance of local ecosystems, degrading entire plant communities and the wildlife they support. Many invasive plants spread quickly and grow so densely that other species cannot grow, or are crowded out. Invasive aquatic plants can clog waterways, disrupt groundwater flows, and lower water quality. Hybridization can also occur, when flowering invasive species cross with flowering native species, altering the genetic makeup of local plant populations. This is being seen today with transgenic corn crossing with native maize landraces that have been selected for over thousands of years.
Another example of an invasive species in Mexico is the Carrizo (Arundo donax L.), a tall perennial grass from eastern Asia that grows in wet soils, growing densely in sand dunes, wetlands, riparian habitats, and disturbed sites. It was originally introduced into California as a fast-growing (up to 10 cm/day) roofing material and to control erosion, but it quickly spread throughout California and Mexico, competing fiercely with native species for water and crowding them out.
BENEFITS OF PLANTING WITH NATIVE SPECIES
Did you know that many of the plant species that are planted as food or in gardens are not actually native, but introduced from somewhere else? For example, [list some examples of local foods that came from elsewhere]. Many of these plants are cultivated crops that have been selected over many generations to grow rapidly and produce large amounts of food, and then die quickly, only to be re-planted again the next year. However, there are many good reasons to plant native plants in your garden, milpa, or farm.
Because native plants have spent thousands of years adopting to the patterns of rainfall in their particular region, they don’t need any extra watering to survive! If you are planting from seed in a garden, you may need to water your seedling until it becomes established, but after that point it should survive just fine with what nature provides it. This not only saves money and hard work, but helps to conserve natural water sources. Modern farming practices rely on massive amounts of irrigated water, diverting it from streams and rivers, and in return burdening rivers with pesticide and fertilizer-laden runoff. This degrades water quality, and creates shortages of potable drinking water. Communities living on top of mountains, where water begins its course down into valleys after falling as rain or melting as snow, often have no choice other than to drink poor-quality water, or to buy expensive bottled water. Much of this could be avoided if we planted with native plants that didn’t need extra water!
Less work involved:
Apart from requiring less water, native plants offer us many other breaks from the labor-intensive nature of industrial farming. For one, weeds are not such a big problem, because native plants compete well for resources in their natural environments. Native plants know how to take care of themselves, and don’t need people to prune them, prop them up, pollinate them, or protect them from birds, insects, and diseases. In fact, many native plants do work for us, by breaking up the soil with their strong roots and enriching it with fallen leaf matter, and in some cases, fixing nitrogen.
As mentioned above, most of the non-native plants that we have selected to plant as vegetables are fast-growing and high-yielding plants that die after we harvest them. This means that we have to re-plant them every year, which involves a lot of extra work. These are called annual plants. On the other hand, most native plants are perennials, which have a life cycle of several years and produce food or flowers anew each year. In order to live so long, perennials must be more robust than annuals, and often they have longer, stronger root systems that tap nutrients and water deep in the soil. This lets rainwater percolate into the soil, and helps prevent erosion and runoff, improving water quality.
Lifting environmental burdens:
Because native plants are sturdier and have evolved in balance with the natural ecosystem, they do not require additions of synthetic fertilizers, or the protection of chemical pesticides. This lifts a huge weight off of the environment, because pesticides and fertilizers contaminate waterways and sicken or kill many life forms. Planting natives also results in less air pollution, because large amounts of fossil fuels are burned in the process of synthesising, transporting, and applying these chemicals.
Local birds, insects, and animals depend on native plants for food, shelter, and breeding requirements. When native habitats are destroyed to make way for large-scale conventional farms, cattle grazing, and coffee plantations, native wildlife species cannot survive. Their populations begin to shrink, and can get so small that they eventually become altogether extinct. This is happening today with migrating songbirds in the US and Mexico, whose winter habitat is being lost to coffee plantations and other agricultural uses, and whose summer habitat is being destroyed to make way for urban development and monoculture agroforestry.
Native plants also offer a much more diverse habitat than conventional farms. There is structural diversity in that plants range in size, hight, shape,density, and so on, which provides a multitude of habitats for a multitude of wildlife species. There is also a temporal (time) diversity, in that different plants sprout, grow, flower, and fruit at different times throughout the year, providing wildlife with continuous sources of food, flowers, and habitat. What if everything fruited all at one time in September, and the rest of the year there was nothing to eat?
In many cases, it is too late to conserve wildlife habitats, because they have already been chopped down, ploughed under, and paved over to make way for cities and agriculture. But these spaces don’t have to be completely devoid of native plants! Flowering shrubs, trees, and other native plants scattered throughout urban landscapes can provide important points of refuge for birds and butterflies, and might serve as crucial links between fragmented habitats. Including them on patios, in backyards, on rooftops, and throughout farms can help conserve not only native plant species, but the other forms of wildlife that depend on them. Native plants can also be used to restore degraded habitats that are no longer being used by people. Their hardiness and strong roots will help to bring life back to the soil and replenish ecosystem health.
Protecting against invasive species:
Each native plant species is a member of a balanced community that includes other plants, animals, and microorganisms. This natural balance keeps each species in check, allowing it to thrive without taking over and crowding out everything else. For this reason, native species rarely become invasive.
It is important to remember that people have also evolved alongside complex plant and animal systems that differ from region to region. Plants provide the most basic foodstuffs and other resources on which civilizations are founded, and cultures are shaped profoundly by the plant and animal life of their home region. Countless native plant species have been and still are used as food, medicine, clothing, dyestuffs, cordage, building material, and more, and people have developed complex systems of knowledge around them. The importance of maize in mesoamerica can be seen in ancient ruins, and written stories dating back hundreds of years To this day maize remains an important staple in the region’s diet and many important cultural traditions. By conserving native plant species, we can work to keep these traditions and knowledge systems alive, as well as privide a tangible link to the past.
Planting native gardens is a wonderful way to teach other people about the cultural and floral heritage of where you live! Planting a school garden of native plants provides a site for inviting family, friends, community members, and other schools to take a garden tour and learn about the importance of native plants and the benefits of cultivating them. This is especially true of rare native species that many people might not know about, and conservation and education can go hand in hand.