Acer rubrum To Zyzyphus jujuba
Essays, Stories, Adventures, Dreams
Chronicles of a Footloose Forester
By Dick Pellek

Pets, Weeds, and Invasive Plants

There are so many ways to think about the animals and plants of this earth that it becomes haltingly tentative for anyone to embark on a meaningful discussion with concise, clear points of view.  Both positive and negative thoughts are pre-packaged and readily available to any age group, to any economic class, in any culture; and regardless of a person’s educational attainment or status in society.  We all have opinions about such mundane things as various plants and animals and those opinions are seldom shaken during the course of our lives.

Firstly, let us briefly discuss the range of opinions regarding animals because animals are easier to understand as living creatures that most people have some personal experience with; and about which their opinions may readily be justified.  One likely entry point of discussion focuses on pets. Most people are fond of dogs and cats.  People who love dogs might overwhelmingly favor them over cats, for reasons that are not always explained. Cat lovers as a group gladly acknowledge their preference over dogs, and are happy to give reasons why.  Plenty of facts can be summoned by either group to support their preferences, but many of the presumed reasons also have to do with their personal opinions about one group or the other.  Facts and opinions abound; and those facts and opinions can readily be listed as either positive or negative.  Overall greater acceptance or rejection of one group over another begins with changing opinions about the animals, not the facts about them.

Being a dog lover or a cat lover usually does not lead to animosity because it is possible to be both—an animal lover.  Animal lovers tend to have a profound level of acceptance for many kinds of animals: rabbits, squirrels, birds, horses; and any manner of wild animals.  Positive attitudes and positive opinions tend to blend into a sense of acceptance of the breathing creatures that share our world.

On the other hand, many if not most animal lovers do not love snakes, spiders, rats, scorpions or other poisonous creatures. The fact of their collective existence is one thing, but the opinions about them are something else. Thus, human beings tend to cozy up to dogs and cats; but tend to shun or kill snakes and spiders.  In a perverse and perhaps subconscious way, they are attempting to manage their local environment to feel more comfortable and secure.  An environment that they go out of their way to foster for their own convenience or pleasure, at least in regard to how they interact with domestic animals that they can control. 

When it comes to plants, humans must also deal with the facts of their existence and their personal opinions regarding what they think are positive attributes about them.  But they also must also cope with what are negative attributes of plants.  As for the positive aspects of plants, some of the issues are fundamental to our very existence.  We grow crops to eat, or to feed other animals that we rely on.  We maintain forest cover as a place that produces fiber for building material and serve as our watersheds. In that sense, we strive to alter our local environment on farms that produce our food; and in forests that produce building materials. Furthermore, we are obliged to change and improve our farms and forests if we are to continue to feed ourselves and sustain key renewable resources.

When it comes to dealing with the world of plants on the farm and in the forest, all of us exhibit one to three traits that evolve from our opinions regarding the importance of plant life.  To have and to grow plants, we must either let it happen, help it happen, and/or make it happen.

In the case of trees and shrubs, we can choose to let it happen because in natural forests the various trees and shrubs found there have prospered on their own for centuries without our direct involvement.  Our presumed forest management policy in natural forests is to let it happen, ostensibly derived from our opinions about plants in natural surroundings.  When our preferences are for tree and shrub species that do not occur there naturally, we can grow them in botanical gardens, orchards, and plantations.  Thus, we make it happen by selecting suitable, adaptable species by transplanting seedlings or growing them from seed. If and when disease threatens to wipe out our plantations or orchards, we can ameliorate the environment by countering the effects of disease, or destruction by fire, wind, or ice.  In that case, we are helping it to happen.

When it comes to growing fruits and vegetables in places where they do not occur naturally, we have no other choice than to make it happen.  Most vegetable crops are annual plants so must be planted every year in order to have a harvest every year.  In the case of fruit trees, we first make it happen by planting in the beginning phase, but help it happen by fertilizing and nurturing the orchards during their formative years.  We are also helping it to happen when we provide irrigation water and fertilizer, as needed.

Weeds, on the other hand, are on the negative side of the ledger of plant life.  The range of our feelings about weeds is as strong as there are categories of weeds.  Some formerly useful plants that escaped into a wild state of plant community existence can legitimately be labeled as weeds.  One simple definition of a weed is a plant that is unwanted.  Thus, the delicious fruit of the guava tree gone wild has become recognized as one the biggest weeds in Hawaiian forests, where it has thrived through seed dispersal by birds that eat the fruit.  Even the commonly cultivated mango has become so abundant in Bangladesh that it is trending toward weediness in the landscape. Foresters in Bangladesh recognize it as one of the most important species currently supplying the timber market.  After mango trees cease to produce fruit, they become weeds in the landscape.

lines of Leucaena plantings on verge of becoming weeds

Some species of plants become weeds if they are not managed in the manner that serves their primary and intended uses.  One of the previously recognized “miracle” trees used in regions of fuelwood shortage became a weed in the landscape when its growth and silvicultural imperatives were overlooked or mismanaged.  Originally used as cattle fodder in Hawaiian pastures and elsewhere, the leguminous Leucaena leucocephala grows fast and provides high protein content when it is cut young.  If left to grow without regular cutting, it grows tall and becomes a large shrub or small tree.  That is one reason why it became a darling in recent years in the agroforestry planting campaigns of fuelwood-short Haiti.  Unfortunately, farmers who used it as a leguminous protein source in small plots; but did not keep up with cutting it back on a regular basis, saw their otherwise subsistent family plots turn into patches of Leucaena shrubs that were difficult to eradicate.  The miracle agroforestry species became a major weed through mismanagement or lack of management. 

Leucaena grows well in the tropical climates of Haiti and elsewhere. Today some 2-5 millon hectares of land in several tropical countries suffer some aspects of its weedy tendencies.  As the young shrubs continue to grow, they can be managed, but if the labor-intensive management does not keep pace, the dense family plots become decidedly weedy.

The fast growing Leucaena that eventually emerges into medium sized trees can, nevertheless, eventually become useful for fuelwood, poles, and light construction timbers—if the former garden patches are thinned and managed for those subsequent purposes. The Footloose Forester recalls seeing one solitary specimen of only a few years of age that was over 10 inches in diameter; and another of about 8 years of age that it was so big that the owner did not have the proper tools to cut it down and transport it elsewhere.

Small patches of Leucaena that were densely planted to produce animal fodder but were abandoned when they grew too woody and unpalatable for animals did not automatically flourish as sources of fuelwood without a conscious plan to thin them frequently, say every few years.  Hundreds of fodder plots stagnated into pencil thin thickets that exhibited both stunted height growth and limited diameter expansion.  At that stage and evermore, the miracle Leucaena became a widespread weed in Haiti.  On the other hand, those few planters who recognized that Leucaena exhibited rapid diameter growth and grew tall in a remarkably short period of years were able to demonstrate that, with scheduled thinning of the plots from an early stage, they could produce a steady supply of fuelwood and building materials from their own lands. Woody plants are, after all, the world’s most readily renewable resources.

What can be said about woody cultivated plants that become weeds can also be said about grasses.  The highly productive Napier Grass (Pennistum pupureum) that is important in the dairy industry can become a noxious weed if it is allowed to escape beyond managed pastures.  Thousands of hectares of otherwise productive farmland in several tropical countries have been supplanted with huge swaths of the menacing foliage that thousands of soldiers have come to know as Elephant Grass.  Like many another escaped plant that originally had useful purposes in mind, Elephant Grass can legitimately be called both a weed and an invasive plant.

Just what should we classify as a weed?  Something that is merely a minor nuisance?  Some otherwise useful plants that escaped their confines to become uncontrollable large colonies? Unmanaged plant communities that are known to be noxious?  Or just plants that have no known useful purposes?