Types of competiton in a bamboo stand
Posted: Tue Jan 14, 2014 2:07 pm
Dear bamboo friends,
You may be interested in my theoretical considerations about competition in a bamboo stand. Comments and first hand reports are welcome.
Regards,
Raimund
Reduction of intraspecific competition in "moso" bamboo forests of South China?
The "moso" bamboo species can be very invasive in South China and even suppress other forest vegetation. "Moso" takes advantage over trees, when it comes to interspecific competition, meaning the competition among different species. But "moso" plants also compete with each other. In this case the term intraspecific competition is used.
When the intraspecific competition is stronger than the interspecific competition, the expansion capacities of invasive species should be consequently reduced. Therefore it is important to understand how invasive species are able to lower the intraspecific competition to a point, where individual plants will not weaken each other too much.
A new research in this field was just published¹. With the aid of sophisticated statistical methods, four groups of bamboo culms, with different ages, were studied and it was concluded, that younger culms were found more frequently in the neighborhood of trees (interspecific competition) than of older culms (intraspecific competition). According to this study, the strategy bamboo plants use to reduce intraspecific competition consists in maintaining distance from each other, but at the same time advancing against trees.
This research certainly deserves much credit, because of all the statistical methods employed, but from a biological perspective, several questions remain unaddressed. It is confusing, for instance, that the study always mentions bamboo plants of different ages, when in fact only culms of different ages were considered.
The careful distinction of terms between "bamboo plants" and "bamboo culms" is of importance, because otherwise it's impossible to distinguish between intraspecific competition and the competition of the culms of one individual plant. It's certainly reasonable to suppose, in relation to competition of culms of an individual plant, that in the course of evolution the ideal distance between culms has been developed. And that has nothing to do with intraspecific competition and could be regulated by the bamboo plant in the same way as trees regulate the ideal distance between their branches and leaves.
Unfortunately we have no possibility to find out, with justifiable resources, how many individual plants constitute a bamboo plantation. If it turned out, in the study case, to involve only a few large individual plants advancing against the trees, then the result of the statistical calculations would not have shown us the reduction of intraspecific competition, but rather only the big average distance between culms, characteristic for "moso" plants.
The study doesn't mention, how the supposed bigger distance between culms of different bamboo plants would be regulated. It may be worth to have a look on a plant native to North America called "pale jewelweed" (Impatiens pallida). This weed behaves altruistically towards kin, avoiding any attempt to overgrow them. The recognition of related plants happens through the rootsystem². It may be possible, that also in the case of "moso" bamboo a reduction of intraspecific competition occurs through altruism towards closely related plants or even genetically identical bamboo plants. Considering evolutionary biology this would make sense, because when a plant cares for the survival of kin, it passes on to the next generation a large number of its "own" genes, not only through the direct descendants, but also through the descendants of their relatives. So, a lot of items remain to be studied.
As bamboo gardeners, we are constantly dealing with the three phenomena: interspecific competition, intraspecific competition and culm competition of the same plant. According to some testimonials in the forum of EBS - Germany, culm competition and intraspecific competition, which occur in the unnatural environment of a rhizome barrier, can be so severe as to compromise the vitality of the whole plantation.
Even planting only one single plantlet inside a barrier, to avoid a clogging with rhizomes before the dreamed large culms sprout, sooner or later the intraspecific competition will occur. The bamboo plant can decay into competing individual plants, caused by dying of old rhizome connections or by damages caused by winter, root voles or the actions of the gardener.
One can interfere in different ways into the so established intraspecific competition relations between plant fragments. A gardener would prefer to spare the larger culms and eliminate the thinner ones. As a consequence, smaller fragments with thinner culms would enter a downward spiral and would disappear sometime from the rhizome barrier. So the tendency of the plantation to decay into fragments would meet the opposing tendency to remain only one fragment.
For bamboo farmers the situation looks different. Also a "moso" grove in its natural environment will decay into fragments, caused by dying of old rhizome connections. But in this case the larger culms would be removed on a regular basis to be used. Supposing, that larger culms are produced in the larger fragments, the intraspecific competition in relation to smaller fragments would be reduced, resulting in the survival of a large number of smaller individual plants. Since we don't know of how many individual plants a bamboo forest is composed of, one can't judge if such a dynamic could lead to a yield reduction for larger culms.
As a gardener, one has to deal with interspecific competition, for instance, in the case of planting together, inside a common barrier, two different bamboo species or a ground cover plant and a bamboo. Two species of Phyllostachys have supposedly very similar environmental requirements. They occupy the same ecological niche and therefore they compete even more. In many cases the gardener will have to act in a regulating manner, to avoid that the weaker species is eliminated inside the barrier. On the other hand, a ground cover plant and a Phyllostachys occupy quite different ecological niches. This reduces the interspecific competition and there are good chances to find a suitable ground cover plant to coexist with a Phyllostachys, provided that sufficient light reaches the ground.
Original title:
DÜKING, R.: Minderung der innerartlichen Konkurrenz in südchinesischen Mosobeständen? Bambus Journal, Ausgabe 4/2013, 24. Jahrgang, S. 18-19
Translation: Hans-Jürgen Kleine, Florianopolis
References:
1. H.S. Sandhu, P. Shi, Q. Yang: Intraspecific spatial niche differentiation: Evidence from Phyllostachys edulis. Acta Ecologica Sinica, Volume 33, Issue 5, October 2013, Pages 287-292
2. Murphy et al. Kin recognition: Competition and cooperation in Impatiens (Balsaminaceae). American Journal of Botany, 2009; 96 (11): 1990
You may be interested in my theoretical considerations about competition in a bamboo stand. Comments and first hand reports are welcome.
Regards,
Raimund
Reduction of intraspecific competition in "moso" bamboo forests of South China?
The "moso" bamboo species can be very invasive in South China and even suppress other forest vegetation. "Moso" takes advantage over trees, when it comes to interspecific competition, meaning the competition among different species. But "moso" plants also compete with each other. In this case the term intraspecific competition is used.
When the intraspecific competition is stronger than the interspecific competition, the expansion capacities of invasive species should be consequently reduced. Therefore it is important to understand how invasive species are able to lower the intraspecific competition to a point, where individual plants will not weaken each other too much.
A new research in this field was just published¹. With the aid of sophisticated statistical methods, four groups of bamboo culms, with different ages, were studied and it was concluded, that younger culms were found more frequently in the neighborhood of trees (interspecific competition) than of older culms (intraspecific competition). According to this study, the strategy bamboo plants use to reduce intraspecific competition consists in maintaining distance from each other, but at the same time advancing against trees.
This research certainly deserves much credit, because of all the statistical methods employed, but from a biological perspective, several questions remain unaddressed. It is confusing, for instance, that the study always mentions bamboo plants of different ages, when in fact only culms of different ages were considered.
The careful distinction of terms between "bamboo plants" and "bamboo culms" is of importance, because otherwise it's impossible to distinguish between intraspecific competition and the competition of the culms of one individual plant. It's certainly reasonable to suppose, in relation to competition of culms of an individual plant, that in the course of evolution the ideal distance between culms has been developed. And that has nothing to do with intraspecific competition and could be regulated by the bamboo plant in the same way as trees regulate the ideal distance between their branches and leaves.
Unfortunately we have no possibility to find out, with justifiable resources, how many individual plants constitute a bamboo plantation. If it turned out, in the study case, to involve only a few large individual plants advancing against the trees, then the result of the statistical calculations would not have shown us the reduction of intraspecific competition, but rather only the big average distance between culms, characteristic for "moso" plants.
The study doesn't mention, how the supposed bigger distance between culms of different bamboo plants would be regulated. It may be worth to have a look on a plant native to North America called "pale jewelweed" (Impatiens pallida). This weed behaves altruistically towards kin, avoiding any attempt to overgrow them. The recognition of related plants happens through the rootsystem². It may be possible, that also in the case of "moso" bamboo a reduction of intraspecific competition occurs through altruism towards closely related plants or even genetically identical bamboo plants. Considering evolutionary biology this would make sense, because when a plant cares for the survival of kin, it passes on to the next generation a large number of its "own" genes, not only through the direct descendants, but also through the descendants of their relatives. So, a lot of items remain to be studied.
As bamboo gardeners, we are constantly dealing with the three phenomena: interspecific competition, intraspecific competition and culm competition of the same plant. According to some testimonials in the forum of EBS - Germany, culm competition and intraspecific competition, which occur in the unnatural environment of a rhizome barrier, can be so severe as to compromise the vitality of the whole plantation.
Even planting only one single plantlet inside a barrier, to avoid a clogging with rhizomes before the dreamed large culms sprout, sooner or later the intraspecific competition will occur. The bamboo plant can decay into competing individual plants, caused by dying of old rhizome connections or by damages caused by winter, root voles or the actions of the gardener.
One can interfere in different ways into the so established intraspecific competition relations between plant fragments. A gardener would prefer to spare the larger culms and eliminate the thinner ones. As a consequence, smaller fragments with thinner culms would enter a downward spiral and would disappear sometime from the rhizome barrier. So the tendency of the plantation to decay into fragments would meet the opposing tendency to remain only one fragment.
For bamboo farmers the situation looks different. Also a "moso" grove in its natural environment will decay into fragments, caused by dying of old rhizome connections. But in this case the larger culms would be removed on a regular basis to be used. Supposing, that larger culms are produced in the larger fragments, the intraspecific competition in relation to smaller fragments would be reduced, resulting in the survival of a large number of smaller individual plants. Since we don't know of how many individual plants a bamboo forest is composed of, one can't judge if such a dynamic could lead to a yield reduction for larger culms.
As a gardener, one has to deal with interspecific competition, for instance, in the case of planting together, inside a common barrier, two different bamboo species or a ground cover plant and a bamboo. Two species of Phyllostachys have supposedly very similar environmental requirements. They occupy the same ecological niche and therefore they compete even more. In many cases the gardener will have to act in a regulating manner, to avoid that the weaker species is eliminated inside the barrier. On the other hand, a ground cover plant and a Phyllostachys occupy quite different ecological niches. This reduces the interspecific competition and there are good chances to find a suitable ground cover plant to coexist with a Phyllostachys, provided that sufficient light reaches the ground.
Original title:
DÜKING, R.: Minderung der innerartlichen Konkurrenz in südchinesischen Mosobeständen? Bambus Journal, Ausgabe 4/2013, 24. Jahrgang, S. 18-19
Translation: Hans-Jürgen Kleine, Florianopolis
References:
1. H.S. Sandhu, P. Shi, Q. Yang: Intraspecific spatial niche differentiation: Evidence from Phyllostachys edulis. Acta Ecologica Sinica, Volume 33, Issue 5, October 2013, Pages 287-292
2. Murphy et al. Kin recognition: Competition and cooperation in Impatiens (Balsaminaceae). American Journal of Botany, 2009; 96 (11): 1990