Logging has many negative affects, but it is necessary.
It can change the rainforest’s levels of light, erosion, temperature, nutrients,
and vulnerability to fire.
RIL logging is a way to try to limit the damage cause in conventional logging
by taking some key precautions:
1. inventory and mapping to reduce waste during logging
2. planning of roads, log decks, and skid trails to minimize ground
disturbance
3. vine cutting one year prior to harvest to eliminate damage to
neighbors of harvest trees
4. planned directional felling and bucking to minimize damage to
future harvests and reduce waste (hurting neighboring trees is one of the
biggest causes of gaps in the canopy)
5. planned extraction to minimize equipment
time during skidding
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Generally, RIL works to really have the lowest impact on the rainforest.
They take the trees they really do need in a clearly planned way and try
to minimize the disturbance that goes into cutting down the huge trees and
transporting them out of the rainforest. (Either way, it’s not just starting
at the edge of the rainforest and cutting straight through, only certain
species are marketable and the roads that are created to harvest several different
individuals of those species are causing a lot of the damage).
In the study, they found that by comparing RIL logged blocks and conventionally
logged blocks of forest, in proportion to the area, the conventionally logged
blocks had twice as much ground damage.
They used a “gap fraction” to measure the damage to the rainforest during
logging. This is the amount of canopy opening caused by felling the trees
and clearing roads etc.
Genetic diversity
With the amount of logging going on the rainforest, a big concern has
been the possible loss of genetic diversity in trees and other flora and
even fauna. However, in this paper, it is made clear that the complex methods
of genetic analysis are too hard to keep up. Instead, we can use other easier
methods in our common practice that should make sure that the loss of genetic
diversity isn’t a big problem.
They argue that in climax, shade tolerant species, the trees big enough
to be over the minimum diameter limit for logging make up only a small
part of the overall population. In those species, there are always a large
number of juveniles carrying the majority of the genetic make up which
can take over for the larger trees when those are felled. However, in those
species that are highly light seeking, there will only be a few juvenile
trees while most are much taller because competing for sunlight requires
that of them. If this happens, it might not be as possible for those populations
to come back because they won’t be as easily replaced.
Things that could cause loss of genetic diversity:
1. population bottlenecks/genetic drift –losing alleles
2. dysgenic selection –only logging the best specimens, leaving less
desirable ones
3. disrupt reproduction/mating systems –increasing distances, inbreeding,
messing up pollinators, etc.
There are actually not that many problems with inbreeding and such because
a lot of tropical trees are self incompatible. And as for the increased
distance, if there are a variety of animal pollinators, those often travel
long distances.
A method of reducing the effects of logging on the populations of light
seeking trees is to “lift” the canopy before hand… to let light in so that
a large number of saplings will get started. Or you can time to logging
to come right after a fruiting event when there should also be a lot of
seedlings.
The paper points out that pioneer species produce a lot of seeds but
have low survival and climax species produce fewer but have higher survival.
Basic population marks should be made known and other decreasing factors
of breeding population such as overlapping generations, etc. should be taken
into account. Also to avoid many of these problems, we can try to lower the
minimum size requirement for logging.
