Of the many approaches and technologies available, it is careful, persistent,
on-the-ground monitoring at fixed locations on Earth that can provide reliable
long-term evidence of ecosystem behaviour. This is the focus of the current
chapter. Most notably, on-the-ground measurements can provide information
on subtle changes in species composition, biomass and carbon storage.
Assessment of modest, long-term ecological change can be difficult using
satellites, as signals often saturate at high biomass (e.g. Mitchard et al. 2009),
technologies change, and sensors degrade. Yet, permanent sample plot work
in the tropics has been very sparse and mostly focused on a few well-known
locations, leaving most of the ~10 million square kilometre expanse of the
world’s richest ecosystems unstudied. This is particularly risky given that no
one tropical forest, or small number of studied forests, can be taken as the
mean state of all forests. Site-centric ecology is invariably skewed, since
peculiar local features – such as fragmentation, unusual soil conditions, cyclones
or fires – colour interpretations. In most fields, such as climate change,
it would be an obvious folly to infer the presence or absence of global effects
from records at a few sites, but in ecological science attempts are still
sometimes made to scale results from a few selected locations to draw
conclusions about what the behaviour of the whole biome might be.