Skip to content
Login Register

#trees

2 public questions tagged with this topic.

Ecosystem Pyramid

In which ecosystem can the pyramid of numbers be inverted?

A forest can display an inverted or spindle-shaped pyramid of numbers because a small number of large trees support many herbivorous insects, birds, epiphytes, and parasites. Counting individuals ignores body size, so one massive producer may sustain thousands of much smaller consumers. Higher predator levels may again contain fewer individuals, creating a spindle profile rather than a simple monotonic inversion. This does not violate energetic constraints: producer biomass and production can still exceed the energy transferred to consumers. Higher trophic levels are often vulnerable because low energy supply produces small populations that are sensitive to habitat fragmentation and environmental variability. Ecological pyramids must be interpreted according to what is measured—individuals, standing dry mass, or energy flux—because these variables need not have the same shape. Standardizing by area and, for rates, by time is essential; otherwise ecosystems of different size, depth, or sampling duration cannot be compared meaningfully. Turnover explains many apparent paradoxes: a small, fast-renewing stock can support a larger consumer stock without reversing the direction of energy transfer.

Ref: Fundamentals of Ecology, Odum & Barrett, 5th Ed., Ch. 3

View Details
Terristial Biomes

In Raunkiaer’s classification, trees and lianas are categorized as:

“Phanerophytes” for in raunkiaer’s classification, trees and lianas are categorized as. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. A biome label describes a broad climatic and structural pattern rather than a single taxonomic assemblage. Similar climates can produce convergent vegetation on different continents even when the species themselves are unrelated. The remaining alternatives—“Chamaephytes”, “Therophytes”, “Hemicryptophytes”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Terrestrial biomes are distinguished primarily by long-term temperature and precipitation regimes, their seasonality, and the vegetation physiognomy those conditions support. Latitude is informative only because it often covaries with climate. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.

Ref: Campbell Biology, Urry et al., 12th Ed., Ch. 52

View Details