The main difference between small, controlled lab experiments and ecosystem-scale experiments is primarily the applicability of the results.
In a controlled lab setting, conditions can be tightly regulated, allowing researchers to isolate specific variables to understand their effects. However, results from such experiments may not fully translate to real-world ecosystems due to the complexity and variability present in natural environments. In contrast, ecosystem-scale experiments incorporate the complexities and interactions of various biotic and abiotic factors, making their findings more applicable to real-world situations, albeit with potentially fewer controls over individual variables.