low photosynthetic capacity but are occasionally exposed to small light bursts. Passive movements are related to drought, where plants employ passive adaptation like increasing leaf reflectance during high light (by for example producing salt crystals on the leaf surface) or developing air-filled hairs. Developmental movements are slow and irreversible. Chloroplast movement Chloroplast movement is one of the plant adaptations to the changing light at the molecular level. A study suggested that chloroplast movement shared the same photoreceptor with leaf movement as they showed similar action spectra. It is fast adaptation, occurring within minutes but limited as it can only reduced 10–20% of the light absorption during high light. Limitations of chloroplast movement could be the presence of other large organelles like vacuole that restrict the chloroplast passage to the desired side of a cell. On top of that, chloroplast movement might not be efficient as natural light tends to scatter in all directions. Photosystem modulation Photosystem modulation is an example of a long term light adaptation or acclimation that usually occurs on the genetic level; transcriptional, translational and post-translational. Plants grown under high light intensity usually have smaller antenna compared to plants grown under low light. A study found that the acclimative modulation of PSII antenna size only involves the outer light harvesting complexes of PSII (LHC-PSII) caused by the proteolysis of its apoprotein. The response towards higher light took up to two days upon enzyme expression and activation. Reduction of outer LHC-II by half through proteolysis took less than a day once activated. By changing the PS numbers, plant are able to adapt to the changing light of the environment. To compensate for the reduction of the red light usually encountered by the plant grown under canopy, they possessed higher PS-II to PS-I ratio compared to the plant grown under the higher light. However the factors involved in the mechanism are not well understood. Study suggested the protein phosphorylation including LHC-II is an important pathway for signal transduction in light acclimatization. Herbaceous plants In temperate zones, many wildflowers and non-woody plants persist in the closed canopy of a forest by leafing out early in the spring, before the trees leaf out. This is partly possible because the ground tends to be more sheltered and thus the plants are less susceptible to frost, during the period of time when it would still be hazardous for trees to leaf out. As