This question is too broad. What type of temperate forest?
The European Environment Agency recognized dozens of temperate forest types:
Acidophilous oak and oak‑birch forest types
Mesophytic deciduous forest types
Beech forest types
Mountainous beech forest types
Broadleaved evergreen forest types
Floodplain forest types
Non‑riverine alder, birch or aspen forest types
Community types will experience different patterns and rates of change based on numerous properties including climate, edaphic conditions, stand density, species pools, specific species characteristics, land use history, etc.
See Wright & Fridley (2010)
-Rate at which woody species colonize and dominate old fields decreases significantly with latitude.
Rates of woody succession were highly correlated with both annual temperature...and measures of soil fertility
See Fridley & Wright (2012)
suggest that climate plays a relatively minor role in community dynamics at the onset of secondary succession, and that site edaphic conditions are a stronger determinant of the rate at which ecosystems develop to a woody-dominated state.
See Peet & Christensen (1980)
- Examined thinning rates based on initial stand densities -- found rates to be higher in denser stands and later densities became similar regardless of initial density (after 40 years).
Further compounding all of this are issues such as invasive species, shifts in herbivore pressure, plant pathogens/pests, etc.
Also, it's hard to find European forests w/out some type of historical major human influence.
From Parviainen 2005:
latest estimates show that there are about 0.3 million ha of virgin forest (0.4 % of the total forest area) left in strict forest reserves and other protection areas in the temperate zone of Europe.
So given all of that, it's hard to definitively nail down specifics to answer your question.
- Each of these above characteristics/variables/issues will influence both individual growth rates (i.e., tree diameter and height) as well as population and community dynamics.
To answer your question a little more directly:
As shown in the paper linked above (Peet & Christensen 1980), stand density rates vary dramatically based on initial stand densities and succesional stage; high-density stands can see HUGE loss of stems/ha in < 40 years, while low-density sites might see very little change.
Diameter distributions can change drastically, but will likely take multiple decades to shift to the "late-succesisonal reverse j". However, this is strongly dependent on frequency and magnitude of disturbances -- large canopy-clearing disturbances such as major wind events will accelerate this shift in distribution.
Species composition can certainly shift fairly quickly (1 or 2 decades), but typically only in transitional stages of succession or due to major disturbance. Late-stage successional forests (i.e., "mature forests") will typically see very little change in species composition in this time frame, but again so many facotrs will influence that. Because of changing climates, mass introductions of invasive species (both competitors and pathogens), etc., forests appear to be changing more rapidly. [See Israel (2011)].
Overall, forests change continuously, with most processes occurring on the time-scale of decades. However, this depends on scope b/c understory plants can change from year to year, while canopy trees can live for centuries. Noticeable shifts in community composition and biomass are visible on decadal timescales, but only long-term evaluation will demonstrate the effects of past disturbances. The takeaway, then, is that forests chnage on multipel time scales and as a result of many variables; as a rsult, one can never consider a forest as a static community or as a climax type.
- However, we have more long-term data sets available and numerous advances in sampling methods that are aiding our ability to understand forest change across time scales. So we are just now beginning to truly understand some of the phenomena on a deeper level.
I'd recommend you start with an overview of the topic:
- Fridley, Jason D., and Justin P. Wright. 2012. “Drivers of Secondary Succession Rates across Temperate Latitudes of the Eastern USA: Climate, Soils, and Species Pools.” Oecologia 168 (4): 1069–77. doi:10.1007/s00442-011-2152-4.
- Israel, Kimberly A. 2011. Vegetation change in Duke Forest, 1977 – 2010. University of North Carolina at Chapel Hill Masters Thesis. 120 pp.
- Parviainen, J. (2005). Virgin and natural forests in the temperate zone of Europe. Forest Snow and Landscape Research, 79(1-2), 9-18.
- Peet, Robert K., and Norman L. Christensen. 1980. “Succession: A Population Process.” Vegetatio 43 (1): 131–40.
- van der Maarel, E. & J. Franklin. 2013. Vegetation Ecology, 2nd Edition. Oxford University Press, New York, New York. Pages 28-70.
- Wright, Justin P., and Jason D. Fridley. 2010. “Biogeographic Synthesis of Secondary Succession Rates in Eastern North America.” Journal of Biogeography 37 (8): 1584–96. doi:10.1111/j.1365-2699.2010.02298.x.