## 3 Results
### Synergistic Effects of Thinning and Climate on Forest Growth  
Examining the relationship between tree growth and environmental and management practices is a crucial aspect of the advancement of precision forestry. In the young forest stage, stand density is generally higher. Thinning reduces competition among trees for nutrient space and resource constraints on tree growth. Based on the 3 PG-MT-LSTM model proposed in this paper, we performed long-term predictions of Norway spruce biomass at the Bily Kriz site. The results showed that, when using the identical thinning strategy, SSP5-8.5's simulation of Norway spruce had the highest overall biomass and single-tree diameter. After combining the differences between different climate scenarios in Section 3.3, we can conclude that solar radiation and temperature are the most important driving variables for Norway spruce growth without considering the impact of extreme climates. This agrees with conclusions from earlier studies examining the environmental factors that influence spruce growth [68; 69; 70]. The observed variations in DBH and biomass across different scenarios indicate that the beneficial impact of forest management is particularly pronounced in warmer climates. The differences observed in SSP5-8.5 compared to other scenarios have evidenced that the Norway spruce species exhibits favorable ecological adaptability and thrives in areas with abundant sunlight and moderate humidity levels. The Norway spruce species can tolerate a variety of environmental conditions but prefers a climate with moderate humidity and lots of sunlight [71]. Temperature and solar radiation will exponentially increase after the 2070s, according to the SSP5-8.5 climate change scenario (Figure 11). The amount of precipitation exhibited a further decrease. As a result, in the SSP5-8.5 scenario, Norway spruce growth continued to increase. But compared to other situations, the growth rate was lower. Different thinning intensities and intervals had a substantial impact on stand growth, in addition to climate change. The regimes taken during the young-aged forest stage for thinning played a decisive role in the growth of the stand's average diameter at breast height. For even-aged spruce forests, we used low thinning to reduce stand density and intra-stand competition. Under the low-thinning method, the heavy thinning of stands in young forests is conducive to the production of large-diameter timber. On this basis, further light thinning of stands in the middle-aged forest stage can increase the growth potential of stand diameter at breast height. Over time, the growth rate of a single tree in the light-to-moderate thinning stand slowed down significantly (at the same time interval, the average increase in diameter at breast height decreased). This is due to the limitations of light resources and soil resources [72]. Managers can improve ventilation and light conditions in the forest at this time by pruning branches and increasing forest gaps. In the thinning stage, there was an inverse relationship between thinning intensity and stand biomass. The higher the thinning intensity, the smaller the stand number and remaining biomass. This is consistent with the findings of [PERSON] and [PERSON] [73]. After thinning, the stand entered a rapid growth period. In Section 3.3, we found that the growth rate of biomass in moderate- and heavy-thinning forests is much higher than that of light-thinning forests. In 2100, the biomass of moderate-thinning stands was the highest compared with other thinning regimes. This is a consequence of the regulation of multiple conditions, such as the total number of trees, soil resources, and competition within the forest. [PERSON] et al. examined the effects of different thinning intensities and intervals on the biomass growth of a 75-year-old Norway spruce stand [13]. They found that light thinning applied at longer intervals (greater than 25 years) resulted in higher stand biomass.