To study the response difference of forest soil aggregate enzyme activity to nitrogen deposition and the influencing factors of aggregate enzyme activity

[JP2

]

taking the alpine P. yunnanensis forest and P. armandii[JP

]

forest in Central Asia of Yunnan Province as the research object

the field simulated nitrogen deposition test was conducted from June 2020 to May 2021. The settings were: control [CK

0 g/(m

2

·a)N

]

low nitrogen [LN

10 g/(m

2

·a)N

]

[JP2

]

medium nitrog

en [MN

20 g/(m

2

·a)N

]

and high nitrogen [HN

25 g/(m

2

·a)N

]

. The[JP

]

soil samples in dry season (February 2021) and rainy season (August 2020) were collected respectively. The variation characteristics of urease(Vre)

invertase(Inv) and acid phosphatase(AP) in soil aggregates and their interaction with environmental factors were analyzed to clarify the response characteristics of soil aggregate enzyme activity to nitrogen deposition under different screening methods. The results showed that: (1) Nitrogen deposition had no significant effect on the distribution of soil aggregates under the two stands

but different screening methods had significant effects; The activities of three enzymes in soil aggregates were promoted by LN and inhibited by MN and HN under different nitrogen deposition levels; (2) Compared with the dry sieving method

the enzyme activity in soil aggregates decreased significantly under the wet sieving method. The decline of enzyme activity in Inv and Ure aggregates was more than 20%

and the decline of AP was the highest

up to 57.55%; (3) The geometric mean GMea of soil dry sieve and wet sieve aggregate enzyme activity was higher than that of mixed soil

and the GMea under dry sieve condition was the highest

with an average increase of 50.35% compared with that under wet sieve condition. The stand among different factors had the greatest impact on Inv

while season had the greatest impact on Ure and AP. In conclusion

soil aggregates can isolate and protect soil enzyme activity. At the same time

the protection effect is jointly affected by season

stand type

screening method

and nitrogen application level. The research results provide a theoretical basis for the soil ecological process of regional forest ecosystem under nitrogen deposition and maintaining the stability of soil ecosystem.