Forestry Work Terminal, Gardening Additionally, Greening Bureau, Beijing , China; 3

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1 Artile Reuing Nutrient Loss Cuse y Thinning: Effets of Four Composts of Forest Thinning Shres on Soil Nutrients n Tree Growth in Semimture Pinus tuliformis Crr., Beijing, Chin Xun Li 1, Huijun Bo 1, Jilei Zhu 1, Jiwei Zhng 2, Jun Hu 3, Fuyong Mu 4 n Lishui Nie 1, * 1 College of Forestry, Beijing Forestry University, Beijing , Chin; @163.om (X.L.); ohuijun@jfu.eu.n (H.B.); zhujilei99@163.om (J.Z.) 2 Forestry Work Terminl, Grening Aitionlly, Greening Bureu, Beijing , Chin; jiweizhng0001@163.om 3 Experimentl Worksttion of Wter Conservtion Forest, Grening Aitionlly, Greening Bureu, Beijing , Chin; wngjing@jfu.eu.n 4 Beitishng Stte Forest Frm, Grening Aitionlly, Greening Bureu, Beijing , Chin; @163.om * Corresponene: nielishui@jfu.eu.n; Tel.: Cittion: Li, X.; Bo, H. J.; Zhu, J. L.; Zhng, J. W.; Hu, J.; Mu, F. Y.; Nie, L. S. Reuing Nutrient Loss Cuse y Thinning: Effets of Four Composts of Forest Thinning Shres on Soil Nutrients n Tree Growth in Semimture Pinus tuliformis Crr., Beijing, Chin. Forests 2022, 13, f Aemi Eitor: Aele Musolo Reeive: 28 Ferury 2022 Aepte: 28 April 2022 Pulishe: 29 April 2022 Pulisher s Note: MDPI stys neutrl with regr to jurisitionl lims in pulishe mps n institutionl ffilitions. Copyright: 2022 y the uthors. Liensee MDPI, Bsel, Switzerln. This rtile is n open ess rtile istriute uner the terms n onitions of the Cretive Commons Attriution (CC BY) liense ( Astrt: Tritionl methos to el with thinning shres (twigs, rk, et.) inlue using them s fuelwoo (rtifiilly tken out of the forest) n stking in situ nturl eompositions (slow eomposition n nutrient return to the fiel). These methos will use the loss of nutrients in the forest, n omposting with itives n effetively promote nutrient irultion effetively. The purpose of our stuy ws to explore the effets of omposts of forest thinning shres with ifferent itives on soil n tree growth in semimture Pinus tuliformis Crr. We selete four omposts of forest thinning shres ( justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P only; : rw mteril grining of thinning shres) n pplie them in the volume of 900 g m 2, whih were me in the erly stge. The soil nutrient ontent, miroil hrteristis, n growing volume of Pinus tuliformis were mesure t 0.5, 1, n 1.5 yers fter fertiliztion. The soil eme i fter one yer of fertiliztion, hving gret impt on the 0 20 m soil lyer. At 0.5 yers of fertiliztion, the totl nitrogen (TN) ontent of the soil with priming ompost () ws 1.5 times higher thn tht of the ontrol group (); the soil orgni mtter (SOM) ws inrese y mg kg 1. After one yer of fertiliztion, the ifferene in the soil miroil ron n nitrogen (MBC n MBN) ontent of eh tretment erese grully. Soil surse tivity ws the highest fter fertiliztion, n ifferent omposts h the gretest impt on urese tivity in the 0 20 m lyer; the lkline phosphtse (AKPse) tivity of soil with ommon ompost () hnge the most, n fter 0.5 yers of fertiliztion, the i phosphtse (APse) tivity of in the two lyers inrese y 0.31 mg g 1 n 0.1 mg g 1, n the inrese in of ws slightly lower thn tht of. There were signifint ifferenes in the numer of teri, fungi, n tinomyetes ompre to n with other tretments. promote the height growth (H) of trees three times higher thn n promote the growth of imeter t rest height (DBH) y 2.5 m. The results showe tht n h ovious effets on promoting soil nutrient ontent, miroil iomss umultion, n forest growth, n the pplition of ompost h no signifint effet on promoting unerstory regenertion. The finings of this stuy show tht using ompost with priming n effetively inrese the soil nutrient ontent, miroil tivity, n quntity of Pinus tuliformis effetively in terms of promoting the growth of trees n reuing the nutrient loss use y thinning. Keywors: ompost; enzymti tivity; miroil popultion; stn volume Forests 2022, 13,

2 Forests 2022, 13, of Introution As n importnt forest mngement mesure, thinning n fertiliztion n effetively improve forest soil fertility, forest qulity, n eologil enefits [1]. Pinus tuliformis Crr. hs the hrteristis of rren resistne n win resistne. It is wiely plnte t n ltitue of m in Chin n is n importnt fforesttion tree speies in northern Chin. Pinus tuliformis nees pproprite fertiliztion in the ontiner seeling n seeling stge to improve the survivl rte n seeling qulity [2]. After rehing the semimture stge, it requires tening n thinning to improve the stn volume n eologil enefits [3,4]. Thinning refers to the regulr n repete utting of some trees in the immture forests (usully inluing twigs, non-trunks, leves, n skins within the sope of the thinning pln, s well s shrus n hers uner the forest) to rete goo environmentl onitions for the retine trees n promote their growth n evelopment. However, oniferous tree speies suh s Pinus tuliformis n Pltylus orientlis (L.) Frno hve low moisture n high mromoleulr ontent suh s oil n lignoellulose [5,6], whih re flmmle n iffiult to eompose; lrge mount of orgni wste proue fter thinning is stke in the forests, whih n not only esily use forest fires n pests, ut is lso very slow in nturl eomposition; the nutrients nnot return to the soil in short time n prtiipte in the nutrient sorption n irultion of soil forests n result in soil nutrient loss [7], thus ffeting the qulity of the forest. Therefore, it is neessry to properly fertilize the semimture Pinus tuliformis plnttion fter thinning in orer to supplement the nutrients in the forest n el with the thinning shres effetively n hrmlessly. At present, the reserh on forest fertiliztion minly fouses on ontiner seeling n seeling fertiliztion [8 10], n only few sholrs hve stuie the fertiliztion of semimture plnttions. The results of stuy in the southestern plin of the Unite Sttes showe tht the semimture lololly pine plnttion h n ovious response to the omintion of nitrogen n phosphorus fertilizer [11]. Sine the 1960s, Chin hs systemtilly stuie the mount, proportion, time, n moe of fertiliztion suitle for Pinus tuliformis systemtilly, s well s isussing the effets of ifferent fertiliztion omintions on the growth of Pinus tuliformis [12,13]. The t showe tht the ovegroun growth n nitrogen lo of Pinus tuliformis seelings inrese with the inrese in fertiliztion [14]; uner high fertilizer level, the seeling height, groun imeter, n single plnt iomss of nnul Pinus tuliformis seelings rehe 1.4, 1.2, n 1.7 times the low fertilizer level, respetively [15]; n eight-yer-ol Pinus tuliformis plnttion with ure n ompoun fertilizer grew signifintly in the first yer, while Pinus tuliformis with hiken mnure (i.e., orgni fertilizer) grew signifintly in the seon yer [16]. However, there re few reports on the response of the semimture Pinus tuliformis forest to fertiliztion fter thinning, whih nees to e stuie n supplemente. Referring to the reuse of green wste, vegetle, n rop orgni wste [17,18], omposting is onsiere to e n effetive wy to tret orgni wste, tht is, orgni wste is trnsforme into stle, hrmless, n nutritious orgni fertilizer y miroil fermenttion through the rtifiil ontrol of wter, C/N rtio, ventiltion, n other onitions [19]. The results showe tht the pplition of ompost h signifint effet on improving soil nutrient ontent n inresing rop yiel: fter the pplition of pig mnure ompost in whet fiel, the inexes of soil totl ron (TC) n totl nitrogen (TN) were signifintly higher thn those in the ontrol tretment (p < 0.05) [20]; the ompost me from green wste ws wiely use s the sustrte for grss n flower plnting [21]; n fter pplying ompost me from whet n rie wste, the iomss of pepper n tomto inrese y pproximtely 25% n the yiel inrese y pproximtely 75% [22]. In ontrst, the pplition of ompost in forestry mostly fouses on improving the mtrix formul of ontiner seelings [23] n the fertiliztion of forest seelings [24]. Some sholrs use Vitex trifoli n ow ung s rw mterils to mke ompost, fining tht it promote the lef re growth of young Pinus tuliformis neeles [25], improve the

3 Forests 2022, 13, of 22 qulity of Pinus tuliformis n Pltylus orientlis seelings, n improve the ontent of soil nutrients [26]. At present, there re no reports on the pplition of ompost me from forest thinning shres pplie to the semimture Pinus tuliformis rtifiil forest fter thinning. In this pper, ifferent types of ompost were me in the forest with the semimture Pinus tuliformis n Pltylus orientlis thinne shres s rw mterils, n then the ompost ws pplie k to the forest. In the 1.5-yer growth yle of Pinus tuliformis, the fertilizer effets of ifferent types of forest thinning ompost in the semimture Pinus tuliformis plnttion ws isusse from the perspetives of soil nutrients, soil miroorgnisms, tree growth, n unerstory regenertion. This pper ims to reue the nutrient loss in the forest fter thinning n effetively el with lrge mount of orgni wste y thinning in orer to promote the nutrient yle in the forest. 2. Mterils n Methos 2.1. Stuy Site Desription Our stuy ws onute t the Beitishng stte forest frm, Huirou Distrit, Beijing, Chin (Figure 1) ( E, N), where the men elevtion is 91 m.s.l. This re is typil wrm temperte humi monsoon limte, with hot n riny summers, ol n ry winters, n short spring n utumn sesons. The verge temperture of yer rnges from 7 C to 19 C, n the men preipittion of yer is 600 to 700 mm; the frost-free perio of the whole yer is 180 to 200 ys, n 80% of the nnul preipittion is onentrte in June to August in the summer. The soil types re rown forest soil lomy n sny soil, with soil thikness of 30 m. The ominnt tree speies re the evergreen onifer Pinus tuliformis with n ge from 20 to 30 yers n semimture Pltylus orientlis, whih re oth wiely istriute in north Chin. The ssoite tree speies re few Ailnthus ltissim (Mill.) Swingle, n Vitex neguno Linn. vr. heterophyll (Frnh.) Reh is the min shru speies. From April to Otoer 2014, thinning mesures were implemente for 806,000 m 3 of forest in the Beitishng stte forest frm, with thinning intensity of 15 18%, resulting in thinning shres of pproximtely 45 t. Figure 1. Lotion of Beitishng stte forest frm, Huirou Distrit, Beijing, Chin.

4 Forests 2022, 13, of Experimentl n Fertiliztion From April to Septemer 2015, the thinning shres of Pinus tuliformis n Pltylus orientlis were use s rw mterils n rushe into 6 m (griner with BC 600XL, VERMEER, Pell, IA, USA). The moisture of ompost rw mterils ws juste to 70%, n ure (Shnghi hoxun Chemil Tehnology Co., Lt., Shnghi, Chin) n imine (64% Totl nutrient, 18% N, 20% P, Shnghi Choxun Chemil Tehnology Co., Lt., Shnghi, Chin) were e to just the C/N to 40 n C/P to 100 (Tle 1). Aoring to whether the rw mterils were juste y C, N, or P, n the itives use, four fertilizers were omposte in situ s four ifferent fertiliztion types in this stuy (Tle 2); together with the ontrol group (CK), 5 types of fertiliztion were forme: : The ompost mterils C/N n C/P were juste, n 0.2% priming ws e. The priming (Bioferment) ws provie y Beijing Golenwy Bio-teh Co., Lt. Beijing, Chin. : The ompost mterils C/N n C/P were juste, n 0.2% ommon ompost ws e. The ommon ompost ws me of Vitex neguno n ow ung using the tritionl omposting metho. : Only the rw mterils C/N n C/P, were juste, without ny itives. : Rw mteril grining of thinning shres, without ny justments n itives. : (CK, short for ontrol hek): ontrol group, no fertiliztion. Tle 1. Chrteristis of thinning shres. Thinning Shres Moisture (%) C/N C/P Totl Nutrient (TN 2 + K2O + P2O5, %) After justment :1 100:1 3.5 Note: 1 The fter justment represents the t hnges in ompost rw mterils, C/N, n C/P, fter eing rushe n juste for moisture; 2 TN represents totl nitrogen. Composts 1 Moisture Content (%) ph Tle 2. Chrteristis of ifferent omposts. Orgni Mtter (%) Totl Nutrient (TN 2 + K2O + P2O5, %) 6 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 7.93 Note: 1 justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; 2 TN represents totl nitrogen; 3 GI represents Germintion Inex. Dt re mens ± stnr error, n = 12. One 24 m 25 m stuy plot ws estlishe in Septemer 2015, whih took ple in ltitue N, longitue E, elevtion 92 m.s.l., n zimuth 88 est y south. The stuy re ws 600 m 2 n ivie into 15 loks of the sme size (Figure 2). There were 54 Pinus tuliformis in totl, with the men H (verge height) of 9.2 m, the men DBH (verge imeter t rest height) of 15.4 m, n the men CD (verge rown imeter) of 3.1 m 3.2 m. ws istriute in the 15 loks rnomly, n eh tretment ws repete 3 times in the plot (Figure 2). From Septemer, fertilizer ws pplie to the soil surfe in the plot. The volume of the fertiliztion ws 900 g m 2, n the fertiliztion metho ws irulr pplition (within 0.5 m of trunk rius), exept for (CK) without ny fertiliztion. C/N GI 3 (%)

5 Forests 2022, 13, of 22 Figure 2. Smple plots showing setting n fertiliztion type istriution. : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. The volume of fertilizer pplie ws 900 g m Dt Colletion Aoring to the 1.5-yer growth yle, soil smples were ollete in Otoer 2015, April 2016, Otoer 2016, n April Soil smples were ollete from 0 20 m n m soil lyers for the mix. One ws rie n sreene to etermine the soil nutrient ontent n enzyme tivity. The other ws store t 4 C to etermine the numer of miroorgnisms in the soil. Tree growth t were ollete in four time perios in the forest. In ition, the regenertion of smll trees n shrus uner the forest ws investigte in Otoer 2016 n April Mesurements of Soil Nutrients The soil ph vlue, totl nitrogen (TN), ville phosphorus (AP), ville potssium (AK), n orgni mtter (SOM) were selete for soil nutrient nlysis. The ph vlue ws mesure using ph meter (FE28, METTLER TOLEDO, Zurih, Switzerln), n orgni mtter ws mesure using H2SO4-K2CrO4 with externl heting [27]. H2SO4- H2O2 igestion ws pplie to TN, AP, n AK, n then they were mesure using Kjelhl nitrogen meter (KDN04A, DECCA, Shenzhen, Chin), spetrophotometry (UV- 5600, FUP, Shnghi, Chin), n flme photometri metho (TD, FUP, Shnghi, Chin) [27] Mesurements of Soil Miroorgnisms Soil miroil iomss ron (MBC) n nitrogen (MBN); urese; invertse; i se phosphtse (AKPse n APse) tivities; n the numer of fungi, teri, n tinomyetes were selete. MBC n MBN were mesure using hloroform fumigtion extrtion (CFE) metho with 0.5 mol L 1 K2SO4 s n extrtnt [28,29]; fter thwing n filtering the extrt, it ws iretly mesure using the TOC nlyzer (Multi N/C 3000, Jen, Germny). Miroil iomss ron (MBC) = EC/KC, n EC represents the ifferene etween the lehe orgni ron of non-fumigte n fumigte ontrol soil; KC is the onversion oeffiient, n the vlue is Miroil iomss nitrogen (MBN) = EN/KN, n EN is the ifferene etween fumigte n non-fumigte ontrol soil minerl nitrogen; KN is the onversion oeffiient, with vlue of Soil urese tivity ws mesure using C6H5ON-NClO olorimetry, invertse tivity ws mesure using 3,5-initrosliyli i (DNS) olorimetry, n the tivities of AKPse n APse were mesure using p-nitrophenyl phosphte (pnpp) olorimetry

6 Forests 2022, 13, of 22 [30,31]. Goshi No.1 gr meium, Mrtin s meium, n eef extrt peptone gr were selete s the ulture mei for tinomyetes, fungi, n teri, respetively. The numer of soil miroorgnisms ws mesure using the grient ilution metho [32]. Three repets were set for eh smple Mesurements of Tree Growth The height (H), imeter t rest height (DBH), n rown with of eh Pinus tuliformis in plots were mesure in four perios. The iniviul volume (1) n unit re volume (2) of Pinus tuliformis were lulte oring to the stnr LY issue y the Ministry of Agriulture of the People s Repuli of Chin. The nme, numer, height, se imeter, n overge of new trees n shrus in the Pinus tuliformis the forest were reore in two perios, n typil regenertion plnts were selete for photo preservtion. Iniviul volume (m 3 ) = D H (1) Unit re volume (m 3 hm 2 ) = Iniviul volume Numer of plnts Plot re (2) 2.7. Dt Anlysis All t mens n stnr evitions of vriles per plot were lulte in Mirosoft Exel (2016 version, Mirosoft Corportion, Remon, WA, USA). Three one-wy ANOVAs were use to etermine in SPSS 20.0 (SPSS 20.0, Shnghi, Chin) for the nlysis, n ifferenes etween mens were ssesse t the level of 0.05 y Dunn s multiple omprison tests to otin the following: The signifint ifferenes mong the soil nutrient ontents in the 0 20 m soil lyer in four perios uner five fertiliztion types; The signifint ifferenes mong the soil nutrient ontents in the m soil lyer in four perios uner five fertiliztion types; The intertion of fertiliztion type n soil lyer on soil nutrient ontent; The signifint ifferenes mong soil miroil ontents in the 0 20 m soil lyer in four perios uner five fertiliztion types; The signifint ifferenes mong soil miroil ontents in the m soil lyer in four perios uner five fertiliztion types; The intertion etween fertiliztion type n soil lyer in soil miroil ontent; The signifint ifferenes in tree growth n volume in four perios uner five fertiliztion types. 3. Results 3.1. Differenes in Soil Nutrient Contents Soil ph, AP, n AK The ph vlue of the two soil lyers experiene proess from i to wek i (Figure 3) within the rnges of the two lyers, n , respetively. h higher ph thn other tretments, n the lowest ph vlue (5.13 n 5.38) ws foun one yer fter fertiliztion oth t 0 20 m n m. The AP ontent in ifferent soil lyers of eh tretment ws foun to e signifint t the 0.05 level. Compre with, the AP ontent of inrese y 47.2 mg kg 1 fter hlf yer of fertiliztion, n y 50.4 mg kg 1 in the 0 20 m soil lyer (Figure 3(1)). In the m lyer, n inrese y 20.4 mg kg 1 n 25.1 mg kg 1 ompre with, respetively (Figure 3(2)).

7 Forests 2022, 13, of (1) 6.5 (2) ph of 0~20 m soil lyer ph of 20~40 m soil lyer AP of 0~20 m soil lyer (mg kg -1 ) e (1) e AP of 20~40 m soil lyer (mg kg -1 ) e (2) 0 0 AK of 0~20 m soil lyer (mg kg -1 ) (1) AK of 20~40 m soil lyer (mg kg -1 ) (2) Figure 3. Soil ph, AP, n AK in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2), (1,2) n (1,2) esrie the ontents of soil ph vlue, ville phosphorus (AP), n ville potssium (AK) t 0 20 m n m, respetively. There ws no signifint ifferene in AK ontent etween n, or n (Figure 3). In the 0 20 m soil lyer, the AK vlue of h smll mplitue n high ontent in the whole perio, while ws stle in the m lyer. After 1.5 yers of fertiliztion, the AK ontent in the 0 20 m soil lyer from high to low ws > > > >. On the sis of our moel, the soil ph, AP, n AK were signifintly ffete y fertilizer. The est result ws foun for the fertilizer, the soil lyer showe the role with

8 Forests 2022, 13, of 22 the lrgest inrese in soil AP, n there ws n intertion etween the soil lyer n fertilizer Soil TN n SOM After hlf yer of fertiliztion, the TN ontent in the 0 20 m soil lyer of ws 1.5 times higher thn tht of, n tht of the m soil lyer ws 1.4 times higher thn tht of (Figure 4). After 1.5 yers of fertiliztion, the ifferene in the soil TN ontent in ifferent soil lyers grully erese, n there ws no signifint ifferene. TN of 0~20 m soil lyer (g kg -1 ) (1) TN of 20~40 m soil lyer (g kg -1 ) (2) SOM of 0~20 m soil lyer (g kg -1 ) e (1) eginning 0.5 yer 1 yer 1.5 yer SOM of 20~40 m soil lyer (g kg -1 ) (2) e eginning 0.5 yer 1 yer 1.5 yer Figure 4. Soil TN n SOM in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2) n (1,2) esrie the ontents of soil totl nitrogen (TN) n orgni mtter (SOM) in the 0 20 m n m soil lyers, respetively. The hnging tren of SOM ontent in ll tretments ws similr, n the ontent of SOM in ws the highest (Figure 4). SOM ontent in the m soil lyer of n ws not signifint fter hlf yer of fertiliztion (Figure 4(2)). Compre with the initil vlue, SOM vlues of the 0 20 m lyer of n inrese y 4.93 g kg 1 n 3.13 g kg 1 fter 1.5 yers of fertiliztion, respetively (Figure 4(1)). At the sme time, the soil SOM of erese to lower thn the initil vlue. In the m lyer, inrese y 6.41 g kg 1, 4.22 g kg 1, n 0.41 g kg 1 fter 1.5 yers, respetively, while n inrese negtively. On the sis of our moel, the soil TN n SOM were signifintly ffete y fertilizer. The est result ws foun for the fertilizer, where the soil lyer showe the role with the lrgest inrese in SOM n there ws n intertion etween the soil lyer n fertilizer.

9 Forests 2022, 13, of Intertion of Fertiliztion Type n Soil Lyer on Soil Nutrient Content The intertion of ifferent fertiliztion types n ifferent soil lyers on soil ph ws not signifint within 1 yer of fertiliztion n rehe very signifint level (0.01) t 1.5 yers of fertiliztion; the intertion etween them showe no signifint ifferene in the umultion of soil TN in the whole fertiliztion yle (Tle 3). The intertion etween the fertiliztion type n soil lyer showe signifint ifferene in soil AP ontent (0.01), while the ifferene in the soil AK ontent ws only signifint fter one yer of fertiliztion (0.05). At 0.5 yers of fertiliztion, the umultion of SOM ontent rehe highly signifint level uner the intertion of fertiliztion type n soil lyer. Tle 3. Intertion of five fertiliztion types n two soil lyers in soil nutrient ontent of Pinus tuliformis. Tretment Lyer 0.5-Yer 1-Yer 1.5-Yer ph ** TN AP ** ** ** AK * SOM ** * The numer represents sig; * represents signifint ifferene t the level of 0.05; ** represents signifint ifferene t the level of Differenes in Soil Miroil Ativity n Contents Soil Miroil Biomss Cron n Nitrogen The soil MBC of n erese rpily fter one-yer fertiliztion, while - h smll mplitue. After hlf yer of fertiliztion, the MBC ontent of ws 1.4 times higher thn tht of in the 0 20 m soil lyer, n the MBC ontent of ws only mg kg 1 (Figure 5(1)). After 1.5 yers of fertiliztion, the MBC ontent of ws two times higher thn tht of, n ws 2.7 times higher thn tht of in the m lyer (Figure 5(2)). MBC of 0~20 m soil lyer (mg kg -1 ) (1) MBC of 20~40 m soil lyer (mg kg -1 ) (2)

10 Forests 2022, 13, of 22 MBN of 0~20 m soil lyer (mg kg -1 ) (1) eginning 0.5 yer 1 yer 1.5 yer MBN of 20~40 m soil lyer (mg kg -1 ) (2) eginning 0.5 yer 1 yer 1.5 yer Figure 5. Soil miroil iomss ron (MBC) n nitrogen (MBN) in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2) n (1,2) esrie the soil miroil iomss ron (MBC) n nitrogen (MBN) in the 0 20 m n m soil lyers, respetively. There ws no signifint ifferene in soil MBN ontent etween n. The ontent of MBN in ws higher thn tht in in the 0 20 m lyer n similr in the m lyer (Figure 5). After 1.5 yers of fertiliztion, there ws no signifint ifferene in, n the orer of tretments ws > > > >. On the sis of our moel, the soil MBC n MBN were signifintly ffete y fertilizer. The est result ws foun for fertilizer, where the soil lyer showe the lrgest inrese in soil MBC, n there ws n intertion etween the soil lyer n fertilizer Soil Urese n Invertse Ativities Soil urese ws negtively orrelte with omposts in the 0 20 m lyer; however, the pplition of ompost h no response to soil urese tivity in the m lyer. The ifferene rnge of n in urese ws mg kg 1, n tht of n ws mg kg 1 (Figure 6(1)). The oeffiient of orreltion ws not foun to e signifint etween n in the m lyer. urese of 0~20 m soil lyer (mg g -1 ) (1) urese of 20~40 m soil lyer (mg g -1 ) (2)

11 Forests 2022, 13, of 22 invertse of 0~20 m soil lyer (mg g -1 ) (1) invertse of 20~40 m soil lyer (mg g -1 ) (2) Figure 6. Soil urese n invertse tivities in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2) n (1,2) esrie the ontents of soil urese n invertse in the 0 20 m n m soil lyers, respetively. In the 0 20 m soil lyer (Figure 6(1)), the soil invertse tivity of ws more stle thn tht of. There ws no signifint ifferene in. In the m soil lyer (Figure 6(2)), the ifferene etween to ws not signifint. The invertse tivity of ws the highest fter 1.5 yers of fertiliztion, n the orer of tretments ws > > > > (Figure 6(1)). On the sis of our moel, the soil urese n invertse were signifintly ffete y fertilizer, with the est result for the fertilizer Soil Phosphtse Ativities The hnging tren of AKPse tivity of in the 0 20 m n m soil lyers ws similr. Compre with 1 yer fter fertiliztion (Figure 7), the AKPse tivity of n inrese slightly fter 1.5 yers of fertiliztion, n showe the lrgest hnge. There ws no signifint ifferene etween n, n the hnging tren of ws stle reltively. AKPse of 0~20 m soil lyer (mg g -1 ) (1) AKPse of 20~40 m soil lyer (mg g -1 ) (2)

12 Forests 2022, 13, of 22 APse of 0~20 m soil lyer (mg g -1 ) (1) eginning 0.5 yer 1 yer 1.5 yer APse of 20~40 m soil lyer (mg g -1 ) (2) eginning 0.5 yer 1 yer 1.5 yer Figure 7. Soil AKPse n APse tivities in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2) n (1,2) esrie the ontents of soil AKPse n APse tivities in the 0 20 m n m soil lyers, respetively. After hlf yer of fertiliztion, the APse tivity of in the 0 20 m soil lyer ws inrese y 0.31 mg kg 1, in the m lyer y 0.1 mg kg 1, n in two soil lyers ws inrese y 0.28 mg kg 1 n 0.07 mg kg 1, respetively (Figure 7). There ws no signifint ifferene in APse tivity etween n. On the sis of our moel, the soil AKPse n APse were signifintly ffete y fertilizer. The est result ws foun for fertilizer, where the soil lyer showe the lrgest inrese in soil APse, n there ws n intertion etween the soil lyer n fertilizer Quntity of Soil Miroorgnisms The h higher quntity of fungi thn other tretments (Figure 8). With the inrese in pplition time, the numer of fungi in erese in the 0 20 m soil lyer rpily n vrie from to (10 4, CFU g 1 ) in the m lyer. After 1.5 yers of fertiliztion, the numer of fungi in ws 2.2 times higher thn tht in in the 0 20 m soil lyer n ws 2.8 times higher thn tht of in the m lyer (Figure 8). The numer of fungi in ws lower thn tht efore fertiliztion. fungi of 0-20 m soil lyer (10 4, CFU g -1 ) (1) fungi of m soil lyer (10 4, CFU g -1 ) (2)

13 Forests 2022, 13, of 22 teri of 0-20 m soil lyer (10 5, CFU g -1 ) (1) teri of 20~40 m soil lyer (10 5, CFU g -1 ) (2) tinomyetes of 0-20 m soil lyer (10 5, CFU g-1) (1) eginning 0.5 yer 1 yer 1.5 yer tinomyetes of m soil lyer (10 5, CFU g-1) (2) eginning 0.5 yer 1 yer 1.5 yer T 1 T 2 T 3 T 4 Figure 8. Quntity of soil fungi, teri, n tinomyetes in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, (1,2), (1,2) n (1,2) esrie the soil fungi, teri, n tinomyetes in the 0 20 m n m soil lyers, respetively. The numer of teri in the soil fter omposting ws the highest, n the hnge in the teri numer ws ovious in the m soil lyer (Figure 8). After 1.5 yers of fertiliztion, the soil teril ontent of ws lose to tht efore fertiliztion, mong whih the ontent ws the highest, with the quntity of (10 5, CFU g 1 ), (105, CFU g 1 ), (10 5, CFU g 1 ), n (10 5, CFU g 1 ), respetively, in the 0 20 m soil lyer. In the 0 20 m soil lyer (Figure 8(1)), h the longest quntity of tinomyetes, n the mximum vlues were (10 5, CFU g 1 ), (10 5, CFU g 1 ), 1.9 (10 5, CFU g 1 ), n 1.3 (10 5, CFU g 1 ), respetively, n the orer of tretments ws > > > > (Figure 8(1)). In the m lyer (Figure 8(2)), the numer of tinomyetes in vrie etween (10 5, CFU g 1 ) n (10 5, CFU g 1 ), n erese most rpily. On the sis of our moel, the soil fungi, teri, n tinomyetes were signifintly ffete y fertilizer. The est result ws foun for fertilizer, where the soil lyer showe the lrgest inrese in soil teri n there ws n intertion etween the soil lyer n fertilizer Intertion etween Fertiliztion Type n Soil Lyer on Soil Miroil Content In the 1.5-yer fertiliztion yle, the intertion of ifferent fertiliztion types n ifferent soil lyers h signifint effet on the umultion of soil miroil iomss (Tle 4). There ws lwys very signifint ifferene in the mount of soil MBC, urese, surse, i phosphtse, n teri (0.01). The ifferene of their intertion in

14 Forests 2022, 13, of 22 the umultion of soil MBN, lkline phosphtse, n tinomyetes erese with the inrese in fertiliztion time, from 0.5 yers of fertiliztion (0.01) to 1.5 yers of fertiliztion; the ifferene in the umultion of soil fungi grully inrese, rehe very signifint ifferene t the time of fertiliztion for 1 yer, n then remine until 1.5 yers. Tle 4. Intertion of five fertiliztion types n two soil lyers in soil miroil ontent of Pinus tuliformis. Tretment Lyer 0.5-Yer 1-Yer 1.5-Yer MBC ** ** ** MBN ** ** Urese ** ** ** Invertse ** ** ** AKPse ** APse ** ** ** Fungi ** ** Bteri ** ** ** Atinomyetes ** ** Note: The numer represents sig; ** represents tht there is signifint ifferene t the level of Differenes in Growth of Pinus tuliformis High Growth of Trees After 1.5 yers of fertiliztion, the ifferene in the mens of tree height growth grully eme signifint (Tle 5). The ifferene etween n ws foun to e signifint t the 0.01 level, n the ifferene etween n ws foun to e signifint t the 0.05 level. The inrement in in the men tree height ws 3 times, 2.5 times, 1.5 times, n 1.5 times higher thn tht of fter 1.5 yers of fertiliztion, respetively. The men DBH inrements in ws 1.7 m, 2.5 m, 1.0 m, 1.5 m, n 1.5 m, respetively (Tle 5). At 0.5 yers of fertiliztion, omposts h the gretest impt on the men growth of tree rowns, n there were ovious ifferenes etween the two iretions. Tle 5. Differenes in height, imeter t rest height, n rown with of Pinus tuliformis. Time Fertilizer Type 1 Men H (m) Men DBH (m) Men CW (m) SN EW 9.3 ± ± ± ± ± ± ± ± 1.1 Beginning 9.1 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± yer 9.2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± yer 9.3 ± ± ± ± ± ± ± ± ± ± ± ± yer 10.5 ± ± ± ± 1.2

15 Forests 2022, 13, of ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.4 Note: 1 : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion; 2 t re represente s signifint ifferenes. Letters represent ifferenes (α = 0.05) Volume of Pinus tuliformis The growth of the iniviul volume of ws signifintly higher thn tht of other tretments. After 1.5 yers of fertiliztion, the inrement in the iniviul volume of ws five times higher thn tht of ; tht of ws 4.6 times, 2.5 times, n 3.5 times higher thn tht of, respetively, n the orer of tretments ws > > > > (Figure 9). The volume per unit re of inrese fster thn in other tretments. In terms of the volume growth per unit re, inrese y 3.6 m 3 hm 2 ; inrese y 5.0 m 3 hm 2 ; n inrese y 3.2 m 3 hm 2, n 1.8 m 3 hm 2, respetively; n the orer of tretments ws > > > > (Figure 9). iniviul volume (m 3 ) () unit re volume (m 3 hm -2 ) () 0.4 eginning 0.5 yer 1 yer 1.5 yer 300 eginning 0.5 yer 1 yer 1.5 yer Figure 9. Iniviul volume n unit re volume of Pinus tuliformis in four perios uner five fertiliztion types. Dt re the men ontent ± stnr evition. Letters represent ifferenes (α = 0.05). : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres; : no fertiliztion. Aitionlly, () n () esrie the iniviul volume n unit re volume, respetively Regenertion of Pinus tuliformis After one yer of fertiliztion, the regenertion in ws ominte y roleve trees suh s Querus mongoli n Ailnthus ltissim (Tle 6). After 1.5 yers of fertiliztion, the speies n quntity of regenertion plnts uner Pltylus orientlis in inrese signifintly n ws minly ompose of Querus mongoli n Vitex neguno; 102 Vitex neguno were newly orn in totl. The se imeter n overge inrese steily in.

16 Forests 2022, 13, of 22 Tle 6. Regenertion of Pinus tuliformis. Time Fertilizer Type * Plnts Numer Men H (m) Men BD Coverge (m) (%) Querus mongoli none yer fter fertiliztion Querus vriilis Querus vriilis Ailnthus ltissim Querus mongoli Vitex neguno Ziziphus juju Vitex neguno Vitex neguno yers fter fertiliztion Querus mongoli Ziziphus juju Vitex neguno Querus vriilis Querus vriilis Vitex neguno Note: * : justment of C/N n C/P + 0.2% priming; : justment of C/N n C/P + 0.2% ommon ompost; : justment of C/N n C/P; : rw mteril grining of thinning shres. 4. Disussion 4.1. Effets of Four Composts of Forest Thinning Shres on Soil Nutrients Soil fertility iretly ffets the growth n evelopment of trees, thus ffeting the qulity of forests. In the 1.5-yer fertiliztion yle, with time, the soil ph showe tren of first eresing n then inresing, whih is onsistent with the previous reserh results [33]. Within one yer of fertiliztion, the soil of eh fertiliztion tretment ws ontinuously iifie n grully eme wek i in yers. This my e euse, in the erly stge of fertiliztion, thinning shres ompost ontinues to relese nitrogen into the soil, resulting in soil iifition; in the lte stge of fertiliztion, with the relese of se ions in thinning shres ompost, soil se sturtion hnges n the ph inreses [34]. In the 0 20 m soil lyer, the iifition egree of thinning shres ompost ( n ) ontining two itives ws less thn tht of other omposte soils; in the m soil lyer, the ph of the soil trete with thinning shres ompost with priming () ws the wekest. This is euse the ility of itive ompost to relese nutrients is more stle n sustinle, n n h little effet on soil ph fter reverse pplition to forest ln. Within one yer fter fertiliztion, TN n SOM in the 0 20 m soil lyer n m soil lyers of,, n were higher thn the ntionl verge level (1.06 n g kg 1 ) [35]; even in 1.5 yers of fertiliztion, the SOM of n in the two soil lyers ws still higher thn the ntionl verge. Fertiliztion n inrese SOM y promoting the formtion of ggregtes lrger thn 2 mm in the soil [34] n n lso use n exittion effet to hnge the turnover rte of nutrients in the soil n inrese the storge of soil nutrients in the Pinus tuliformis plnttion fter thinning. Exogenous nutrients (nturl eomposition of litter, rtifiil fertiliztion, et.) n the wethering of roks re the min soures of ville nutrients in soil [36]. Nutrients relese from thinning shres of ompost n quikly supplement phosphorus n potssium in the soil, n the ontents of AP n AK re minly ffete y the eomposition rte of ompost. The ompost with two itives eomposes rpily uner the tion of miroorgnisms, n the slow-relese pity n e mintine for t lest 1.5 yers, whih gretly llevites the nutrient loss use y thinning.

17 Forests 2022, 13, of 22 With the inrese in the soil lyer, the ontents of TN, AP, AK, n SOM in the soil of the Pinus tuliformis plnttion erese, whih ws onsistent with other reserh results [37]. Within 0.5 yers of fertiliztion, the soil nutrient ontent of umulte rpily n rehe its pek; from 0.5 yers, the soil nutrients of eh tretment erese grully, n the ereses in n were the smllest, initing tht the nutrient relese ility of the thinning shres ompost with itives ws etter thn tht of other omposts, n the omposting effet with priming gent ws the est. Within 1.5 yers of fertiliztion, most of the soil nutrient ontents of,, n were higher thn tht of. Thinning shres of ompost enhne the soil fertility retention ility of the Pinus tuliformis plnttion fter thinning. Compring the two soil lyers, the nutrient ontent of the 0 20 m soil lyer ws higher thn tht of the m soil lyer. This is euse there is less litter in the Pinus tuliformis forest n the forest surfe over is thin, so the soil surfe temperture is high, the wter ontent is low [38], n the miroliving tivities of the lower soil re wekene. In ition, C n N re pprent [39], the sorption of P y soil is strong, the minerliztion of eep soil is loke, n the ownwr migrtion of vrious omponents in the soil is reue. On the sis of our moel, the soil nutrient ontent ws signifintly ffete y fertilizer. The est result ws foun for fertilizers n, where the soil lyer showe the lrgest inrese in soil AP n SOM, n there ws n intertion etween the soil lyer n fertilizer Effets of Four Composts of Forest Thinning Shres on Soil Miroil Biomss Aumultion Soil miroil iomss ron (MBC) ounts for only 1%~3% of soil orgni ron, ut it is key link in the mteril yle n energy flow of the forest eosystem [40]. Within 0.5 yers fter fertiliztion, MBC n MBN in the two soil lyers of eh fertiliztion tretment ontinue to inrese, n the ontents of n were signifintly etter thn those of in 0.5 yers. It n e seen tht ompost provies suffiient nutrition n energy for the survivl n reproution of forest soil miroorgnisms in orer to inrese the soil miroil iomss [41]. Among them, the effet of priming tlyzing the trnsformtion of stey-stte nutrients into ville nutrients in thinning shres ompost is signifintly etter thn tht of other omposts. From 0.5 to 1.5 yers of fertiliztion, MBN ontent erese rpily. There ws no signifint ifferene in MBN ontent etween the two soil lyers fter 1.5 yers of fertiliztion, whih ws minly ue to the high minerliztion rte n lehing of forest soil nitrogen [42]. Soil enzymes re involve in tlyzing series of iohemil retions in the soil n trnsforming orgni mtter into nutrients ville to plnts [43]. After thinning, the soil nutrient ontent n enzyme tivity will eline to ertin extent, n the forest soil will show elining tren [33]. In this stuy, the numer of min soil enzymes inrese signifintly when the omposts of ifferent kins of thinning shres were pplie to the thinning Pinus tuliformis soil, espeilly the omposts with two itives. Soil miroil tivity n iomss umultion were ffete y soil temperture. The soil temperture ereses with the eepening of the soil lyer [44]. On the whole, ompre with the topsoil, the enzyme tivity of the m soil lyer rely hnge fter fertiliztion, n only the thinning shres ompost with priming showe signifint ifferenes in ifferent enzyme tivities. This shows tht soil enzyme tivity hs the sme surfe ggregtion effet s soil nutrients, n urese tivity in shllow soil is higher, whih is onsistent with previous stuies [45,46]. Stuies hve shown tht urese tivity my e ffete y orgni mtter ontent [47], n soil surse is losely relte to soil orgni mtter metolism n nitrogen n phosphorus ontent [48]. The tivities of urese n surse erese grully from 0.5 yers fter the thinning ompost ws pplie to the soil of the thinning Pinus tuliformis plnttion. This ws ue to the nturl loss of nutrients in thinning shres of ompost sore y trees, ouple with the slow nturl eomposition rte of thinning ompost n the reution in ron soures in

18 Forests 2022, 13, of 22 soil. In this stuy, the phosphtse tivity of n tretments flutute in smll rnge in the lte stge of fertiliztion, with rising tren. This my e euse the itives promote the growth n reproution of soil miroorgnisms, inrese the emn for phosphorus, n re more suitle for the growth of phosphtse tivity with the inrese in soil ph. The numer of ulturle miroorgnisms in soil n iretly reflet the miroeologil effet of soil [49]. The results show tht with the inrese in soil epth, the numer of teri, tinomyetes, n fungi ereses, whih is onsistent with the reserh results of sholrs [50]. However, some stuies hve shown tht the numer of teri n tinomyetes inreses with the eepening of the soil lyer, while the numer of fungi ereses [51]. The reson for this ifferene my e tht the types n quntities of exogenous nutrients (litter, fertilizer, et.) re ifferent, n the nutrients n environment tht n e provie for miroorgnisms re lso ifferent. In generl, the numer of teri in the thinning Pinus tuliformis plnttion inrese the most fter pplying thinning shres ompost; the inrement in soil miroil iomss in ws the lrgest mong the omposts of ifferent thinning shres. This my hve een euse in severl ifferent types of ompost, the priming, s n itive, provies the most nutrients for omposting; t the sme time, the tretment hs high moisture ontent n low toxiity (Tle 2), whih provies reltively suitle environment for soil miroorgnisms. Some sholrs hve proven tht itives n hnge the symioti moe of the teril ommunity, n the key teril groups with strong ility to egre ron soures re relte to the inrese in ellulse n urese tivities [52]. The speifi ifferenes in the environment provie y the omposting of ifferent thinning shres for soil miroorgnisms n the hnges in ifferent soil lyers nee to e further stuie. On the sis of our moel, the soil miroil iomss umultion ws signifintly ffete y fertilizer. The est result ws foun for fertilizer ; the soil lyer showe the lrgest inrese in soil MBC, APse, n teri; n there ws n intertion etween the soil lyer n fertilizer Effets of Four Composts of Forest Thinning Shres in the Growth of Pinus tuliformis The DBH, height, n volume of the tree lyer re importnt inexes to evlute the environmentl enefits of the stn. In this stuy, fter pplying ifferent types of thinning shres ompost, the growth inexes suh s tree height, DBH, n rown with of the semimture Pinus tuliformis plnttion fter thinning h no signifint ifferene within 0.5 yers. At this time, the thinning shres ompost is still slowly eomposing n relesing nutrients, n the sorption n utiliztion of nutrients in thinning shres ompost y Pinus tuliformis is still very limite. Some sholrs hve foun tht the meium nitrogen level (10 nmol L 1 ) is the most fvorle for the height growth of Pinus tuliformis, n the high nitrogen level (20 nmol L 1 ) is the most fvorle for the thikening of sl imeter [10]. From 0.5 yers fter fertiliztion, the rown with first showe ifferenes in the growth yle, n the tree height n DBH grully showe signifint ifferenes fter 1 yer of fertiliztion. The results showe tht in the erly stge of fertiliztion, ue to the top vntge, the rown with grew first, while the ron n nitrogen relese y thinning shres ompost s ron soure n nitrogen soures were not enough; with the ontinuous eomposition of thinning shres ompost in the soil, the miroil tivity inrese, the umulte nitrogen in the soil inrese, n the tree height growth n stem growth egn to respon. In this stuy, ompre with other nutrient ontents, the ontent of soil SOM n TN erese less within yers fter fertiliztion, whih n lso e use s eviene. Stn volume is omprehensive refletion of stn verge DBH n verge tree height [53]. After fertiliztion, the volume per plnt n stn volume of the thinning Pinus tuliformis plnttion showe ontinuous growth tren, n the volume per plnt grully showe ifferene etween n from the first 0.5 yers. This shows tht on the sis of the etter growth environment of the Pinus tuliformis forest rought

19 Forests 2022, 13, of 22 out y the initil thinning mesures, the thinning shres ompost ontinuously n slowly relese nutrients, whih ontinues the forest growth use y externl stimultion to ertin extent. Witnin 1.5 yers of fertiliztion, there ws signifint ifferene etween the thinning ompost with two itives n no fertiliztion. It n e seen tht the ompost with itives hs ontinuously positive impt on the single plnt volume n stn volume of Pinus tuliformis forest for t lest 1.5 yers. Resonle forest thinning n not only improve the verge DBH, tree height, n single tree volume of the stn ut lso promote regenertion uner the forest [54]. This is enefiil for soil fertility n enzyme tivity to rely on nturl regenertion fter the ler-utting of the Pinus tuliformis plnttion [33]. In this stuy, y ompring the vegettion renewl sttus in the smple plot when fertilizing for 1 yer n 1.5 yers, it ws foun tht there ws no signifint ifferene in the numer, speies, verge height, verge se imeter, n overge of the regenerte vegettion uner the Pinus tuliformis forest upon pplying ifferent kins of thinning shres ompost ( ), n the renewl sitution of the tretment without fertiliztion () ws etter thn tht of fertiliztion within 1.5 yers. This my hve een euse the mount of fertilizer use in this stuy ws too lrge for unerstory shrus, grsses, n seelings, n the nutrient onentrtion relese y thinning ompost uring the fertilizer effet perio will inhiit unerstory regenertion. On the sis of our moel, the growth of Pinus tuliformis ws signifintly ffete y fertilizer, with the est result for the fertilizers n. Among them, n signifintly promote the growth of tree height, n n promote the growth of tree DBH. 5. Conlusions In this stuy, forest thinning shres were use s rw mterils to mke ifferent types of thinning shres ompost in the forest, n then they were pplie to the thinning semimture Pinus tuliformis plnttion in the sme mount; in the growth yle of 1.5 yers, from the epths of 0 20 m n m, the ifferenes in soil nutrient ontent, soil miroil iomss ron n nitrogen ontent, soil enzyme tivity, soil miroil quntity, forest growth, single plnt volume, n stn volume, s well s unerstory regenertion were isusse in orer to verify the fertilizer effet of ompost of ifferent forest thinning shres. The min onlusions re s follows: (1) The hnge trens of soil nutrient ontent, soil enzyme tivity, n soil miroil iomss were similr fter the reverse pplition of thinning shres ompost to Pinus tuliformis forest ln. It inrese rpily within 0.5 yers fter fertiliztion, n grully erese from 0.5 yers, n the tren of soil ph ws the opposite. (2) All inexes of the 0 20 m soil lyer of the Pinus tuliformis the forest were greter thn those of the m soil lyer. (3) The ompost of eh thinning shres first promote the growth of the Pinus tuliformis nopy fter the reverse pplition of forest ln n signifintly promote the growth of tree height n DBH in the lter stge. (4) The effet of thinning shres ompost on the stn volume of Pinus tuliformis ws greter thn tht on single tree volume. (5) It ws not foun tht thinning shres ompost h positive effet on the unerstory regenertion of the thinning semimture Pinus tuliformis plnttion. In generl, the fertilizer effet of thinning shres ompost with priming ws the est for the thinning semimture Pinus tuliformis plnttion. Author Contriutions: L.N. n X.L. oneive n esigne the experiments; X.L., J.Z. (Jiwei Zhng) n J.H. prtiipte in the isussion of the esign n visite the stuy site; F.M. provie humn support t Beitishng stte forest frm; H.B. n J.Z. (Jilei Zhu) performe the experiments; X.L. ollete smples n nlyze the t; X.L. wrote the pper. All uthors hve re n gree to the pulishe version of the mnusript. Funing: 2015BAD07B00 (2015BAD07B02), the Key Tehnologies R&D Progrm of Chin. Institutionl Review Bor Sttement: Not pplile. Informe Consent Sttement: Not pplile.