Effects of thinning on soil carbon storage in Pinus ... · Effects of thinning on soil carbon...
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Effects of thinning on soil carbon storage in Pinus laricio forest Muscolo Adele, Settineri G., Mallamaci C., Attinà E., Sidari M. Forests act as a natural storage for carbon at the global scale, contributing approximately 80% of terrestrial aboveground, and 40% of terrestrial below-ground carbon storage. The relatively rapid change in the status of forests– from a steady state of minimal CO2 emission/sequestration to major CO2 emitter – during this time period may offer a cautionary tale of how quickly the source/sink status of large-scale forest C stocks can change. Our understanding of how forest management influences standing C stocks, however, is limited because many forest C studies have focused on quantifying trends in unmanaged forests. Among silvicultural practices, thinning, reducing tree density and altering microclimate and organic matter budget can affect soil carbon (C) storage and soil ecosystem functioning. In Italy, thinning of pine forests is the most effective silvicultural treatment to enhance the ecological value of these stands; however, changes in soil C, soil microbial biomass and activity after thinning in pine forests are not well elucidated yet. Our objectives were to understand how thinning affects the dynamics of total carbon in forest ecosystems as well as each of its component pools. We estimated carbon stocks in Pinus laricio stands, evaluating carbon pool dynamics in forest subject to different thinning intensities (0, 30 and 60%) and clear cut over two contrasting seasons (winter and summer), to verify if the environmental conditions affect in short term soil carbon pool. Our aim was to identify the silvicultural practice that increased carbon storage in pinus forest. Our hypothesis-driven research was that increasing thinning intensities physico- chemical, microbiological and biochemical properties of soil related to soil quality and fertility decreased, while improving stand stability, quality, diameter and growth volume of the remaining stand. Results showed that soil carbon content and C/N ratio were significantly higher in T60 than in T0, T30 and CC. Under T60, the soils had the highest enzymatic activities, MBC, and colonies of fungi and bacteria (Tables 1, 2). 60% thinning having lower density of trees compared to control and higher ones compared to CC and T30, determined regimes of light, temperature and humidity at soil level that increased the amount and diversity of herbaceous vegetation, promoting an increase in overall soil microbial biomass, and in bacteria responsible for the production of enzymes involved in carbon transformation. Humification indices confirmed that humification process prevailed in T60 with consequent carbon storage (Table 3). Additionally, dendro-auxometric parameters evidenced that pinus accretion and wood density changed with the treatments. H/D ratio in 60% thinning was lower than in 30% thinning and control suggesting that the positive effect of 60% thinning on the mechanical stability of the trees is related to their ability to accumulate large amounts of carbon in their wood (data not shown). This study shows that T60 is a sustainable forest management practice able to improve in parallel soil quality and C storage already after few years of treatments. In short we found that 60% thinning was the silvicultural practice to adopt for increasing carbon storage in plant and soil. Our study provides scientific information for predicting the consequences of current management practices for future forest productivity, and understanding how ecological processes interact with human interventions to influence soil carbon storage. The results of our research are important for land managers policymakers, carbon accountants, and scientists working on a variety of forest- related issues. Season OM C/N FDA PROT CAT DHA MBC T30 18.35 b* 16.5 b 58.52 b 80.35 b 1.69 b 7.36 b 7574 b T60 24.21 a 19.5 a 71.92 a 90.90 a 1.88 a 11.15 a 7997 a Summer CC 16.86 c 15.8 b 53.18 c 76.07 c 1.13 c 6.23 c 6810 c T0 7.68 d 12 c 45.86 d 68.22 d 0.74 d 5.89 d 6378 d T30 14.49 b 12 b 53.25 b 59.86 b 1.32 b 3.77 b 6800 b Winter T60 15.54 a 13 a 61.80 a 63.01 a 1.41 a 4.40 a 7550 a CC 13.48 c 9 d 50.10 c 56.81 c 1.03 c 2.24 c 6352 c T0 12.32 d 11 c 42.85 d 52.79 d 0.94 d 1.93 d 6027 d Replicates 5 5 5 5 5 5 5 Factors P- value P- value P- value P- value P- value P- value P- value Results of ANOVA Season <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Treatment <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Interaction <0.05 =0.1 <0.05 <0.05 <0.05 <0.05 <0.05 Tab. 2: Effect of 0% thinning, T0; 30% thinning, T30; 60% thinning, T60 and clear cut, CC on total organic carbon (TOC), total extractable carbon (TEC), humic acid (HA), fulvic acid (FA), humic acid plus fulvic acid carbon CHA+FA, humic acid/fulvic acid (HA/FA), humification index (HI), humification rate (HR), humification degree (DR). Tab. 1: Chemical and biochemical soil analysis: organic matter (OM%), C/N ratio, fluorescein diacetate (FDA, μg fluorescein released g-1 dry soil), protease (PROT, μg tyrosine g-1dry soil/2h), catalase (CAT, % O2/3min/g dry soil), dehydrogenase (DHA, μg TTF g-1 h-1), microbial biomass C (MBC, mg C g-1dry soil) under Pinus laricio plantation differently managed: thinning 0%, T0l; thinning 30%,T30; thinning 60%, T60 and clear cut, CC. Tab. 3 Colonies of fungi and bacteria (CFU g -1 dry soil) in soil under Pinus laricio plantation differently managed: 0% thinning, T0; 30% thinning, T30; 60% thinning, T60 and clear cut, CC. Season Treatment Fungi Bacteria Total count T30 2x10 4 a* 1.8x10 5 b 2.0 x10 5 b T60 6.7x10 3 d 2.2x10 5 a 2.3 x10 5 a Summer CC 1.3x10 4 b 1.6x10 5 c 1.8 x10 5 c T0 1.0x10 4 c 9.7x10 4 d 1.1 x10 5 d T30 3.3x10 3 b 5.3x10 4 b 5.63 x10 4 b Winter T60 1.7x10 3 c 6.3x10 4 a 6.47 x10 4 a CC 3.3x10 3 b 5.3x10 4 b 5.63 x10 4 b T0 6.7x10 3 a 2.3x10 4 c 2.97 x10 4 c Replicates 5 5 5 Factors Results of ANOVA Season <0.05 <0.05 <0.05 Treatment <0.05 <0.05 <0.05 Interaction <0.05 <0.05 <0.05 Season TOC % TEC % C HA+FA % HA/FA HI HR % DR % T30 10.66 b* 8.4 b 6.77 b 1.42 a 0.24 c 63.5 b 80.5 b Summer T60 14.07 a 12.6 a 10.83 a 1.17 c 0.16 d 77.0 a 85.9 a CC 9.80 c 7.6 c 5.56 c 1.43 a 0.37 a 56.7 c 73.1 c T0 4.46 d 3.3 d 2.61 d 1.25 b 0.26 b 58.5 c 79.1 b T30 8.42 b 6.6 b 4.95 b 1.96 a 0.33 b 58.8 c 75.2 c Winter T60 9.03 a 7.8 a 6.85 a 1.22 d 0.14 d 75.3 a 87.5 a CC 7.83 c 6.2 c 5.0 b 1.67 b 0.24 c 63.3 b 80.7 b T0 7.16 d 5.3d 3.85 c 1.58 c 0.38 a 53.5 d 72.1 c Replicates 5 5 5 5 5 5 5 Factors P- value P-value P-value P-value P-value P-value P-value Results of ANOVA Season <0.05 <0.05 <0.05 <0.05 <0.05 =0.4 =0.4 Treatment <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Interaction <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 *Different letters in the same column indicate, within each season, significant differences (Tukey’s test, p ≤0.05) *Different letters in the same column indicate, within each season, significant differences (Tukey’s test, p ≤0.05). INTRODUCTION OBJECTIVES Fig. 1: Pinus laricio forest MAIN RESULTS Fig. 2: Pinus laricio forest CONCLUSION
Transcript of Effects of thinning on soil carbon storage in Pinus ... · Effects of thinning on soil carbon...
Effects of thinning on soil carbon storage in Pinus laricio forest
Muscolo Adele, Settineri G., Mallamaci C., Attinà E., Sidari M.
Forests act as a natural storage forcarbon at the global scale,contributing approximately 80%of terrestrial aboveground, and40% of terrestrial below-groundcarbon storage. The relativelyrapid change in the status offorests– from a steady state ofminimal CO2emission/sequestration to majorCO2 emitter – during this timeperiod may offer a cautionary taleof how quickly the source/sinkstatus of large-scale forest Cstocks can change. Ourunderstanding of how forestmanagement influences standingC stocks, however, is limitedbecause many forest C studieshave focused on quantifyingtrends in unmanaged forests.Among silvicultural practices,thinning, reducing tree densityand altering microclimate andorganic matter budget can affectsoil carbon (C) storage and soilecosystem functioning. In Italy,thinning of pine forests is themost effective silviculturaltreatment to enhance theecological value of these stands;however, changes in soil C, soilmicrobial biomass and activityafter thinning in pine forests arenot well elucidated yet.
Our objectives were tounderstand how thinning affectsthe dynamics of total carbon inforest ecosystems as well as eachof its component pools. Weestimated carbon stocks in Pinuslaricio stands, evaluating carbonpool dynamics in forest subject todifferent thinning intensities (0,30 and 60%) and clear cut overtwo contrasting seasons (winterand summer), to verify if theenvironmental conditions affectin short term soil carbon pool.Our aim was to identify thesilvicultural practice thatincreased carbon storage in pinusforest. Our hypothesis-drivenresearch was that increasingthinning intensities physico-chemical, microbiological andbiochemical properties of soilrelated to soil quality and fertilitydecreased, while improving standstability, quality, diameter andgrowth volume of the remainingstand.
Results showed that soil carboncontent and C/N ratio weresignificantly higher in T60 than inT0, T30 and CC. Under T60, thesoils had the highest enzymaticactivities, MBC, and colonies offungi and bacteria (Tables 1, 2).60% thinning having lowerdensity of trees compared tocontrol and higher onescompared to CC and T30,determined regimes of light,temperature and humidity at soillevel that increased the amountand diversity of herbaceousvegetation, promoting an increasein overall soil microbial biomass,and in bacteria responsible for theproduction of enzymes involvedin carbon transformation.Humification indices confirmedthat humification processprevailed in T60 with consequentcarbon storage (Table 3).Additionally, dendro-auxometricparameters evidenced that pinusaccretion and wood densitychanged with the treatments.H/D ratio in 60% thinning waslower than in 30% thinning andcontrol suggesting that thepositive effect of 60% thinning onthe mechanical stability of thetrees is related to their ability toaccumulate large amounts ofcarbon in their wood (data notshown). This study shows thatT60 is a sustainable forestmanagement practice able toimprove in parallel soil qualityand C storage already after fewyears of treatments.
In short we found that 60% thinning wasthe silvicultural practice to adopt forincreasing carbon storage in plant andsoil. Our study provides scientificinformation for predicting theconsequences of current managementpractices for future forest productivity,and understanding how ecologicalprocesses interact with humaninterventions to influence soil carbonstorage. The results of our research areimportant for land managerspolicymakers, carbon accountants, andscientists working on a variety of forest-related issues.
Season OM C/N FDA PROT CAT DHA MBC
T30 18.35 b* 16.5b 58.52b 80.35b 1.69b 7.36b 7574b
T60 24.21a 19.5a 71.92a 90.90a 1.88a 11.15a 7997a
Summer CC 16.86c 15.8b 53.18c 76.07c 1.13c 6.23c 6810c
T0 7.68d 12c 45.86d 68.22d 0.74d 5.89d 6378d
T30 14.49b 12b 53.25b 59.86b 1.32b 3.77b 6800b
Winter T60 15.54a 13a 61.80a 63.01a 1.41a 4.40a 7550a
CC 13.48c 9d 50.10c 56.81c 1.03c 2.24c 6352c
T0 12.32d 11c 42.85d 52.79d 0.94d 1.93d 6027d
Replicates 5 5 5 5 5 5 5
Factors P-
value
P-
value
P-
value
P-
value
P-
value
P-
value
P-
value
Results of
ANOVA
Season <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05
Treatment <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05
Interaction <0.05 =0.1 <0.05 <0.05 <0.05 <0.05 <0.05
Tab. 2: Effect of 0% thinning, T0; 30% thinning, T30; 60% thinning, T60and clear cut, CC on total organic carbon (TOC), total extractable carbon(TEC), humic acid (HA), fulvic acid (FA), humic acid plus fulvic acidcarbon CHA+FA, humic acid/fulvic acid (HA/FA), humification index (HI),humification rate (HR), humification degree (DR).
Tab. 1: Chemical and biochemical soil analysis: organic matter (OM%), C/N ratio,fluorescein diacetate (FDA, μg fluorescein released g-1 dry soil), protease (PROT, μgtyrosine g-1dry soil/2h), catalase (CAT, % O2/3min/g dry soil), dehydrogenase (DHA, μgTTF g-1 h-1), microbial biomass C (MBC, mg C g-1dry soil) under Pinus laricio plantationdifferently managed: thinning 0%, T0l; thinning 30%,T30; thinning 60%, T60 and clearcut, CC.
Tab. 3 Colonies of fungi and bacteria (CFU g-1 dry soil)in soil under Pinus laricio plantation differentlymanaged: 0% thinning, T0; 30% thinning, T30; 60%thinning, T60 and clear cut, CC.
Season Treatment Fungi Bacteria Total count
T30 2x104 a* 1.8x105 b 2.0 x105 b
T60 6.7x103 d 2.2x105 a 2.3 x105 a
Summer CC 1.3x104 b 1.6x105 c 1.8 x105 c
T0 1.0x104 c 9.7x104 d 1.1 x105 d
T30 3.3x103 b 5.3x104 b 5.63 x104 b
Winter T60 1.7x103 c 6.3x104 a 6.47 x104 a
CC 3.3x103 b 5.3x104 b 5.63 x104 b
T0 6.7x103 a 2.3x104 c 2.97 x104 c
Replicates 5 5 5
Factors
Results of
ANOVA
Season <0.05 <0.05 <0.05
Treatment <0.05 <0.05 <0.05
Interaction <0.05 <0.05 <0.05
Season TOC
%
TEC
%
CHA+FA
%
HA/FA HI HR
%
DR
%
T30 10.66b* 8.4b 6.77b 1.42a 0.24c 63.5b 80.5b
Summer T60 14.07a 12.6a 10.83a 1.17c 0.16d 77.0a 85.9a
CC 9.80c 7.6c 5.56c 1.43a 0.37a 56.7c 73.1c
T0 4.46d 3.3d 2.61d 1.25b 0.26b 58.5c 79.1b
T30 8.42b 6.6b 4.95 b 1.96a 0.33b 58.8c 75.2c
Winter T60 9.03a 7.8a 6.85a 1.22d 0.14d 75.3a 87.5a
CC 7.83c 6.2c 5.0 b 1.67b 0.24c 63.3b 80.7b
T0 7.16d 5.3d 3.85c 1.58c 0.38a 53.5d 72.1c
Replicates 5 5 5 5 5 5 5
Factors P-
value
P-value P-value P-value P-value P-value P-value
Results of ANOVA
Season <0.05 <0.05 <0.05 <0.05 <0.05 =0.4 =0.4
Treatment <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05
Interaction <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05
*Different letters in the same column indicate, within each season, significant differences (Tukey’s test, p ≤0.05)
*Different letters in the same column indicate, within each season, significant differences (Tukey’s test, p ≤0.05).
INTRODUCTION OBJECTIVES
Fig. 1: Pinus laricio forest
MAIN RESULTS
Fig. 2: Pinus laricio forest
CONCLUSION
