Effects of forest gap on hemicellulose dynamics during foliar litter decomposition in an subalpine forest

doi:10.17521/cjpe.2015.0022

Abstract

Abstract: Aims

As part of fiber structures, the hemicellulose degrades and transforms during foliar litter decomposition along with other components of leaf tissue. Forest gaps and crown canopies may regulate hemicellulose dynamics during foliar litter decomposition by redistributing winter snow cover and altering the temperature, precipitation and solar radiation during the growing season, but little information is available concerning those effects and the consequences. Therefore, our objective was to study the effects of forest gap on hemicellulose dynamics during foliar litter decomposition in an subalpine forest.

Methods

A field litterbag experiment was conducted in an subalpine fir (Abies faxoniana) forest in a transitional area located in the upper reaches of the Yangtze River and the eastern Qinghai-Xizang Plateau. Litterbags containing cypress (Sabina saltuaria), red birch (Betula albosinensis), larch (Larix mastersiana), azalea (Rhododendron lapponicum) and fir (Abies faxoniana) were placed on forest floor from the gap center to under the closed canopy. Samples of litterbags were retrieved at the stages of snow formation, snow cover, and snowmelt as well as during the growing season. Hemicellulose contents of the remaining litter were measured.

Important findings

After one-year decomposition, all five types of foliar litter exhibited a tendency of hemicellulose accumulation. The needle-leaved litter and broad-leaved litter showed greater hemicellulose losses at the snow cover and snowmelt stages, respectively. Greater hemicellulose losses in the gap center and under the canopy were observed at both snow cover and snowmelt stages. In contrast, there was less litter hemicellulose accumulation in the gap center during the growing season. Statistical analysis of the resulting data indicated that both environmental factors and litter quality were significantly correlated with the litter hemicellulose losses. Our results suggested that forest gap enhanced the hemicellulose losses in winter and constrained the hemicellulose accumulation during growing season, implying that the formation of forest gap in subalpine forest promoted hemicellulose degradation during litter decomposition.

Key words: forest gap, foliar litter, hemicellulose, seasonal snowpack, subalpine forest

LI Han,WU Fu-Zhong,YANG Wan-Qin,XU Li-Ya,NI Xiang-Yin,HE Jie,HU Yi. Effects of forest gap on hemicellulose dynamics during foliar litter decomposition in an subalpine forest[J]. Chin J Plan Ecolo, 2015, 39(3): 229-238.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2015.0022

https://www.plant-ecology.com/EN/Y2015/V39/I3/229

Figures/Tables 9

References 29

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物种 Species	半纤维素Hemicellulose (%)	C (%)	N (%)	P (%)	木质素Lignin (%)	纤维素Cellulose (%)	C:N	C:P	N:P	Lignin:N
方枝柏 Sabina saltuaria	8.06 ± 0.09^b	51.64 ± 1.77^bc	0.88 ± 0.01^b	0.12 ± 0.01^cd	14.07 ± 0.74^b	12.22 ± 0.38^a	58.86 ± 2.21^b	416.02 ± 14.04^a	7.08 ± 0.41^ab	16.04 ± 1.01^a
岷江冷杉 Abies faxoniana	12.86 ± 0.11^c	50.56 ± 2.96^b	0.88 ± 0.01^b	0.11 ± 0.01^bc	15.85 ± 0.36^b	12.19 ± 0.20^b	57.77 ± 3.53^b	443.51 ± 36.69^ab	7.68 ± 0.72^b	18.11 ± 0.42^b
四川红杉 Larix mastersiana	5.50 ± 0.20^a	54.35 ± 0.63^c	0.86 ± 0.04^b	0.13 ± 0.01^d	27.21 ± 2.21^d	16.45 ± 0.44^d	63.32 ± 3.49^b	407.08 ± 2.42^a	6.44 ± 0.38^a	25.95 ± 1.08^c
红桦 Betula albosinensis	12.74 ± 0.10^c	49.69 ± 1.45^b	1.33 ± 0.02^d	0.09 ± 0.01^a	36.68 ± 0.62^b	12.47 ± 0.38^e	37.24 ± 1.35^a	544.94 ± 31.72^c	14.63 ± 0.36^d	25.99 ± 0.37^c
高山杜鹃 Rhododendron lapponicum	8.07 ± 0.31^b	50.29 ± 0.16^b	0.67 ± 0.02^a	0.11 ± 0.01^b	20.81 ± 0.18^c	14.07 ± 0.41^c	75.54 ± 4.47^c	471.14 ± 42.04^b	6.25 ± 0.65^a	31.24 ± 0.69^d

物种 Species	半纤维素Hemicellulose (%)	C (%)	N (%)	P (%)	木质素Lignin (%)	纤维素Cellulose (%)	C:N	C:P	N:P	Lignin:N
方枝柏 Sabina saltuaria	8.06 ± 0.09^b	51.64 ± 1.77^bc	0.88 ± 0.01^b	0.12 ± 0.01^cd	14.07 ± 0.74^b	12.22 ± 0.38^a	58.86 ± 2.21^b	416.02 ± 14.04^a	7.08 ± 0.41^ab	16.04 ± 1.01^a
岷江冷杉 Abies faxoniana	12.86 ± 0.11^c	50.56 ± 2.96^b	0.88 ± 0.01^b	0.11 ± 0.01^bc	15.85 ± 0.36^b	12.19 ± 0.20^b	57.77 ± 3.53^b	443.51 ± 36.69^ab	7.68 ± 0.72^b	18.11 ± 0.42^b
四川红杉 Larix mastersiana	5.50 ± 0.20^a	54.35 ± 0.63^c	0.86 ± 0.04^b	0.13 ± 0.01^d	27.21 ± 2.21^d	16.45 ± 0.44^d	63.32 ± 3.49^b	407.08 ± 2.42^a	6.44 ± 0.38^a	25.95 ± 1.08^c
红桦 Betula albosinensis	12.74 ± 0.10^c	49.69 ± 1.45^b	1.33 ± 0.02^d	0.09 ± 0.01^a	36.68 ± 0.62^b	12.47 ± 0.38^e	37.24 ± 1.35^a	544.94 ± 31.72^c	14.63 ± 0.36^d	25.99 ± 0.37^c
高山杜鹃 Rhododendron lapponicum	8.07 ± 0.31^b	50.29 ± 0.16^b	0.67 ± 0.02^a	0.11 ± 0.01^b	20.81 ± 0.18^c	14.07 ± 0.41^c	75.54 ± 4.47^c	471.14 ± 42.04^b	6.25 ± 0.65^a	31.24 ± 0.69^d

林窗位置 Gap positions	土壤表层温度特征 Soil surface temperature characteristics	雪被形成期 Snow formation stage	雪被覆盖期 Snow cover stage	雪被融化期 Snow melt stage	冬季 Winter	生长季节 Growing season	全年 The whole year
林窗中心 Gap center	日均温 DMT (℃)	-3.97	-3.97	2.14	-1.97	9.62	4.11
	正积温 PAT (℃)	378.47	1 004.85	1 604.30	2 987.62	20 713.40	23 701.02
	负积温 NAT (℃)	-2 296.28	-4 433.95	-482.58	-7 212.81	-217.40	-7 430.21
	冻融循环 FSFC (times)	43	75	54	172	-	172
林冠林窗 Canopy gap	日均温 DMT (℃)	-2.90	-3.25	1.13	-1.77	7.81	3.43
	正积温 PAT (℃)	408.92	1 066.50	922.70	2 398.12	17 454.67	19 853.79
	负积温 NAT (℃)	-1 799.92	-3 875.67	-287.33	-5 962.92	-98.00	-6 061.92
	冻融循环 FSFC (times)	56	100	29	185	-	185
扩展林窗 Expanded gap	日均温 DMT (℃)	-3.46	-4.15	1.82	-2.22	7.87	3.26
	正积温 PAT (℃)	356.75	1039.04	1 418.50	2 814.29	17 971.93	20 786.22
	负积温 NAT (℃)	-2 017.08	-4 624.67	-391.25	-7 033.00	-140.25	-7 173.25
	冻融循环 FSFC (times)	50	92	49	191	-	191
郁闭林下 Closed canopy	日均温 DMT (℃)	-3.54	-3.67	1.24	-2.15	7.79	3.29
	正积温 PAT (℃)	448.50	1328.92	1 005.50	2 782.92	17 598.58	20 382.50
	负积温 NAT (℃)	-2 149.17	-4 501.00	-305.08	-6 955.25	-61.89	-7 017.14
	冻融循环 FSFC (times)	59	105	38	201	-	201

林窗位置 Gap positions	土壤表层温度特征 Soil surface temperature characteristics	雪被形成期 Snow formation stage	雪被覆盖期 Snow cover stage	雪被融化期 Snow melt stage	冬季 Winter	生长季节 Growing season	全年 The whole year
林窗中心 Gap center	日均温 DMT (℃)	-3.97	-3.97	2.14	-1.97	9.62	4.11
	正积温 PAT (℃)	378.47	1 004.85	1 604.30	2 987.62	20 713.40	23 701.02
	负积温 NAT (℃)	-2 296.28	-4 433.95	-482.58	-7 212.81	-217.40	-7 430.21
	冻融循环 FSFC (times)	43	75	54	172	-	172
林冠林窗 Canopy gap	日均温 DMT (℃)	-2.90	-3.25	1.13	-1.77	7.81	3.43
	正积温 PAT (℃)	408.92	1 066.50	922.70	2 398.12	17 454.67	19 853.79
	负积温 NAT (℃)	-1 799.92	-3 875.67	-287.33	-5 962.92	-98.00	-6 061.92
	冻融循环 FSFC (times)	56	100	29	185	-	185
扩展林窗 Expanded gap	日均温 DMT (℃)	-3.46	-4.15	1.82	-2.22	7.87	3.26
	正积温 PAT (℃)	356.75	1039.04	1 418.50	2 814.29	17 971.93	20 786.22
	负积温 NAT (℃)	-2 017.08	-4 624.67	-391.25	-7 033.00	-140.25	-7 173.25
	冻融循环 FSFC (times)	50	92	49	191	-	191
郁闭林下 Closed canopy	日均温 DMT (℃)	-3.54	-3.67	1.24	-2.15	7.79	3.29
	正积温 PAT (℃)	448.50	1328.92	1 005.50	2 782.92	17 598.58	20 382.50
	负积温 NAT (℃)	-2 149.17	-4 501.00	-305.08	-6 955.25	-61.89	-7 017.14
	冻融循环 FSFC (times)	59	105	38	201	-	201

变异来源 Variation source	df	F	p
T	3	163.580	0.000^**
S	4	590.699	0.000^**
G	3	13.908	0.000^**
T × S	12	74.056	0.000^**
T × G	9	32.429	0.000^**
S × G	12	19.384	0.000^**
T × S × G	36	19.846	0.000^**