Interactive influence of rainfall manipulation and livestock grazing on species diversity of the herbaceous layer community in a humid savannah in Kenya

doi:10.1016/j.pld.2019.04.005

Abstract

Abstract: Changes in rainfall regime and grazing pressure affect vegetation composition and diversity with ecological implications for savannahs. The savannah in East Africa has experienced increased livestock grazing and rainfall variability but the impacts associated with those changes on the herbaceous layer have rarely been documented. We investigated the effect of livestock grazing, rainfall manipulation and their interaction on the composition and diversity of the herbaceous community in the savannah for two years in Lambwe, Kenya. Rainfall manipulation plots were set up for vegetation sampling; these plots received either 50% more or 50% less rainfall than control plots. Simpson's diversity and Bergere-Parker indices were used to determine diversity changes and dominance respectively. The frequency of species was used to compute their abundance and their life forms as determined from the literature. Grazing significantly increased species diversity through suppression of dominant species. Rainfall manipulation had no significant impact on plant diversity in fenced plots, but rainfall reduction significantly reduced diversity in grazed plots. In contrast, rainfall manipulation had no impact on dominance in either fenced or grazed plots. The interaction of grazing and rainfall manipulation is complex and will require additional survey campaigns to create a complete picture of the implications for savannah structure and composition.

Key words: Plant diversity, Grazing, Rainfall, Moist savannah

Joseph O. Ondier, Daniel O. Okach, John C. Onyango, Dennis O. Otieno. Interactive influence of rainfall manipulation and livestock grazing on species diversity of the herbaceous layer community in a humid savannah in Kenya[J]. Plant Diversity, 2019, 41(03): 198-205.

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^**