Response of soil nematode community structure and diversity to increased nitrogen in alpine meadows of northern Tibet

doi:10.11686/cyxb2022165

Abstract

Abstract:

Soil nematodes play an important role in material cycling and energy transfer processes in alpine meadow ecosystems. Alpine meadow plants are extremely sensitive to nitrogen deposition， but the effect of increased nitrogen on the structure and diversity of the soil nematode community remains unclear. In this study， we conducted a simulated nitrogen deposition experiment in alpine meadows in Nagqu， Tibet， with four levels of nitrogen enrichment： 0 （CK）， 7， 20， and 40 kg N·ha^-1·yr^-1. Then， we investigated the effects of nitrogen enrichment on the structure and diversity of the soil nematode community. The results showed that： 1） Increased nitrogen significantly changed the soil nematode community composition in alpine meadows and reduced nematode diversity and evenness； 2） the N₂₀ and N₄₀ treatments significantly increased the relative abundance of bacterivore （Ba） taxa by 30.4% and 31.7%， respectively， compared with the control group； 3） The treatments could be ranked， from highest nematode diversity index and evenness index to lowest， as follows： N_ck>N₄₀>N₂₀>N₇. There were no significant differences in the plant parasite index， maturity index， and Wasilewska index （WI） among the treatments. The nematode channel ratio was greater than 0.5 and the WI was greater than 1 under different nitrogen enrichment conditions， indicating that the soil nematode taxa in the study area were mainly bacterivore nematodes， and that the main players in the mineralization pathway were bacterivore and fungivore nematodes； 4） The ammonia nitrogen content in soil was significantly and positively correlated with the total numbers of nematodes and bacterivores. This study clarified that the increase in the total number of soil nematodes in the alpine meadows of northern Tibet under nitrogen deposition is because of increased numbers of bacterivore nematodes. These results provide a reference for exploring how alpine meadow ecosystems in northern Tibet will respond to nitrogen deposition.

Key words: nitrogen deposition, ecological index, nematode channel ratio, soil fauna, plant productivity

Yu-bao SHA, Ganjurjav HASBAGAN, Guo-zheng HU, Xue-xia WANG, Jun YAN, Shi-cheng HE, Qing-zhu GAO. Response of soil nematode community structure and diversity to increased nitrogen in alpine meadows of northern Tibet[J]. Acta Prataculturae Sinica, 2023, 32(1): 154-164.

Figures/Tables 6

References 44

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属Genus	营养类群Trophic group	c-p值c-p values	N_ck	N₇	N₂₀	N₄₀
拟丽突属Acrobeloides	Ba	2	+++	+++	++	++
头叶属Cephalobus	Ba	2	++	++	++	++
丽突属Acrobeles	Ba	2	++	++	++	++
鹿角唇属Cervidellus	Ba	2	++	++	++	++
小杆属Rhabditis	Ba	1	+	-	-	-
中小杆属Mesorhabditis	Ba	1	++	++	++	++
真头叶属Eucephalobus	Ba	2	+	++	++	-
无咽属Alaimus	Ba	4	++	++	++	++
绕线属Plectus	Ba	2	+	++	-	+
唇绕线属Bastiania	Ba	3	-	-	+	+
单宫属Monhystera	Ba	2	++	-	-	-
棱咽属Prismatolaimus	Ba	3	++	++	++	++
威尔斯属Wilsonema	Ba	2	+	-	-	-
似绕线属Anaplectus	Ba	2	++	++	++	++
原杆属Protorhabditis	Ba	1	-	-	+	+
杆咽属Rhabdolaimus	Ba	3	+	+	+	+
鞘线虫属Hemicycliophora	Pp	3	++	++	++	+
纳格尔属Nagelus	Pp	2	-	+	+	+
针属Paratylenchus	Pp	2	+	++	++	-
垫刃属Tylenchus	Pp	2	+	++	++	++
丝尾垫刃属Filenchus	Pp	2	++	++	++	++
叉针属Boleodorus	Pp	2	++	-	-	-
矮化属Tylenchorhynchus	Pp	3	++	++	+	+
野外垫刃属Aglenchus	Pp	2	-	+	+	+
螺旋属Helicotylenchus	Pp	3	+	++	++	++
短体属Pratylenchus	Pp	3	+	-	-	-
剑尾垫刃属Malenchus	Pp	2	+	+	+	+
环属Criconema	Pp	3	+	-	+	+
盘旋属Rotylenchus	Pp	3	-	-	+	-
默林属Merlinius	Pp	2	+	++	+	++
类短体属Pratylenchoides	Pp	3	++	++	++	++
小孔咽属Aporcelaimellus	Om	5	++	-	-	-
盘咽属Discolaimus	Om	5	+	-	-	-
三孔属Tripyla	Om	3	-	+	+	-
色矛属Chromadorita	Om	3	-	+	-	-
异色矛属Achromadora	Om	3	+	-	-	-
中矛线属Mesodorylaimus	Om	5	++	++	++	++
大矛属Enchodelus	Om	4	-	+	+	-
锉齿属Mylonchulidae	Om	4	+	+	+	-
拱唇属Labronema	Om	4	++	-	-	-
Allodorylaimus	Om	4	++	++	++	++
表矛线属Epidorylaimus	Om	4	+	-	-	-
牙咽属Dorylaimellus	Om	5	+	++	+	+
单齿属Mononchus	Om	4	+	-	+	+
缢咽属Axonchium	Om	4	++	++	++	++
滑刃属Aphelenchoides	Fu	2	++	-	-	-
拟滑刃属Paraphelenchus	Fu	2	+	-	-	-
垫咽属Tylencholaimus	Fu	4	++	++	++	-
拟矛线属Dorylaimoides	Fu	4	++	-	-	-
细齿属Leptonchus	Fu	4	+	-	-	-
真滑刃属Aphelenchus	Fu	2	++	++	+	+
双垫刃属Ditylenchus	Fu	2	+	++	++	++
短矛属Doryllium	Fu	4	+	-	-	-

属Genus	营养类群Trophic group	c-p值c-p values	N_ck	N₇	N₂₀	N₄₀
拟丽突属Acrobeloides	Ba	2	+++	+++	++	++
头叶属Cephalobus	Ba	2	++	++	++	++
丽突属Acrobeles	Ba	2	++	++	++	++
鹿角唇属Cervidellus	Ba	2	++	++	++	++
小杆属Rhabditis	Ba	1	+	-	-	-
中小杆属Mesorhabditis	Ba	1	++	++	++	++
真头叶属Eucephalobus	Ba	2	+	++	++	-
无咽属Alaimus	Ba	4	++	++	++	++
绕线属Plectus	Ba	2	+	++	-	+
唇绕线属Bastiania	Ba	3	-	-	+	+
单宫属Monhystera	Ba	2	++	-	-	-
棱咽属Prismatolaimus	Ba	3	++	++	++	++
威尔斯属Wilsonema	Ba	2	+	-	-	-
似绕线属Anaplectus	Ba	2	++	++	++	++
原杆属Protorhabditis	Ba	1	-	-	+	+
杆咽属Rhabdolaimus	Ba	3	+	+	+	+
鞘线虫属Hemicycliophora	Pp	3	++	++	++	+
纳格尔属Nagelus	Pp	2	-	+	+	+
针属Paratylenchus	Pp	2	+	++	++	-
垫刃属Tylenchus	Pp	2	+	++	++	++
丝尾垫刃属Filenchus	Pp	2	++	++	++	++
叉针属Boleodorus	Pp	2	++	-	-	-
矮化属Tylenchorhynchus	Pp	3	++	++	+	+
野外垫刃属Aglenchus	Pp	2	-	+	+	+
螺旋属Helicotylenchus	Pp	3	+	++	++	++
短体属Pratylenchus	Pp	3	+	-	-	-
剑尾垫刃属Malenchus	Pp	2	+	+	+	+
环属Criconema	Pp	3	+	-	+	+
盘旋属Rotylenchus	Pp	3	-	-	+	-
默林属Merlinius	Pp	2	+	++	+	++
类短体属Pratylenchoides	Pp	3	++	++	++	++
小孔咽属Aporcelaimellus	Om	5	++	-	-	-
盘咽属Discolaimus	Om	5	+	-	-	-
三孔属Tripyla	Om	3	-	+	+	-
色矛属Chromadorita	Om	3	-	+	-	-
异色矛属Achromadora	Om	3	+	-	-	-
中矛线属Mesodorylaimus	Om	5	++	++	++	++
大矛属Enchodelus	Om	4	-	+	+	-
锉齿属Mylonchulidae	Om	4	+	+	+	-
拱唇属Labronema	Om	4	++	-	-	-
Allodorylaimus	Om	4	++	++	++	++
表矛线属Epidorylaimus	Om	4	+	-	-	-
牙咽属Dorylaimellus	Om	5	+	++	+	+
单齿属Mononchus	Om	4	+	-	+	+
缢咽属Axonchium	Om	4	++	++	++	++
滑刃属Aphelenchoides	Fu	2	++	-	-	-
拟滑刃属Paraphelenchus	Fu	2	+	-	-	-
垫咽属Tylencholaimus	Fu	4	++	++	++	-
拟矛线属Dorylaimoides	Fu	4	++	-	-	-
细齿属Leptonchus	Fu	4	+	-	-	-
真滑刃属Aphelenchus	Fu	2	++	++	+	+
双垫刃属Ditylenchus	Fu	2	+	++	++	++
短矛属Doryllium	Fu	4	+	-	-	-

指数Index	N_ck	N₇	N₂₀	N₄₀
H′	3.08±0.11a	1.94±0.25c	2.03±0.18c	2.50±0.16b
J	0.91±0.01a	0.57±0.08c	0.59±0.06c	0.74±0.07b
MI	2.20±0.13a	2.01±0.10a	2.09±0.05a	2.10±0.12a
PPI	0.67±0.14a	0.81±0.09a	0.74±0.02a	0.70±0.05a
NCR	0.63±0.06b	0.63±0.10b	0.73±0.08a	0.76±0.05a
WI	2.50±0.91a	1.71±0.28a	1.86±0.16a	2.08±0.23a

指数Index	N_ck	N₇	N₂₀	N₄₀
H′	3.08±0.11a	1.94±0.25c	2.03±0.18c	2.50±0.16b
J	0.91±0.01a	0.57±0.08c	0.59±0.06c	0.74±0.07b
MI	2.20±0.13a	2.01±0.10a	2.09±0.05a	2.10±0.12a
PPI	0.67±0.14a	0.81±0.09a	0.74±0.02a	0.70±0.05a
NCR	0.63±0.06b	0.63±0.10b	0.73±0.08a	0.76±0.05a
WI	2.50±0.91a	1.71±0.28a	1.86±0.16a	2.08±0.23a

项目Item	N_ck	N₇	N₂₀	N₄₀
禾莎草高度Gramineae height （cm）	3.42±0.62c	3.22±1.48c	5.39±0.40b	7.62±1.81a
禾莎草盖度Gramineae coverage （%）	39.62±4.62c	44.00±3.65c	52.32±7.26b	67.35±3.31a
杂类草高度Forb height （cm）	1.69±0.15c	1.51±0.37c	2.30±0.26b	2.84±0.19a
杂类草盖度Forb coverage （%）	18.02±5.36b	33.07±6.95a	30.27±3.48a	22.82±5.66b
地上生物量Above-ground biomass （g·m^-2）	44.23±2.85d	70.33±0.81c	98.33±3.51b	106.00±6.45a
地下生物量Below-ground biomass （g·m^-2）	1054.77±65.20a	1192.35±67.77a	1333.75±56.29a	1284.71±85.35a
氨态氮NH₄⁺-N （mg·kg^-1）	11.04±1.38b	14.10±1.65ab	24.07±3.30a	31.22±3.01a
硝态氮NO₃^--N （mg·kg^-1）	2.29±0.21b	4.17±0.24ab	4.85±0.98a	10.86±2.36a