The influence of environmental variables on soil mite communities (Acari: Mesostigmata) from overgrazed grassland ecosystems – Romania

Figures & data

Figure 1. Geographical position of the investigated grassland ecosystems.

Table I. Abiotic factors from the grassland ecosystems (G1–G6) from Trascău Mountains (± standard deviation). T, Temperature; H, Soil water content; pH, Soil acidity; C, Carbon content; Nt, Total nitrogen; C/Nt, Carbon content/total nitrogen.

Abiotic factors	G1	G2	G3	G4	G5	G6
T°	31.22 (± 5.59)	32.58 (± 10.40)	29.24 (± 0.43)	8.41 (± 0.21)	20.56 (± 0.30)	12.93 (± 0.13)
H%	50.88 (± 7.16)	48.44 (± 7.87)	60.28 (± 5.41)	85.48 (± 2.63)	74.56 (± 3.72)	72 (± 3.12)
pH	6.16 (± 0.94)	4.51 (± 0.13)	4.90 (± 0.42)	5.36 (± 0.20)	5.77 (± 0.20)	5.53 (± 0.07)
C%	1.75 (± 0.80)	2.36 (± 0.35)	2.15 (± 0.43)	4.32 (± 1)	5.66 (± 1.24)	4.62 (± 0.80)
Nt%	0.14 (± 0.05)	0.19 (± 0.03)	0.19 (± 0.03)	0.33 (± 0.06)	0.38 (± 0.05)	0.33 (± 0.04)
C/Nt	14.54 (± 1.68)	14.43 (± 1.13)	12.82 (± 1.09)	15.06 (± 2.49)	17.15 (± 1.45)	16.18 (± 1.55)

Figure 2. Individual-based accumulation curve for species richness of mite community. The shaded area represents the 95% confidence intervals.

Table II. Numerical abundance of the mesostigmatid mites identified from investigated grassland ecosystems (G1–G6).

No.	Species	G1	G2	G3	G4	G5	G6	Total
1	Amblyseius sp.					3		3
2	Androlaelaps casalis (Berlese, 1887)						1	1
3	Arctoseius semiscissus (Berlese, 1892)		1					1
4	Asca bicornis (Canestrini & Fanzago, 1887)	17	3		8	2	11	41
5	Cheroseius bryophilus Karg, 1969						5	5
6	Eviphis ostrinus (C.L. Koch, 1836)			1				1
7	Gamasellodes bicolor (Berlese, 1918)	2						2
8	Hypoaspis claviger (Berlese, 1882)					1	2	3
9	Hypoaspis vacua (Michael, 1891)	4	5	4	13	22	7	55
10	Hypoaspis astronomica (C.L. Koch, 1839)					1	1	2
11	Hypoaspis austriaca Sellnick, 1935				1			1
12	Hypoaspis aculeifer (Canestrini, 1883)	58	1	6		4	59	128
13	Hypoaspis angusta Karg, 1965	2						2
14	Hypoaspis oblonga (Halbert, 1915)				4	22	31	57
15	Hypoaspis preasternalis (Wilmann, 1949)	11		16	24	51	93	195
16	Hypoaspis sp.			3	2	1	5	11
17	Hypoaspis karawaiewi (Berlese, 1903)	2			1		2	5
18	Hypoaspis miles (Berlese, 1882)				1			1
19	Iphidonopsis pulvisculus (Berlese, 1921)				1		1	2
20	Iphidonopsis sp.						1	1
21	Lasioseius berlesei (Oudemans, 1938)					1		1
22	Lasioseius sp.					4	2	6
23	Leioseius insignis (Hirschmann, 1963)				2			2
24	Lysigamasus misellus (Berlese, 1904)				2	1	7	10
25	Macrocheles recki Bregetova & Koroleva, 1960		1				2	3
26	Ololaelaps placentulus (Berlese, 1887)		1	2			1	4
27	Ololealaps sellnicki Bregetova & Koroleva, 1964						4	4
28	Oplitis minutissima (Berlese, 1903)				3	1	7	11
29	Pachylaelaps furcifer Oudemans, 1903			1				1
30	Pachylaelaps pectinifer (G. & R. Canestrini, 1881)	1					1	2
31	Parazercon radiatus (Berlese, 1910)					1		1
32	Proctolaelaps pygmaeus (Muller, 1860)	1						1
33	Protogamasellus mica (Athias-Henriot, 1961)			6				6
34	Prozercon kochi Sellnick, 1943			1				1
35	Rhodacarellus perspicuus Halaskova, 1958	1	2		3		3	9
36	Rhodacarellus silesiacus Willmann, 1953	8	3	3	2	3	10	29
37	Rhodacarus coronatus Berlese, 1921						2	2
38	Rhodacarus denticulatus Berlese, 1921		11	6	4			21
39	Rhodacarus roseus Oudemans, 1902						1	1
40	Trachytes irenae Pecina, 1969			1				1
41	Trachytes pauperior Berlese, 1914						2	2
42	Uropoda orbicularis (O.F. Muller, 1776)				1		3	4
43	Veigaia exigua (Berlese, 1916)						2	2
44	Zercon berlesei Sellnick, 1958			1				1
45	Zercon hungaricus Sellnick, 1958			1				1
46	Zerconopsis remiger (Kramer, 1876)				1		1	2
	Total Acari	107	28	52	73	118	267	645

Table III. Model selection results. Models are ranked in a decreasing Akaike weight order. For clarity, models with Akaike weight < 0.04 are not shown. Statistics include the log likelihood (LL), the number of estimated parameters (K), the second-order Akaike information criterion corrected for small sample sizes (AICc), AIC difference (ΔAICi) and Akaike weights (w_i). Nt = Total nitrogen; Nt + H = Total nitrogen + Soil water content; Nt + T = Total nitrogen + Temperature; Nt + H + C = Total nitrogen + Soil water content + Carbon content; Nt + C = Total nitrogen + Carbon content; Nt + H + T = Total nitrogen + Soil water content + Temperature; Nt + pH = Total nitrogen + Soil acidity.

	Abundance					Species richness
Model	LL	K	AICc	∆AIC	wi	LL	K	AICc	∆AIC	wi
Nt	−187.43	4	383.7	0	0.09	−95.4	4	197.54	0	0.1
Nt + H	−189.71	5	384.34	0.64	0.07	−98.68	5	197.57	0.03	0.1
Nt + T	−188.18	6	384.78	1.08	0.05	−98.18	5	197.92	0.38	0.08
Nt + H + C	−190.72	5	385.08	1.38	0.05	−100.12	6	199.42	1.88	0.04
Nt + C	−192.51	4	385.39	1.69	0.04	−96.89	5	199.46	1.91	0.04
Nt + H + T	−188.35	5	385.47	1.77	0.04	−101.89	6	199.55	2	0.04
Nt + pH	−188.3	5	385.62	1.92	0.04	−96.96	5	199.65	2.11	0.04

Figure 3. Canonical correspondence analysis bi-plot of abundance mite species and environmental variables. Length and direction of arrows indicate the relative importance and direction of change in the environmental variables (Ar. se. – Arctoseius semiscissus; As.bi. – Asca bicornis; Am.sp. – Amblyseius sp.; Ch. br. – Cheroseius bryophilus; Ga.bi. – Gamasellodes bicolor; Hy.ac. – Hypoaspis aculeifer; Hy.as. – Hypoaspis astronomica; Hy.ka. – Hypoaspis karawaiewi; Hy.ob. – Hypoapis oblonga; Hy.pr. – Hypoaspis preasternalis; Hy.va. – Hypoaspis vacua; Ev.os. – Eviphis ostrinus; Ip.pu. – Iphidonopsis pulvisculus; Ol.se. – Ololaelaps sellnicki; Pa.pe. – Pachylaelaps pectinifer; Pr. ko. – Prozercon kochi; Pr. py. – Protogamasellus pygmaeus; Pr.mi. – Protogamasellus mica; Rh.de. – Rhodacarus denticulatus; Rh.si. – Rhodacarellus silesiacus; Tr.ir. – Trachytes irenae; Tr. pa. – Trachytes pauperior; Ze.re. – Zerconopsis remiger).

Figure 4. Canonical correspondence analysis bi-plot of abundance of mite species and habitat types (Am.sp. – Amblyseius sp.; Ch. br. – Cheroseius bryphilus; Ga.bi. – Gamasellodes bicolor; Hy.ac. – Hypoaspis aculeifer; Hy.ka. – Hypoaspis karawaiewi; Hy.pr. – Hypoaspis preasternalis; Hy.sp.1 – Hypoaspis sp.; Hy.va. – Hypoaspis vacua; La. sp. – Laioseius sp.; Le.in. – Leioseius insignitus; Ol. pl. – Ololaelaps placentulus; Pr.mi. – Protogamasellus mica; Rh de – Rhodacarus denticulatus; Rh.pe. – Rhodacarellus perspicuus; Rh.si. – Rhodacarellus silesiacus).