Vertical distribution of soil free-living nematode in a playa habitat in the North-Western Negev desert, Israel

Treatment	Dry season			Wet season
Treatment	SM*(%)	OM (%)	EC (ms cm^-1)	SM (%)	OM (%)	EC (ms cm^-1)
0 – 10 cm
playa	1.28±0.73a**	0.25±0.05a	2.20±1.15a	7.16±1.70a	0.14±0.07a	1.97±0.63a
loessial plain	0.11±0.05b	0.07±0.04b	0.05±0.00b	1.93±0.54b	0.05±0.04b	0.08±0.01b
10 – 20 cm
playa	2.42±0.68a	0.18±0.03a	3.35±0.59a	5.44±0.53a	0.16±0.13a	1.77±0.32a
loessial plain	0.09±0.03b	0.07±0.04b	0.05±0.00b	1.14±0.15b	0.04±0.03a	0.07±0.01b
20 – 30 cm
playa	3.08±0.95a	0.13±0.03a	3.03±0.75a	6.75±0.89a	0.14±0.07a	2.85±0.97a
loessial plain	0.13±0.03b	0.06±0.06b	0.05±0.00b	0.84±0.17b	0.02±0.00b	0.07±0.01b
30 – 40 cm
playa	3.81±1.05a	0.10±0.02a	2.99±0.68a	5.69±0.90a	0.15±0.08a	2.63±0.39a
loessial plain	0.16±0.06b	0.03±0.02b	0.06±0.01b	0.80±0.17b	0.02±0.00b	0.06±0.00b
40 – 50 cm
playa	1.23±1.35a	0.04±0.04a	1.09±0.75a	3.47±1.65a	0.10±0.05a	1.83±0.80a
loessial plain	0.42±0.40a	0.05±0.05a	0.06±0.03b	0.80±0.12b	0.04±0.01b	0.07±0.01b

* SM: soil moisture; OM: soil organic matter content; EC: electrical conductivity.

** Means and standard deviation from four replicates, different letters at each soil layer in a column denote significant differences as assessed by t-test (P < 0.05).

Table 2

Univariate analysis of variance of the soil properties, nematode population and ecological indices.

Index	Location (L)		Depth (D)		Season (S)		L×D		L×S		D×S
Index	F-value	P-value	F-value	P-value	F-value	P-value	F-value	P-value	F-value	P-value	F-value	P-value
Soil Properties
SM*	139.81	< 0.0001	6.36	0.0002	139.81	< 0.0001	7.12	< 0.0001	45.04	< 0.0001	6.80	0.0001
OM	1.16	< 0.0001	4.95	0.0016	1.16	NS	2.72	0.0376	0.54	NS	1.64	NS
EC	1.73	< 0.0001	5.25	0.0011	1.73	NS	5.35	0.0009	2.02	NS	2.45	NS
Trophic Group
TN	69.36	< 0.0001	6.42	0.0002	8.88	0.0042	6.21	0.0003	7.63	0.0076	1.08	NS
BF	49.67	< 0.0001	4.39	0.0035	6.80	0.0115	4.17	0.0048	5.48	0.0226	1.24	NS
FF	24.00	< 0.0001	3.67	0.0097	4.44	0.0394	3.65	0.0100	4.22	0.0443	0.92	NS
PP	36.87	< 0.0001	3.63	0.0102	1.87	NS	3.63	0.0103	1.87	NS	2.10	NS
OP	45.42	< 0.0001	3.68	0.0096	4.22	0.0442	3.66	0.0099	4.14	0.0462	0.69	NS
Ecological Indices
F/B	8.71	0.005	0.76	NS	0.48	NS	0.34	NS	1.19	NS	0.52	NS
NCR	17.50	0.0001	0.66	NS	0.63	NS	0.39	NS	1.16	NS	0.63	NS
T	55.27	< 0.0001	0.57	NS	0.78	NS	0.51	NS	0.53	NS	0.50	NS
H'	618.16	< 0.0001	1.29	NS	22.40	< 0.0001	1.69	NS	23.27	< 0.0001	0.76	NS
Λ	177.50	< 0.0001	0.93	NS	2.82	NS	1.79	NS	20.50	< 0.0001	0.41	NS
SR	139.82	< 0.0001	0.36	NS	3.39	NS	1.25	NS	8.16	0.0062	0.45	NS
MI	22.25	< 0.0001	1.74	NS	1.24	NS	2.71	0.0417	5.07	0.0292	1.84	NS
MMI	12.18	0.001	1.27	NS	0.95	NS	2.20	NS	0.33	NS	0.51	NS
EI	9.75	0.0032	1.69	NS	5.78	0.0206	0.41	NS	0.01	NS	0.14	NS
SI	22.56	< 0.0001	0.56	NS	1.66	NS	3.08	0.0253	11.82	0.0013	1.85	NS

* SM: soil moisture; OM: organic matter; EC: electrical conductivity; TN: total number of nematodes; BF: bacterivores; FF: fungivores; PP: plant-parasite nematodes; OP: omnivore-predator nematodes; F/B: fungivores/bacterivores ratio; NCR: nematode channel ratio T: trophic diversity; H’: Shannon index; λ: genus dominance; SR: species richness; MI: maturity index; MMI: modified maturity index; EI: enrichment index; SI: structure index. NS: no significant.

Vertical distribution of total number of nematode at five soil depths in the playa and loessial plain areas during the dry and wet seasons. PD-playa area during the dry season; PW-playa area during the wet season; CD-loessial plain area during the dry season; CW-loessial plain area during the wet season.