Responses of bryophyte diversity, community and Chlorophyll content to rocky desertification succession

doi:10.21203/rs.3.rs-17326/v1

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Responses of bryophyte diversity, community and Chlorophyll content to rocky desertification succession

https://doi.org/10.21203/rs.3.rs-17326/v1

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Background : bryophytes have great potential for the restoration of rocky desertification. At present, research on the correlation between bryophytes and the rocky desertification environment is in its infancy, and basic questions about the ecological response of bryophytes to rocky desertification, including biodiversity, community succession, interspecific relationships and photosynthetic physiology need to be answered urgently.

Results : results showed that significant differences in diversity, interspecific association and chlorophyll characteristics were observed among different degrees of rocky desertification. With the increase of rocky desertification degrees, the biodiversity of bryophytes decreases obviously, and the bryophytes which drought tolerance gradually dominates in communities. The interspecific association tend to be positive in rocky desertification succession, and positive association will be beneficial to the positive development of vegetation communities. Some bryophytes can adapt to the rocky desertification environment by reducing chlorophyll content and increasing chlorophyll a/b ratios that is beneficial to light trapping.

Conclusions : With the increase in rocky desertification, the biodiversity of bryophytes decreased obviously, and bryophytes with drought tolerance gradually dominated in the communities. The interspecific association tended to be positive in rocky desertification succession, and a positive association will be beneficial to the positive development of vegetation communities. Some bryophytes adapted to the rocky desertification environment by reducing their chlorophyll content and increasing their chlorophyll a/b ratios, which are beneficial for light trapping. The results of this study are useful for the management of desertified karst ecosystems.

Agroecology

Rocky desertification

bryophyte

diversity

community

chlorophyll

Table 1: Classification standard of Karst rocky desertification. Xiong et al. (2002) classified the karst rocky desertification (KRD) into five degrees including: 1) nil rocky desertification (Nil RD); 2) potential rocky desertification (Pot RD); 3) slight rocky desertification (Sli RD); 4) moderate rocky desertification (Mod RD); and 5) severe rocky desertification (Sev RD).

	The standard of the Karst rocky desertification
	Nil	Potential	Slight	Moderate	Severe
Percentage of vegetation (%)	>80	<80	<70	<50	<30
Slope (°)	<15	>15	>15	>20	>25
Percentage of bare rock (%)	<20	>20	>40	>60	>80
Average depth of top soil (cm)	>20	<20	<15	<10	<5

Table 2: 2 × 2 contingency table or species association table. A 2 × 2 species association table was listed as table 2. For each pair of species A and B, we can obtain the following:

		Species B		∑
		Present	Absent
Species A	Present	a	b	m = a + b
	Absent	c	d	n = c + d
	∑	r = a + c	s = b + d	N = a + b + c + d

Table 3: List of bryophytes in the study area. We have counted the families, genera, species, and important values of all bryophytes we collected.

Family	Genus	No.	Species	Importance value
Family	Genus	No.	Species	Nil	Potential	Slight	Moderate	Severe
Leucobryaceae	Leucobryum	1	Leucobryum glaucum (Hedw.) Angstr.	1.45	—	—	—	—
		2	Leucobryum juniperoideum (Brid.) Müll. Hal.	2.69	—	—	3.95	—
	Campylopus	3	Campylopus fragilis (Brid.) Bruch & Schimp.	9.26	—	—	3.95	—
		4	Campylopus ericoides (Griff.) A. Jaeger	1.50	—	—	—	—
Leskeaceae	Claopodium	5	Claopodium gracillimum (Cardot & Thér.) Nog.	0.81	—	1.91	—	—
	Lindbergia	6	Lindbergia sinensis (Müll. Hal.) Broth.	—	—	—	—	4.41
Metzgeriaceae	Metzgeria	7	Metzgeria consanguinea Schiffn.	7.00	—	—	—	—
Lophocoleaceae	Chiloscyphus	8	Chiloscyphus minor (Nees) J.J. Engel & R.M. Schust.	1.45	—	—	—	—
	Heteroscyphus	9	Heteroscyphus coalitus (Hook.) Schiffn.	3.21	—	—	—	—
Pottiaceae	Didymodon	10	Didymodon fallax (Hedw.) R.H. Zander	—	1.82	—	3.95	4.52
		11	Didymodon ditrichoides (Broth.) X.J. Li & S. He	—	5.72	2.93	—	5.22
		12	Didymodon constrictus (Mitt.) Saito	1.71	2.60	5.99	11.44	6.18
	Bryoerythrophyllum	13	Bryoerythrophyllum inaequalifolium (Taylor) R.H. Zander	—	—	2.27	—	—
		14	Bryoerythrophyllum alpigenum (Vent.) P.C. Chen	1.07	—	—	—	—
	Gymnostomum	15	Gymnostomum aeruginosum Smith	—	2.34	—	—	—
	Trichostomum	16	Trichostomum brachydontium Bruch	1.45	5.20	3.15	4.70	5.05
	Barbula	17	Barbula unguiculata Hedw.	1.32	—	—	2.84	—
	Tortula	18	Tortula planifolia X.J. Li	—	—	2.70	—	10.11
	Hyophila	19	Hyophila involuta (Hook.) A. Jaeger	1.60	9.63	8.22	3.68	4.68
		20	Hyophila setschwanica (Broth.) Hilp. Ex P.C. Chen	—	4.06	—	3.06	—
		21	Hyophila javanica (Nees & Blume) Brid.	0.94	—	2.93	2.61	—
	Weissia	22	Weissia controversa Hedw.	—	4.16	—	—	—
Diphysciaceae	Diphyscium	23	Diphyscium foliosum (Hedw.) D. Mohr	2.75	—	—	4.21	—
Frullaniaceae	Frullania	24	Frullania chenii S. Hatt. & P.J. Lin	—	—	2.09	—	—
Hypnaceae	Hypnum	25	Hypnum sakuraii (Sakurai) Ando	0.94	—	—	—	—
		26	Hypnum oldhamii (Mitt.) A. Jaeger	2.85	—	—	—	—
		27	Hypnum submolluscum Besch.	—	—	2.39	—	—
	Taxiphyllum	28	Taxiphyllum taxirameum (Mitt.) M. Fleisch.	0.94	—	—	—	—
	Pseudotaxiphyllum	29	Pseudotaxiphyllum pohliaecarpum (Sull. & Lesq.) Z. Iwats.	3.84	—	—	—	—
Pylaisiaceae	Pylaisia	30	Pylaisia falcata Schimp.	0.94	—	3.46	—	3.71
Sematophyllaceae	Sematophyllum	31	Sematophyllum subpinnatum (Brid.) E. Britton	3.05	—	—	—	—
		32	Sematophyllum phoeniceum (Müll. Hal.) M. Fleisch.	—	5.37	—	—	—
Entodontaceae	Erythrodontium	33	Erythrodontium julaceum (Schwaegr.) Paris	—	4.94	14.64	3.72	5.86
	Entodon	34	Entodon concinnus (De Not.) Paris	—	6.51	4.13	3.19	3.17
Pterobryaceae	Pterobryopsis	35	Pterobryopsis crassicaulis (Müll. Hal.) M. Fleisch.	—	2.08	—	—	—
Pylaisiadelphaceae	Brotherella	36	Brotherella henonii var. henonii	1.07	—	—	—	—
Plagiotheciaceae	Plagiothecium	37	Plagiothecium cavifolium (Brid.) Z. Iwats.	—	5.10	—	—	10.65
		38	Plagiothecium laetum Bruch & Schimp.	1.32	—	—	—	—
		39	Plagiothecium neckeroideum Buch & Schimp.	4.84	—	—	—	—
Anomodontaceae	Anomodon	40	Anomodon minor (Hedw.) Lindb.	—	2.86	—	—	—
Brachytheciaceae	Brachythecium	41	Brachythecium brotheri Paris	4.05	2.60	—	3.28	—
		42	Brachythecium albicans (Hedw.) Bruch & Schimp.	5.01	5.20	7.63	12.72	—
		43	Brachythecium pulchellum Broth. & Paris	—	3.64	2.13	—	—
		44	Brachythecium formosanum Takaki	—	—	2.27	—	—
		45	Brachythecium amnicolum Müll. Hal.	—	—	2.44	—	—
		46	Brachythecium populeum (Hedw.) Bruch & Schimp.	1.32	—	—	—	—
	Okamuraea	47	Okamuraea brachydictyon (Cardot) Nog.	—	—	2.13	—	—
	Palamocladium	48	Palamocladium euchloron (Müll. Hal.) Wijk & Margad.	—	2.60	—	—	—
Dicranaceae	Dicranum	49	Dicranum scoparium Hedw.	2.24	—	—	—	—
Fabroniaceae	Fabronia	50	Fabronia papillidens C. Gao	—	—	2.18	—	—
Ptychomitriaceae	Ptychomitrium	51	Ptychomitrium gardneri Lesq.	—	2.19	2.36	—	—
Mniaceae	Plagiomnium	52	Plagiomnium cuspidatum (Hedw.) T.J. Kop.	—	—	2.13	—	6.40
		53	Plagiomnium rostratum (Schrad.) T.J. Kop.	0.99	—	—	—	—
Lejeuneaceae	Lejeunea	54	Lejeunea curviloba Steph.	—	3.28	—	—	—
Dicranellaceae	Dicranella	55	Dicranella heteromalla (Hedw.) Schimp.	—	4.16	—	—	—
		56	Dicranella coarctata (Müll. Hal.) Bosch & Sande Lac.	1.07	2.79	—	—	—
Thuidiaceae	Pelekium	57	Pelekium versicolour (Hornsch. Ex Müll. Hal.)A. touw	—	2.08	—	—	—
	Thuidium	58	Thuidium tamariscinum (Hedw.) Schimp.	7.15	12.44	3.02	9.04	5.00
Bryaceae	Bryum	59	Bryum argenteum Hedw.	0.94	3.18	3.15	2.30	11.02
		60	Bryum algovicum Sendt. Ex Müll. Hal.	3.08	10.10	5.95	12.32	7.48
		61	Bryum dichotomum Hedw.	1.07	—	10.16	3.72	—
		62	Bryum billarderi Schwägr.	1.07	—	—	—	—
Lepidoziaceae	Lepidozia	63	Lepidozia subtransveersa Steph.	4.48	—	—	—	—
Bartramiaceae	Philonotis	64	Philonotis mollis (Dozy & Molk.) Mitt.	—	3.38	—	—	—
Grimmiaceae	Grimmia	65	Grimmia incurva Schwaegr.	1.07	—	—	—	—

Table 4: Diversity of bryophytes under different rocky desertification degrees. There is no significant difference (P>0.05) between degrees with the same letter, and there are significant differences (P<0.05) between degrees with different letters.

Index	Nil	Potential	Slight	Moderate	Severe
R	24.75±1.50a	13.6±1.81b	12.75±1.51b	11.20±0.84b	7.75±1.71c
H	19.68±1.49a	7.57±0.49b	10.19±0.85c	5.29±0.96d	2.14±0.96e
J	5.45±0.19a	2.38±0.15b	3.09±0.09c	2.03±0.15d	0.69±0.14e

Table 5: Similarity index of bryophytes between different degrees of rocky desertification. There is no significant difference (P>0.05) between degrees with the same letter, and there are significant differences (P<0.05) between degrees with different letters.

Degrees	Potential	Slight	Moderate	Severe
Nil	0.27±0.04a	0.35±0.02b	0.31±0.05c	0.25±0.05a
Potential	——	0.65±0.06d	0.52±0.06e	0.58±0.12f
Slight	——	——	0.49±0.03g	0.49±0.04g
Moderate	——	——	——	0.54±0.09e

Table 6: Dominant species of bryophytes under different degrees of rocky desertification. Species with the top importance values (approximately 40 % to 50 % of the total species) were selected as the dominant species of rocky desertification to calculate the association coefficient (AC) index.

NO.	Nil RD	Pot RD	Sli RD	Mod RD	Sev RD
1	Campylopus fragilis	Thuidium tamariscinum	Erythrodontium julaceum	Bryum algovicum	Bryum argenteum
2	Thuidium tamariscinum	Bryum algovicum	Bryum dichotomum	Didymodon constrictus	Plagiothecium cavifolium
3	Metzgeria consanguinea	Hyophila involuta	Hyophila involuta	Brachythecium albicans	Tortula planifolia
4	Sematophyllum phoeniceum	Entodon concinnus	Brachythecium albicans	Thuidium tamariscinum	Bryum algovicum
5	Brachythecium albicans	Didymodon ditrichoides	Didymodon constrictus	Trichostomum brachydontium	Brachythecium albicans
6	Plagiothecium neckeroideum	Brachythecium albicans	Bryum algovicum	Bryum billarderi	Plagiomnium cuspidatum
7	Lepidozia subtransveersa	Trichostomum brachydontium	Entodon concinnus	Diphyscium foliosum	Didymodon constrictus
8	Brachythecium brotheri	Plagiothecium cavifolium	Pylaisia falcata	Didymodon fallax	Erythrodontium julaceum
9	Pseudotaxiphyllum pohliaecarpum	Erythrodontium julaceum	Trichostomum brachydontium	Campylopus fragilis	Didymodon ditrichoides
10	Heteroscyphus coalitus	Dicranella heteromalla	Bryum argenteum	——	——
11	Bryum algovicum	Weissia controversa	——	——	——
12	Sematophyllum subpinnatum	——	——	——	——
13	Hypnum oldhamii	——	——	——	——
14	Diphyscium foliosum	——	——	——	——
15	Leucobryum juniperoideum	——	——	——	——
16	Dicranum scoparium	——	——	——	——

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Responses of bryophyte diversity, community and Chlorophyll content to rocky desertification succession

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