The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China

Ding, Jingyi; Zhao, Wenwu; Daryanto, Stefani; Wang, Lixin; Fan, Hao; Feng, Qiang; Wang, Yaping

doi:https://doi.org/10.5194/hess-21-2405-2017

Articles | Volume 21, issue 5

https://doi.org/10.5194/hess-21-2405-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

Vegetation changes under a changing environment and the impacts...

https://doi.org/10.5194/hess-21-2405-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 21, issue 5

Research article

|

09 May 2017

Research article |

| 09 May 2017

The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China

Jingyi Ding, Wenwu Zhao, Stefani Daryanto, Lixin Wang, Hao Fan, Qiang Feng, and Yaping Wang

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Final revised paper (published on 09 May 2017)
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Preprint (discussion started on 17 May 2016)
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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of “The distribution pattern of desert riparian forests and its relationship with soil moisture and soil properties in the low reaches of Heihe River, China”, by Ding and co-authors', Anonymous Referee #1, 16 Jun 2016
- AC1: 'response to reviewer1', J. Y. Ding, 01 Aug 2016
RC2: 'Comment to Manuscript: The distribution pattern of desert riparian forests and its relationship with soil moisture and soil properties in the low reaches of Heihe River Basin, China', Anonymous Referee #2, 21 Jun 2016
- AC2: 'response to reviewer2', J. Y. Ding, 01 Aug 2016

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (26 Sep 2016) by Kevin Bishop

AR by J. Y. Ding on behalf of the Authors (18 Nov 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (20 Nov 2016) by Kevin Bishop

RR by Anonymous Referee #1 (01 Dec 2016)

Suggestions for revision or reasons for rejection

I reviewed an earlier version of this MS and find this revision much improved. The authors implemented several of my suggestions, gathering a large amount of spatial and long-term data (NDVI and soil moisture) to support their conclusions. However, the manuscript remains in places inconsistent, incomplete, or unclear, and language must be improved (as of now, it is not up to the standards of HESS). The accuracy of the added remotely sensed soil moisture data needs to be stated to assess if patterns are significant. My comments are listed below (I did not report all the numerous language issues):

P2, L15: I would report the 43.5% of the total variance explained, rather than the fraction of explained variance captured by spatial heterogeneity factors. The 43.5% figure better represents the overall explaining power.
P2, L17: missing word “35.9% of the total…”
P2, L19: add that the 100 cm moisture is obtained from remote sensing products
P3, L25: check verb tenses
P4, L6: soil moisture is water, so writing “Apart from water… soil moisture…” seems contradictory
P4, L11: “another study”
P4, L12: sentence structure does not work “with… exerted”?
P7, L9: “water conveyance was delivered” (?)
P7, L16 and elsewhere: gradients should include measurement points at different distances. Here it seems you are referring to zones or bands at a given distance from the river
P7, L25: try to be specific “number of herb species” or “number of individual plants”?
Section 2.3: clarify which product you are using for the soil moisture fields, and the expected accuracy. Without that, it is hard to trust the observed trends. Also, how was soil moisture sampled in 2013-2015? Same sampling regime as in the present study?
P9, L3: as stated, RH and RC are defined in the same way – do they differ or not?
Figure 3, legend: “Unchanged”
P14, L10: sentence structure does not work “with… were”?
Figure 5(b): units are missing. Values suggest that this NDVI change rate is not simply calculated as the difference between NDVI values between two years. Please clarify what is shown on the y-axis
P17, L2: “gradients” or “bands” at a given distance?
Figure 8, caption: “Pearson correlation coefficient”
Section 3.5: not clear how spatial and temporal data have been integrated. In Table 3, the fractions of explained variance in space and time are combined, yielding the odd result that adding explanatory variables (i.e., adding temporal factors to the spatial factors) decreases the fraction of explained variance. Overall this part of the results is not clear. Also check the number of significant digits in Table 3.
P21, L4: soil moisture is higher around 1000 m from the river because the soil has finer texture. This pattern has not to do with the available amount of water, but it is caused by using volumetric or gravimetric moisture content data across a texture gradient.
P21, L11: fine particles are expected to decrease the infiltration capacity, not increase it (saturated hydraulic conductivity is lower in fine-textured soils)
P22, L2: check sentence structure “elevate of groundwater”?
P23, L10: “soil nutrients”
P23, L16: check sentence structure “vegetation recovery especially herbs”?
P24, L4: “a sharp decrease”
P24, L29: tree cover has no significant relation with soil biogeochemical pools, including organic matter (if I interpret correctly Table 1), so the claim on the role of trees is not supported
P25, L4: “gradient” or “band”?
P25, L6: use “change” instead of “destroy”?
P25, L12 and L18: other odd sentences, please re-phrase

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RR by Anonymous Referee #3 (21 Dec 2016)

Suggestions for revision or reasons for rejection

The authors used one-time field survey data in July 2015 to detect the spatial pattern of community characteristics in desert riparian forest across different distances from the rivers, and NDVI data from 2000-2014 to analyze the temporal variation of desert riparian forests. My first concern is that the gaps of previous studies to be figured out or the novelty of this study is not explicitly highlighted or addressed. The second concern is that the effects of environment factors on spatial pattern and temporal variation of desert riparian forests should be analyzed separately. In the current version, it seems that there are mixed. The spatial pattern is mainly subjected to spatial heterogeneity of soil properties, soil water content and ground water, but the temporal variation is mainly affected by variation of soil water content, ground water and runoff. The soil properties did not played an important role in the temporal variation of desert riparian forests in certain cite as it almost remained unchanged. Third, the writing is somewhat tedious, and it should be condensed and polished.

1.There were five transects along the river to conduct field survey. Is there any variability of vegetation characteristic among those transects?
2.The soil moisture and ground water during 2000-2014 were extracted from the retrieved remote sensing data. The results should be validated by comparing with measured data available in some years or some sites. This is important.
3.The Ejina Oasis is mainly subjected to the runoff at Donghe station, not Zhengyixia station which influences the whole downstream of Heihe River Basin.
4.The variation of groundwater across different distance should be shown in Fig. 6, and incorporated to the analysis of correlation between distribution pattern and environmental factors.

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ED: Publish subject to revisions (further review by Editor and Referees) (30 Dec 2016) by Kevin Bishop

AR by J. Y. Ding on behalf of the Authors (03 Feb 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Feb 2017) by Kevin Bishop

RR by Anonymous Referee #4 (17 Mar 2017)

Suggestions for revision or reasons for rejection

Comments
While this manuscript (MS) is interesting and at this stage pretty well written, there are still several ambiguities and shortcomings. After I read the MS I went back to the first round of reviews to see what comments other referees had, and to my surprise I recognized some of my own comments there. That is, some comments from the first round are still valid and have not been properly addressed.

All in all, the language in the main text of the MS is fine now (though I found some wordings that sound strange to me, especially in the Introduction, and the language of the Supplementary, especially S4, needs improvement), but the presentation is still unclear in certain parts of the MS. For instance, in the Discussion it was at times not clear to me what are results/conclusions of this work and what is conclusions from the literature (this comment also applies to parts of the Introduction). This may be a language issue, since past tense is used throughout, even for previously published results. This usage gives the impression that the authors are talking about their results although they are actually discussing results from the literature. An example:
“Bulk density accounted for 13.51% of the total explanation of the vegetation variance and was negatively correlated with the annual average NDVI (NDVI_a) and the annual variability of NDVI (NDVI_c). In the hyperarid zone, soils with high bulk density were often characterized as having a high proportion of coarse soil particles but low clay content” (P21, lines 18-22)

I guess the first sentence here refers to results from this study whereas the second sentence refers to the literature. However, the usage of “were” instead of “are” in the second sentence give the impression that this is a result of the present study (though this has not been shown in the MS). This kind of wording is very confusing, but common throughout the Discussion (see also e.g. P19, lines 12-19) and Introduction.

Some of the sampling procedures and monitoring require better descriptions (and this was one of the comments from the first round of reviews). For instance, how were the vegetation quadrats chosen? Randomly? How does the groundwater monitoring transect look like (e.g. how many wells, how deep were the wells, what was the precision and accuracy of the HOBOs and at what distances from the river were the wells located)? Same thing with soil moisture monitoring – where was this done? At how many sites? And where were the sites located? Adding the locations of these monitoring sites to the map would be helpful.

I am not familiar with all the indices used in the manuscript but I found the description of some of them incomplete. For example, how are the variables/parameters in equations 1 and 2 defined? Also, could you please cite a source for this method? What does A and Ai stand for in equation 4? What do you mean by “importance value” (P. 10, line 26)? The variables TN, TP and TS are never defined – what do they stand for (again, this was a comment by one of the first referees)? How is riparian zone defined? Based on distance, geomorphology, soil properties, topography or something else?

Not all data are reported. The soil characteristics, which are key to the paper, are never reported. Why not add a table with those data?

Some of the supplementary material is not referred to in the main text. If it is essential for the MS, it should be referred to.

Based on the history of this MS I perhaps should recommend rejection, especially since not all previous comments have been addressed. However, the main story is interesting (though I have to admit that the topic is far beyond my own competence, not being a desert ecologist). I therefore suggest major revisions of the MS before the editor should consider it for publication.

Detailed comments (these are only the most important minor comments I found)
P3, line 2: what do you mean by “diversity level”? Biodiversity?
P3, line 13: What oasis area? Do you refer to a specific oasis or oases in general?
P3, lines 18-29: I found this section confusing. You start off with general statements but then suddenly you refer to specific results. It was not clear to me what refers to desert forests in general and what is specific info about desert forests in the Heihe Basin.
P4, line 5-6: Does soil moisture affect hydrological processes? Or are hydrological processes affecting soil moisture?
P4, line 9: Are you talking about diversity or abundance? Most of the MS is about diversity so I find it strange that you talk about abundance here.
P4, line 12: Changes due to what?
P5, line 6-8: I do not think you ever address the second part of this objective, and I do not think that you should either. I suggest you remove it; you do not present any results related to this objective (“appropriate restoration and protection measures … under a changing environment”).
P5, line 8: I suggest you use “studied” or “sampled” instead of “used”.
P5, line 11: What sampling? You have not described any sampling thus far.
P6, line 5: Roads are used for transport and travel – remove this sentence, it is a tautology
P6, line 11: I don’t think these are formal soil types according to common soil classification schemes (e.g. FAO)
P6, Figure 1. The second sentence is repetition from the main text – is it necessary?
P8, line 8: 1000 m sound pretty coarse to me – what is the cause of this resolution?
P 11, line 1: what is a “contribution rate”?
P15, lines 18-19: this is really methods description
P17, lines 11-13: this is really methods description
P17, lines 13-17: I do not understand all these percentages – could you clarify? Also, I guess you should refer to Fig S7 here.
P19, line 10: what does “this region” and “They” refer to?
P19, line 12-19: Are these conclusions based on this study? I do not think it is possible to draw these conclusions based on the data from this study. The wording is confusing.
P20, line 4: No results presented to show this
P20, line 14: No results presented to show this
P23, lines 15-19: I do not think this paragraph is necessary and suggest that you remove it.
P23, lines 26-27: This has not been mentioned before. I guess you could describe the ecological water conveyance better in the Introduction
P24, lines 1-5: I do not think this paragraph is necessary and suggest that you remove it.

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ED: Publish subject to minor revisions (further review by Editor) (29 Mar 2017) by Kevin Bishop

AR by J. Y. Ding on behalf of the Authors (07 Apr 2017) Author's response Manuscript

ED: Publish as is (09 Apr 2017) by Kevin Bishop

AR by J. Y. Ding on behalf of the Authors (16 Apr 2017) Manuscript

Short summary

In this study, we focused on exploring the spatial distribution and temporal variation of desert riparian forests and their influencing factors based on field experiment and remote sensing data. Our result revealed how the environmental factors shape the spatial distribution and temporal variation of desert riparian forest in the downstream Heihe river. The results of this study provide support for the effective restoration of desert riparian forest in the hyperarid zone.