在本研究中，我们沿降雨时间梯度连续5年进行了田间试验，以研究巴丹吉林沙漠南缘灌木草本植物群落的相互作用，更具体地说，研究了优势灌木物种Calligonum mongolicum对非生物环境变量和树冠下植物物种表现的影响。我们发现灌木可以改善树冠下的水循环、土壤性质、植物生物量、密度、覆盖度和丰富度，更重要的是，灌木在夏季对树冠下土壤湿度的积极影响会随着降雨量的减少而减弱，这种模式可以部分解释灌木与其下层植物之间的积极相互作用的崩溃。这些结果提供了经验证据，即在极端干旱环境中，灌木对林下植物群落的积极作用可能会随着干旱胁迫的增加而减弱，并变得中性。", "ds_source": "
2013-2016年7月初，在一个永久性样地（100×200 m）中随机选取了25株大小相似的C. mongolicum灌木，并做了相应的标记。样地中的优势树种为Calligonum mongolicum，树冠下的所有树种（目标树种）均为一年生植物。每年9月，在每种选定灌木的冠层下建立一个1×1 m的四分点，并在灌木间隙建立一个露地四分点，每种选定灌木的露地四分点延伸5-8 m。然后测量每个四分区内地下植被的地上生物量、个体密度、总盖度和物种丰富度。2012年9月下旬，我们从永久样地中随机选取了19株灌木，在灌木下和灌木间隙建立的四分区（1×1 m）内测量了林下植被的个体密度、总盖度和物种丰富度。由于鼠害和虫害，2013年和2015年选取的6种和4种灌木样本在分析前被剔除。", "ds_process_way": "
采用最大似然估计法拟合的线性混合效应模型(LMM)来衡量生长季降雨量对灌木调节的非生物因素的影响。为了分析对SWC的影响，将每个生长季的降雨量、生境类型（灌木下或开阔地的四分区）和月份（调查土壤湿度时）作为固定项，配对灌木作为随机项。\n
采用广义线性混合效应模型(GLMM)来衡量生长季降雨和土壤水分对亚冠层植物群落的影响。为了分析降雨对灌木调节的林下植物的影响，将降雨和生境作为固定项，配对灌木作为随机项。", "ds_quality": "
灌木除了影响旱地的土壤湿度外，还可影响其林下微生境中的其它非生物因素。我们的研究结果表明，在Calligonum mongolicum灌木下，蒸发、辐照度、土壤有机质和容重都会受到调节。它们在生产力低下的生态系统中具有促进作用，通常有利于它们周边植物，并有助于植物与植物之间的积极关系。", "ds_acq_start_time": "2013-01-01 00:00:00", "ds_acq_end_time": "2015-12-31 00:00:00", "ds_acq_place": "巴丹吉林沙漠南缘灌木草本植物群落", "ds_acq_lon_east": 100.11666666666666, "ds_acq_lat_south": 39.36666666666667, "ds_acq_lon_west": 100.11666666666666, "ds_acq_lat_north": 39.36666666666667, "ds_acq_alt_low": null, "ds_acq_alt_high": null, "ds_share_type": "open-access", "ds_total_size": 18846, "ds_files_count": 3, "ds_format": "", "ds_space_res": null, "ds_time_res": "", "ds_coordinate": "无", "ds_projection": "", "ds_thumbnail": "81ba9544-0489-4793-a3b3-6fab31fc64fc.png", "ds_thumb_from": 0, "ds_ref_way": "", "paper_ref_way": "", "ds_ref_instruction": "", "ds_from_station": null, "organization_id": "0a4269e1-65f4-45f1-aeba-88ea3068eebf", "ds_serv_man": "敏玉芳", "ds_serv_phone": "0931-4967596", "ds_serv_mail": "ncdc@lzb.ac.cn", "doi_value": "", "subject_codes": [ "170.45" ], "quality_level": 3, "publish_time": "2023-07-14 10:50:41", "last_updated": "2023-07-24 10:24:58", "protected": false, "protected_to": null, "lang": "zh", "cstr": "11738.11.NCDC.ZENODO.DB3959.2023", "i18n": { "en": { "title": "Extreme drought stress shifts net facilitation to neutral interactions between shrubs and sub-canopy plants in an arid desert（2013-2015）", "ds_format": "", "ds_source": "
In early July 2013–2016, 25 similar-sized C. mongolicum shrubs were randomly selected from a permanent sample plot (100×200 m) and marked accordingly. Calligonum mongolicum was the dominant species in the sample plot, and all the sub-canopy species (target species) were annuals. In September of each year, a single 1×1 m quadrat was established under the canopy of each selected shrub, and an open-area quadrat was placed in shrub interspaces, extending from 5 to 8 m for each selected shrub. Then the above-ground biomass, individual density, total cover, and species richness of the understory vegetation were measured within each of the quadrats. In late September of 2012, we randomly selected 19 shrubs from the permanent sample plot and measured the individual density, total cover, and species richness of understory plants within quadrats (1×1 m) that were established both underneath the shrubs and within shrub interspaces. The total cover of understory species was estimated using the Braun–Blanquet scale (Westhoff and Van der Maarel 1978), and aboveground biomass of the understory species was measured using an electronic balance, after oven-drying at 80°C for 48 h. Due to rodent and pest damage, the samples of six and four of the shrubs selected in 2013 and 2015 were eliminated before analysis.", "ds_quality": "
In addition to affecting the soil moisture of drylands, shrubs can also affect other abiotic factors in their understory microhabitats. Our results indicated that evaporation, irradiance, soil organic matter, and bulk density are all modulated beneathCalligonum mongolicum shrubs. They have facilitative effects in underproductive ecosystems, generally benefiting their neighbours, and contributing to positive plant–plant", "ds_ref_way": "", "ds_abstract": "
In the present study, we conducted a field experiment along a temporal rainfall gradient for five consecutive years, in order to investigate interactions in a shrub-herbaceous plant community at the southern edge of the Badain Jaran Desert, and, more specifically, investigated the effects of Calligonum mongolicum, a dominant shrub species, on both abiotic environmental variables and the performance of sub-canopy plant species. We found that shrubs can improve sub-canopy water regimes, soil properties, plant biomass, density, cover, and richness and, more importantly, that the positive effect of shrubs on sub-canopy soil moisture during the summer diminishes as rainfall decreases, a pattern that partly explains the collapse of the positive interaction between shrubs and their understory plants. These results provide empirical evidence that the positive effect of shrubs on understory plant communities in extreme arid environments may decline and become neutral with increasing drought stress.
", "ds_time_res": "", "ds_acq_place": "Shrub and herb communities in the southern edge of Badain Jaran Desert", "ds_space_res": "", "ds_projection": "", "ds_process_way": "Linear mixed-effects model (LMM) that was fitted using maximum likelihood estimation was used to measure the effects of growing-season rainfall on abiotic factors modulated by shrubs. To analyse the effect on SWC, the rainfall of each growing season and habitat type (quadrats beneath shrubs or in open areas) and months (when soil moisture was investigated) were included as fixed terms, with paired shrubs as random terms. \n
Generalized linear mixed-effect model (GLMM) was used to measure the effects of growing-season rainfall and soil moisture on sub-canopy plant communities. To analyse the effect of rainfall on the understory plants modulated by shrubs, rainfall and habitat were included as fixed terms, with paired shrubs as random terms.", "ds_ref_instruction": "" } }, "submit_center_id": "ncdc", "data_level": 0, "license_type": "CC BY 4.0", "ds_topic_tags": [ "生物量", "个体密度", "物种丰富度", "生境类型" ], "ds_subject_tags": [ "地理学" ], "ds_class_tags": [], "ds_locus_tags": [ "巴丹吉林沙漠南缘灌木草本植物群落" ], "ds_time_tags": [ 2013, 2014, 2015 ], "ds_contributors": [ { "true_name": "赵文智", "email": "zhaowzh@lzb.ac.cn", "work_for": "中国科学院西北生态环境资源研究院", "country": "中国" }, { "true_name": "周海", "email": "zhouhai1201@126.com", "work_for": "中国科学院西北生态环境资源研究院", "country": "中国" } ], "ds_meta_authors": [ { "true_name": "赵文智", "email": "zhaowzh@lzb.ac.cn", "work_for": "中国科学院西北生态环境资源研究院", "country": "中国" } ], "ds_managers": [ { "true_name": "赵文智", "email": "zhaowzh@lzb.ac.cn", "work_for": "中国科学院西北生态环境资源研究院", "country": "中国" } ], "category": "生态" }