Table of Content

10 November 2023, Volume 42 Issue 11

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Comparison of growth, photosynthetic, and chlorophyll fluorescence characteristics for different provenances of Arcocarpus fraxinifolius.

CHEN Tianxiao, BAI Xiaogang, ZHANG Zhiwei, HE Qian, HU Bing, ZENG Bingshan, LU Zhaohua

2023, 42(11):  2561-2568.  doi:10.13292/j.1000-4890.202311.023

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We examined the growth, photosynthetic pigment content, photosynthetic response parameters, and chlorophyll fluorescence parameters of 1-year-old seedlings of three provenances of Arcocarpus fraxinifolius (Hechi Duan, Baise Tianlin and Xishuangbanna) and analyzed the influences of climatic factors of the provenance sites. The results showed that: (1) The maximum net photosynthetic rate (P_max), light saturation point (LSP), chlorophyll a (Chla), chlorophyll b (Chlb), carotenoid (Car), PSⅡ primary light energy conversion efficiency (F_v/F_m), electron transfer efficiency (ETR) and actual photochemical efficiency (Φ_PSⅡ) of Hechi Duan provenance were significantly higher than those of the other two provenances (P<0.05), while apparent quantum efficiency (AQY), light compensation point (LCP) and luminescence chemical quenching coefficient (NPQ) showed no variation among the three provenances (P>0.05). It indicated that Hechi Duan provenance had a wider range of light adaptation, higher light energy conversion efficiency and higher maximum net photosynthetic rate, which was consistent with its growth performance. (2) The climatic factors of the provenance site had a significant impact on the growth characteristics and photosynthetic characteristics. The Hechi Duan provenance, whose climatic factors (average annual rainfall and annual sunshine duration) were closer to that of the experimental site, showed the best growth and the largest P_max. The Xishuangbanna provenance with larger difference in climatic factors to the experimental site had the lowest growth and the smallest P_max. It is concluded that genetic differences caused by climatic differences of provenance sites are one of the main reasons responsible for the differences in growth and photosynthetic characteristics of A. fraxinifolius among different provenances.





Effects of microhabitat on the growth of Phellodendron amurense saplings.

LIU Chang, LU Qi, WANG Shengcai, CHEN Mengyuan, XING Shaohua

2023, 42(11):  2569-2577.  doi:10.13292/j.1000-4890.202311.029

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The dominant factors affecting plant growth vary across the stages of life history. Understory microhabitats play a significant role on plant growth and development during juvenile stage. In 2021, we surveyed Phellodendron amurense saplings planted in 2014 beneath a natural forest in Baihuashan Nature Reserve, and measured the biotic factors (density of con and heterospecific seedling neighbors, density of herbaceous and shrub neighbors, and adult neighborhood index) and abiotic factors (leaf area index, soil nutrients, and microtopography indices) around the saplings. Linear mixed models were used to assess the effects of biotic factors and abiotic microhabitat factors on the growth rates of the established saplings. The results showed that both biotic and abiotic factors affected the growth of P. amurense saplings, with different magnitudes in their impacts. Heterospecific adult neighbors had the most significant negative effect on the growth of saplings, explaining 34.1%-47.7% of the variance in their growth. Light intensity also had a negative effect, which explained 18.1%-25.3% of the variance. Soil nitrogen, available potassium, and organic carbon promoted the crown extension of P. amurense, accounting for 21.1% of the variance of the growth. Among the microtopographic factors, the topographic wetness index had a significant positive impact on the growth of saplings, explaining 19.5% of the variance, whereas slope had a negative but weak effect on the growth, accounting for 11.5% of the variance. Shrubs and grasses and the conspecifics did not affect the growth of P. amurense saplings. In conclusion, deciduous broad-leaved forests with flat microtopography, moist and fertile soil, rich in nitrogen and potassium, and high canopy density would facilitate the ex situ conservation of P. amurense.





Effects of different water supply amounts on physiology, growth, and fruit quality of walnut trees.

CHEN Tuqiang, XU Guiqing CHEN Jiazhen, LIU Shensi, LI Jinyao, HU Haifang

2023, 42(11):  2578-2587.  doi:10.13292/j.1000-4890.202311.016

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Water is a key factor limiting the improvement of both quality and yield of walnut industry in arid areas. The effects of different water supply amounts on physiology, growth, and fruit quality of walnut trees remain unclear. We conducted an irrigation experiment with three treatments, i.e., deficit (DI), conventional (CI), and excess irrigation (EI). We measured leaf hydraulic traits, photosynthetic physiological characteristics, soluble sugar content, leaf area, branch growth, fruit morphology and no kernel or deflated kernel rate at different canopy heights of ‘Wen 185’ walnut trees. The results showed that: (1) Midday leaf water potential decreased significantly  with decreasing irrigation and increasing canopy height. Midday leaf water potential at the upper canopy was significantly lower than that at the lower canopy. (2) Different irrigation amounts did not affect light compensation point, light saturation point, maximum net photosynthetic rate, maximum photochemical efficiency, and chlorophyll SPAD. (3) Irrigation treatments did not significantly affect soluble sugar content of leaves and fine roots, but the soluble sugar content of walnut kernels was significantly increased with decreasing irrigation and accumulated with increasing canopy height. (4) Leaf area was significantly decreased and Huber value was significantly increased with the reduction of irrigation. The reduction of irrigation did not affect fruit morphology, but increased the no kernel or deflated kernel rate, with a rate being 87.9% higher in the DI group than in the EI group. The no kernel or deflated kernel rate at the upper canopy was 41.8% higher than that at the lower canopy. Our results indicated that walnut trees resist drought by increasing Huber value and decreasing leaf area to maintain stable photosynthesis, but the hydraulic restriction caused by increasing canopy height will aggravate the drought stress of plants, resulting in an increase in the no kernel or deflated kernel rate.





Responses of soil AMF community composition in artificially reseeding grassland to different grazing durations.

SU Yingying, LI Xuxu, LI Xiangjun, GONG Jinchao, WANG Wen, MA Congyu, SUN Feida, ZHANG Xinquan, ZHOU Jiqiong

2023, 42(11):  2588-2596.  doi:10.13292/j.1000-4890.202311.013

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To understand the effects of different grazing durations in artificial reseeding grasslands on the symbiotic relationship between soil arbuscular mycorrhizal fungi (AMF) and plants and the composition of AMF community, we investigated plant community diversity, mycorrhizal colonization rate, AMF spore density and mycelium density in soil of abandoned land, grassland grazed for 25 years, and grassland grazed for 5 years in Yunnan Provincial Breeding and Promotion Center, and analyzed the community composition of AMF in soil by Illumina sequencing. The results showed that compared with abandoned land, grazing increased the proportion of legumes in grasslands and decreased AMF mycelium density, but there was no significant difference in soil AMF spore density and mycorrhizal colonization rate between grazed grasslands and abandoned land. Grazing increased AMF community richness compared to abandoned land, but the richness did not change significantly with increasing grazing duration. The AMF community str〖JP2〗ucture varied significantly across different grazing durations. Endemic species of AMF -Glomus-group-B-Glomus-ORVIN-GLO4-VTX00278- emerged in the grassland grazed for 25 years. Legume importance value, soil pH, NH₄⁺-N and available phosphorus content were the main factors affecting the composition of AMF community.





Spatial differentiation of soil fertility in a photovoltaic power station in rocky desertification zone.

WU Zhiquan, LUO Zhongxin, LUO Jiufu, SUI Xin, WU Sainan, LUO Xiaolin

2023, 42(11):  2597-2603.  doi:10.13292/j.1000-4890.202311.005

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We investigated the effects of environmental heterogeneity in photovoltaic (PV) field on soil nutrient and fertility quality of the vegetation restored soil in PV field of rocky desertification area, aiming to provide scientific and technological support for ecological restoration in fragile rocky desertification area. The horizontal (intervals/underneath of panels and front/rear of panel eaves) and vertical (0-20, 20-40, and 40-60 cm) spatial differentiation characteristics of soil nutrients in the vegetation restoration area were analyzed by principal component analysis and one-way ANOVA to assess the effects of shading by PV panels on soil fertility. The results showed that different degrees of shading of PV panels had minor effects on soil water-soluble organic carbon and available phosphorus concentrations, with no differences among different locations (P>0.05). Total nitrogen, total carbon and nitrate nitrogen concentrations showed no difference in the location under the panels compared with the location between the panels (P>0.05), and available potassium concentration was significantly elevated (P<0.05). In addition, different degrees of shading of PV panels did not affect soil quality index (SQI) (P>0.05), and soil nutrients had significant surface aggregation characteristics, indicating that the protection and improvement of topsoil in the PV field is of great significance for vegetation restoration.





Effects of nitrogen reduction fertilization on sugarcane biomass and the concentrations of soil nitrate and ammonium nitrogen.

MAO Bing, ZENG Yue, LAI Caiting, YANG Yan, ZHOU Chunhong, LI Zhuoting, XU Qiangsheng, LI Tinghua

2023, 42(11):  2604-2612.  doi:10.13292/j.1000-4890.202311.014

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Excessive nitrogen fertilizer application is widespread in sugarcane planting in China. It is important to investigate the effects of nitrogen application rates on sugarcane biomass and concentrations of soil inorganic nitrogen for formulating reasonable nitrogen application rates to reduce the risk of environment pollution caused by nitrogen leaching. In this study, a field experiment was carried out to explore the effects of four nitrogen application rates \[0 (N0), 300 (N300), 400 (N400), and 500 kg N·hm^-2 (N500, the conventional nitrogen application rate)\] on sugarcane biomass and soil inorganic nitrogen concentration in different soil depths (0-10, 10-20, 20-40 cm) on May 9, May 19, June 19, July 20, August 19, September 21, October 20 and November 19, 2021. The results showed that sugarcane height, stem biomass, and root biomass were significantly higher under the treatments of N400 and N500 than that under N0 from June to November. There were no significant differences in sugarcane height and stem biomass between the treatments of N400 and N500 in September, October, and November. Sugarcane height and biomass of leaf, stem and root varied across different months, while nitrogen application rates significantly affected sugarcane height and root biomass. The concentrations of soil nitrate and ammonium nitrogen decreased with soil depth. However, the accumulated amount of soil nitrate and ammonium nitrogen at 0-10 cm soil depth was generally lower and that at 20-40 cm soil depth was generally higher. Growth month and nitrogen application rates significantly affected the concentration and accumulation of soil ammonium and nitrate nitrogen. Across different growth months, the accumulation of soil ammonium and nitrate nitrogen in the N500 treatment was generally higher than that in other fertilizer treatments. Therefore, the risk of inorganic nitrogen leaching may increase with increasing nitrogen application rates. Compared with conventional nitrogen application rate, reduced nitrogen application did not affect sugarcane biomass but could reduce the risk of soil inorganic nitrogen leaching.





Decomposition of green manures and their effects on soil carbon and nitrogen, and crop yield in a dryland spring maize field.

ZHANG Yining, WANG Jun

2023, 42(11):  2613-2621.  doi:10.13292/j.1000-4890.202311.007

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To provide scientific basis for rational utilization of green manures in dryland cropping systems, we examined the characteristics of decomposition and nutrient release of green manure. Four types of green manures (including crimson clover, vetch, ryegrass and oat) were used for onsite decomposition incubation and their impacts on soil organic carbon and total nitrogen and crop yield were investigated in a spring maize system. All green manures decomposed rapidly in 0-14 d after incorporation, while the decomposing rate slowed down after six weeks. On the 42 d after the incorporation, the cumulative decomposition was more than 55% for all green manures, with a carbon releasing rate of 59.79%-74.75% and a nitrogen releasing rate of 60.79%-76.61%. On the 130 d after the incorporation, the cumulative decomposition rate was greater than 60% for all green manures, which was higher for leguminous green manure than gramineous green manure. Incorporation of green manures increased the contents of soil organic carbon and total nitrogen. Compared to the control without green manure, the incorporation of green manures increased maize yield by 2.21%-7.06%, with stronger effects of the leguminous green manures than gramineous green manure. In conclusion, leguminous green manure is more suitable for soil health and crop production in dryland cropping systems in northwest China.





Effects of soil moisture threshold on photosynthetic physiological parameters of potato leaves in semi-arid region.

YANG Yang, ZHAO Hong, TANG Guoying, HUANG Xiaoyan, WANG Heling

2023, 42(11):  2622-2629.  doi:10.13292/j.1000-4890.202311.024

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Using artificial water supplementation and natural water control methods, we measured the light response process of photosynthetic physiological parameters of potato leaves under different water conditions and further analyzed the threshold effects for the responses to soil water. Soil moisture was set as 55%, 65% and 75% field water-holding capacity for drought stress treatments, 80% field water-holding capacity for control treatment and 85% field water-holding capacity for waterlogging treatment. The results showed that net photosynthetic rate (P_n), water use efficiency (WUE), and light response parameters of potato leaves had obvious water critical effects. The apparent quantum efficiency (AQY), maximum net photosynthetic efficiency (P_nmax), and light saturation point (LSP) increased first and then decreased with increasing soil water content, while light compensation point (LCP) and dark respiration rate (R_d) first decreased and then increased. Under waterlogging or drought stress, the ability of light absorption and conversion of potato leaves under weak light was reduced, the utilization of strong light and weak light was inhibited, and dry matter accumulation was maintained by reducing respiratory consumption. With increasing soil moisture, P_n and WUE increased first and then decreased, but the critical values of moisture were different. The relative soil water content (W_r) at 56.7% was the critical point of stomatal limitation in potato leaves. The W_r at 96.3% was water saturation point of P_n, and W_r at 70.1% was the high efficiency point of WUE. Photosynthetic capacity of potato leaves under waterlogging was higher than that under drought stress. The moisture threshold of potato in semi-arid area was determined by mathematical model. The W_r value between 70.1% and 96.3% was high-yield and high-efficiency water, in which the photosynthetic productivity and water use efficiency of potato were higher. Therefore, W_r between 70.1% and 96.3% is suitable for potato growth in semi-arid area. Photosynthetic capacity of potatoes under waterlogged conditions is significantly higher than that under drought stress in semi-arid area.





Effects of short-term fertilization and enclosure on plant biomass and species richness in an alpine meadow.

ZHAO Wei, BENG Shaohao, ZHOU Xiaolong, ZHANG Shiting, REN Zhengwei

2023, 42(11):  2630-2637.  doi:10.13292/j.1000-4890.202311.002

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Fertilization and enclosure are two important factors affecting plant biomass and diversity of alpine mea-dow. It is of great scientific significance to elucidate the processes and mechanisms underlying how both factors affect plant community for the sustainable development of alpine meadow. In this study, we analyzed the responses of plant community and species richness to fertilization (nitrogen, phosphorus, and potassium) and enclosure (grazing exclusion) in an alpine meadow on the eastern Qinghai-Tibet Plateau, and examined the underlying mechanisms of species loss. The treatments of fertilization and fertilization + enclosure significantly increased community aboveground biomass, while enclosure alone had no such effect. Community light transmittance and species richness significantly decreased in all the three treatments. At the functional group level, changes of aboveground biomass under fertilization and fertilization + enclosure mainly resulted from a significant increase in grass biomass and a significant decrease in sedge biomass. There was no significant difference in miscellaneous forb biomass among different treatments. At the species level, species composition changed significantly under fertilization and fertilization + enclosure treatments, with Elymus nutans and Poa poophagorum gradually replacing Kobresia setschwanensis as the dominant species. There was a significant negative linear relationship between light transmittance and total community biomass and a significant positive linear relationship between community light transmittance and species richness, indicating that the increase of total biomass intensified the light limitation in the lower layer, and then led to the decrease of species richness through light competition. In summary, our results demonstrated that increased light competition caused by the increases of total biomass was an important driver for species loss under fertilization and enclosure conditions, providing a scientific basis for future biodiversity maintenance and management of alpine meadow.





Effects of climate factors on geographical distribution patterns of Ribes species in Heilongjiang, China.

ZHAO Wenbo, WU Liren, GUO Baitao, ZHANG Lei, ZHOU Shuang, ZHOU Chunwei, FANG Lei, LI Pengju, LIU Jia, DUAN Yadong

2023, 42(11):  2638-2645.  doi:10.13292/j.1000-4890.202311.012

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Climate is the most determinant one among factors shaping plant distribution. In this study, we explored the effects of climate factors on the distribution pattern of six Ribes species in Heilongjiang Province, China. Based on the latitude and longitude information of geographic distribution of six Ribes species in Heilongjiang Province, climatic data of the distribution points were extracted from WorldClim database by ArcGIS technology. The kernel density analysis, MaxEnt model, statistical analysis, linear regression equation, redundancy analysis and Monte Carlo test were used to quantify the contribution of climatic factors to their geographic distribution. The results showed that: (1) The six species were mainly distributed in the northwest and southeast regions of Heilongjiang Province, especially in the northwestern part, with obvious overlapping distribution. Natural habitats of the six species were characterized by dry and cold climatic conditions. The spatial distribution predicted by MaxEnt model was evidenced by field investigation. (2) Longitudinal distributions of the six species were mainly driven by the coefficient of variation of precipitation, isothermality, annual precipitation, aridity index, precipitation of the driest month. The latitudinal distributions, however, were mainly determined by mean temperature in the coldest quarter and precipitation in the wettest quarter. (3) Climate factors accounted for 100% of the cumulative variation of all data in the two axes. Results of Monte Carlo test further revealed the first three climatic factors with the highest explanatory powers for the distribution differences of the six Ribes species along latitude and longitude were mean temperature of the coldest quarter (85.7%), annual precipitation (54.2%), and maximum temperature of the warmest month (42.8%), indicating that these three climatic factors dominated the geographical distribution pattern of the Ribes species in Heilongjiang Province.





Succession characteristics and driving factors of phytoplankton functional groups in the germplasm resources reserve of middle reaches of Huaihe River.

WANG Dongwei, CHEN Yongjin, ZHOU Yanfeng, ZHANG Minying, YU Zhenfei

2023, 42(11):  2646-2654.  doi:10.13292/j.1000-4890.202311.006

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A one-year quarterly sampling survey in 2020 was conducted to explore the characteristics and driving factors of phytoplankton functional groups in the Jingtuxia Cyprinus carpio and Leiocassis longirostris national aquatic germplasm resources reserve of Huaihe River. Based on functional group classification, the temporal and spatial variations of phytoplankton community structure in the reserve were examined. Correlation analysis and redundancy analysis were used to analyze the data sets, and river ecological health index was used to explore water status in the reserve. The results showed that the phytoplankton in the reserve could be classified into 27 functional groups, and dominant functional groups were H1, J, P, Y, X2, D and MP. The seasonal variation followed a pattern of MP/P/Y (winter)-H1/J/P/Y (spring)-H1/P/X2 (summer)-D/X2 (autumn), with functional group P as the dominant functional group in spring, summer and winter. H1, P, and X2 were the common dominant functional groups in each region of the reserve, and D was the unique dominant functional group of Guohe River. Redundancy analysis results showed that chlorophyll a, permanganate index (COD_Mn), and pH were the main driving factors for the succession of phytoplankton dominant functional groups in the reserve. The ecological health index of the reserve ranged from 1.29 to 3.98, with an average of 3.07±0.72, and the water quality was generally good.





Characteristics of phytoplankton functional groups and their responses to environmental factors in the connected river-lake system of Guangzhou Haizhu National Wetland Park.

SUN Pingyu, HU Ren, OU Linjian, YANG Yufeng, WANG Qing

2023, 42(11):  2655-2664.  doi:10.13292/j.1000-4890.202311.021

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To understand the responses of phytoplankton functional groups to connectivity and heterogeneity in the connected river-lake system of Guangzhou Haizhu National Wetland Park, we conducted a quarterly survey on the phytoplankton community structure and environmental characteristics in the Shiliugang River and Haizhu Lake in 2021. A total of 168 phytoplankton species belonging to 6 phyla and 76 genera were detected, mainly consisting of Chlorophyta, Bacillariophyta, Euglenophyta, and Cyanophyta. The average abundance of phytoplankton in Haizhu Lake (64.76×10⁶ cells·L^-1) was significantly higher than that in Shiliugang River (24.09×10⁶ cells·L^-1) (P<0.05), while Shannon diversity index and Pielou evenness index in the Shiliugang River were significantly higher than those in Haizhu Lake (P<0.05). The phytoplankton in the connected river-lake system of Guangzhou Haizhu National Wetland Park could be classified into 28 functional groups according to their ecological functions. The dominant functional groups were group L_o, group J, and group P, which was represented by Merismopedia, Scenedesmus, and Aulacoseira, respectively. Water temperature, ammonium nitrogen, and total phosphorus were the main environmental factors affecting the dominant functional groups. The results indicate that the connected river-lake system has reached the level of eutrophication.





Spatiotemporal variations and driving factors of vegetation coverage on the Qinghai-Tibet Plateau.

GUO Jianxiao, SANG Huiyong, ZHAI Liang

2023, 42(11):  2665-2674.  doi:10.13292/j.1000-4890.202311.020

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Systematically understanding the spatiotemporal variations of vegetation coverage and driving factors on the Qinghai-Tibet Plateau can provide scientific basis for ecological sustainable development. By integrating MODIS normalized difference vegetation index (NDVI), land surface temperature and meteorological data, we explored the spatiotemporal variations of vegetation coverage and the relationships with the factors of precipitation, temperature, and human activities on the Qinghai-Tibet Plateau from 2001 to 2020, using dimidiate pixel model, trend analysis, partial correlation analysis, and residual analysis. Vegetation coverage on the Tibetan Plateau showed a fluctuating upward trend from 2001 to 2020, and increased spatially from northwest to southeast. There were positive correlations between vegetation coverage and climate factors, with complementarity between the effects of precipitation and temperature. There was a negative correlation between vegetation cover and surface temperature. The rise and fall amplitudes of land surface temperature were higher than that of air temperature. Air temperature was more likely to be a factor limiting the growth of vegetation. The areas where human activities have improved vegetation cover were mainly located in north-central Qinghai and north of Ngari. The degraded areas included some grassland areas of central-eastern Yushu and parts of Nagqu and Lhasa.





Effects of temperature and parental reproductive age on color morph differentiation of offsprings of peaaphid (Acyrthosiphon pisum).

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LIU Huiping, ZHANG Tingwei, LYU Ning, LIU Changzhong

2023, 42(11):  2675-2681.  doi:10.13292/j.1000-4890.202311.025

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To clarify the effects of different temperatures and parental reproductive ages on the offspring color morph differentiation, the newly-born first-instar nymphs of the red and green pea aphid (Acyrthosiphon pisum) on the 2^nd, 7^th, and 12^th parental reproductive age from F₀-F₅ were continuously raised for five generations at three temperatures (15, 22, and 26 ℃). Results showed that temperature and parental reproductive age had a significant effect on the offspring color morph differentiation. Red color morph A. pisum tended to produce green color morph offsprings at 15 ℃, while green color morph A. pisum tended to produce red color morph offsprings at 26 ℃. The proportion of non-parental color morph offspring produced by red and green parents at 22 ℃ was significantly lower than that at 15  and 26 ℃ (P<0.05). Furthermore, different parental reproductive age also had a certain effect on the offspring color morph differentiation. The parental reproductive age affected the proportion of color differentiation and the time of color differentiation in the offsprings of pea aphid (P<0.05), indicating that the onset of color differentiation in the offsprings of red and green pea aphid was related to different parental reproductive ages at the same temperature.





Habitat selection of Père David’s deer in spring, summer, and autumn in Dafeng coastal wetland of Jiangsu Province.

GAO Wenjia, WU Yongbo, ZOU Xinghong

2023, 42(11):  2682-2689.  doi:10.13292/j.1000-4890.202311.022

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Habitat selection is the process that animals actively select suitable habitats to escape predators, reproduce, and forage, reflecting the ecological needs of animals. Land covers and seven habitat variables of Jiangsu Dafeng Milu National Nature Reserve were investigated by unmanned aerial vehicle (UAV) remote sensing and field surveys in spring, summer, and autumn of 2019. The Vanderploeg selection coefficient and Scavia selection index were calculated, and statistical test and principal component analysis were performed. The results showed that: (1) in spring, Père David’s deer preferred to select the habitats of Spartina alterniflora, Imperata cylindrica, and Carex scabrifolia communities with vegetation coverage less than 30%, vegetation density less than 150 plants·m^-2, aboveground biomass less than 100 g·m^-2, and the distance to water source less than 210 m (P<0.05); (2) in summer, they preferred the habitats of S. alterniflora and I. cylindrica communities with aboveground biomass less than 40 g·m^-2 (P<0.05); and (3) in autumn, they preferred to select the habitats of I. cylindrica, S. alterniflora and Suaeda glauca communities with vegetation height less than 4 cm and vegetation density more than 30 plants·m^-2 (P<0.05). Key factors affecting habitat selection of Père David’s deer in different seasons were feeding factor, food abundance factor, and water source factor, respectively. Through revealing the differences in habitat selection by Père David’s deer in spring, summer, and autumn, our results provided the reference for the conservation and restoration of Père David’s deer and their habitats in Dafeng Milu National Nature Reserve.





Activity pattern analysis of golden takin （Budorcas taxicolor bedfordi) using infrared camera traps.

QI Hongyun, GONG Minghao, WEN Wanyu

2023, 42(11):  2690-2694.  doi:10.13292/j.1000-4890.202311.028

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Golden takin (Budorcas taxicolor bedfordi) is a seasonal short-day species, but few studies focused on takin’s evening rhythm. Most studies collected activity data at a fixed time, resulting in poor data integrity and continuity of its all-weather activity rhythm. To understand the activity patterns and influencing factors of golden takin, camera trapping was used to monitor golden takin in Sangyuan National Nature Reserve in Shaanxi Province from October 2018 to May 2020. Golden takins are mainly diurnal activities. The peak activity occurred at 06:00-08:00, 10:00-12:00, and 17:00-19:00, and at 21:00, 24:00, and 04:00 at night. The intensity and frequency of activities at night were significantly weaker than that during the day, and with a relatively short duration. The independent sample t test was used to analyze the activity intensity of takin. The results showed that the activity intensity of the solitary at night was lower than that of the group (t=-2.982, P=0.006), and it was only active during the period from 01:00 to 02:00. The activity intensity of the family group was higher than that of the mixed group (t=2.073, P=0.046), especially from 00:00 to 06:00, while the mixed group tended to rest during the same period. The activity intensity of the solitary during the farrowing period was lower than that during the mating period (t=-2.253, P=0.030), while the activity rhythm of the takin group showed an opposite pattern (t=3.810, P=0.001). Our results suggest that the activity rhythm of golden takins is affected by group form, community structure, and reproductive drive, which helps improve the effectiveness of monitoring and conservation of this species.





The individual differences of standard metabolic rate and behavior and their relationships in Macropodus opercularis.

ZHOU Wenqian, ZHENG Shilong, ZHANG Yulin, FU Shijian, FU Cheng

2023, 42(11):  2695-2701.  doi:10.13292/j.1000-4890.202311.018

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Personality is the constant intraspecific difference in animal behaviors. Energy metabolism provides energy for behavioral output. The relationship between energy expenditure and behavioral activities is still controversial. We investigated the correlation between standard metabolic rate (SMR) and personality, as well as the connection among different personality traits in a highly aggressive fish species, Macropodus opercularis. The results showed that there were significant inter-individual differences in behavior. SMR was positively correlated with the average velocity during measurements of spontaneous activity and aggressiveness, indicating that SMR can reflect the activity level of M. opercularis. However, SMR was not related to any other indicators of aggressiveness and boldness. It might be due to the more profound increase of SMR in lower social status individuals as the consequence of stress caused by intraspecific competition, which may obscure the relationship between SMR and most of personality traits. Our results suggested that the relationship between energy metabolism and personality in fish was quite complex, and that the weak correlation between SMR and personality in M. opercularis might be due to intense intraspecific competition.





Effects of different altitudes and environmental factors on biodiversity and community structure in Yuhe River, Qinling Mountains.

SUN Haotian, CHEN Wenwu, HAO Yongrong, CHEN Qiqi, SONG Jinxi, GUO Jiahua

2023, 42(11):  2702-2711.  doi:10.13292/j.1000-4890.202311.019

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Compared with traditional taxonomy methods, environmental DNA macrobarcoding technology can detect biodiversity in ecosystems more comprehensively and efficiently. To clarify the responses of biodiversity and community structure at multiple trophic levels to changes in altitude gradient and environmental factors, we collected water and sediment samples from 11 sampling points in the upper reaches of the Yuhe River and its tributary, the Xiaoyu River in June 2021. Biodiversity and community structure of fish, phytoplankton, and zoobenthos were investigated using environmental DNA metabarcoding. The results showed that a total of 16 fish species in 16 genera were detected in the upper reaches of the Yuhe River and the Xiaoyu River, along with 128 phytoplankton species in 140 genera, and 47 species in 175 genera of benthic fauna. Among them, Cypriniformes was the dominant fish species, Bacillariophyta was the dominant phytoplankton species, and Arthropods was the dominant zoobenthos. There were significant differences in alpha diversity between the upper and lower reaches of the Xiaoyu River and the upper reaches of the Yuhe River. The community structure of fish and phytoplankton exhibited prominent spatial heterogeneity. Altitude significantly negatively correlated with environmental factors, including water temperature, pH, electric conductivity (EC), salinity (SAL), and total dissolved solids (TDS). Results of the DistLM analysis and correlation heat map analysis showed that organisms with lower trophic levels were more sensitive to changes in altitude and environmental factors. Among them, altitude, water temperature, pH, EC, SAL, TDS, total phosphorus (TP), and nitrite nitrogen (NO₂^--N) significantly impacted phytoplankton and zoobenthos. The main influencing factors for fish were altitude, water temperature, pH, and total nitrogen (TN). For species with the highest abundance at each sampling point, environmental factors (i.e. water temperature, suspended solids (SS), pH, SAL, and TDS) and altitude exerted both direct and indirect impacts on organisms of different trophic levels. Our results provide a reference for biodiversity conservation and water ecological health assessment in the Qinling Mountains.





Spatiotemporal variation of ecosystem water use efficiency and its influencing factors in the Ili River-Balkhash Lake Basin.

CUI Gang, LI Qiongfang, ZHAO Jianhua, CHEN Qihui

2023, 42(11):  2712-2720.  doi:10.13292/j.1000-4890.202311.015

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Water use efficiency (WUE) is an important indicator to link the coupling between ecosystem water and carbon cycles. Understanding the spatiotemporal variation of ecosystem WUE and its influencing factors is essential for optimizing the integrated management of regional water and carbon resources and improving ecosystem productivity. With remote sensing data from MODIS, meteorological data from CRU, and land use data from CCI, the spatial distribution and temporal variations of ecosystem WUE in Ili River-Balkhash Lake Basin were investigated by using MK test and Sen’s trend analysis. The factors influencing WUE were further detected by partial correlation analysis. The results showed that the multi-year average values of annual, spring and autumn WUE illustrated same change patterns from the southeast to northwest, with a trend of increasing at first, then decreasing, and increasing at last. However, WUE values in summer displayed an opposite spatial variation as described above and WUE values of most areas in winter were close to zero. WUE values were highest in summer, followed by spring, autumn, and winter. The average annual WUE value over the whole basin increased slightly with time, with significantly increasing annual WUE in the lower reaches. The summer WUE values decreased with time in more than 90% of the basin, especially in the areas near Balkhash Lake, Ili River Valley, and Tianshan Mountains. Moreover, the annual WUE values in the upper reaches of the basin were obviously higher than those in the middle reaches, and the annual WUE values were lowest in the lower reaches of the basin. The interannual variations and trends of annual WUE values in the upper, middle and lower reaches of the basin were not significant. The rank of summer WUE values in the upper, middle and lower reaches of the basin was absolutely reverse to that of annual WUE values. The summer WUE values in the upper and lower reaches of the basin showed a significant decreasing trend, while the decreasing trend in the middle reaches of the basin was not significant. The intra-annual distribution of WUE in the basin was extremely uneven, with a peak value in August. In terms of influencing factors, gross primary productivity and precipitation showed stronger influences on WUE than evapotranspiration and temperature, respectively.





Effect of green space landscape elements on temperature under different urbanization levels: A case study of Guanzhong Plain urban agglomeration.#br#

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AO Yong, WANG Zhouhang, ZHAO Yonghua, JIANG Lingfeng, ZHANG Mengna

2023, 42(11):  2721-2729.  doi:10.13292/j.1000-4890.202311.003

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The urban heat island effect seriously affects daily life and health of urban residents. Urban green space is an effective way to alleviate urban heat island effect and reduce urban surface temperature in summer. We selected the main urban areas of Tianshui, Xi’an, and Yuncheng (the three cities belong to the Guanzhong Plain urban agglomeration) as the research areas. Based on the MODIS, Landsat 8 and Sentinel-2 data from July to August 2021, the land surface temperature was inverted, and the green space information was extracted. Using GIS spatial analysis, landscape ecology and statistical analysis methods, we examined the impacts of green space patch area, shape characteristics and landscape pattern index on cooling effect. The results showed that under different urbanization levels and scales, green space patches had a stable cooling effect. With the increases of urbanization level, the cooling effect of same green space patches was enhanced. Compared with the scattered small-area green space with complex shapes, the large-area green space with continuous concentration and regular shape had a better cooling effect. When the green space area reached 10 hm² or the area/perimeter ratio increased to 3, the enhancement range of cooling effect decreased as the green space area increased and the shape became regular. Our results provide a scientific basis for green space planning in areas with different urbanization levels.





Effects of particulate matter and negative ions on human comfort in different landscape spaces.

WANG Qiaochu, LI Yu, LI Muni, MENG Huan, ZHANG Zhi, ZHANG Tong, ZHANG Weikang

2023, 42(11):  2730-2736.  doi:10.13292/j.1000-4890.202311.017

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Different forms of plant landscapes in urban parks can affect the concentrations of particulate matter (PM) and negative ions (NAI) in the air, which in turn affect human health. In this study, we investigated the effects of five plant landscapes with different characteristics in Shenyang Dongling Park on human comfort by constructing a human comfort index model based on PM and NAI concentrations during July to October 2019. The results showed that plant landscapes had a significant effect on PM concentrations (P<0.05), but did not affect NAI concentrations (P>0.05). The underlying surface without hard pavement was more effective in reducing PM concentration in the landscape space, while the semi-open space form was more conducive to NAI  production. The human comfort index of different plant landscapes showed an initial increasing and then decreasing trend, with the period of 16:00-19:00 being the most comfortable time during a day. In addition,  structure of tree-shrub-herb, the underlying surface without hard pavement, and the semi-open spatial characteristic were beneficial to improving human comfort. Compared with the traditional comfort model, considering PM and NAI as influencing factors for human comfort evaluation  to an average reduction of 11.66% in comfort hours across landscape spaces. Therefore, it is necessary to consider not only the impacts of plant landscape on microclimate, but also the influence of different plant spaces on PM and NAI to create a green space more suitable for visitors’ activities.





Research advances in the effect mechanism and evaluation of flash drought on crop growth process.

JI Ruipeng, YU Wenying, FENG Rui, WU Jinwen, MI Na, ZHANG Yushu

2023, 42(11):  2737-2746.  doi:10.13292/j.1000-4890.202311.008

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Flash drought is a rapidly intensifying process of water shortage characterized by unexpected occurrence, rapid development, severe intensity, and extreme destructiveness. The rate of drought onset is a crucial feature distinguishing traditional drought and flash drought. Flash drought, as a “new normal” type of drought, is increasing in frequency and severity under global warming. Clarification of the impacts of flash drought on agricultural production and quantification its impacts on crops are helpful for fully understanding the impacts of drought disaster on crops, which is of great significance for stable and high grain yields in China and even in the world. In this review, we summarize research progress on the characteristics, definition, drivers, and main identification methods of flash drought in the past decade. We elaborate the methods of assessing the impacts of flash drought on crop growth, the sensitivity of crops to flash drought, the physiological mechanism by which flash drought affects crop growth and development, and the impacts of flash drought on crop yields. Challenges remain in the study of the effect mechanism and assessment of crop loss attributable to flash drought. For example, discrimination of traditional drought and flash drought events remains unresolved, the mechanism by which flash drought affects crop growth and yield is unclear, the ability to simulate and evaluate the effects of flash drought on crops is inadequate. Future research should focus on the following aspects: establishing methods for identification of flash drought suitable for different regions, different crops, and different growth stages; clarifying the differences in the effect mechanism between traditional drought and flash drought on crops; quantitatively simulating the responses of crop growth to flash drought, and clarifying the effects of flash drought on crop growth and yields.





Rice-fish co-culture mode: A review.

LIANG Yugang, YU Zhengjun, ZHAO Yang, KUANG Wei, DAI Li, KUANG Na, FANG Baohua

2023, 42(11):  2747-2755.  doi:10.13292/j.1000-4890.202311.027

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As an important component of rice production in China, rice-fish co-culture is a model of the combination of rice planting and aquaculture, with a long history and obvious economic, ecological, and social benefits. It has been widely used in different rice-producing regions. We reviewed the development history, distribution area, and main modes of rice-fish co-culture, as well as related fundamental studies in terms of economic benefits, rice yield, growth characteristics, soil and water ecological environments, biodiversity, and greenhouse gas emissions. There are some problems in rice-fish co-culture, including lack of in-depth research, non-standard planting and breeding technology, emphasis on breeding, few suitable rice cultivars, high density of fish breeding. To fully develop the production potential of rice-fish co-culture, we proposed development opinions from the aspects of technical training, focusing on rice planting, screening of suitable rice cultivars, and controlling water pollutions, which provides theoretical supports for improving the quality and efficiency of agriculture and its sustainable development.





Research progresses on the effects of functional microorganisms on wine flavor.

CHENG Siqi, YE Dongqing, SUN Yue

2023, 42(11):  2756-2766.  doi:10.13292/j.1000-4890.202311.026

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Wine flavor is one of the key factors evaluating the quality of wine. Flavor and aroma precursors in grape berries are released by microorganisms including fungi (yeasts and mould) and bacteria (lactic acid bacteria and acetic acid bacteria). The final flavor of wine is affected by the interactions of microorganisms during wine fermentation. Although microbial community structure and wine flavor components have been clearly revealed by multi-omics technologies, the role of these microorganisms in the formation of wine flavor is still unclear. We summarized wine microbial population succession and wine flavor change characteristics during winemaking, as well as the influences of microorganisms at different stages of fermentation on the formation of complex wine aroma and flavor. By exploring the potential of wine yeasts and bacteria in flavor formation and promoting the synthesis of flavor substances during winemaking, this review provides reference for the production of characteristic wine to meet consumers’ demand.





Application of machine learning technology in ecology.

LI Huijie, WANG Bing, NIU Xiang, LIANG Yongliang, LI Jingyao

2023, 42(11):  2767-2775.  doi:10.13292/j.1000-4890.202311.009

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With the gradual deepening of ecological research, ecology has entered the era of big data. As one of the core technologies of artificial intelligence, machine learning has been widely used to efficiently process ecological big data. We systematically summarized and analyzed the relevant research and the application of machine learning in recent years. The applications of machine learning in hydrology, soil, meteorology and climate, vegetation and other factors were analyzed with examples, which were involved in many research fields, including hydrological cycle, carbon cycle, meteorological prediction, climate change, species distribution, health assessment, landscape ecology, and resource management. Finally, its future trend was prospected based on the analysis of the problems of machine learning technology in ecological research. In general, random forest and neural network are the most commonly used machine learning methods in ecological research due to their characteristics. Integrating multiple machine learning algorithms, or integrating machine learning with traditional statistical methods and ecological models, is the best solution for future machine-learning-based ecological research.





Eco-environmental assessment of Kurustai grassland based on Google Earth Engine.

LIU Yujia, PENG Jian, LI Gangyong, HAN Wanqiang, LIU Liang, GUAN Jingyun, JU Xifeng, ZHENG Jianghua

2023, 42(11):  2776-2785.  doi:10.13292/j.1000-4890.202311.010

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Kurustai grassland is important for agriculture and animal husbandry development in the Tacheng region of Xinjiang, China. To fighting against the increasingly prominent environmental problems such as severe grassland degradation, desertification, and salinization, China has implemented a series of ecological restoration projects to improve grassland environment. Timely, objective, and quantitative evaluations of spatial and temporal variations in ecological environment quality are important for the implementation of environmental protection and restoration projects and policymaking. Using Google Earth Engine (GEE), a remote sensingbased ecological index (RSEI) was constructed based on highquality Landsat images in 2009, 2012, 2015, 2018, and 2021, to assess spatiotemporal variations and spatial clustering patterns of environment quality in Kurustai grassland. The results showed that: (1) The mean value of RSEI increased from 0.294 to 0.324 during 2009-2021, indicating a fluctuating upward trend for the overall environmental quality of the Kurustai grassland. (2) Spatially, the areas with poor and fair environment quality levels were distributed in the western, northwestern, and southwestern regions of Kurustai grassland at relatively low elevations, whereas those with good and excellent environment quality levels were primarily concentrated in the central and eastern regions with high forest cover and less human activities at high elevations. (3) From 2009 to 2021, the global Moran’s I values of RSEI were 0.508-0.687, indicating a positive correlation with the spatial distribution of environment. The local spatial autocorrelation clustering map of RSEI showed that high-high (H-H) clustering areas were primarily distributed in the central region with low elevation, whereas low-low (L-L) clustering areas were in the southwest and northwest parts of the region with sparse vegetation and high elevation.





Rapid detection of livestock targets in pastoral areas based on improved lightweight deep network.

ZHU Junfeng, LIU Yang, WANG Xingtian, CAO Liang

2023, 42(11):  2786-2796.  doi:10.13292/j.1000-4890.202311.001

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To achieve fast and accurate detection of livestock targets in grazing areas, we proposed a lightweight livestock target detection algorithm with improved YOLOV3-tiny, which is a lightweight object detection algorithm for real-time detection on Jetson Nano embedded motherboard. In terms of network structure, the anchor frame clustering algorithm is optimized according to the characteristics of livestock targets in grazing areas, and the prediction output scale is increased to enhance the use of shallow information. The pyramid network is used for multi-scale feature fusion to improve the detection rate of small targets while ensuring the detection rate of large targets. The improved target detection mechanism can effectively improve the accuracy of target detection under complex light conditions (e.g., direct sunlight). The experimental results showed that the detection accuracy of the improved YOLOV3-tiny algorithm reached 83.2%, and the detection speed on the embedded platform Jetson Nano was 12 frames·s^-1. The algorithm improved the detection accuracy by 8.7% on average compared with the YOLOV3-tiny algorithm while satisfying the portability.





Habitat suitability assessment of large mammals and rare birds in Xianju County based on MaxEnt modeling.

LYU Huanxin, XIA Shaoxia, GU Jingjing, SU Changhong, WANG Chunxiao, CUI Peng

2023, 42(11):  2797-2805.  doi:10.13292/j.1000-4890.202311.011

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Assessment of habitat suitability and identification of the driving factors are crucial to the protection and management of species and their habitats, and also are the premise and basis for biodiversity conservation planning. In this study, the distribution of key habitats and their suitability in Xianju National Park pilot area of Xianju County were evaluated using a MaxEnt model based on species occurrence data for large mammals and rare birds sourced from field investigations. Furthermore, the main driving factors and their contributions to habitat suitability were analyzed. The conservation gaps were identified by overlaying these variables on current distribution of protected areas. Finally, suggestions for future regional biodiversity protection and planning are proposed. The results showed that mean value of the area under the curve (AUC) for the 13 target species was 0.956, indicating that the outcome of the MaxEnt model used in this study was reliable. Human population density, mean temperature in the wettest quarter, and land use types were the main factors affecting habitat suitability for mammals. The annual temperature range and mean temperature of the wettest quarter were the main factors affecting the distribution of pheasants, while altitude and slope were the main factors affecting the distribution of suitable areas for wetland birds. In terms of habitat distribution, suitable areas for mammals and pheasants were mainly located around Kuocang Mountain in the south of Xianju County, while suitable areas for wetland birds were located near the Yong’an River. Currently, the protected areas in Xianju County are 316.80 km², while the suitable habitats located outside the existing protected areas are 160.37 km² for mammals, 178.67 km² for pheasants, and 422.65 km² for wetland birds, indicating some conservation gaps within the current protected system. We suggest the strengthening of biodiversity protection in Xianju County in conjunction with the construction of the Xianju National Park pilot area, which can provide a theoretical basis and best practice guidelines for regional sustainable development.





Evapotranspiration partitioning and its response to drought in Inner Mongolia.

LI Xinyue, XUE Baolin, WANG Guoqiang, LIU Junfang, WANG Libo, LIU Tingxi, DUAN Limin, BAO Yufeng

2023, 42(11):  2806-2816.  doi:10.13292/j.1000-4890.202311.004

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The arid zone of Inner Mongolia is an important part of the ecological barriers of plateaus in China, whose ecological environment is directly related to ecological security of northern China. To understand the responses of ecosystem evapotranspiration partitioning to drought, a SiB2 model was constructed using eddy covariance data to simulate vegetation transpiration (T) and surface evapotranspiration (ET). The ratio of T/ET was calculated based on eddy-related data from the flux station and the SiB2 model, respectively. Combined with the drought degree assessment index (SPEI), the changes of ET and T/ET ratio under different dry and wet conditions in the study area were analyzed. The results showed that the ET in the study area was significantly affected by drought, and that there was a negative correlation between ET and drought degree. The lag time of drought effect on ET v increased  when drought was severe or extremely severe. The T/ET ratios calculated by SiB2 model from 2003 to 2012 was strongly correlated with drought degree. In the humid year (2003), the T/ET ratio reached the highest value of 0.64, indicating that vegetation transpiration played a dominant role in evapotranspiration. In the relatively dry year (2005), T/ET value was 0.39, indicating that vegetation transpiration decreased under drought stress and that soil evaporation played a dominant role in evapotranspiration. In the case of continuous drought, the fluctuation range of T/ET and ET was weak, indicating that vegetation could self-regulate under drought, which plays a certain role in maintaining ecosystem stability. The results have significance for promoting rational allocation of regional water resources and improving water use efficiency in arid areas.