Indicators for green spaces in contrasting urban settings

Urban green spaces (GS) are essential for the well-being of the population. Several works have shown a positive correlation between the amount of GS and the household incomes in both developed and developing countries. Thus, the higher the incomes, the larger the total area covered by GS, the better the quality of these spaces, the higher the amount of private GS. Public policies seek to correct this inequality, but existing indicators, especially the amount of GS per inhabitant, do not provide enough information for effective decision-making. Our aim was to provide tools to evaluate and plan better the location and quality of GS in complex urban areas. For this we applied a set of indicators for GS at two spatial scales city-level and local-level, in order to disclose existing inequalities. The indicators considered (i) the total area of GS in relation to population and urban context, (ii) the quality of GS based on its size, shape and vegetation cover, and (iii) the spatial distribution and accessibility of GS. The proposed indicators were tested in three municipalities, belonging to the Metropolitan Area of Santiago (Chile), with different household incomes. The indicators showed large differences in terms of quantity of GS per inhabitant, vegetation cover and accessibility. The GS proved to be an effective strategy to reduce areas that lack vegetation cover. The sustainability assessments must consider how the diversity of structural attributes of GS has an impact on the well-being of urban inhabitants.     

The vascular plant‐pathogenic bacterium Ralstonia solanacearum produces biofilms required for its virulence on the surfaces of tomato cells adjacent to intercellular spaces

The mechanism of colonization of intercellular spaces by the soil‐borne and vascular plant‐pathogenic bacterium Ralstonia solanacearum strain OE1‐1 after invasion into host plants remains unclear. To analyse the behaviour of OE1‐1 cells in intercellular spaces, tomato leaves with the lower epidermis layers excised after infiltration with OE1‐1 were observed under a scanning electron microscope. OE1‐1 cells formed microcolonies on the surfaces of tomato cells adjacent to intercellular spaces, and then aggregated surrounded by an extracellular matrix, forming mature biofilm structures. Furthermore, OE1‐1 cells produced mushroom‐type biofilms when incubated in fluids of apoplasts including intercellular spaces, but not xylem fluids from tomato plants. This is the first report of biofilm formation by R. solanacearum on host plant cells after invasion into intercellular spaces and mushroom‐type biofilms produced by R. solanacearum in vitro. Sugar application led to enhanced biofilm formation by OE1‐1. Mutation of lecM encoding a lectin, RS‐IIL, which reportedly exhibits affinity for these sugars, led to a significant decrease in biofilm formation. Colonization in intercellular spaces was significantly decreased in the lecM mutant, leading to a loss of virulence on tomato plants. Complementation of the lecM mutant with native lecM resulted in the recovery of mushroom‐type biofilms and virulence on tomato plants. Together, our findings indicate that OE1‐1 produces mature biofilms on the surfaces of tomato cells after invasion into intercellular spaces. RS‐IIL may contribute to biofilm formation by OE1‐1, which is required for OE1‐1 virulence.     

Effect of park age,size, shape and isolation on ant assemblages in two cities of Southern Spain

In the context of conservation biology, we have searched for the most influential characteristics of urban parks on ecological diversity. In this study, therefore, we studied the ant community of 24 parks in two cities of Southern Spain (Cordoba and Seville). In total, 46 species were found. Abundant and widely distributed species were synanthropic ones, such as Lasius grandis, Pheidole pallidula or Tapinoma nigerrimum, and exotic species such as Cardiocondyla mauritanica. However some parks also harbored natural habitat‐preferring species. Park size, shape and distance to city outskirts were the most important predictors of species richness and diversity. Likewise, park age influenced the composition of the ant fauna.     

如何在北京充分实现受胁鸟类栖息地保护?

实现有效生物多样性保护的关键在于提升生物多样性丰富的人口密集区的保护效率。北京人口密集且生物多样性丰富, 存在3类具有生态保护功能的区划——自然保护区、生态保护红线和限制建设线。上述区域可视为生态保护潜力区。本文以在北京有分布的30种受胁鸟类为主要对象, 探讨现有生态保护潜力区对这些物种栖息地的覆盖程度, 并对如何改善上述受胁鸟类栖息地的保护状况进行了建议。根据物种对栖息地的选择, 基于高分辨率卫星解译的土地利用类型图, 利用最大熵模型(MaxEnt)掩膜栖息地分布图, 得到各受胁鸟类的预测空间分布。叠加这些分布获得北京受胁鸟类丰富度分布格局并进行验证。依据物种丰富度高低, 将受胁鸟类栖息地划分为一至四级(最重要的栖息地是一级栖息地, 以此类推)。同时, 依据地表覆盖类型和人类活动强度高低将北京市域划分为城市建成区、乡村生境区和自然生境区。分别计算3类保护潜力区对上述3类区域以及四级栖息地的覆盖面积比例。结果表明: (1) 95.64%的一级关键栖息地和86.32%的二级关键栖息地分布在乡村生境区, 但仅有0.69%和15.15%的乡村生境区分别被自然保护区和生态保护红线覆盖; (2)未受到自然保护区和生态保护红线覆盖的一、二级关键栖息地主要为水域和沼泽地等湿地、高覆盖度草地和部分耕地, 以及含有较高比例水体的大型城市绿地。基于以上结果, 我们建议至少在一定区域内试行如下保护措施: (1)严格保护湿地及其周边的高覆盖度草地, 确保面积不减少; (2)维持基本农田规模和粮食种植模式; (3)将乡村生境区位于河道附近的水域、沼泽地、高覆盖草地和灌木林纳入生态保护红线范围; (4)在公园绿地中划定生物多样性保护区; (5)优化平原地区林地结构。以上措施将使北京的受胁鸟类栖息地得到更好保护, 为中国东部人口密集区生物多样性保护提供示范。     

城市街旁绿地的生物多样性支持功能及其环境影响

街旁绿地的休闲、美化功能及其环境设计已有大量的讨论,而生态功能尤其是生物多样性支持功能却常常被忽略。通过上海浦东世纪大道沿线街旁绿地的鸟类多样性实测调查与统计,对街旁绿地与其他对照组绿地的鸟种数量、密度和多样性进行比较,分析街旁绿地与周边绿地的鸟类物种丰富度与相似性,探讨对鸟类等物种多样性有支持功能的环境影响要素。研究结果表明：1）街旁绿地作为一种面积有限的微型绿地,可以成为鸟类等城市野生动物的庇护所和中转站,在城市绿地系统布局中应该重视该类“边角料”用地的生物多样性支持功能;2）干扰边界比例和首层乔木退界率对街旁绿地的鸟类物种多样性具有一定的影响,尽可能降低周边人工环境对生物的干扰是提升街旁绿地生物多样性的主要路径。研究为街旁绿地的生态功能及其环境影响提供了新的研究视角,研究结论可为设计、建设和管理城市生物友好型街旁绿地提供科学依据和方法,也为进一步探讨街旁绿地在高密度城市生态绿网中的生物“踏脚石”作用机制奠定基础。     

基于CLUE-S模型的县域生产-生活-生态空间冲突动态模拟及特征分析

随着经济、社会发展速度不断加快,多功能空间之间的竞争不断增强,国土空间的协调与稳定受到严重影响。因此,模拟生产、生活和生态空间(简称"三生"空间)冲突格局,并分析其演变特征,对于科学利用国土空间,实现区域发展格局优化有着重要意义。以昌黎县为研究区,以2005和2015年土地利用现状数据为基础,采用CLUE-S模型预测研究区2025年土地利用格局;基于土地利用主导功能和次要功能将国土空间划分为生活生产空间、生产生态空间、生态生产空间及生态空间,依据景观生态指数构建空间冲突测度模型,测算昌黎县2005—2025年三期"三生"空间冲突变化趋势。结果表明:①2005—2025年昌黎县以生产生态空间为主。2015年末,生活生产空间、生产生态空间大量占用生态生产空间和生态空间,尤其是河流附近,空间转换更加显著;到2025年,各空间类型转变较少,但生活生产空间转入量仍相对较大。②2005—2025年昌黎县空间冲突水平呈上升趋势,到2025年,空间冲突逐渐以较强空间冲突为主。这主要是由于生产生态空间、生活生产空间不断向外扩张。随着城镇化、产业发展速度的加快,生活生产空间、生产生态空间向外扩张强度逐渐增大,生态生产空间、生态空间将面临威胁。     

C4 grasses adapted to low precipitation habitats show traits related to greater mesophyll conductance and lower leaf hydraulic conductance

In habitats with low water availability, a fundamental challenge for plants will be to maximize photosynthetic C-gain while minimizing transpirational water-loss. This trade-off between C-gain and water-loss can in part be achieved through the coordination of leaf-level photosynthetic and hydraulic traits. To test the relationship of photosynthetic C-gain and transpirational water-loss, we grew, under common growth conditions, 18 C₄ grasses adapted to habitats with different mean annual precipitation (MAP) and measured leaf-level structural and anatomical traits associated with mesophyll conductance (g_m) and leaf hydraulic conductance (K_leaf). The C₄ grasses adapted to lower MAP showed greater mesophyll surface area exposed to intercellular air spaces (S_mes) and adaxial stomatal density (SD_ada) which supported greater g_m. These grasses also showed greater leaf thickness and vein-to-epidermis distance, which may lead to lower K_leaf. Additionally, grasses with greater g_m and lower K_leaf also showed greater photosynthetic rates (A_net) and leaf-level water-use efficiency (WUE). In summary, we identify a suite of leaf-level traits that appear important for adaptation of C₄ grasses to habitats with low MAP and may be useful to identify C₄ species showing greater A_net and WUE in drier conditions.     

Leaf patch clamp pressure probe measurements on olive leaves in a nearly turgorless state

The non‐invasive leaf patch clamp pressure (LPCP) probe measures the attenuated pressure of a leaf patch, P_p, in response to an externally applied magnetic force. P_p is inversely coupled with leaf turgor pressure, P_c, i.e. at high P_c values the P_p values are small and at low P_c values the P_p values are high. This relationship between P_c and P_p could also be verified for 2‐m tall olive trees under laboratory conditions using the cell turgor pressure probe. When the laboratory plants were subjected to severe water stress (P_c dropped below ca. 50 kPa), P_p curves show reverse diurnal changes, i.e. during the light regime (high transpiration) a minimum P_p value, and during darkness a peak P_p value is recorded. This reversal of the P_p curves was completely reversible. Upon watering, the original diurnal P_p changes were re‐established within 2–3 days. Olive trees in the field showed a similar turnover of the shape of the P_p curves upon drought, despite pronounced fluctuations in microclimate. The reversal of the P_p curves is most likely due to accumulation of air in the leaves. This assumption was supported with cross‐sections through leaves subjected to prolonged drought. In contrast to well‐watered leaves, microscopic inspection of leaves exhibiting inverse diurnal P_p curves revealed large air‐filled areas in parenchyma tissue. Significantly larger amounts of air could also be extracted from water‐stressed leaves than from well‐watered leaves using the cell turgor pressure probe. Furthermore, theoretical analysis of the experimental P_p curves shows that the propagation of pressure through the nearly turgorless leaf must be exclusively dictated by air. Equations are derived that provide valuable information about the water status of olive leaves close to zero P_c.     

Circadian rhythm in behavioral activities and diurnal abundance of stray street dogs in the city of Sambalpur,Odisha, India

ABSTRACT

This is the first research article that documents circadian variability in behavioral variables, namely resting (Rt) and standing (St) in stray street dogs of Sambalpur city, India. We also estimated the abundance as a function of time of the day and gender in a population of stray dog inhabiting streets of the city. In addition, we determined the association between the behavioral variables and the environmental variables, such as light intensity, sound intensity, temperature and humidity. We determined the abundance of street dogs at 10 hotspots using the photographic capture-recapture technique and Lincoln index equation. In another study, we determined dogs’ density along the three randomly selected routes that connect the beginning (Dhanupali) and end (P.C. Bridge) of the city precincts. We recorded the resting and standing activities of the stray street dogs using still and video cameras at four times of the day continuously over a longitudinal timescale of 72 hours. This study was conducted at four randomly selected dog hotspots. Subjecting the log-transformed time series data to the Cosinor rhythmometry we obtained three different rhythm parameters, such as mesor (M), amplitude (A) and acrophase (Ø) of the rhythm in resting and standing behavior of stray street dogs. We found out both spatial and temporal variability in the behavior of street dogs. The sightings of dogs were always more during the evening and nighttime irrespective of the investigated routes and hotspots. Further, we also observed that the abundance of male dogs was always significantly more as compared with the bitches. A lack of association between two attributes the time of the day and gender apropos the number of sightings of the street dogs was validated by the Fisher’s exact test. Using Pearson’s correlation analysis technique we found a negative relationship between light intensity and resting activity. In addition, we also found a negative association between standing activity and ambient environmental temperature. These findings were complimentary to the observed circadian variability in the resting and standing behavior of the stray street dogs. In conclusion, despite a few limitations, this study documents a statistically significant circadian rhythm in activities of stray street dogs. It also highlights spatial variability in the abundance of dogs on the streets and hotspot localities of the urban Sambalpur. We do have a hunch. It is likely that similar phenomenamight be of common occurrence in many urban areas of the world. These data might also help in addressing street dog menace – one of the major problems the people and administrative authorities of most of the Indian cities and elsewhere worldwide are experiencing since quite long.