Combined effects of abiotic factors on Collembola communities reveal precipitation may act as a disturbance

Global increases in temperature and atmospheric CO₂, coupled with increasingly sporadic and intense precipitation regimes, may affect the biodiversity of boreal forest communities, potentially leading to shifts in functional process rates such as decomposition. However, the effects of these factors on microarthropod community composition have not been thoroughly studied in combination in controlled settings. We conducted a full factorial experiment exposing moss/soil mesocosms to three temperatures (11.5, 15.5, and 19.5 °C), two CO₂ levels (430 ppm and 750 ppm), and three moisture levels (drought, intermediate, and saturated conditions) for 18 weeks. Following treatment, we quantified effects on species diversity of a representative group of mesofaunal microarthropods, the Collembola. We also quantified the effects of these factors on the distribution of collembolan body sizes as an indicator of functional changes in the community. We found that moisture regime was a dominant factor, with increased precipitation leading to decreased collembolan abundance and richness. The mechanisms of these detrimental effects are unclear but may be due to the saturation of air-filled soil pore space or competition with moisture-tolerant species. Severe precipitation regimes caused a general loss of abundance in species of all sizes, which may have long term effects on boreal forest soil food webs.     

三维扫描技术在获取杨树树冠结构特征参数上的应用

【目的】树冠结构影响光能截获能力从而直接影响生物量的积累。杨树冠形特征参数的研究能够为杨树优良品种的选育提供有力的选择依据，但是因为杨树的树型高达，树冠结构复杂，树冠结构特征参数难以直接观测。【方法】建立了利用三维扫描技术获取树冠结构特征参数的方法，并测量了高密度(2 m ×3 m)人工林中6年生杨树03-04-171的冠形特征参数，包括不同生长单元早发枝和同期枝一级枝的枝长、分枝角度、方位角、枝条曲率及弯曲度。对直接测量(砍伐)与三维扫描方法测量的胸径、树高进行回归分析，检测三维扫描测量的精度。【结果】回归分析结果表明：胸径的回归系数分别为 R2=0.96772，显著值为 P =8.26×10－13，树高回归系数为 R2=0.96527，显著值为 P=1.44029×10－12。结果说明三维扫描方法具有较高的测量精度，可以应用于树冠结构特征的测量。扫描参数结果显示，树冠上每一个生长单元的上部枝条长度较长，分枝角度较小，曲率较大，数量少，为早发枝；中下部枝条数量多，短而平直，为同期枝，这与已有的研究结果一致。【结论】三维扫描技术可以应用于树冠结构特征的研究。     

Forced locomotor activity improves walking ability of male turkeys and modifies carcass characteristics

ABSTRACT

1. This trial investigated the effect of forced locomotor activity (training) on walking ability, leg posture, and growth performance, as well as carcass composition and meat quality in male fattening turkeys.

2. A flock of 744 commercial turkeys was divided into three experimental groups, either without any training period (control), training from weeks 2 to 8 (short-term), or training from weeks 2 to 21 (long-term). All birds were slaughtered at an age of 21 weeks. To study the effect of short vs. long time lapse between shackling and stunning (suspension time), each training group was split into two halves that were hooked on the shackle for either 15 s or 3 min prior to stunning.

3. Long-term physical training, compared to short-term or no training, resulted in better walking ability and in a lower percentage of leg malposition, as assessed at the end of fattening. No effect on final body weight was detected.

4. In a subsample, the composition of 80 carcasses was determined by dissection. Long-term training favoured the percentage of the drumstick over that of the breast cut in comparison to the group without any training.

5. Meat quality parameters were determined for breast muscle. The pH values 20 min post-mortem were reduced by long-term training, and the highest value was observed for a combination of no training with short suspension. After 24 h, pH values did not differ between experimental groups. The breast muscles were characterised as fast-glycolysing. Prolonged suspension time resulted in higher electrical conductivity after 24 h, and in higher a* values (redness).

6. In conclusion, the study revealed that a long-term training period improved walking ability and leg posture of heavy male turkeys. Thus, training can contribute to the improvement of animal welfare in turkey husbandry. Meat quality variables of breast muscles were partially influenced by locomotor activity and suspension time.     

冬季不同饲养密度对肉羊生产性能的影响

为探讨冬季气候条件下不同饲养密度对舍饲肉羊生长性能的影响,将6月龄体质量相近的144只新疆阿勒泰大尾羊F1代品改断奶羔羊随机分成4组,每组36只,试验1~4组的饲养密度分别为每只0.35m2、0.7m2、1.05m2和1.4m2,在饲料配方、饲喂与管理方法完全一致的条件下育肥45d。结果表明,各组的总采食量差异不显著(P0.05),1~4组的平均日增质量分别为(87.86±52.26)g、(111.43±57.33)g、(114.34±43.91)g和(137.27±55.93)g,第4组的平均日增质量最大并与第1组、第2组、第3组差异显著(P0.05),第2组与第3组的平均日增质量相近且差异不显著(P0.05),第2组、第3组与第1组差异显著(P0.05);各组的体尺增长与体质量增长趋势完全相同的是体长、体高和胸深,只有管围差异不显著(P0.05)。说明,25kg左右的新疆阿勒泰大尾羊F1代羔羊在冬季舍饲育肥时的饲养密度以第2组(每只0.7m2)较为适宜,而且饲养密度显著影响该羊的体高、体长和胸深。     

Assessing the effect of broadleaf woodland expansion on acidic dry deposition and streamwater acidification

The study aim was to determine whether enhanced dry deposition of acidic atmospheric pollutants by broadleaf woodland expansion could increase the potential for acidification of surface waters in acid-sensitive areas. Dry sulphur (S) and nitrogen (N) deposition was modelled with the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model using a roughness length value calculated specifically for birchwoods. Two scenarios were investigated for an acid-sensitive area in Scotland where broadleaf woodland expansion, mainly as birchwood, is occurring: (1) 2002 emissions and broadleaf woodland cover of 5.6%; (2) 2020 projected emissions and broadleaf cover of 29%. The roughness length calculated for birch with Raupach’s simplified drag-partition model was 0.73 m, lower than the value of 1.0 m for conifers which is the default for forest land cover in FRAME. Modelled dry S and N deposition increased between 2002 and 2020 from 8.7 to 29 × 10⁻³ keq ha⁻¹ year⁻¹ of H⁺. However, modelled total dry and wet non-marine S and N deposition decreased during the same period from 1070 to 682 × 10⁻³ keq ha⁻¹ year⁻¹ of H⁺ due to the lower projected emissions in 2020 and the dominance of wet deposition in the remote and upland study area (mean annual rainfall 2275 mm). The modelled total non-marine S and N deposition was used to calculate streamwater critical loads exceedance with the First-order Acidity Balance (FAB) model for five catchments in the study area. The modelled deposition for both the 2002 and 2020 scenarios was less than the calculated streamwater critical loads so the catchments were not considered at risk of streamwater acidification under the projected future emissions and increased broadleaf woodland cover. Nevertheless, broadleaf expansion could pose a greater risk of acidification in acid-sensitive areas with lower rainfall, closer to pollutant sources, where dry deposition accounts for a higher proportion of total S and N deposition.     

Increased utilization of lengthening growing season and warming temperatures by adjusting sowing dates and cultivar selection for spring maize in Northeast China

Global warming has lengthened the theoretical growing season of spring maize in Northeast China (NEC), and the temperatures during the growing season have increased. In practise, crop producers adjust sowing dates and alternate crop cultivars to take advantage of the lengthening growing season and increasing temperatures. In this study, we used crop data and daily weather data for 1981–2007 at five locations in NEC to quantify the utilization of the lengthening growing season and increasing temperatures by adjusting sowing dates and cultivar selection for spring maize production. If these two positive factors are not fully utilized, then it is important to know the potential impacts of these climatic trends on spring maize grain yields. The results show that in NEC, both the actual and theoretical growing seasons are lengthening, i.e., the sowing dates have been advanced and the maturity dates have been delayed. The actual sowing dates are 1–8 days later and the actual maturity dates are 6–22 days earlier than the theoretical perspective. Advancing sowing dates and changing cultivars led to 0–5 days and 6–26 days extension of the growing season. For the potential thermal time (TT), adjusting the sowing dates decreased the unutilized TT before sowing, while the cultivar selection increased the utilized TT and decreased the unutilized TT after maturity. On average, the unutilized heating resource before sowing is less than that after the maturity date (0.3–1.9% vs. 2.1–7.8%). During 1981–2007, for per day extension of the growing season, the spring maize grain yield increased by 75.2 kg ha⁻¹. The spring maize grain yields have increased by 7.1–57.2% when both early sowing and changing cultivars during 1981–2007. In particular, adjusting the sowing dates increased the grain yield by 1.1–7.3%, which was far less than the increase effect (6.5–43.7%) from switching to late maturing cultivars. Therefore, selecting late maturing cultivars is an important technique to improve maize grain yields in NEC under the global warming context. Nevertheless, if the currently unutilized TT were fully explored, the local spring maize grain yield would have increased by 12.0–38.4%.     

Warming favours small-bodied organisms through enhanced reproduction and compositional shifts in belowground systems

The increased prevalence of smaller-bodied species under warmer conditions (community downsizing) is hypothesized as an ecologically critical consequence of climate change, leading to changes in trophic transfer efficiency, and rates of nutrient and energy flux within ecosystems. This study used 100 intact peat-soil mescosms to measure changes in belowground biodiversity under three manipulated climate variables: elevated temperature, elevated CO₂, and altered water table. Changes in species richness, abundance, community composition and body size spectra were used to determine whether climate change factors led to community downsizing, and elucidate any underlying mechanisms. Warming was the primary driver of compositional shifts in belowground fauna communities with the strongest effect among the smaller-bodied, non-sexually reproducing species. Increases in abundance driven by enhanced reproduction in small-bodied species rather than an increased extinction-rate among large-bodied predators was the basis of the observed downsizing. The overall consequences of warming-induced changes in belowground systems on ecosystem function are still unclear. However, as body size is intricately linked to metabolism, observed community downsizing suggests reductions in food web trophic transfer efficiency with consequences for nutrient and energy dynamics in belowground systems.     

二郎山山地鸡鸡距生长测定及分析

本试验以二郎山山地鸡为研究对象,分析其2个品系鸡距的生长发育规律,希望能将其鸡距的长度作为区分两品系的标志之一。本试验从23周龄开始,每个品系测定100只公鸡的距长,每周测1次(第1阶段),结果发现,同一品系中4次测定结果均差异不显著(P0.05);从27周龄开始,改为每个月测1次(第2阶段),结果表明:2个品系的距长发育整齐度并不是很高,距长与个体发育有关,与生长时间不呈绝对正比,且与体重不相关(R0.3);SD03系公鸡的距明显长于SD02系(P0.05)。试验结果表明,可以将距长作为区分2个品系的标志之一,但在实际生产中该方法对饲养时间较短的商品肉鸡不可行。     

NaCl胁迫对3种草地早熟禾种子萌发特性的影响

用室内模拟的方法,对"午夜""新歌来德""抢手股"3种草地早熟禾种子进行4种不同浓度(0、1、1.5、2mmol·L-1)的NaCl溶液盐胁迫试验,结果表明:盐浓度越高,植物受到的盐胁迫越大;3种早熟禾种子中,发芽率、胚根长度和胚芽长度最高的均为午夜种子,最低的为抢手股种子。午夜种子的综合能力较强,最适合应用于抗盐碱土地中,新歌来德次之,而抢手股不适合种植在盐碱地中。