水分和养分添加对羊草功能性状和地上生物量的影响

研究水分和养分添加对植物功能性状的影响, 对于揭示植物对环境变化的响应和适应规律至关重要。该文采用盆栽试验的方法, 进行不同水平水分处理(增水50%, 减水50%, 以498 mm降水量作为对照)和养分添加(无养分添加, 单施氮肥, 单施磷肥, 氮磷共施), 研究羊草(Leymus chinensis)的10种功能性状和地上生物量对水分和养分添加的响应。得出以下结论: (1)双因素方差分析结果表明, 水分主效应对羊草株高、分蘖数、茎生物量、叶生物量、叶面积、叶质量、净光合速率、蒸腾速率、水分利用效率存在显著影响; 养分主效应对羊草分蘖数、茎生物量、净光合速率、蒸腾速率、水分利用效率存在显著影响; 水分和养分的交互作用对羊草分蘖数、茎生物量、蒸腾速率、水分利用效率存在显著影响。(2)各功能性状对降水量的响应在不同养分添加水平是不同的, 分蘖数和叶面积在单施氮肥和氮磷共施条件下随降水量增加而增加, 而在无养分添加和单施磷肥条件下无显著变化; 茎生物量在无养分添加、单施氮肥和单施磷肥条件下随降水量增加而增加, 而在氮磷共施条件下无增加趋势; 比叶面积在单施氮肥条件下增水处理显著低于对照组, 而在其他养分添加条件下无明显变化。(3)短期氮磷处理显著影响羊草叶片光合生理性状, 而对叶形态性状影响不显著。(4)羊草地上生物量随降水量的增加呈现上升趋势, 并且在单施氮肥条件下, 增水处理使地上生物量达到最高, 为522.55 g·m ^-2。总之, 羊草的功能性状对降水量增加表现出明显的响应, 响应格局在不同养分条件下不同, 反映了其对水肥环境变化的适应。     

山西太岳山不同径级油松种内竞争与叶功能性状

为探究不同径级油松的种内竞争与叶功能性状变化规律,以山西太岳山油松人工林为研究对象,将样地中油松按5cm的间隔进行径级划分,并在每个径级中选取3株油松进行叶片取样。测定了不同径级油松的种内竞争强度、比叶面积、叶干物质含量、叶氮含量、叶磷含量及其叶氮磷比。采用单因素方差分析检验不同径级间油松的种内竞争与叶功能性状的差异,并利用Pearson相关性分析油松叶功能性状之间的相关性。结果显示：(1)油松的种内竞争在不同径级间差异明显,种内竞争随径级的增加而减小。(2)油松的胸径与竞争指数二者之间呈幂函数关系(P<0.01)。竞争指数随着对象木胸径增大而逐渐减小,当对象木胸径达到20cm以上时,竞争指数进一步减小并维持在较低水平。(3)面对不同的种内竞争强度,不同径级油松的叶功能性状表现出不同的适应性策略,小径级油松倾向于资源获取型策略,而大径级油松则倾向于资源保守型策略。(4)油松1年生叶与多年生叶的比叶面积与叶干物质含量、叶氮含量与叶氮磷比呈极显著负相关性,叶干物质含量与叶氮含量呈显著正相关性;1年生叶中比叶面积与叶氮含量在呈负相关性,而多年生叶中呈极显著负相关性;1年生叶中叶磷含量与比叶面积、叶氮含量无相关性,叶氮含量与叶氮磷比呈正相关性,而多年生叶呈负相关性、极显著正相关性与无相关性。表明1年生叶与多年生叶叶功能性状之间存在着不同的制约关系。因此在油松人工林管理中,应当充分考虑油松的种内竞争和不同径级的叶功能性状变化规律,为油松人工林的保护与管理提供参考依据。     

围封与放牧管理对高寒草甸植物功能性状和功能多样性的影响

植物功能性状能够响应生存环境的变化并直接决定着生态系统功能。为了揭示围封与放牧管理对物种共存和驱动群落构建的影响机理,该研究以青藏高原东缘高寒草甸为对象,分析了围封与放牧处理对植物功能性状和功能多样性的影响。结果显示:(1)在群落水平,放牧显著降低了比叶面积和植物高度;在物种水平,放牧群落中多数杂类草比叶面积减小,而莎草类和禾草类的比叶面积在处理间无显著差异。(2)叶干物质含量与比叶面积在围封和放牧处理中均呈显著负相关关系,在放牧处理中,叶干物质含量与植物高度呈显著的二次函数关系,即随着叶干物质含量的增大,植物高度先减小后增大;在同等比叶面积的情况下,与围封相比,放牧降低了叶干物质含量;在相同叶干物质含量的情况下,与围封相比,放牧降低了植物高度。(3)放牧在总体上降低了种间性状的平均差异,植物性状表现出趋同响应,具体表现为放牧减小了叶干物质含量和植物高度的种间差异;与围封相比,放牧显著提高了功能均匀度,减小了功能分离度。研究表明,不同植物种对放牧的响应模式存在差异,放牧降低了种间对光资源的竞争,可能增加了对土壤养分的竞争,放牧驱动群落构建的过程中,土壤养分是非常重要的作用因子,说明放牧影响物种共存依赖于对多种资源的竞争。     

南岭中段森林优势树种及其生态位随海拔梯度变化特征

本研究在南岭中段海拔400~1 800 m天然林保存良好的区域建立45块生态监测样地,并根据这些样地的海拔分布范围和树种组成归类为4种森林植被类型。通过调查评估关键生态位特征参数指标及生态位资源利用假说的论证,研究不同海拔梯度优势树种的差异及其生态位特征。结果显示：（1）不同海拔梯度优势种存在一定差异性,海拔高差越大,优势种组成差异越明显。（2）高海拔的常绿阔叶矮林区域优势树种对资源需求具有高度的一致性,种间竞争最激烈。（3）优势树种的生态位宽度与其重要值呈弱正相关,与重要值变异系数则呈显著负相关;生态位宽度与生态位的重叠和相似性之间存在一定的联系,但这种联系无明显的规律。（4）重要值和生态位宽度较大且变异系数较小的树种为甜槠（Castanopsis eyrei （Champ.） Tutch）、青冈（Cyclobalanopsis glauca （Thunb.） Oerst）和木荷（Schima superba Gardn. et Champ.）,提示这几个树种是南岭中段地区主要的建群树种。（5）中低海拔区域的林分对资源利用方式的划分较符合生态位理论资源利用假说中的随机生态位边界假说;高海拔区域的林分对资源利用方式符合生态位优先占领假说。     

云南大理古城牛背鹭与其竞争种的巢空间生态位分化动态研究

牛背鹭（Bubulcus ibis）作为入侵物种由非洲向美洲的扩散得到了广泛关注,然而牛背鹭与其竞争物种之间的巢空间生态位分化动态尚不明确。为了解牛背鹭与其他混群繁殖鹭类的巢空间生态位分化动态,2012、2016和2021年春夏季,对中国云南大理古城繁殖鹭类的群落结构和巢空间分布进行了调查。结果表明,2012和2016年中国云南大理古城繁殖鹭类群落的组成物种均为牛背鹭、夜鹭（Nycticorax nycticorax）和白鹭（Egretta garzetta）,其中夜鹭为优势鸟种;2021年繁殖群落增加了中白鹭（Ardea intermedia）,且牛背鹭变为优势鸟种。从2016年到2021年群落巢密度增加,其中牛背鹭的巢密度明显增加,夜鹭和白鹭巢密度均减少。对比2016和2021年牛背鹭、夜鹭和白鹭3种鹭的巢空间生态位宽度数值的变化,发现牛背鹭利用的巢空间生态位更泛化,而夜鹭和白鹭更特化;巢空间生态位重叠值变化表明,2021年牛背鹭对夜鹭、白鹭的巢址竞争比2016年的更激烈,而且2021年牛背鹭与夜鹭之间的巢址竞争比牛背鹭与白鹭之间的更激烈。研究表明,在2012、2016和2021年,在大理古城鹭类繁殖地中,牛背鹭在与比自身个体大的夜鹭的竞争中胜出,群落优势鸟种由夜鹭变为牛背鹭,繁殖鹭类的群落结构和生态位分化均发生了明显变化。     

Comparative root system structure of post-fire Pinus halepensis Mill. and Cistus monspeliensis L saplings.

To describe root system topology of Pinus halepensis and Cistus monspeliensis saplings co-inhabiting natural post-fire sites, 55 P. halepensis and 26 C. monspeliensis saplings were extracted by the total excavation method from a burnt pine stand. Seedlings were individually labelled when emerging after fire and extracted three years later, at the sapling phase. In order to evaluate the effect of inter-specific competition of C. monspeliensis on P. halepensis root system, a stratified sampling was carried out according to density and height of the saplings. Topological parameters considered in the analysis were magnitude, total external pathlength, and altitude of the root systems. Weight and length of roots were also measured in order to estimate the specific root length, an index commonly used in morphological studies. Results clearly evidenced greater variability in root system topology of P. halepensis than C. monspeliensis saplings. Herringbone architecture (i.e., the most ordered pattern possible, with branching confined to the main axis) characterised small pine saplings, regardless of competition from C. monspeliensis, which changed to random branching in large saplings. In medium sized saplings, the root system was affected by inter-specific competition, which delayed changes in root branching. In contrast, C. monspeliensis invariably adopted randomly branched architecture, regardless of intra-specific competition. It is concluded that such different topological patterns make C. monspeliensis more competitive during the early stages of post-fire succession, because its root system is much more transport-efficient in the nutrient-rich environment. Those pines which finally branch roots by random pattern will reach higher stem height and magnitude, a factor which allows them to successfully compete with C. monspeliensis for soil nutrients and water. The morphological analysis showed a significant increase in the specific root length with competition, both in P. halepensis and C. monspeliensis saplings, which could be interpreted as a consequence of the reduction of root diameter in response to nutrient depletion.     

Does morphology predict behavior? Correspondence between behavioral and morphometric data in a Tyrant‐flycatcher (Tyrannidae) assemblage in the Santa Marta Mountains,Colombia

ABSTRACT Morphology is commonly used as a predictor of ecological relationships among species when studying local assemblages of Neotropical birds. Nevertheless, most evidence supporting ecomorphological correspondence in birds comes from studies of communities and not from local assemblages and, moreover, from temperate latitudes. To increase our understanding of ecomorphological correspondence in Neotropical assemblages, we used three multivariate approaches to evaluate correspondence between morphological and foraging behavior data in a tyrant‐flycatcher assemblage (N= 12 species) in the Santa Marta Mountains in Colombia. Principal components analyses revealed similar species ordinations when using morphological measurements (beak size and shape, tarsus length, wing length, and tail length) or behavioral data (behavioral types of searching for prey and prey capture) separately. Discriminant function analyses tested the ability of morphological traits to predict foraging behavior, showing that more than 90% of all measured individuals (N= 267) were correctly classified in previously defined categories of search and attack behavior. Finally, Canonical correlation analyses revealed a significant correlation between morphological data and two independent datasets of search and attack behavior. Our results demonstrate that morphology can accurately predict ecology in an assemblage of Neotropical tyrannids, and similar results have been reported in previous studies of temperate Tyrant‐flycatchers. Our results also show that bill size and shape, wing length, and tarsus length are the best predictors of foraging behavior in this assemblage. Testing for ecomorphological correspondence in other Neotropical taxa would help identify subsets of phenotypic traits that could be used for a practical, but reliable, determination of ecological relationships within different assemblages.     

云南元江不同胸径厚皮树的水力性状变异格局

为探讨不同胸径径级树木的水力性状变异格局,该研究以元江干热河谷生态系统中优势乔木树种厚皮树(Lannea coromandelica)为研究对象,测定了56棵不同胸径(0<DBH≤9 cm)厚皮树的整枝(叶片和枝条)、叶片和枝条的导水率分布格局及其形态学特征,进而探讨这些性状在胸径径级(0<DBH≤3, 3<DBH≤6和6<DBH≤9 cm)间的变异格局。结果表明:(1)3个胸径径级的厚皮树的枝条导水率均显著大于叶片导水率,表明其枝条和叶片之间存在水力分割现象且水力分割程度相似。(2)在3个胸径径级之间,平均叶柄长度、树皮密度、边材密度、胡伯尔值和比叶重等形态学性状存在显著差异,但是整枝、叶片和枝条导水率无显著差异。(3)在3个胸径径级中,整枝导水率与叶片导水率和枝条导水率均呈显著正相关。枝条导水率与树皮密度呈显著负相关,与边材密度呈显著正相关。叶片导水率与胡伯尔值呈显著负相关。综上所述,尽管一些形态学性状在不同胸径径级之间存在显著差异性,但在不同生长阶段,厚皮树叶片和枝条之间存在着相似的水力分布格局。该研究结果为了解树木体内的水分传输机制具有重要的生理学意义。     

Resource partitioning through oceanic segregation of foraging juvenile southern elephant seals (<Emphasis Type="Italic">Mirounga leonina</Emphasis>)

In highly dynamic and unpredictable environments such as the Southern Ocean, species that have evolved behaviors that reduce the effects of intra-specific competition may have a selective advantage. This is particularly true when juveniles face disadvantages when foraging due to morphological or physiological limitation, which is the case for many marine mammals. We tracked the at-sea movements of 48 juvenile southern elephant seals (Mirounga leonina) between the ages of 1 and 4 years from the population at Macquarie Island using locations derived from recorded light levels. There were significant differences in the total amount of the Southern Ocean covered by the different age-groups. The younger seals used a smaller area than the older seals. On average, the younger individuals also made more trips to sea than the older seals and did not travel as far on each trip. Females spent more time at sea than males and there were no significant differences between the total areas used by male and females. In summary, younger seals remained closer to the island at all times, and they spent more time in more northerly regions that older seals. These differences in behavior created temporal and spatial segregation between juveniles of different ages. Therefore, we suggest that these temporal and spatial separations help to avoid intra-specific competition for resources on land, space on beaches, and at-sea foraging areas. Such modifications of haul-out timing and behavior enable them to exploit a patchy and unpredictable environment.     

鄱阳湖典型湿地土壤微生物活性对季节性水位变化的响应

为探究湿地土壤微生物对季节性水位变化的响应关系,以鄱阳湖湿地土壤为研究对象,在2014年3、6、10及2015年1月4个季节采集了3个不同高程样带的土壤样品,对土壤微生物基础呼吸、生物量及胞外酶等活性进行了测定。研究结果表明:(1)季节性水位变化不仅显著改变了土壤有机碳、溶解性有机碳、有效磷等含量,也使得微生物量碳和4种水解酶β-葡萄糖苷酶、β-木糖苷酶、N-乙酰氨基葡萄糖苷酶、磷酸酶活性表现出夏冬季较高、秋季最低的动态变化,而2种氧化酶酚氧化酶和过氧化氢酶的表现正好相反。(2)水位高程和地上植被类型同样对土壤微生物产生了显著影响,表现为南荻样带有较高营养元素含量和微生物活性。(3)一些土壤理化指标(含水量、铵态氮、有机碳、有效磷等)与微生物活性(微生物量、基础呼吸、酶活)显著相关;季节水位变化对微生物活性的影响大于高程差异。研究结果表明水位波动对湿地土壤微生物活性产生了重要影响,鄱阳湖水文节律的改变将影响到湿地土壤的正常生态功能。     

闽楠叶形态与叶脉网络性状关系对城市生长环境的响应

植物叶形态与叶脉网络功能性状的协同变异与权衡关系,对深入理解植物叶脉网络功能性状对环境变异的生态适应,以及预测植物物种生活习性对城市化过程的响应具有重要意义。闽楠作为珍贵的常绿阔叶树种,正在城市绿化中逐步推广。针对不同生长环境中（行道与植物园混交林）的闽楠,开展了叶形态与叶脉网络功能性状关系对城市生长环境的响应研究。研究结果表明：闽楠叶性状值基本满足正态分布,各性状变异系数保持在10%-20%之间,群体内性状变异较为丰富,单因素方差分析表明两种环境对叶形态性状的影响比叶脉网络系统的影响更明显;两种生长环境下闽楠叶形态性状组与叶脉网络功能性状组都具有极显著相关性,行道和植物园混交林典型性相关系数分别为0.804和0.795,叶形态性状与叶脉直径呈显著正相关,形态性状、叶脉直径与初级脉密度呈显著负相关;闽楠在响应城市生长环境的过程中呈现出相应的经济权衡机制,行道环境中闽楠以较大的初级脉密度和较小叶面积来确保水分获取和光合之间的平衡,植物园闽楠则采用较低初级叶脉密度、较高叶面积和叶脉直径的叶形态和叶脉网络构建模式。在选择闽楠作为城市绿化树种时,可将叶片形态性状组与叶脉网络功能性状组的协同变化和权衡关系作为选种依据,以提高闽楠在城市环境中的成活率和适应性。     

邻体竞争对城市森林微景观中针叶树视觉形态性状的影响

树木视觉形态性状是城市绿地微景观美学质量的重要影响因素之一,树木视觉形态性状的变化与其周围邻体木的竞争作用息息相关,但邻体竞争对树木视觉性状的作用机制尚不明确。研究于2022年8—10月对北京市城市公园中常见的针叶树种白皮松、侧柏、油松、圆柏展开调查,从树冠形态、干冠协调、树干形态3个方面构建了9个树木视觉形态性状指标,采用3个不同的竞争指标分析邻体竞争对针叶树种视觉形态性状的影响。结果表明,针叶树的树冠形态对邻体竞争的响应比较敏感,竞争中的白皮松、侧柏、油松、圆柏偏冠指数与孤立木相比分别提高了16.95%、28.95%、22.76%、17.67%;树冠缺失率分别提高了3.92%、6.09%、4.87%、4.95%。与孤立木相比,部分针叶树种高径比、分枝角变异度在多侧竞争环境中显著提高,而树冠舒展度则显著降低。邻体竞争强度越大,针叶树树冠的偏移与缺失程度越大。当针叶树受到强烈的侧方竞争时,对象木树冠和树干的径向生长显著受阻,表现为树冠舒展度大幅度下降、高径比显著提高,使树冠向细高方向发展。当针叶树上方的生长空间被占据时,其轴向生长同样受到严重阻碍,树木的冠径比和高径比维持较稳定状态。总体而言,四种针叶树种在视觉形态上对竞争胁迫的响应具有一定差异性,其中油松最为敏感,圆柏次之。综上,在城市森林微景观中,邻体竞争会导致针叶树种的树冠及树形发生明显变化,这种变化主要受综合资源竞争的影响,与其周围潜在生长空间的大小及对称性有关。在城市森林景观营建时,建议将针叶树栽植在对称的竞争环境中,但是其邻体木不宜过高,通过四周邻体木的适度竞争,能够促进针叶树的轴向生长,同时降低树冠偏移或变形的风险,提高其视觉美学效果。