乡村地区生态系统服务权衡与协同关系——以湖州市为例

湖州是中国"美丽乡村"发源地,十多年来乡村面貌发生较大改变,从而对其生境维持、文化保护带来压力,定量评估湖州乡村的生态系统服务及相关关系对其可持续发展具有重要意义。基于Thornthwaite Memorial模型、Miami模型、InVEST模型、水量平衡法、Maxent模型等方法对该区域2010-2018年粮食供给、碳贮存、水源涵养、文化服务等四项生态系统服务进行时空演变分析,探究不同生态系统服务间的权衡与协同关系。结果表明：(1)在2010-2018年,湖州市乡村地区粮食供给在波动中下降,一级区以东、西部的平原耕地为主;碳贮存均值与总量年际变化极小,中、西部的高山林地碳储量最高;水源涵养均值呈现先增后减的小幅波动,空间分布特点与碳贮存相似;文化服务能力逐年增强,一级区向景点区域集聚并扩张。(2)在权衡与协同分析中,水源涵养与碳贮存、粮食供给之间以协同效应为主,文化服务与水源涵养、粮食供给、碳贮存之间以权衡效应为主,粮食供给与碳贮存之间由权衡效应向协同效应转变,各服务间相关关系总体逐渐增强且存在空间差异性。(3)热点区域识别研究显示,Ⅰ类热点区主要为提供粮食供给的耕地,占比多且略有增强;Ⅱ类热点区主要为提供碳贮存、水源涵养的林地,总体有所减少;Ⅲ类热点区主要为提供碳贮存、水源涵养,以及粮食供给或文化服务的林地和耕地,占比较多并不断扩大;Ⅳ类热点区、非热点区分别位于山地-平原过渡区、靠近城镇区域,均占比极少且变化小。研究结果以期为揭示乡村地区生态系统供给、调节、文化服务间的关系,优化乡村经济结构与发展模式,推进乡村的合理规划和可持续发展提供参考。     

Temperature and life history: experimental heating leads female tree swallows to modulate egg temperature and incubation behaviour

1. Life-history decisions are strongly affected by environmental conditions. In birds, incubation is energetically expensive and affected significantly by ambient temperature. We reduced energetic constraints for female tree swallows (Tachycineta bicolor) by experimentally heating nests during incubation by an average of 6.9 degrees C to test for changes in incubation behaviour. 2. Females in heated boxes (hereafter 'heated females') increased time spent incubating and maintained higher on-bout and off-bout egg temperatures. This indicates that female energetic constraints, not maximizing developmental conditions of offspring, determine incubation investment. Furthermore, this result suggests that embryonic developmental conditions in unmanipulated nests are suboptimal. 3. We found individual variation in how females responded to experimental heating. Early-laying (i.e. higher phenotypic quality) females with heated nests increased egg temperatures and maintained incubation constancy, while later-laying (lower quality) heated females increased incubation constancy. Changes in egg temperature were due to changes in female behaviour and not due directly to increases in internal nest-box temperatures. 4. Behaviour during the incubation period affected hatching asynchrony. Decreased variation in egg temperature led to lower levels of hatching asynchrony, which was also generally lower in heated nests. 5. Our study finds strong support for the prediction that intermittent incubators set their incubation investment at levels dictated by energetic constraints. Furthermore, females incubating in heated boxes allocated conserved energy primarily to increased egg temperature and increased incubation attentiveness. These results indicate that studies investigating the role of energetics in driving reproductive investment in intermittent incubators should consider egg temperature and individual variation more explicitly.     

西藏草地多项供给及调节服务相互作用的时空演变规律

基于统计数据及MODIS产品,计算西藏草地2000与2010年载畜支持服务、肉类供给服务、水源涵养服务和碳吸收服务的功能量。构建Pearson相关系数、总生态系统服务(TES)、供给-调节服务互竞指数(TO),分析了4项生态系统服务相互作用关系随纬度、海拔及时间变化的规律。结果表明:西藏草地两项供给服务和两项调节服务之间分别为相互协同作用,且随时空变化不大。供给服务和调节服务之间的相互作用随海拔和纬度升高时,基本由相互竞争转变为相互协同,在高纬度时则无相互作用。4项服务在低纬度及低海拔呈相互竞争关系时,其生态系统服务总体水平也较低,中纬度及中高海拔呈协同关系时,其总体水平较高。从2000年到2010年,西藏草地4项生态系统服务皆发生较大变化。在变化中,12%的草地供给服务与调节服务发生相互竞争作用,33%的草地则为相互协同关系。发生相互竞争作用的草地主要集中在中低纬度的一江两河地区,而相互协同的区域主要为藏北羌塘高原中南部。     

Rainfall variability and fine‐scale life history tradeoffs help drive niche partitioning in a desert annual plant community

Tradeoffs have long been an essential part of the canon explaining the maintenance of species diversity. Despite the intuitive appeal of the idea that no species can be a master of all trades, there has been a scarcity of linked demographic and physiological evidence to support the role of resource use tradeoffs in natural systems. Using five species of Chihuahuan desert summer annual plants, I show that demographic tradeoffs driven by short‐term soil moisture variation act as a mechanism to allow multiple species to partition a limiting resource. Specifically, by achieving highest fitness in either rainfall pulse or interpulse periods, variability reduces fitness differences through time that could promote coexistence on a limiting resource. Differences in fitness are explained in part by the response of photosynthesis to changing soil moisture. My results suggest that increasing weather variability, as predicted under climate change, could increase the opportunity for coexistence in this community.     

Prey location,biomechanical constraints,and motor program choice during prey capture in the tomato frog, <Emphasis Type="Italic">Dyscophus guineti</Emphasis>

This study investigated how visual information about prey location and biomechanical constraints of the feeding apparatus influence the feeding behavior of the tomato frog, Dyscophus guineti. When feeding on prey at small azimuths (less than ± 40°), frogs aimed their heads toward the prey but did not aim their tongues relative to their heads. Frogs projected their tongues rapidly by transferring momentum from the lower jaw to the tongue. Storage and recovery of elastic energy by the mouth opening muscles amplified the velocities of mouth opening and tongue projection. This behavior can only occur when the lower jaw and tongue are aligned (i.e., within the range of motion of the neck). When feeding on prey at large azimuths (greater than ± 40°), frogs aimed both the head and tongue toward the prey and used a muscular hydrostatic mechanism to project the tongue. Hydrostatic elongation allows for frogs to capture prey at greater azimuthal locations. Because the tongue moves independently of the lower jaw, frogs can no longer take advantage of momentum transfer to amplify the speed of tongue projection. To feed on prey at different azimuthal locations, tomato frogs switch between alternative strategies to circumvent these biomechanical constraints.     

Using hybrid systems to explore the evolution of tolerance to damage

Hybridization is common and important to the adaptive evolution of plants. Hybridization has resulted in the formation of new species and the introgression of traits between species. This paper discusses the advantages of using hybrid systems to explore the evolution of tolerance to herbivore damage (i.e., the ability to diminish the negative effects of damage on fitness). The major consequence of hybridization likely to make it influential for tolerance evolution is that hybridization generates broad variation in traits that can be selected for or against. In addition to generating greater variation in tolerance to damage and its putative traits (e.g., traits associated with allocation patterns and meristem production), hybridization can generate greater independence among tolerance traits and between tolerance and defense traits. Greater independence may provide a greater ability to discern mechanisms of tolerance, give a greater probability of detecting allocation costs of tolerance, and provide an effective means to evaluate tradeoffs between tolerance and defense. Interspecific hybrid systems can also be used to evaluate the importance of co-adaptation of tolerance traits. Moreover, recombinant hybrids can be used in selection studies focusing on tolerance to damage to discern whether parental combinations of tolerance traits are favored over novel combinations. Research in hybrid systems that investigate the selective importance of tolerance, the patterns of inheritance of tolerance traits, and the genetic architecture of plant species involved can be vital to our evaluation of the adaptive role of tolerance to damage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cost and Precision Functions for Aerial Quadrat Surveys: a Case Study of Ring-Necked Ducks in Minnesota

ABSTRACT Cost considerations may be as important as precision when making survey-design choices, and the ability to accurately estimate survey costs will be essential if survey budgets become more constrained. We used data from a survey of ring-necked ducks (Aythya collaris) to illustrate how simple distance formulas can be used to construct a cost function for aerial quadrat surveys. Our cost function provided reasonable estimates of effort (hr) and costs, and allowed us to evaluate plot-size choices in terms of expected cost-precision tradeoffs. Although factors influencing costs in wildlife surveys can be complicated, we believe that cost functions deserve more attention and should be routinely considered in conjunction with traditional power analyses.     

Evolutionary responses of Drosophila melanogaster to selection at different larval densities: changes in genetic variation,specialization and phenotypic plasticity

Abstract We studied the evolutionary response to novel environments by applying artificial selection for total progeny biomass in populations of Drosophila melanogaster maintained at three different larval population densities. We found the relative amount of genetic variability for characters related with biomass to be lower and the correlation between them more negative at the intermediate density, and that selection resulted in changes in phenotypic plasticity and in patterns of resource allocation between traits. We found some evidence for tradeoffs between densities, which suggests that populations living at heterogeneous densities might be subject to disruptive selection. Our results show that adaptation to new environments may be a complex process, involving not only changes in trait means, but also in correlations between traits and between environments.