Overgrazing is a primary driver of biodiversity loss and soil function degradation in grassland ecosystems. To mitigate the negative impacts of overgrazing, grazing exclusion by enclosures has been widely implemented as an effective management strategy for the conservation and restoration of alpine grasslands. This study investigated five paired sites of typical alpine meadows with long-term grazing exclusion (no less than 10 years) and continual grazing on the eastern Qinghai-Tibetan Plateau. Paired t-tests were conducted to assess the long-term effects of grazing exclusion on plant diversity, community similarity, and soil physicochemical properties. Our findings revealed that (1) Plant community alpha-diversity declined significantly after long-term grazing exclusion. (2) Plant community similarity was lower under long-term grazing exclusion compared to grazed communities. Notably, similarity trends differed among functional groups, with forbs being the main driver of reduced community similarity. (3) Principal Component Analysis (PCA) indicated that communities under grazing exclusion were linked to fast-growing plant traits and soils with higher organic matter content. In contrast, grazed communities were associated with higher species richness and greater structural complexity. Structural Equation Modeling (SEM) further demonstrated that grazing exclusion altered soil physicochemical properties, consequently influencing plant traits and growth strategies, ultimately driving the observed reduction in alpha-diversity and an increase in beta-diversity. While grazing exclusion promotes plant productivity, our study demonstrates that it concurrently leads to reduced species diversity and decreased structural stability within plant communities. Therefore, moderate grazing management should be integrated with grazing exclusion such as enclosure periods less than ten years may better balance restoration and diversity in the alpine grassland.

Climate warming is expected to contribute to the decline of arthropod species diversity and biomass around the world. However, direct experimental evidence is lacking. Here, we report on a field experiment documenting arthropod species diversity and biomass responses to passive simulated warming for six consecutive years in an alpine meadow on the Tibetan Plateau. The field warming experiment consisted of six large open-top chambers (15 × 15 × 2.5 m), with three chambers warmed and three non-warmed, resulting in mean temperature differences of 0.18°C and 0.57°C in the growing season and the non-growing season, respectively. Warming decreased arthropod species diversity by 39% and arthropod biomass by 18% during the experiment. Specifically, the richness of large-bodied species decreased, while small-bodied species were not significantly affected. Moreover, the abundance of small-bodied species increased, but that of large-bodied ones decreased, resulting in decreases in community size spectrum and community-weighted mean body size under warming. Results of structural equation model suggest that the decreases in arthropod species diversity (represented by species richness and community size spectrum) and biomass were primarily caused by a warming-induced shift from forb- to graminoid-dominated plant communities, which could be attributed to a warming-induced decrease in soil moisture. Moreover, the warming effect on arthropod species diversity and biomass was more pronounced in later years of the experiment, which could be partly related to the increase in mean annual temperature over the course of the experiment and progressing shift in plant community species composition over time. Our study provides unique experimental evidence that even very modest warming may result in declines in both species diversity and biomass of arthropods through cascades of indirect effects, and identifies important mechanisms underlying biodiversity loss.

Net nitrogen mineralization (net Nmin) is crucial for soil nitrogen (N) availability and grassland productivity. However, the response of soil net Nmin and its seasonal variation to alpine grassland degradation are not fully studied, and key environmental factors and their effects on soil net Nmin were also less known. We conducted an in-situ experiment in differently degraded meadows during growing season, including non-degraded meadow (NDM), lightly degraded meadow (LDM), moderately degraded meadow (MDM), and heavily degraded meadow (HDM) to investigate how meadow degradation affects soil net Nmin in the Zoige Basin, China. Compared with NDM, soil net Nmin rate decreased by 29.7

Although global warming is known to shift animal phenology, its effects on daily activity remain poorly understood. We used long-term field warming with large open-top chambers (15 × 15 × 2.5 m), which increased mean annual air temperature by 0.42°C from 2017–2023, to test whether warming alters daily activity time and body size of the nocturnal slug Agriolimax agrestis in an alpine meadow on the eastern Tibetan Plateau. Warming increased slug activity time by 37.17 min (+ 24.86%) in 2022 and 49.55 min (+ 29.16%) in 2023, and increased body size by 64.51% and 57.11%, respectively, without changing growth phenology. A complementary short-term experiment using small open-top chambers (2 × 2 × 2 m) elevated temperature by 0.44°C and similarly increased activity time by 180.18% and body size by 35.63% under controlled feeding. Slug abundance increased by ca.500% in warmed plots from 2019 to 2023, likely driven by enhanced body size and survival. Overall, warming substantially extends daily activity time, thereby enlarging slug body size and promoting population growth, highlighting an overlooked mechanism by which climate warming affects animal traits and demographics in cold regions.

The mainstream radiation transport models represented by the PROSPECT model regard the internal substances of the leaf as uniformly distributed. The influence of the uneven distribution of substances inside the leaf on the spectra of the leaf was not considered. The PIOSL-3 model proposed in this study assumes that the leaf is composed of three layers of optical properties. The particle swarm optimization algorithm (PSO) was used to determine the distribution proportion of biochemical parameters including chlorophyll, water and dry matter in each layer of leaves. In this paper, the LOPEX and ANGERS datasets were used to verify the spectral simulation effect of the PIOSL-3 model, and it can be seen from the optimization results of the parameters that the structural parameters in the leaves of different plant types are higher in the upper layer, and the distribution of chlorophyll also shows similar characteristics, while water and dry matter mainly exist in the lower layer of the leaves, and some plants also show different characteristics. In terms of simulated spectra, the PIOSL-3 model reduced RMSE mean values by 1.78, 0.39, 6.12, and 0.9, and SAM mean values by 0.07, 0.0094, 0.2267, and 0.03 compared to the PROSPECT model on the LOPEX and ANGERS datasets, respectively. The hypothesis of layered simulation is feasible, and the proposal of PIOSL-3 model provides a new idea for modeling the leaf radiation transmission process.

Fencing is an important and common grassland management strategy for restoring areas degraded by grazing. However, experimental evidence regarding the differences between the effects of short-term and long-term fencing on grassland structure remains insufficient, and the mechanisms by which fencing influences plant diversity and community structure are not yet fully understood. A long-term fencing experiment was conducted in a Tibetan meadow. We investigated Hill diversity, aboveground net primary productivity (ANPP), plant community height, species richness, and the biomass and height of four plant functional groups (including grasses, forbs, legumes, and sedges) after 1, 2, 3, and 13 years of fencing. This allowed us to compare the differing impacts of fencing on diversity and community structure over time. Additionally, we collected data on environmental factors such as soil compaction, soil moisture, soil nutrients, and plant litter biomass to elucidate the effects of fencing on plant communities. Our results indicated that short-term fencing increased Hill diversity within plant communities. Conversely, long-term fencing significantly decreased Hill diversity in alpine meadows. Furthermore, fencing reduced aboveground net primary productivity across all four assessment periods. Plant diversity exhibited a positive correlation with soil compaction and soil moisture, but a negative correlation with community height, litter biomass, and litter height. Fencing primarily influenced the diversity of litter biomass, community height, and soil nitrate nitrogen content across all biotic and abiotic factors. Our findings demonstrate that the effects of short-term and long-term fencing on plant communities differ markedly. Long-term fencing can adversely affect plant communities through litter accumulation and alterations in soil physical properties; therefore, the duration of fencing must be considered in grassland restoration efforts.

为阐明高寒草甸植物群落对长期季节放牧的响应机制,本试验选取有10年以上冷、暖季放牧历史的湿生、中生、旱生高寒草甸进行探究.结果显示暖季放牧(6月至10月)下,湿生草甸香农指数与物种丰富度均显著小于冷季放牧(11月至翌年5月)(P<0.05),而旱生草甸多样性指数显著大于冷季放牧(P<0.05);冷季放牧地上生物量显著高于暖季放牧(P<0.05),其中暖季放牧下莎草科地上生物量所占比例最高.湿生草甸暖季牧场与旱生草甸冷季牧场莎草科重要值最高,其余牧场均为双子叶杂草重要值最高(P<0.05);经ANOSIM检验,季节性放牧下群落结构均有显著差异(P<0.01),湿生、旱生草甸群落结构差异较大,而中生草甸群落结构差异较小.本研究表明长期季节性放牧会影响植物群落结构特征,研究可为不同生境草甸的放牧制度和可持续发展提供理论基础.

四川红杉(Larix mastersiana)是维持川西亚高山森林生态系统功能和景观度的重要组成树种,其种子具有休眠等生物学特性以及天然生境中种源缺乏等因素导致生态恢复实践中其种子萌发率和幼苗保存率较低.为攻克四川红杉快速繁育技术,以来自四川红杉自然分布区3个海拔梯度(2 870、3 250、3 760 m)的种子为材料,施以10％微肥溶液、200 mg/L赤霉素溶液、0.6 mg/L S-诱抗素溶液、10％微肥溶液+0.6 mg/L S-诱抗素溶液混合液、10％微肥溶液+200 mg/L赤霉素溶液混合液5种溶液浸泡种子以及喷施幼苗,比较不同溶液对四川红杉种子萌发和幼苗生长指标及其与种子大小、养分含量之间的相关关系,探讨最适合种子萌发和幼苗生长的技术方法.结果显示:10％微肥溶液促进了3个海拔梯度四川红杉种子快速萌发且提高了种子发芽率、发芽指数、活力指数;其余4种溶液均显著促进了3个海拔四川红杉幼苗根粗、总生物量的增长,200 mg/L赤霉素溶液对四川红杉幼苗根茎增粗效果显著,0.6 mg/L S-诱抗素溶液显著提高四川红杉幼苗叶片可溶性糖和可溶性淀粉的含量;四川红杉种子的发芽率、活力指数、幼苗茎长和总生物量与种子千粒重呈显著正相关关系,同时种子活力指数与种子全氮含量呈显著正相关,幼苗根长、茎长和总生物量与种子全碳、全氮含量呈显著正相关关系;较低浓度0.6 mg/L诱抗素溶液施于千粒重和营养元素较大的3 250 m海拔的四川红杉种子,种子萌发和幼苗生长效果最好.上述结果说明,10％微肥溶液所起作用体现在种子萌发阶段,而其余4种溶液所起的作用体现在幼苗生长阶段,另外种子萌发与种子千粒重和养分含量密切相关.在今后实践中,可选用形态饱满的大种子分阶段使用不同的溶液,最大效果上促进种子萌发和幼苗生长,解决红杉种子雨少、种源缺乏的问题,利用有限的种子提高其萌发率和存活率,辅助其种群进行自然更新,同时为工程建设受损生态系统修复材料提供快速繁育技术.

针对西南亚高山区大量退化灌丛恢复技术缺乏的问题,在浓密灌丛抑制建群树种幼苗更新的生态系统,采用调控灌丛冠幅和适当去除地被物层技术,以改善灌丛生态系统中限制建群树种更新和生长的环境因子,促进幼苗生长和更新;在缺乏种源的灌丛生态系统,利用灌丛微环境的直播和栽植技术补充种源.对调控处理后的幼苗存活、生长及微环境的变化进行了动态监测(2018-2020),发现:(1)水平或垂直去除部分灌丛冠幅增加了粗枝云杉(Picea asperata)建群种幼苗的基径和株高,其中水平去除处理使得幼苗基径和株高分别增加了51.5％和61.6％;(2)仅凋落物去除和地被物全部去除后,灌丛空地移栽的云杉幼苗死亡率从20.8％下降到7.1％,且株高和基径增长率为24.6％-35.8％,均高于地被物保留时的对照幼苗(4.0％-20.7％);(3)野外原位播种四川红杉(Larix mastersiana)和粗枝云杉种子的萌发率为密灌＞疏灌＞草地(P＜0.05),抚育方式对种子萌发和保存的影响均为微肥＞CK＞微肥+保水剂＞保水剂(P＜0.05);(4)未添加有机底肥条件下,栽植在灌丛根围区域和非根围区域的云杉幼苗存活率分别为56.9％和30.0％,其中栽植在灌丛坡位上方位更有利于幼苗存活,添加底肥促进了栽植在无灌丛植被区域的云杉的存活,存活率达到100％.可见,在有建群树种幼苗的浓密灌丛区,通过改善抑制幼苗生长的微环境,建群树种的生长得到明显改善;在次生灌丛无建群树种种源区,通过引入建群树种种源,能促进建群树种幼苗定居;上述研究结果为亚高山退化森林生态系统的恢复提供了新的思路和技术途径.

Understanding phenotypic responses is crucial for predicting and managing the effects of environmental change on native species. Color and display size are typically used to evaluate the utilization value of ornamental plants, which are also important ornamental characters of Lonicera nervosa Maxim. (L. nervosa). However, there is limited documentation of its floral environmental adaptation. The environmental conditions for the development of an organism changes with altitudinal variation. The aim of this research was to find flower trait variability maintenance and the tradeoff among the organs in five different populations of L. nervosa growing at distinct altitudes. We investigated the distribution patterns of floral color, floral display, and biomass tradeoff along a 700-m altitude gradient from 2,950 to 3,650 m. One-way ANOVA analysis was performed to assess the variability of flower traits and floral color across different altitudes. Moreover, correlations and tradeoffs between flowers and vegetative organs were also observed at different altitude ranges. The results indicated that L. nervosa flowers had a strong adaptability along the elevation and divergent altitude-range-specific patterns, which was divided by an altitude breakpoint at around 3,300 m. Below 3,300 m, petal lightness (petal L) decreased, but total floral display area (TFDA), individual floral dry mass (IFDM), and total floral dry mass (TFDM) increased with an increase in altitude. Whereas, above 3,300 m no significant difference was observed in petal L, TFDA, IFDM, and TFDM decreased slightly with an increase in altitude. The responsibility for the selection on floral color at a lower altitude was stronger than that at a higher altitude, while the selection agents on floral biomass had significant effects within the entire altitude range. However, the effects on floral biomass were opposite on both sides of 3,300 m. Thus, floral trait and floral color can be useful indicators for the domestication of horticultural plants and help to evaluate and initiate management and conservation actions.

[目的]为研究岷江上游人工植被恢复下土壤养分及土壤质量状况.[方法]本研究以人工植被恢复措施5年后的高石砾弃渣边坡、原生植被自然边坡、高石砾弃渣场边坡为对象,测定了土壤容重、pH、饱和水含量、毛细管孔隙度、总孔隙度、有机碳、全氮、全磷、速效钾和有效磷含量等理化指标,分析了土壤化学计量特征,采用土壤质量综合指数法对土壤质量进行了评价.[结果]①人工植被恢复弃渣场土壤容重显著低于弃渣场边坡,土壤理化指标(土壤饱和水含量、毛细管孔隙度、总孔隙度、有机质含量、总氮含量、全磷含量、速效钾含量和有效磷含量)显著高于原生植被自然边坡和弃渣场边坡,说明人工植被恢复改善了土壤结构,提高了土壤养分含量.②人工植被恢复弃渣场土壤N∶P和C∶P显著高于弃渣场,土壤化学计量比处理平衡状态,不受C和P的限制.③土壤综合指数为植被恢复的弃渣坡面＞原生植被坡面＞弃渣场.[结论]表明人工植被恢复能改善土壤质量,在高石砾弃渣边坡治理土壤环境的改善中发挥了积极作用.

介绍"十三五"国家重点研发计划项目"西南高山亚高山退化森林生态系统恢复重建技术研究"的主要研究内容、技术路线和取得的进展,展望西南高山亚高山退化森林生态系统恢复未来的研究重点.该项目针对西南高山亚高山退化森林迹地恢复困难、次生灌丛演替缓慢、低效林结构不合理以及生态功能低下等主要问题,从森林恢复演替不同阶段的角度,研发了森林采伐和火烧迹地恢复、次生灌丛生态系统恢复、低效次生林功能提升等关键恢复技术,以及特色资源培育与开发技术,为长江上游生态屏障建设提供了科技支撑.

亚热带常绿阔叶林植物幼树阶段适应林内生境并开枝散叶是其长成大树的一个重要过程,植物一年内多次抽枝的现象及其在抽枝展叶过程中小枝伸长、枝茎增粗与叶面积的增加优先顺序及其内在驱动机制还有待进一步研究.该研究对青城山常绿阔叶林木本植物多次抽枝发生比例进行了调查,并以茶(Camellia sinensis)、细枝柃(Eurya loquaiana)、短刺米槠(Castanopsis carlesii var.spinulosa)、润楠(Machilus nanmu)和大叶山矾(Symplocos grandis)5种植物的幼树为研究对象,比较分析了植物在多次抽枝中小枝和叶片生长动态及适应策略的差异.结果显示:1)一、二次抽枝分别开始于春季(4月)和夏末(8月下旬),小枝水平上二次抽枝率乔木小于灌木,常绿植物小于落叶植物.2)一次抽枝小枝枝长、单叶面积,小枝直径和叶片数量(除大叶山矾外)均高于二次抽枝,但二次抽枝单叶面积相对生长速率均高于一次抽枝,二次抽枝叶片比叶质量(LM4)的增长速率高于一次抽枝.3)一次抽枝小枝枝长、叶片数量、小枝直径(除细枝柃和短刺米槠外)和总叶面积(除短刺米槠外)最大相对生长速率均高于二次抽枝,且大部分物种最大相对生长速率出现在抽枝开始的第一、二周.4)两次抽枝中,物种先侧重于叶片的生长,其次是小枝枝长的生长,最后是小枝直径的增粗.单叶面积和总叶面积皆随着小枝枝长和小枝直径的增加呈显著的异速生长关系,表明叶片的增长速度大于小枝.单叶面积与叶片数呈显著大于1的异速生长关系,暗示单叶面积的增长速度大于叶片数的增加速度.小枝枝长与小枝直径也呈显著大于1的异速生长关系,揭示小枝枝长的增长速度大于小枝直径.综上所述,两次抽枝过程中,植物枝叶的优先生长顺序反映了植物为获取更多的资源(尤其是光源)而形成特定的抽枝展叶策略;二次抽枝单叶面积相对生长速率和LM4增长速率高于一次抽枝,这可能与植物即将面临的昆虫取食和气温降低压力有关.因此,了解植物抽枝策略对于理解物种生态适应机制,揭示物种生活史过程中存在的权衡关系具有重要的理论意义.

Soil organic carbon (SOC) fractions play a crucial role in the carbon cycle of alpine wetland ecosystems and regional climate regulation. In the last decades, alpine marshes at Tibetan Plateau have undergone increased degradation. The effects of marsh degradation on soil labile and recalcitrant organic carbon fractions and on SOC stability remain unclear. In this study, we investigated changes in SOC fractions with different biochemical recalcitrance and stability in the marsh ecosystems with various levels of degradation in the Zoige Wetland, Eastern Qinghai-Tibet Plateau. Soil samples of relatively pristine marsh (RPM), lightly degraded marsh (LDM), moderately degraded marsh (MDM), heavily degraded marsh (HDM) and severely degraded marsh (SDM) were collected and analysed using the acid hydrolysis method. Compared with RPM, the concentrations of SOC labile fraction I (non-cellulosic polysaccharides), SOC labile fraction II (cellulose) and recalcitrant organic carbon (ROC) in degraded marshes decreased significantly: 29–97, 38–95 and 32–99%, respectively, except for the LDM. The SOC recalcitrance index (RIc) in the HDM and SDM was significantly lower than that in RPM by 11–35 and 15–47%, respectively; compared with RPM, the stability of organic carbon was significantly lower in the HDM and SDM. Additionally, the marsh degradation increased vertical variation in the concentrations of SOC fractions. The degradation of alpine marshes decreases the capacity for carbon (C) sequestration via decreasing the resistance of SOC to biodegradation, indicating that the alpine marsh degradation may weaken the carbon sink capacity of the Zoige Plateau, thus aggravating the global greenhouse effect.

为明确湿地退化过程中土壤有机氮组分的变化及其生物有效性,采用实地采样调查、室内分析与数理统计法,研究若尔盖自然湿地保护区内相对原生沼泽(RPM)向轻度退化沼泽(LDM)、中度退化沼泽(MDM)、重度退化沼泽(HDM)退化过程中土壤有机氮组分的演变特征及与有效氮的耦合关系.结果表明,当沼泽发生中度、重度退化时,土壤全氮(TN)含量分别降低33.4％～77.8％、69.4％～93.7％(P<0.05),碱解氮(AN)含量分别降低36.8％～80.2％、57.6％～82.2％(P<0.05).4类湿地土壤的酸解氨态氮、氨基酸态氮、未知态氮含量均按RPM、LDM、MDM、HDM的顺序降低.与RPM相比,HDM土壤酸解氨态氮与未知态氮含量分别降低66.3％～70.8％、62.2％～78.4％(P<0.05),MDM和HDM土壤氨基酸态氮含量分别降低47.2％～68.6％、85.7％～86.7％(P<0.05).氨基糖态氮含量随着湿地退化先升高后降低.随着湿地退化程度的加剧,氨基糖态氮与酸解氨态氮占全氮的比例上升,而氨基酸态氮的比例下降.酸解氨态氮和未知态氮分别是影响RPM和HDM土壤碱解氮含量的主要有机氮组分,LDM与MDM土壤碱解氮含量却主要受有机氮组分中氨基酸态的控制.若尔盖湿地退化降低了土壤全氮及酸解组分氮含量,减弱了土壤氮"汇"功能,改变了有机氮组分对氮素有效性的贡献.

植物叶片非结构性碳水化合物(NSC)不仅为植物代谢提供重要能量,还能一定程度上反映植物对外界环境的适应策略.以亚热带常绿阔叶林林下6种植物:茶(Camellia sinesis、细枝柃(Eurya loquaiana)、润楠(Machilus pingii)、短刺米槠(Castanopsis carlesii)、大叶山矾(Symplocos grandis)和薄叶山矾(Symplocos anomala)为对象,研究各物种抽枝展叶进程中叶片大小、比叶重(LMA)、光合色素以非结构性碳水化合物及其组分含量的动态变化,分析NSC组分之间及与光合色素与LMA间的相互关系,探讨展叶过程中引起叶片NSC差异的原因.结果表明:(1)各物种单叶面积随叶片展开而增加直至明下旬达到最大,为9.20(茶)-40.81 cm2(大叶山矾);而LMA在展叶初期下降后随叶片展开逐步升高,直到次年1月下旬还在持续缓慢增加,因各物种不同,最大值为82.90-152.10 g/m2;光合色素则在展叶进程中逐渐增加,6月下旬达到较高值后在整个夏秋季维持较高的含量,次年1月有所下降.(2)在整个当年生叶片生长进程中,6种植物叶片可溶性糖含量总体上由展叶初期逐渐增加,而淀粉含量随着叶片的生长成熟逐渐降低;各物种NSC含量为87.00(薄叶山矾)-163.35 mg/g(细枝柃),除大叶山矾和薄叶山矾外,NSC含量随着叶片生长进程逐渐增加;(3)各物种可溶性糖含量随着淀粉含量的增加而降低,叶绿素含量随着LMA的增加而显著增加,可溶性糖与LMA具有显著的正相关关系,而淀粉与LMA-呈显著负相关(R2=0.51-0.86,P＜0.004),表明展叶后期部分淀粉转化为可溶性糖,这与展叶后期林内光资源的可利用性以及植物的生理活动相关.综上所述,随着展叶进程,非结构性碳水化合物及其组分具有不同的变化规律,一方面与叶片增大增厚进程中的生理活动有关,另一方面也反映了叶片功能属性间的权衡关系,研究结果可为阐明亚热带常绿阔叶林林下木本植物展叶期的碳代谢提供理论基础,亦丰富了森林植物生活史对策理论.

生物学肥力是土壤肥力的重要构成部分,能够指示生态恢复措施下沙化草地的土壤质量变化.以围栏禁牧草本模式(enclosure plus grass,EG)、围栏禁牧灌草间作模式(enclosure intercropping shrub-grass,ESG)和围栏禁牧沙障+灌草间作模式(enclosure plus sand-barrier and shrub-grass,ESSG)3种恢复地为研究对象,以未恢复的沙化草地(deser-tification grassland without restoration,CK)为对照,采用调查采样法、综合评价法研究生态恢复措施及年限对沙化草地土壤微生物数量、微生物生物量及酶活性的影响.结果表明,3种恢复模式提高了沙化草地土壤中各项生物学肥力指标,ESSG模式下土壤质量的恢复效果最优,生物学肥力指数(biological fertility index,BFI)分别显著高出EG和ESG模式41.5％和43.1％(P<0.05).EG和ESG模式下,土壤各项生物学肥力指标随恢复年限的增加而增加,≤5、7～9和≥15 a恢复地的BFI值均显著高于未恢复地(0年)(P<0.05),且≥15 a的恢复地又显著高于≤5和7～9 a恢复地(P<0.05).因此,在本研究的时间范围内,时间越长生态措施下土壤质量的恢复效果越好,但其最佳恢复期有待进一步研究确定.

生物量分配是整个植株净碳获取的重要驱动因子,对植物未来的生长与繁殖具有直接的影响;川西北高寒草甸植物群落结构丰富、物种多样性高,研究高寒草甸不同类型植物的生物量分配格局对理解植物生活史对策有重要意义.对川西北高寒草甸中天然草地、干扰草地和冬季返青草地等3类样地中不同功能型和生活型的植物共72个物种进行调查,采用标准化主轴估计(SMA)和异速生长分析(Allometric scaling analysis)的方法,比较研究不同植物类群的生物量分配对策.结果显示:(1)不同功能型植物各构件生物量百分比差异显著,禾草的茎生物量百分比最高(60.60％±3.07％),莎草的根生物量百分比较高(37.49％±11.86％),杂草类植物(Forb)的叶生物量百分比更高(26.37％±1.64％),各构件生物量之间的异速生长斜率在各功能型间无显著差异且均呈显著的同速生长关系;(2)生活型影响植物各构件生物量百分比大小,一年生植物对茎和繁殖构件投入的生物量比例相对更高,多年生植物则将更多生物量投资到根部;(3)样地类型对杂草类植物各构件的生物量具有显著影响,天然草地植物和返青植物的叶片与繁殖分配比更高,而干扰草地植物的茎生物量分配比更高.本研究表明植物功能型和生活型决定植物各构件生物量分配固有的异速生长关系,而人为干扰则显著影响植物的生物量大小,这对加强草地应对人类干扰和气候变化的响应研究以及高寒草甸生态系统的科学管理都有重要的理论与实践意义.

自然保护区是就地保护生物多样性最为经济有效的措施,而生物入侵已对全球生物多样性造成严重威胁.采用野外踏查和样方调查的方法,对著名的国家级自然保护区和风景名胜区九寨沟核心景区的外来植物的种类和分布格局进行研究.结果如下:(1)共发现13种外来植物,来自6科l1属,以豆科、菊科植物最多.(2)引入方式主要是有意引入(绿化)和无意的旅游活动引入,人为因素起着主导作用,外来植物出现的概率与受人为干扰程度成正相关.(3)根据重要值(Important value)和外来入侵植物危害等级计算得出危害系数,小蓬草(50.2439)、红车轴草(41.1528)、野胡萝卜值(40.6883)较高,但目前外来植物在研究区域还未形成大规模的入侵现象.(4)影响外来植物分布和扩散的因素有生境适合性、路距、群落盖度,路距具有重要影响(P＜0.05).(5)随着栈道距离的增加,外来植物(以草木犀为例)的重要值呈显著下降趋势.综上所述,九寨沟核心景区的外来植物分布主要受人为影响,豆科、菊科植物种类多且危害系数较高.