Growth and morphological responses of Fargesia angustissima to altitude in the Wolong Nature Reserve, southwestern China

The strong altitudinal gradients leading to dramatic variations in environmental conditions in mountain regions provide unique and sometimes the best opportunities to study plant responses and adaptation to global climate change. We investigated the morphological characteristics, aboveground biomass and its allocation of Fargesia angustissima (Mitford) T.P. Yi along an altitudinal gradient ranging from 1200 m (the lowest distribution boundary of F. angustissima) to 1810 m a.s.l. (the uppermost distribution limit) in the Wolong Nature Reserve, southwestern China. Except for a nearly linear increase in internode number and a linear decrease in shoot biomass with increasing elevation, other parameters studied changed non-linearly with increasing elevation. These results may imply that the local-environmental conditions do not change linearly with altitude. The growth of F. angustissima, as a low-altitude species, may be impacted by precipitation rather than by temperature. Hence, this dwarf bamboo species may be more sensitive to change in the amount and pattern of precipitation caused by rapid global climate change.     

卧龙自然保护区亚高山暗针叶林树种更新研究

在卧龙亚高山暗针叶林中选取有代表性的18个林窗斑块以及对照的林下样方进行群落学调查,记录乔木树种和灌木树种的相关数量特征。按照树种在林窗内外的重要值差异结合树种本身生态学特性将群落中出现的乔木层树种划分为先锋组和耐荫组两类生态种组。林窗内外乔木树种的组成明显不同,两类生态种组树种幼苗在林窗与林下环境中的更新表现出差别,这与树种本身的生态学特性以及所处林窗的环境有关,同时亚高山暗针叶林中灌木层优势种小径竹的生长对树种更新方式也产生一定的影响。     

黑龙江胜山保护区阔叶红松林不同演替阶段径向生长与气候变化的关系

黑龙江黑河为我国红松(Pinus koraiensis)分布的北界, 在研究红松林的生长、演替、分布, 及其对气候变化的响应上有独特的意义。该文通过研究胜山保护区内阔叶红松林的演替系列(软阔叶林、硬阔叶林、阔叶红松近熟林和成熟林4个阶段), 分析了树木径向生长与气候变化的关系在不同演替阶段的差异。结果表明: 从演替早期的软阔叶林到晚期的红松成熟林, 年表统计特征表明树木径向生长对气候波动的敏感性逐步降低。对年轮-气候关系的分析结果也表明气候对树木径向生长的影响随着演替的进展呈现规律性的变化。上年6月和12月的气温与红松成熟林的径向生长显著正相关, 表现出明显的“滞后效应”。红松成熟林的轮宽指数与当年6月气温显著负相关, 而与当年6月降水量显著正相关, 反映出生长季水分对红松生长的限制。上述这些限制作用均随着演替的进展而增强, 但在演替的早期影响不显著。相反, 上年6月降水量与软阔叶林的生长显著负相关, 但该限制作用在演替的中晚期消失。这些差异反映出随着演替的进展, 优势树种对水分的需求逐步提高。滑动相关分析表明研究区近几十年明显的气候干暖化趋势对各林型的生长兼具有利和不利的影响。不同因素综合作用下, 软、硬阔叶林阶段生长尚未产生清晰的长期变化趋势。但由于水分对红松林生长的限制作用增强, 红松林生长明显下降。今后气候进一步干暖化可能对红松林的生长、恢复演替和分布有不利影响。     

Allometric relationships of field populations of two clonal species with contrasting life histories, Cladium jamaicense and Typha domingensis

Allometric analysis was used to examine morphological relationships in field populations of two clonal plants, Cladium jamaicense and Typha domingensis, in a Florida Everglades wetland. We found that allometric relationships of individuals sampled from field populations could be adequately derived and applied to analyzing both leaf and ramet growth responses to site differences along a nutrient gradient. Overall, the allometric relationships showed a significant departure from isometry which indicates that the relationships were size-dependent. Leaf-level morphological relationships were significantly different between species and between sites along the nutrient gradient. These differences, however, were not expressed on the ramet-level. Neither species expressed a plastic allocation response to site differences along the nutrient gradient. Biomass allocation between above- and below-ground for both species indicated significant size-dependent relationships with decreasing relative allocation below-ground with increasing size. Models for predicting total plant biomass (above- and below-ground) for both C. jamaicense and T. domingensis were developed based on two non-destructive measurements that are easily obtainable in the field. The models followed the equation log (biomass) = α + β₁ × log (height) + β₂ × log (basal area), where α was species specific while β₁ and β₂ were similar for both species but significantly different according to site along the nutrient gradient. Analysis of this model showed that plant height had a relatively greater influence on biomass than basal area at all sites. This difference was greatest at the un-enriched area where plants tend to be short and thick and the least at the moderately enriched site where the relative influence of both parameters was similar.     

Growth response of Abies georgei to climate increases with elevation in the central Hengduan Mountains,southwestern China

Climatic harshness is expected to increase at higher elevations; however, elevational trends of tree radial growth response of high-elevation forests to climate change need to be investigated at different locations because of existing local variability in site-specific climatic conditions. We developed tree-ring width chronologies of Yunnan fir (Abies georgei) along elevation gradients at two sites in the central Hengduan Mountains (HM). High-elevation forests of A. georgei showed growth synchronicity and common growth signals along elevation gradients, indicating a common climatic forcing, although tree radial growth rates decreased with increasing elevation. Radial growth of Yunnan fir showed positive correlations with summer temperatures and February precipitation and moisture availability, but were negatively correlated with spring temperatures. The strongest positive relationship indicated summer (July) mean and minimum temperatures are the most important growth determining climatic factors for tree radial growth in the cold environment of HM, and this relationship revealed a clear elevational trend with stronger correlations at higher altitudes. In contrast, tree radial growth was negatively correlated with June precipitation and moisture availability. The whole study period 1954–2015 was split in two sub-periods of equal length. Comparing the early sub-period (1954–1984) to the later sub-period (1985–2015), tree growth response to the summer temperatures strongly increased, while it became weaker to June precipitation and moisture availability. High-elevation Yunnan fir forests in the HM currently benefit from elevated growing season temperatures under humid summer conditions. However, increasing temperatures may induce drought stress on tree radial growth if the observed decreasing trend in humidity and precipitation continues.     

卧龙巴郎山川滇高山栎群落植物叶特性海拔梯度特征

川滇高山栎林是中国植被非常特殊的亚高山硬叶栎林类型,广泛分布在横断山地区。为了阐明植物群落植物叶型组成对海拔梯度的响应,对卧龙自然保护区巴朗山阳坡川滇高山栎群落植物叶型特征随海拔梯度（15海拔梯度,海拔2200～3600 m）的变化进行了研究。卧龙自然保护区巴朗山各个梯度川滇高山栎群落维管束植物的叶级以小型叶为主,占总种数的平均百分率为36.09％;细型叶和中型叶的维管束植物比例相当,分别为25.64％,25.22％;大型叶和巨型叶维管束植物分别占6.82％～9.94%和0.00％～0.71%;微型叶植物比例在1.28～5.59%;小型叶维管束植物的比例随海拔先降低后升高再降低,最低值出现在海拔3000 m左右。各个海拔梯度川滇高山栎林内维管束植物的叶型以单叶为主,平均占总种数的75.89％,其余为复叶植物,占总种数的24.11％;维管束单叶型植物物种比例随海拔升高变幅较小,在73.84％～78.78％之间,但在海拔2500 m有一个最低值,其比例为73.85％;复叶维管束植物在各海拔梯度群落物种数比例在21.21％～26.15％之间。各海拔川滇高山栎林内维管束植物的叶质以纸叶型为主,平均占总种数的46.03％,其次为薄叶植物（29.17％）,革质（22.00%）和厚革质植物（2.79％）。川滇高山栎群落内纸质与厚革质维管束植物种类的比例随海拔升高而降低;革质与薄叶型维管束植物种类的比例随海拔升高而升高。全缘维管束和非全缘维管束植物种类分别占总数的50.50％和49.50％;全缘类维管束植物随海拔升高呈正二项式分布,而非全缘维管束植物则呈相反的分布格局。     

Spatial covariance in resources affects photosynthetic rate and water potential,but not the growth of Glechoma longituba fragments

Glechom longituba is a widespread clonal plant and usually experiences diverse patchiness of its growing sites. The hypothesis was tested that spatial covariance in resources differentially affects the growth and physiology of G. longituba. Plants were exposed to two patchy habitats where above- and below-ground resources were either positively or negatively associated, and to four control habitats. When equal amounts of resources were given, G. longituba fragments from two patchy habitats had similar biomass, root weight ratio, leaf weight ratio, fluorescence yield, specific petiole length, and specific root length; fragments under reciprocal patchiness significantly increased photosynthetic rate and decreased leaf water potential. Biomass of clones grown in patchy habitats was equal or less than that of counterparts from the control habitats, not supporting the notion that clonal growth is more advantageous in patchy habitats than in uniform habitats. In addition, no evidence was detected for spatial division of labour because biomass allocation to roots and leaves was similar in patchy habitats compared with the control habitats.     

越冬地气候条件对鄱阳湖自然保护区白琵鹭种群数量的影响

分析了1985—2011年鄱阳湖国家级自然保护区白琵鹭(Platalea leucorodia)越冬种群数量的年际变化趋势,检验了白琵鹭种群年际数量变化与越冬地气候变化的相关性,气候变量包括月平均气温、月平均最高气温、月平均最低气温和月降水量。研究结果表明,1985—2011年鄱阳湖国家级自然保护区白琵鹭种群数量为(4 632±470)只,呈显著的线性增长趋势,但年际波动较大。在越冬地,白琵鹭的种群数量与白琵鹭越冬期当年冬季各月的气温和降水变量相关系数较小,且均没有显著的相关性。同时,发现越冬地的气候条件对白琵鹭种群数量的影响存在显著的时滞效应:越冬期的月值气候变量与1—9a后的白琵鹭种群数量几乎都存在显著正相关性;10月降水量与2a后的白琵鹭种群数量存在显著负相关,12月平均最高气温与8a后的白琵鹭种群数量存在显著负相关。多元线性回归分析结果表明,越冬地2a前的10月平均最高气温、4a前的11月平均最高气温、8a前的11月降水量、4a前的12月平均气温是白琵鹭种群数量变化的显著预测变量,共同解释了白琵鹭种群数量年际变化的78.9%;其中前3个变量可以共同解释白琵鹭种群数量变化的72.1%,这两个月份正是白琵鹭的越冬初期,是结束长距离迁徙的阶段,可能是白琵鹭补充能量的关键时期,这个时期越冬地恶劣的天气可能导致白琵鹭无法获得充足的能量,不利于能量的恢复,从而可能给种群造成不利的影响。     

Growth,biomass allocation,and autofragmentation responses to root and shoot competition in Myriophyllum spicatum as a function of sediment nutrient supply

Plant growth, biomass allocation and autofragmentation were investigated in response to root and shoot competition in the submersed macrophyte Myriophyllum spicatum L. growing in two sediment environments. Biomass accumulation and allocation were significantly affected by sediment fertility, with a higher total biomass observed in fertile sediment (average: 4.69 g per plant vs. 1.12 g per plant in infertile sediment). Root-to-shoot ratios were 0.34 and 0.06 in the infertile and fertile sediments, respectively, reflecting the high investment placed on roots under infertile conditions. In the presence of root, shoot, and full competition, whole plant biomass decreased by 18%, 12% and 24% in the infertile sediments, and 23%, 25% and 33% in the fertile sediments, respectively. Root weight ratios (RWRs) increased with root competition by 38% (P < 0.001) and 12% (P = 0.002), while leaf weight ratios (LWRs) decreased with shoot competition by 6% (P = 0.042) and 5% (P = 0.001) in the infertile and fertile sediments, respectively. A total of 406 autofragments were harvested in the fertile sediments, but none were obtained from the infertile sediments. In the control, autofragment number and biomass was 166% and 175% higher compared to the competition treatment. Root and shoot competition resulted in a 21% (P = 0.043) and 18% (P = 0.098) decrease in the autofragment biomass, respectively. These results indicated that M. spicatum responds to different sediment fertility by changing its allocation patterns. Moreover, both root and shoot competition influenced plant growth and autofragmentation, while sediment nutrient availability played an important role in M. spicatum autofragmentation.     

竹巴笼矮岩羊昼间行为节律和时间分配

2008年11月中旬至2009年1月中旬和2009年3月至8月,采用瞬时扫描取样法和目标取样法在竹巴笼自然保护区对矮岩羊的昼间行为节律和时间分配进行了研究,结果表明:矮岩羊的昼间行为活动有明显的节律性,活动高峰出现的时间与矮岩羊昼间取食高峰时间基本一致。取食和卧息是最主要的行为方式,分别占总观察频次的53.83%和27.76%,频次较少的是站立和移动,分别占总观察频次的9.93%和8.24%,其它行为所占频次最少,只有0.24%,昼间2个取食高峰(9:00-11:00, 17:00-19:00)和1个卧息高峰(11:00-16:00),呈现出取食-休息-取食的规律。Kruskal-Wallis H 检验表明,季节因素对矮岩羊取食(P <0.05)、卧息(P <0.05)和其它行为(P <0.05)所占时间影响显著,而对移动(P >0.05)和站立(P >0.05)行为影响不显著。各年龄段之间其它行为所占的时间比例差异显著(P<0.05),而取食(P>0.05)、移动(P>0.05)、卧息(P>0.05)和站立(P>0.05)所占时间比例差异不显著;对比分析不同性别矮岩羊昼间行为时间分配差异,雌性的取食、移动和卧息的时间略高于雄性,而站立和其他行为时间低于雄性;Mann-Whitney U 检验对不同性别矮岩羊昼间的各种行为差异进行分析表明:性别因素对矮岩羊昼间时间分配和行为节律产生一定程度的影响,但差异不显著(P>0.05)。     

Using 137Cs technique to quantify soil conservation capacities of different ecosystems in Wolong Natural Reserve, southwestern China

Reliable information about soil conservation capacities of different natural ecosystems is an important reference for the design of targeted erosion and sediment control strategies. The objective of this paper is to quantify the soil conservation capacities of different natural ecosystems that can represent different climatic zones. The 137Cs technique has been used to estimate soil redistribution rates in different natural ecosystems over the past 40 years in Wolong Nature Reserve. The reserve, transiting from the Chengdu plain to the Qinghai-Tibet plateau, maintains rich ecosystems from subtropical to frigid.The net soil erosion rates of 5 selected ecosystems that represent a warm coniferous-broadleaf-mixed forest, a cold-resistant deciduous taiga forest, a cold-resistant shrub, an evergreen cold-resistant taiga servation capacities are reversed in order. The reference inventories for 137Cs in different ecosystems velop effective erosion and sediment strategies in areas with similar climates should consider natural ecosystem types.     

Using 137Cs technique to quantify soil conservation capacities of different ecosystems in Wolong Natural Reserve, southwestern China

Reliable information about soil conservation capacities of different natural ecosystems is an important reference for the design of targeted erosion and sediment control strategies. The objective of this paper is to quantify the soil conservation capacities of different natural ecosystems that can represent different climatic zones. The ¹³⁷Cs technique has been used to estimate soil redistribution rates in different natural ecosystems over the past 40 years in Wolong Nature Reserve. The reserve, transiting from the Chengdu plain to the Qinghai-Tibet plateau, maintains rich ecosystems from subtropical to frigid. The net soil erosion rates of 5 selected ecosystems that represent a warm coniferous-broadleaf-mixed forest, a cold-resistant deciduous taiga forest, a cold-resistant shrub, an evergreen cold-resistant taiga forest, and an alpine meadow are 0.17, 0.16, 0.13, 0.11 and 0.06 kg·m⁻²·a⁻¹, respectively. Their soil conservation capacities are reversed in order. The reference inventories for ¹³⁷Cs in different ecosystems range from 1658 to 3707 Bq·m⁻² with the altitude. Results of this study indicate that any attempt to develop effective erosion and sediment strategies in areas with similar climates should consider natural ecosystem types. Supported by the National Natural Science Foundation of China (Grant No. 40321101)     

卧龙竹类非结构性碳水化合物与叶氮含量对海拔的响应

山地由于海拔变化导致的环境因子显著差异,成为研究植物环境适应性及其对全球气候变化响应的理想区域。以卧龙自然保护区内油竹子(Fargesia angustissima Yi)与华西箭竹(Fargesia nitida(Mitford)Keng f.ex Yi)为对象,沿海拔梯度研究了两种竹子在各自海拔分布区间内组织非结构性碳水化合物(NSC)含量、比叶面积(SLA)、以及基于单位叶面积和单位叶质量的叶氮含量(Narea,Nmass)。除油竹子叶NSC,Narea和华西箭竹Nmass随海拔升高不发生变化外,两种竹子其它调查因子对海拔的响应均是非线性的,反映了环境因子随海拔的非线性变化。所有调查因子对海拔的响应均表现出明显的种间差别,这一结果除了种间生理生态特性差别的原因外,可能意味着两竹种对温度的敏感性不同。高海拔种(华西箭竹)比(中)低海拔种(油竹子)对全球气候暖化可能更加敏感。     

Impact of the 2008 Wenchuan earthquake on biodiversity and giant panda habitat in Wolong Nature Reserve,China

Natural disasters such as earthquakes have profound effects on the earth’s biodiversity. However, studies on immediate earthquake impacts are rarely conducted at fine scales due to logistical constraints. We conducted the first post-earthquake field survey in Wolong Nature Reserve, Wenchuan, China, less than 1 year after it was hit by a magnitude 8.0 earthquake in 2008. Since Wolong harbors approximately 10% of the endangered wild giant panda (Ailuropoda melanoleuca) population, the impact of the earthquake on the giant panda and its habitat is of particular concern. We established 15 transects in three focus areas within the Reserve where we classified occurrences of earthquake damage according to vegetation and geophysical characteristics. In the 11.2 km² area sampled, we recorded 156 occurrences of earthquake damage consisting of landslides and mudflows, which comprised a total area of 0.88 km². Of all earthquake damage occurrences sampled, only 36% of occurences (73% of surface area) corresponded to damaged areas previously detected through broad-scale remote sensing. The remaining damaged areas mainly consisted of occurrences too small to be detected without field observation. Although there were significant losses to tree and shrub species diversity and richness in earthquake-damaged areas, remnant vegetation was found in the majority (80%) of damaged areas, suggesting the potential for forest recovery. Most earthquake-damaged areas were too steep to be classified as suitable giant panda habitat (79%). In addition, a sizable number of signs of giant panda (67) and other wildlife (148) were observed near the earthquake-damaged areas, and there appeared to be avoidance of earthquake damage only at short-range distances. This study has implications for understanding the impact of natural disasters on biodiversity and highlights the importance of fine scale on-the-ground assessments of disaster impacts on wildlife and their habitats.     

40年岷山地区白河自然保护区川金丝猴的生境格局动态

好的生境质量是野生动物生存和繁衍的必备条件,生境质量的变化将对动物的生存产生深远影响,定量客观的评估生境变迁过程显得尤为必要。川金丝猴作为我国一级保护动物,评定其生境质量变化过程有利于制定有效的保护措施。3S技术的不断发展与广泛应用为研究川金丝猴生境格局的动态变化提供了有利的工具。以岷山白河自然保护区为例,利用陆地资源卫星的MSS/TM/OLI遥感影像,并基于专家知识的决策树分类方法对遥感影像进行分类,获取了5个时期的覆被类型空间分布图;根据NDVI与郁闭度的相关性获取了研究区郁闭度的时空变化信息。然后,通过对野外观测数据的数理统计与空间分析,获取了川金丝猴的生活习性特征,并结合AHP方法构建了川金丝猴生境质量的评价体系,对5个时期的生境质量进行了评价,最后定量分析了40年来川金丝猴的生境格局的动态变化趋势。研究表明,近40年来白河自然保护区内及周边的生境经历了由良好到不断恶化,再到逐渐恢复的过程,其中最适宜和适宜生境呈现先降低后逐渐升高的趋势,而不适宜和勉强适宜则表现为先增加后减小的趋势。1975—1982年时段内,各生境等级变化剧烈,尤以最适宜和不适宜等级变化显著,生境质量整体呈恶化趋势;1982—1994年,各生境等级变化剧烈程度较前一时期有所缓和,生境质量得到较大改善,呈良性发展趋势;1994—2003年时段内,研究区内生境质量进一步改善,环境恶化状况得到了缓解;2003—2014年时间段内整体质量改善的速度明显减缓,生境质量达到平衡状态。除1975—2014时段外,前4个时段的各综合变化指标呈现递减趋势,前期生境等级变化剧烈,后期趋缓。气候变化和人为干扰为导致生境变化的主要因素,其中20世纪80年代生境变化与气候变化关系密切,而20世纪90年代之后人为干扰因素明显增加。研究有助于理解气候变化与人为干扰背景下,川金丝猴生境格局时空变化特征,为野生濒危动物生境保护管理和政策制定提供科学依据。     

Escalating human–wildlife conflict in the Wolong Nature Reserve,China: A dynamic and paradoxical process

Human–wildlife conflict (HWC) has become a conservation focus for both protected area management and local communities in many parts of the world. The incidence and mediation of HWCs are rooted in coupled environmental and socioeconomic contexts. A systematic analysis of HWCs was undertaken in 2016 in the Wolong Nature Reserve located in Sichuan Province, southwestern China. Semi‐structured interviews were conducted with 201 local households to understand the occurrence of wildlife damage, the wildlife species involved, the typical losses incurred, and the mitigation measures employed. The results revealed that local HWC has increased rapidly in recent years due to effective biodiversity conservation and ecological restoration policies. Despite the widespread occurrence of HWCs, with nearly all respondents stating that they had suffered a financial loss, appropriate compensation schemes are lacking. Local respondents' expected compensation amount and style were investigated, and it was concluded that integrated compensation and community development plans are needed to mediate and resolve HWC. In particular, greater attention should be given to reduce local households' dependence on agriculture and transform local livelihood strategies to alternative economic activities not related to farming, such as ecotourism development and migrating employment.     

Growth and development of infant giant pandas (Ailuropoda melanoleuca) at the Wolong Reserve,China

From 1991 to 1993 inclusive, seven infant giant pandas (Ailuropoda melanoleuca) were born at the China Conservation and Research Center for the Giant Panda. Average daily weight gain in the first 6 months for mother-reared infants (n = 5) was 71.3 g/day; for one partially mother-reared and partially hand-reared infant, 41.5 g/day; and for one completely hand-reared infant, 50.3 g/day. There was a significant difference in growth rates across the first 6 months in all methods of rearing. In addition, a comparison of growth rates across the three rearing methods showed significant differences in the first, second, third, fifth, and sixth months. Average daily body length increase for mother-reared infants was 4.1 mm/day; for partially mother-reared/partially hand-reared infants, 4.0 mm/day; and for the completely hand-reared infant, 2.8 mm/day. In mother-reared infants, body length increase during the first month was significantly greater than during the following months, and was slowest during the sixth month. At birth, infants were all pink in color with a light white coat of lanugo. Black pigmentation was first noted at 7–10 days of age, which was also the time that initial hair coat growth was seen. Eyes opened at 35–48 days of age. Ears opened at 31–50 days of age. Deciduous dentition was first seen at 82–121 days of age, while permanent dentition began to erupt at 350 days of age. © 1996 Wiley-Liss, Inc.     

Using ~(137)Cs technique to quantify soil conservation capacities of different ecosystems in Wolong Natural Reserve, southwestern China

Reliable information about soil conservation capacities of different natural ecosystems is an important reference for the design of targeted erosion and sediment control strategies. The objective of this paper is to quantify the soil conservation capacities of different natural ecosystems that can represent dif-ferent climatic zones. The 137Cs technique has been used to estimate soil redistribution rates in differ-ent natural ecosystems over the past 40 years in Wolong Nature Reserve. The reserve, transiting from the Chengdu plain to the Qinghai-Tibet plateau, maintains rich ecosystems from subtropical to frigid. The net soil erosion rates of 5 selected ecosystems that represent a warm coniferous-broadleaf-mixed forest, a cold-resistant deciduous taiga forest, a cold-resistant shrub, an evergreen cold-resistant taiga forest, and an alpine meadow are 0.17, 0.16, 0.13, 0.11 and 0.06 kg·m-2·a-1, respectively. Their soil con-servation capacities are reversed in order. The reference inventories for ~(137)Cs in different ecosystems range from 1658 to 3707 Bq·m-2 with the altitude. Results of this study indicate that any attempt to de-velop effective erosion and sediment strategies in areas with similar climates should consider natural ecosystem types.     

乌伊岭国家级自然保护区植被覆盖演变及其对气候突变的响应

探究中国北方高纬度森林覆盖区植被演变受到气候因子变化乃至突变的影响,选用MODIS-NDVI数据与TM/ETM+数据,结合62年的气象观测数据,运用像元二分法模型、累计距平分析、Mann-Kendall非参数检验、滑动T检验与相关性分析,探讨了乌伊岭国家级自然保护区1975—2016年气候变化及其突变对植被覆盖的演化规律,并对不同气候因子与植被覆盖类型的空间变化进行相关性分析。结果表明:(1)乌伊岭保护区气候变化呈现暖干化发展的趋势。年均气温上升(0.557℃/10a),年均最低气温与冬季增温幅度最快,秋季最慢。降水量年际变化较小(-14.052 mm/10a),季节性变化明显。经突变性检验,1980—1995年是气候增温减湿的突变时期。(2)研究区植被生长季的NDVI为0.673,有植被覆盖的区域占87.69%,其中高等植被覆盖区所占比最大。(3)气候突变时期,生长季NDVI显著下降,植被退化严重。低植被覆盖区无显著变化,而高植被覆盖区开始逐渐退化为中等与中低等植被覆盖区。在空间上植被覆盖的退化状况主要由中心山地沿四周低山丘陵区累年逐渐降低。不同植被覆盖区域下降的幅度:混交林草地针叶林耕地湿地。(4)乌伊岭保护区年均最大NDVI与年均气温和年均降水量的相关系数分别为0.261、0.068,其中呈正相关区域占总面积56.67%和42.79%,在分布趋势上两者都表现出明显的空间差异性。而气温因子影响植被覆盖的空间范围与能力更强,空间相关性更高,也是影响植被退化的主导因素。     

Long-term plasticity in growth,storage and defense allocation produces drought-tolerant juvenile shrubs of Prosopis alpataco R.A. Philippi (Fabaceae)

Evaluation of phenotypic plasticity of plants is important to predict the long-term fate of populations exposed to environmental change. Climate scenarios predict a decrease in rainfall and increase in temperature for Northern Patagonia (Argentina). The long-term assessment of the effect of water shortage on allocation patterns of Prosopis alpataco provides insights into how climate change could affect this dominant shrub of the Monte Desert. A single-factor (water supply) field experiment was conducted. Phenotypic plasticity in biomass partitioning and allocation to storage and defense was assessed over the course of pre-reproductive growth during five years. Water-effect and size-dependent effects were sorted out. Our results indicate that as plants grow larger, root:shoot ratio increases, as well as total non-structural carbohydrates pool, irrespective of water treatment. Increasing belowground allocation through partitioning to reserves instead of allocation to non-storage mass, favors carbohydrate forms that later can be mobilized. Spine mass ratio increased 3-fold in response to drought. These conservative strategies might facilitate the persistence of Prosopis alpataco in a novel and drier environment, through the production of drought-tolerant juvenile individuals.