Biological Survey of Ironwood Forest National Monument

Exotic Plants Assessment

The 54 exotic plants constitute 9.6% of the IFNM flora. This compares favorably with the Tucson Mountains flora, 13% of which is exotic (Rondeau et al. 1996). 外来物种的比例较低可能反映了铁木森林国家保护区的人为干扰程度较低. However, 有几个外来物种是主要关注的，因为它们有可能取代本地植物并严重破坏群落的完整性.

Action Exotics

Buffelgrass: By far the most serious threat to Ironwood Forest National Monument is buffelgrass (Pennisetum ciliare). Since the deliberate introduction of this perennial, shrublike Old World grass into Sonora in the 1960s it has become widespread in the Sonoran Desert. 它甚至在像索诺拉西北部Pinacate地区这样干旱的栖息地中也存在(Felger 2000)。. Introduced plants often exhibit a period of latency (Wilson et al., 2002; Ewell 1986). For several decades they maintain small, weak populations and seem to be innocuous. Once they adapt to the new environment, they begin to spread rapidly. Buffelgrass seems to be undergoing an exponential expansion into desert habitats. 2022世界杯下注警觉地注意到，在2001年的严重干旱期间，IFNM内的黄草斑块通过建立幼苗而增加了面积覆盖. It may be capable of dramatic increases during wet years, and has a high potential to seriously degrade large areas of desert communities in the Monument.

There are numerous buffelgrass sites in Ironwood Forest National Monument; they are concentrated in the Pan Quemado and Sawtooth mountains. It is most common on south-facing rocky slopes and is rare on bajadas and valley floors. See more discussion in the fire section.

It is feasible to eradicate buffelgrass, and this should be a high priority to protect the ecological integrity of IFNM. 在20世纪90年代，通过集中的志愿者努力，它成功地控制了风琴管仙人掌国家纪念碑(Rutman和Dickson 2002)。. 如今，他们只需要偶尔从从墨西哥边境的农田里运来的种子中拔出新的植株. 亚利桑那州本土植物协会有一个积极的计划，从图森山脉(萨瓜罗国家公园西单元和图森山脉县公园)根除它。. 必须持续努力至少三年，以防止从土壤种子库重建. After that it is fairly easy to eliminate new occurrences.

Sahara mustard: The second most serious threat is probably Sahara mustard (Brassica tournefortii). 这种非洲冷季一年生植物于1927年和1957年分别在美国加利福尼亚州和亚利桑那州被首次发现, Malusa et al. 2003). Since then it has spread rapidly across the low desert Southwest, particularly in sandy soils. 在某些年份，撒哈拉芥花几乎完全取代了莫霍克沙丘和豪斯沙丘等地区的春季野花(Dimmitt pers). obs. R.S. Felger, pers. comm.). Like buffelgrass, Sahara mustard seems to have recently begun rapid range expansion.

Unlike buffelgrass, Sahara mustard is rare in the Monument, though it may be more common in wetter years. 2022世界杯下注只在纪念碑边界以东的英里宽路上找到了两条记录和一小部分人口. 在纪念碑区最容易受到撒哈拉芥子气侵害的栖息地可能是最西部边缘的沙地. 这个地区应该每年监测一次，任何发现的芥菜都应该在它们结实之前杀死. It can be eradicated if action is taken before a seed bank is established (West and Nabhan 2002). Aguirre Valley’s silty soils should also be monitored. 第三个可能的入侵地点是沿着通往阿瓜布兰卡牧场的曼维尔路的沙地延伸.

A few other action exotics are identified in the map at right and briefly discussed below. 强烈建议采取控制方案，以改善纪念碑的生态完整性，防止可能的进一步入侵.

Bermuda grass (Cynodon dactylon)被列入行动清单和已建立的杂草清单，因为2022世界杯下注尚未确定其威胁的程度. This Asian perennial has been in the Sonoran Desert region for many years (Tellman 2002), and generally does not invade large areas of undisturbed desert habitat. Once established, however, it is very persistent and spreads slowly. 由于百慕大草(Dimmitt pers)的大量入侵，托尔托利塔山脉蜜蜂峡谷河岸群落的林下植被严重退化. obs.). 在IFNM，2022世界杯下注发现它几乎只出现在较大的河床底部，有时也出现在路边. We did not find it around many of the livestock water catchments, 但这些地方是它建立密集林分的理想场所，也是向下游传播种子的理想场所. A common seed source is Bermuda grass hay. Cattle and horses pass viable seeds in their manure, and seeds may blow off bales if hay is transported through the Monument. 在世界杯app软件推荐，当2022世界杯下注停止使用百慕大草干草时，2022世界杯下注几乎消除了百慕大草的侵扰. Control of Bermuda grass is desirable to prevent a possible outbreak in the Monument. Because of its deep stolons, herbicide is the only feasible method of killing it.

Fountain grass (Pennisetum setaceum) is currently rare in IFNM, but has become a serious pest in washes and roadsides in the Tucson Mountains and can probably invade the same habitats in the Monument (Chambers and Hawkins no date; Dimmitt pers. obs.). This very drought-tolerant, perennial African grass is also a major problem in southern California and in the Phoenix, Arizona vicinity. Once introduced, it can spread rapidly along roads and washes. It should be watched carefully and eradicated wherever it is found.

Lehman lovegrass (Eragrostis lehmanniana) was found only in the Roskruge Mountains and three sites on the adjacent edge of Avra Valley. 这种多年生非洲草需要至少4到6英寸的夏季降雨量才能成功地从种子中吸收(钱伯斯和霍金斯没有日期)。, so it will probably not become a serious pest in IFNM. 它在亚利桑那-索诺拉世界杯app软件推荐(Arizona-Sonora Desert Museum)的场地上提供志愿者服务，主要是在有灌溉或径流集中的地区. However, control is desirable to lessen the probability of its adapting to drier conditions.

Saltcedar and athel tree (Tamarix chinensis and T. aphylla) occur only in the two wettest washes in the area, Cocío and Greene washes. Athel tree needs more water than saltcedar, and probably can’t survive elsewhere in the Monument except perhaps at some water catchments. It is also nearly sterile and rarely volunteers from seed. Saltcedar is a very different plant. It is more drought tolerant and volunteers freely from abundantly-produced seeds. 它可能会侵入其他河流，并肯定会在牲畜的集水区建立. 它建立在加利福尼亚东南部极端干旱地区的路边小蓄水池中(dimmitpers). obs.). Efforts to eradicate both of these African trees are strongly recommended. 然而，在格林沃什绵延数英里的土地上，阿瑟尔树是如此丰富，控制它可能是不可行的. 这个位置也在纪念碑的一个偏僻的角落，附近没有其他合适的栖息地. Most Athel trees in Cocío Wash are on ASARCO property, and the wash drains from here through a long section of IFNM. The tree should be monitored for signs of further spread.

Tree tobacco (Nicotiana glauca) is also currently rare in the Monument; we found this giant perennial herb only in Greene Wash. It can probably establish in other major washes and livestock catchments, and perhaps roadsides. 它发生在Anza-Borrego沙漠州立公园(加利福尼亚州)的一些大型洗刷中，这比铁木森林国家纪念碑(Dimmitt pers)更干旱. obs.). The abundant tiny seeds of this vigorous South American native can be dispersed by wind and water, and large populations can develop in a short time. It should be killed wherever it is found.

Malta starthistle (Centaurea melitensis) was found at only one place, on a roadside in Avra Valley. This winter annual from Eurasia is a serious pest in drier areas than Ironwood Forest National Monument (Chambers and Hawkins no date; Van Devender pers. obs.), so we feel it has the potential to become a problem in the Monument. It should be sought and destroyed to prevent an invasion.

Established Exotics with no Feasible Control Available

The following exotic plants are firmly established in southern Arizona and are often abundant. 他们中的大多数人还通过身体竞争和支持火来取代当地人，从而显著地改变了他们生活的生物群落. No feasible control is known for most of them, but they should be monitored to determine their impact on IFNM.

Red brome (Bromus rubens) is a major threat to Sonoran Desertscrub communities above about 3000 feet. It is present at numerous sites in IFNM, but probably will not become abundant. See discussion under Fire Assessment section.

Filaree (Erodium cicutarium), London rocket (Sisymbrium irio), and Mediterranean grass (Schismus barbatus) are widespread and common almost throughout the Monument. Filaree was found on nearly every plot. 至少在低海拔地区，在降雨正常的年份，地中海草可能几乎一样常见. London rocket is usually common only under shrubs; otherwise it is probably as ubiquitous as the other two. These three Eurasian winter-growing weeds are undoubtedly displacing native annuals, but at present there is no feasible method of control.

Cheeseweed (Malva parviflora), goosefoot (Chenopodium murale), and sowthistles (Sonchus oleraceus and S. asper) were not common during the dry survey period, but are probably abundant in disturbed areas during normal and wetter years. These Eurasian winter annuals can be common enough to displace native species, but no feasible methods of control are known. Unlike the three weeds in the preceding paragraph, these do not grow well in undisturbed habitats.

Many other exotic plant species were documented (asterisked species in the flora list). Most of them are rare to uncommon, and at this time present no apparent threat to the ecological integrity of the Monument. Artificial water impoundments, roadsides, campsites, 其他受干扰的地区应该监测新的外来物种的出现或现有物种变得更具侵略性的迹象. 在保护区的53种非本地物种中，有38%只在受干扰的旱生生境中发现.